Radiation Protection Today and Tomorrow

An Assessment of the Present Status and Future Perspectives of Radiation Protection


This document is the expression of the collective opinion by the NEA Committee on Radiation Protection and Public Health (CRPPH) about the status of radiation protection today and developments which might affect its status in the foreseeable future. It is an outgrowth of an NEA workshop entitled, "Radiation Protection on the Threshold of the 21st Century," which was held in Paris on 11-13 January 1993, and draws upon the papers presented there. The assessment does not dwell on accomplishments, which are considerable. Rather, it focuses on issues and speculates about the future, because a primary purpose is to provide guidance to the CRPPH on a programme for the future whose goal is to enhance radiation protection.

The assessment of the present status and the future developments of radiation protection is intended mainly for the radiation protection community and others who might influence the overall quality of protection through research, technology development, regulation, programme support and education. While the assessment is a technical document, an attempt has been made to minimize the type of terminology and details familiar only to the specialist since another important purpose is to provide information about radiation protection to decision makers and a broad segment of the public which is interested because of the ubiquitous nature of radiation, both natural and man made. The Executive Summary briefly describes the main aspects of the collective opinion.

The views expressed in this document about the quality of radiation protection today relate to the situation in OECD Member states unless otherwise indicated. In some countries, outside the OECD area, radiation protection appears to be at least as good as it is in OECD countries. In others, it is not. Radiation protection infrastructures in a number of countries are known to be poor. In such instances, many specific protection problems have been identified, but their full significance has not been explored in detail by the CRPPH.

This document has been prepared for the CRPPH by a Drafting Group composed of:

  • Richard CUNNINGHAM – United States
  • Osvaldo ILARI – NEA
  • Hideharu ISHIGURO – Japan
  • Henri METIVIER – France
  • Herwig PARETZKE – Germany
  • Serge PRETRE – Switzerland
  • Annie SUGIER – France
  • Antonio SUSANNA – Italy

Table of Contents

Executive Summary

  1. Introduction
  2. Scientific Foundation
  3. Conceptual Framework
  4. Radiation Protection Infrastructure
  5. Application to Practices and Interventions
  6. Radiation Protection Technology
  7. Conclusions

Executive Summary

Radiation protection concerns the protection of workers, members of the public, and patients undergoing diagnosis and therapy, against the harmful effects of ionising radiation. In order to cope with the expanding radiation and nuclear practices, and in view of the particular character of the radiation risks, radiation protection has developed during the last few decades a unique and elaborate system of concepts, principles and techniques for the prevention and control of radiological risks.

A largely held view in the radiation protection community today is that the degree of scientific knowledge which serves radiation protection so far constitutes an acceptable basis for a conservative system of protection. For example, the current level of scientific knowledge resulting from the epidemiological study of the Hiroshima and Nagasaki atomic bomb survivors and other groups of people has allowed the protection experts to establish a number of assumptions about the dose-effect relationships (e.g., linearity of the dose-effect curve without a threshold) which resulted in a reasonable choice of a risk factor for effects such as cancer induction. However, there is a growing feeling that future scientific advances in biology might result in other breakthroughs in fundamental scientific knowledge capable of affecting radiation protection principles and doctrine. These advances could lead to changes in the dose-effect relationship and the risk models, and provide genetic analysis techniques capable of specifically identifying radiation-induced tumours above the general background of cancer incidence. Consequently, these scientific advances could have a profound effect on many aspects of radiation protection, e.g., the cost of protection.

The present conceptual framework for radiation protection, as proposed by the International Commission on Radiological Protection (ICRP), provides the basis for operational criteria and guidance, applicable to the various protection situations (e.g., nuclear power, medical applications of radiation, chronic exposure to natural radiation), which are developed by international intergovernmental organisations such as the International Atomic Energy Agency (IAEA) and other United Nations (UN) agencies, the Commission of the European Communities (CEC) and OECD/Nuclear Energy Agency (NEA). Essentially all countries incorporate ICRP concepts in their radiation protection regulations and operations.

Radiation protection concepts can only be implemented through an effective infrastructure which includes adequate laws and regulations, a well structured complex of experts and operational provisions, and a "safety culture" shared by all those involved with protection responsibilities, from the workers up through management levels. The OECD countries generally have well established infrastructures for radiation protection and the standard of protection across the OECD area appears good and sometimes excellent. This conclusion is supported by trends showing significant dose reduction in many practices through diligent application of the protection principles in several OECD Member countries. A similar conclusion can be drawn for some, but not all countries throughout the rest of the world.

A fundamental component of radiation protection is the availability of adequate measurement equipment and techniques as well as modelling and assessment methods and software. These are well developed for most situations. However, the evolution of radiation protection technology is expected to continue with gradual improvements in instrumentation, modelling, assessment methods and quality control, in parallel with developments in fields such as electronics, environmental studies and the nuclear industry in general.

Radiation protection is a dynamic field. Regardless of the general status of protection, there are a number of conceptual and practical issues which still remain open. Examples include: better adaptation of the protection concepts to cope with situations of chronic exposure resulting from natural radiation or contamination from accidents or past practices; developing practical methodologies for the assessment and regulation of situations where there is a potential for exposure, usually as a result of accidents, but with no certainty of occurrence; and satisfactorily addressing those radiation protection and long-term safety aspects of radioactive waste disposal which continue to be the subject of public controversy. Other issues can be expected to be raised by some new practices which are currently being developed or are expected to be introduced in the near future.

Moreover, the social dimension of radiation protection decisions, both in managing work force and in coping with the impact of large scale nuclear operations, including possible accidents, is now more fully recognised. It requires the development of better mechanisms for the involvement of social parties and the public in the decision processes and the search for a closer integration of the management of radiation risks with that of other hazardous substances or situations.

When considering current issues, the prospect of new scientific information which might affect important aspects of protection, the expansion of radiation and nuclear practices, and changing public attitudes toward risk, it is clearly important that the wealth of expertise and resources for protection and related fields which has been accumulated so far is preserved in order to continue to guarantee adequate and cost-effective protection.

Although speculative, there is a broad movement emerging that might influence radiation protection concepts and infrastructures. It is the search to find a common basis to manage risk, particularly risk from hazardous materials, including radioactive materials. It is being driven, in large measure, by a need to improve allocation of resources. How this will affect radiation protection is not clear. Radiation protection concepts and infrastructures often appear to be more advanced than are most other systems for protection from hazardous materials. Also, knowledge about the effects of radiation is substantially greater than for other hazardous materials in general. Therefore, the field of radiation protection might lead the way toward a more integrated system and better allocation of resources for protection. There are other possible consequences resulting from a more integrated system of risk management. Better allocation of resources might mean reduced funding for radiation protection. However, it would mean that radiation risk could be placed in a more realistic perspective to other risks when more closely coupled through integrated management.

1. Introduction

Radiation protection concerns the protection of workers, members of the public, and patients undergoing radiation diagnosis and therapy against the harmful effects of ionizing radiation. It has its origins early in the twentieth century. The benefits of radiation were first recognised in the use of Xrays for medical diagnosis, very soon after the discoveries of radiation and radioactivity. The rush to exploit the benefits led fairly soon to the recognition of the other side of the coin, that of radiation-induced harm. In those early days only the most obvious forms of harm, now known as deterministic effects, were observed and protection efforts focused on their prevention, but mainly for practitioners rather than patients. Although the issue was narrow, this was the origin of radiation protection as a discipline. Over the middle decades of this century, it was gradually recognised that there were other, less obvious harmful radiation effects such as radiation induced cancer, now called stochastic effects, that could not be completely prevented, but whose risk could only be minimised. This has led to the overt balancing of benefits from nuclear and radiation practices against stochastic risk and efforts to reduce the residual risk. This has become a major feature of radiation protection.

In order to cope with the expanding practices involving radiation, and in view of the particular character of the radiation risks, radiation protection has developed during the last few decades a unique and elaborate system of concepts, principles and techniques for the prevention and control of radiological risks. In fact, the depth and scope of its doctrine, the level of scientific knowledge about the effects of radiation and the behaviour of radioactive substances in humans and the environment, as well as the developments in protection technologies and radiation measurements and assessments have permitted the achievement of a significant increase in the levels of protection provided to workers, patients and members of the public in most practices and situations.

The degree of these achievements, however, is still uneven, both in terms of scientific and technical developments, and in terms of levels of protection and management of risks among different practices. Moreover, radiation protection is currently undergoing a new period of evaluation and debate. This was initiated by the publication of the 1990 recommendations (ICRP Publication 60) of the International Commission on Radiological Protection (ICRP), which introduced several novel elements in the doctrine of prevention of radiation risks and broadened its recommendations to include a number of radiation exposure situations that were not sufficiently considered in the past. Also, current trends in research and development, both in the scientific field and in the technology of radiation applications, suggest that new radiation protection issues and approaches could appear in the near future.

In view of this background, the time appears appropriate for a general appraisal of the present status and future directions of radiation protection in terms of science, policies and applications.

2. Scientific Foundation

Based upon the information about ionizing radiation and its biological effects which has been developed in this century, one could reasonably conclude that the degree of scientific knowledge accumulated so far constitutes an acceptable basis for a satisfactory system of protection.

Deterministic effects of radiation appeared soon after the discovery of radioactivity and ionizing radiation. Lethal radiation dose values are known today with a reasonable degree of accuracy as are the relative biological effects of the various types of radiation. Sufficient data resulting from relatively high doses of radiation are available to provide a reasonably accurate picture of the changes in certain physiological parameters (haematology, chromosome aberrations, etc.) which, when combined with physical techniques, make it possible to carry out reliable biological dosimetry.

In the case of doses below those resulting in deterministic effects, stochastic carcinogenic effects have been observed in several population groups, including the survivors of the Hiroshima and Nagasaki atomic explosions. The general sensitivity of the various tissue types to tumour induction can be assessed with an accuracy that is growing with accumulation of data from Hiroshima and Nagasaki and other sources of information. However, since these data are based mainly on relatively high dose and dose-rate exposures to low linear energy transfer (LET) radiation, extrapolation of these data to low doses and dose-rates and to high LET radiation is a matter of some debate.

The current level of scientific knowledge resulting from the Hiroshima and Nagasaki studies, as well as other epidemiological studies, has allowed the radiation protection community to make a number of assumptions about the dose-effect relationships at low doses and dose-rates (e.g., linearity of the dose- effect curve without a threshold as an extrapolation of epidemiological data at high dose/dose-rate to low dose/dose-rate) which resulted in a reasonable choice of the radiation risk factors for stochastic effects (mainly from cancer induction). Standards based on this model are adjusted from time to time to take into account the accumulation of scientific knowledge about the risk, but still employ assumptions about stochastic risk that are believed to be conservative, in line with the degree of uncertainty associated with present knowledge.

While this situation provides an acceptable basis for the establishment of concrete policy objectives and operational provisions for the protection of both workers and members of the public, there are still considerable uncertainties about the basic mechanisms for the induction of cancer and other detrimental effects, such as genetic effects from ionizing radiation. Moreover, the results of the many radio-epidemiological studies conducted throughout the world on groups of workers and members of the public are affected by significant uncertainties and practical difficulties such as accounting for confounding factors and need for sufficient follow-up. Occupational studies offer the most promise of providing results from exposures at low doses and dose-rates which are statistically significant owing to the availability of large populations with a range of individual dose estimates and long periods of observation. Pooling separate studies adds to the statistical power.

It seems well established that children are at greater risk of leukaemia induction as a result of direct exposure to ionizing radiation than are adults. They may be more sensitive to other types of consequences as well. An increase of thyroid cancer cases in children living in areas contaminated by the l986 Chernobyl accident has been reported from the Ukraine and Belarus. However, the 1994 UNSCEAR report on epidemiology studies notes that the supporting data are difficult to interpret and that further studies are required before conclusions can be drawn about this aspect of risk to children. Also, the risk of radiation effects on the developing brain of the embryo/foetus is not completely clear, mainly with regard to the question of whether severe mental retardation after irradiation during the 8-15 weeks period of gestation is a phenomenon with a threshold or whether the effect behaves like a stochastic effect.

Regardless of opportunities to increase knowledge and, therefore, contribute to enhance radiation protection, the no-threshold, linear dose-effect relationship is believed to be sufficiently robust to conservatively assess stochastic risk and make decisions about radiation protection requirements. The breadth of knowledge achieved in the various scientific fields associated with radiation protection appears generally satisfactory for adequate protection and is often better than that achieved by science in fields relevant to protection against other hazardous substances or situations. As indicated, however, there are some areas where further research might enable protection to be enhanced; for example for potentially sensitive groups, such as foetuses and children.

There is, also, a growing feeling that future advances in biology might result in other breakthroughs in fundamental scientific knowledge which could change the dose- effect relationship and the risk models and also provide genetic analysis techniques capable of specifically identifying radiation- induced tumours above the general background of cancer incidence. Further epidemiology studies, particularly those of radiation worker populations, might enhance understandings leading to changes.

Some of the speculative scientific and technical reasons for the possibility of fundamental changes in radiation protection concepts and application of principles are:

  • a better picture of the mechanisms of tumour induction at the gene level from results of biological research. Recent research seems to indicate that it might be possible to identify certain radiation-induced cancers as well as individuals who are significantly more radiosensitive than normal. If this is confirmed, it would have important implications for the management of the system of protection.
  • biological investigations which allow differentiation of DNA damage resulting from high and low LET radiation and which provide a better understanding of cellular repair mechanisms. There might be a threshold for causation of somatic and/or genetic mutations by low LET radiation at low doses and low dose-rates.
  • adaptive responses or stimulation of cellular repair at very low doses. Most experimental data on such effects, if confirmed, could affect concepts and assessment of detriment and in turn lead to revised approaches to situations such as those involving intervention. However, it should be noted that there is no evidence that adaptive response in cells decreases the incidence of late effects, and mechanisms of adaptation might coexist with the mechanisms induced by low doses that may result in malignant transformations. Further investigations in these areas are needed before conclusions can be drawn.
  • interactive effects of radiation on other "poor health" conditions, including immune defense depression due to virus infections. This could affect matters such as intervention strategies and employment policies.

Developments such as these could affect or change the conceptual bases of radiation protection. They could also affect the cost of protection and, therefore, the allocation of resources. They would also raise significant problems and require new solutions in the management and the practical conduct of operational radiation protection. For example, research leading to better understanding of biological mechanisms affecting sensitivity to radiation as related to specific genetic conditions, while of great benefit, could create ethical problems in the field of radiation protection. If science were to develop the ability to determine that certain individuals are much more sensitive to radiation than normal, or at greater risk than the population in general, ethical questions about the need for additional protection and work limitations for such persons could arise.

Thus, workers might be sorted following criteria of genetic predisposition and assigned to specific posts. Specific dose restrictions might be established for those with significantly greater sensitivity to radiation than normal . Even if such an approach were socially acceptable, there would still be cause to question the real ethical and economic benefits of such a selection. It is noted, however, that health predispositions, such as allergies, lead to such selections and pose similar problems in many industries.

Another field of science that supports an important component of the radiation protection activities is environmental research. The studies on the behaviour of radionuclides in the environment and their transfer to humans through the ecological and food chains have been pursued with a large commitment of resources during several decades. Worldwide fallout from atmospheric nuclear explosions was the main stimulus for environmental transport studies starting in the 1950's. Subsequently, radioecological research concentrated on the more specific aspects of food chain contamination from nuclear facility discharges of radioactive effluents and the development of increasingly sophisticated mathematical models to describe environmental transport and assess public exposure, both in normal and accidental situations.

The widespread and long-lasting environmental contamination resulting from the Chernobyl accident provided an opportunity to test and validate these models. It also shed light on some limitations of knowledge in selected areas, such as the influence of environmental characteristics and radioecological processes on the long-term contamination of the environment. The current state of development of radioecological research and environmental modelling is generally satisfactory for the conduct of day-to-day radiation protection of members of the public, although the new issues highlighted by the environmental implications of the Chernobyl accident and the residues of military nuclear activities have raised concerns and the demand for further, more focused, research in this field.

In summary, present scientific developments are encouraging. If continued, there is a good possibility of reducing the uncertainties and building a more solid and realistic basis for the system of protection. Continuation of fundamental biological research is particularly important to realizing significant advancements and should be strongly supported. It is also important, however, to pursue epidemiology, particularly studies of worker populations subject to low doses, and to improve understanding of environmental phenomena as they relate to radiation protection.

There is, however, always the risk that early indications of scientific developments and inference of their potential implications in the operational field could be misinterpreted and misused. Much more research is needed before significant changes to operational radiation protection on the basis of scientific developments might be justified. The time scales for scientific developments such as those discussed are difficult to predict, because they depend on a variety of factors including research funding levels. Therefore, although these developments should be closely followed, care should be exercised to avoid using early scientific advances to modify operational criteria and regulatory approaches before the results of research are confirmed and sufficiently consolidated.

3. Conceptual Framework

Since its founding in 1928, the ICRP has been a primary source of international expert guidance on radiation protection. It is largely responsible for the evolution of the conceptual framework for protection commonly accepted throughout the world. As previously described, fundamental to this framework is the presumption that even small doses of radiation may produce deleterious health effects. Also fundamental is the recognition that, besides scientific judgments, social, ethical and economic considerations have a role in protection decisions since the aim of radiation protection is to provide an appropriate standard of protection for man without unduly limiting beneficial practices giving rise to radiation exposure. These two aspects of the conceptual framework are central to today's system of protection.

The conceptual framework, as proposed by the ICRP, provides the basis for operational criteria and guidance applicable to specific protection situations, which are developed by international intergovernmental organizations such as the International Atomic Energy Agency (IAEA) and other United Nations (UN) agencies, the Commission of the European Communities (CEC) and the NEA. Essentially all countries incorporate ICRP concepts in their radiation protection regulations and practices.

The breadth of the international recommendations on radiation protection has grown constantly throughout the years, from the extremely simple guidance on protection against Xrays issued in the 1930s up to the very comprehensive system of protection which covers practically all existing sources of human exposure, artificial as well as natural, recommended by the ICRP in its Publication 60 (see figure). There is a growing consensus that the latest ICRP recommendations, accompanied by new International Standards for the Protection against Radiation and the Safety of Radiation Sources (BSS) developed through a joint effort by the Food and Agricultural Organization of the United Nations (FAO), the IAEA, the International Labor Organization (ILO), the NEA, the Pan American Health Organization (PAHO) and the World Health Organization (WHO), constitute a set of conceptual and applicative recommendations appropriate for developing radiation protection regulations and operational requirements.

In addition to the scientific aspects, there is an ethical dimension to radiation protection. The protection principles of justification of practices and interventions, optimisation of protection and individual dose limitation have an ethical foundation, which is believed to be sound. However, it is worthwhile to study this foundation in order to find out if the three principles adequately address all appropriate consideration of ethics. In particular, there would be benefit from further development of ethical guidance on subjects such as how to deal with the long-term aspects of radioactive waste management and with the societal implications of interventions following catastrophic accidents.

There are problems with public understanding and acceptance of the rationale suggesting that dose limits apply in the case of practices but not in the case of interventions to reduce existing exposures, such as exposure from contamination resulting from past practices or past emergency situations. There is, therefore, a need to do more to improve public understanding of the differences in approaches to control doses from practices and intervention situations, both from a conceptual and practical standpoint.

Scope of Radiation Protection 

For types of situations which are not so critical as to be treated as an emergency, but cannot be considered as "normal," there also is a need to develop a specific approach by appropriately modifying and adapting the concepts separately established for intervention and for practices. Examples of these grey areas are radon gas and its decay products in above ground workplaces, and cosmic ray doses to flight personnel, particularly ones that are pregnant. Such situations are not simple to treat as "normal practices". Application of the concepts embodied in "intervention" to these types of situations also requires further study and experience, and the concepts modified to better accommodate such situations if feasible.

A more extreme situation which involves a distinction between "intervention" and "normal" conditions is one involving very large scale land contamination by long lived radionuclides resulting from an accident, e.g., the Chernobyl accident. Everybody can understand and accept that in an emergency special and unusual rules apply. But any emergency situation should have an end and, after a not too long delay, there should be a return to "normality". That means that any emergency situation should, after a few years, be such as to be manageable like a "practice" or at least like a chronic "radon exposure situation" for members of the public.

The social impact of an accident situation must be taken into account. As long as only some individuals or limited groups within a population are affected by the radiological emergency, the social impact is not dominant and the problem can be solved by applying the principles for intervention. But when the whole population of a region is concerned, e.g. in case of a large scale contamination of long duration, the usual principles based on the protection of individuals do not cope well with the dimension of the problem. In fact, it seems that, when a whole region is affected, society may be more directly concerned with restrictions due to land contamination than with radiation doses to individuals, because of its disruptive and economic impacts. More thorough consideration of these social aspects of intervention will be a challenge for the possible future management of a large scale radiological accident having long term consequences. It seems that a society needs some sort of "normality" in the same sense as individuals need good health. For such extreme cases, new principles or criteria are needed to help national authorities confronted with such an emergency in finding the adequate strategy for intervention.

In addition to issues which might be characterized as relating to the conceptual framework itself, there are also practical problems of implementation. One of the main current problems in this respect concerns potential exposure. A notable feature of the recent ICRP recommendations, further developed in applicative terms by ICRP itself and in the BSS, is the movement toward an integrated approach to the management of radiation risks, covering not only protection against exposures which are likely, as has been the case in the past, but also potential exposures. These are exposures which are not very likely to occur, but could result from accidents or other disruptive events.

This integrated approach to radiological risk management is conceptually attractive, but there are difficult problems with its application. An ideal goal is to be able to quantify risk from potential exposure in a manner that parallels the quantification of risk from normal exposure. However, most practices are assessed on the basis of sound science, good engineering practice and operating experience to ensure that the likelihood of accidents with serious consequences is extremely small, rather than attempting to quantify the risk in probabilistic terms. This assessment methodology, coupled with well established safety practices, generally has served very well in achieving adequate radiation protection. However, protection could be enhanced if probabilistic assessments could be used to complement these deterministic assessments.

Probabilistic safety assessment (PSA) is a methodology which in principle can be employed to identify, quantify and manage risk. It was mainly developed for the aerospace and nuclear power industry. Its applicability within the nuclear power industry is still evolving and there are further difficulties in applying existing PSA methodologies to other practices. For example, there are problems with the assessment of probabilities and consequences of events which might happen in the very far future, as might occur with radioactive waste disposal. In the case of more simple practices, such as the use of radioisotope devices employed in industry and medicine, risk is mainly human- dominated rather than machine-dominated. Existing PSA methodology is not directly applicable and much too complex for practical application to these practices. However, limited research has been initiated to develop ways to effectively apply PSA to the more simple practices. Thus far, this research holds promise of a simplified application of PSA methodology as a valuable adjunct to deterministic engineering approaches. Its main value, particularly for practices such as radiation medicine where technology evolves quite rapidly, would be early identification of accident vulnerabilities of new technologies or designs, which are not predicted in the deterministic approach and for which little operational data are yet available. It is also to be noted that a sound quality assurance programme is the key to safety, particularly in those circumstances where risk is mainly human-dominated as mentioned above.

In addition to the need to develop suitable potential exposure assessment methodologies before the concept of integrated risk management can be applied rigorously, there are other problems with the adoption of the concept. For complex installations, such as many nuclear facilities, difficulties of application are compounded by the need to find a harmonious integration with the long-standing principles and criteria developed by the nuclear safety community for nuclear power reactors and nuclear fuel cycle installations. However, significant progress is being made, especially within the framework of the NEA radiation protection and nuclear safety committees, to bridge this gap and move toward a unified approach to radiation safety.

There are several other problems with the constantly evolving conceptual system of radiation protection that are difficult to overcome. The first is stability of the system. New scientific and technology developments necessarily require changes to be incorporated into the system. However, there are other changes, such as changes in terminology, units and definitions, which are sometimes of questionable need and costly to adopt in radiation protection infrastructures. They also add difficulty to training and the ability to have a well informed public. While there will always be some delay in the incorporation of new scientific knowledge into radiation protection infrastructures, the delay can be extended by the sheer bulk of these other questionable and costly changes that are usually made at the same time. Also, the radiation protection system itself is complex and difficult to understand except by those in the profession. This complexity can inhibit proper use of protection principles at the operational level and contribute to poor public understanding, which becomes especially acute in times of crisis. Finally, the application of some principles is itself very complex. For example, the application of the optimization principle to certain cases, such as long-term disposal of radioactive waste and treatment of risk from potential exposure, while feasible in theory, is poorly achieved in practice for a number of reasons, for example, uncertainties in modelling the long distant future. However, it is recognized that optimization is an extremely valuable tool for protection and its implementation should be further promoted and pursued.

Although speculative, there is a broad movement emerging that might influence radiation protection concepts and infrastructures. It is the search to find a common basis to manage risk, particularly risk from hazardous materials, including radioactive materials. It is being driven, in large measure, by a need to improve allocation of resources. How this will affect radiation protection is not clear. Radiation protection concepts and infrastructures often appear to be more advanced than are most other systems for protection from hazardous materials. Also, knowledge about the effects of radiation is substantially greater than for other hazardous materials in general. Therefore, the field of radiation protection might lead the way toward a more integrated system and better allocation of resources for protection. There are other possible consequences resulting from a more integrated system of risk management. Better allocation of resources might mean reduced funding for radiation protection. However, it would mean that radiation risk could be placed in a more realistic perspective to other risks when more closely coupled through integrated management.

4. Radiation Protection Infrastructure

Radiation protection concepts can only be implemented through an effective infrastructure which includes adequate laws and regulations, an efficient regulatory system, a well structured complex of experts and operational provisions and, last but not least, a "safety culture" shared by all those involved with protection responsibilities, from the workers up through the management levels. In this respect, there is a significant diversity of situations throughout the world. The OECD countries generally have well established infrastructures for radiation protection, with exhaustive regulations, kept under continuous review, strong and competent regulatory bodies, adequate operational protection and emergency response structures, and advanced research institutions. There are obvious variations in the level and size of these infrastructures, linked to the different levels of radiation and nuclear power applications in the various countries, but, as a whole, the standard of radiation protection across the OECD area appears good and sometimes excellent. This conclusion is supported by trends showing significant dose reduction in many practices through diligent application of the protection principles in several OECD Members countries.

The situation is much more uneven in the rest of the world. Beside countries where the infrastructure and the standard of protection are fully comparable with those of the OECD countries, lay a large number of countries which, owing to their lower degree of economic development or the presence of significant political instability and, in several cases, to a severe shortage of resources where priorities are assigned to more pressing societal needs, do not have a sufficient or even a significant infrastructure for radiation protection. Thousands of sources, particularly those used in medicine and industry, are employed in situations where there is little control because of a lack of a well organised radiation protection infrastructure to assure safety during use and disposal. This has led to serious consequences in some instances. Of particular concern is the illegal transport of uncontrolled sources across national borders. There is, therefore, a strong need to assist those countries with resources and technical advice to allow them to put in place an acceptable system of protection which is stable and durable. The IAEA is particularly active in this area.

There are trends which will affect radiation protection infrastructures, even in those countries where they are believed generally to be good. Some trends are for the better while others should be of concern. On the positive side, society is showing an ever increasing interest in and willingness to being involved in decisions affecting the life and the well-being of its members. This tendency is particularly evident in matters dealing with human health and protection of the environment.

Therefore, decision-making in several areas of radiation protection can less and less be made in isolation from its social dimensions. For example, decisions concerning requirements for the protection of workers cannot ignore their potential social impact in terms of employment, sex discrimination, etc. Concerns of this kind exist for specific groups of workers (miners, women working during pregnancy, some categories of medical workers, etc.) with respect to the need for more restrictive dose limitations as proposed by the ICRP. Another important area of public concern is the profound societal impact that may be associated with the aftermath of a major nuclear accident. In this case, the societal disruption due to the long-term contamination of land and the possible need for relocation of large populations may even overshadow the direct radiological impact on humans.

The need to involve the social parties (labour and employers organisations, citizen groups, etc.), as well as the public in general, in deliberations and decisions concerning radiation protection when a potential exists for a social impact of these decisions must be accommodated. One impediment to doing so, as stated earlier, is the conceptual complexity of radiation protection. Making such complexity more transparent should be a goal. Also, it is to be recognised that the mechanisms for public involvement are still largely imperfect and that the scientific and technical concepts and the associated health objectives, on one side, and the societal requirements, on the other, are sometimes conflicting. The general issue of public involvement in radiation protection decisions needs to receive closer attention in the future with a view to achieving a better integration of the social dimension and a more effective dialogue between the social and scientific parties. It is also to be noted, however, that the modes and the stages of the decision- making processes in which the various social parties should intervene must be carefully considered in order to avoid confusion and mismanagement in the decisions.

Better involvement of social parties in radiation protection decisions requires improvement in the information and education of interested parties about radiation, its benefits and impacts, and the protection against these impacts. This requires a reinforced and better focused effort, which needs to be preceded by a critical analysis of the low degree of success achieved so far in this area.

Finally, a concern for adequate radiation protection in general, as foreseen by those engaged in the field, is the downward trend in the recruitment, training and education of radiation protection professionals. Radiation protection infrastructures are not static. They can either improve or deteriorate. The need for strong fundamental support in related fields such as radiation effects research (e.g., molecular biology) and technology development (e.g., improved instrumentation) cannot be overemphasised. Here too, there is concern that funding these supporting activities is not as strong as it once was. Without these kinds of support the consequences can be less than optimal protection and fewer of the many potential benefits from nuclear and radiation practices.

5. Application to Practices and Interventions

5.1 Practices

The practical achievements, in recent times, of applying the radiation protection conceptual framework through an effective infrastructure have been considerable. This is reflected by the substantial and continuing decrease of the doses to workers and members of the public, essentially from all types of sources and practices, and the very low level of exposures currently attributed each year to the majority of workers and almost all members of the public.

Although the situation may appear satisfactory in terms of trends, and also in absolute terms for some practices, there is room for improvement. The quality of radiation protection varies considerably among practices. This may be partly due to inherent difficulties experienced in certain fields or to the emergence of new, previously unforeseen issues. The single most likely reason for the observed variations, however, is the different level of attention, concern and resources that has been devoted to protection in these different fields.

Although medical applications of radiation were the main, if not the only concern before the World War II, the advent of nuclear power, with its novel and substantial problems of protection, absorbed the majority of attention and resources and attracted the largest number of protection experts, both in the regulatory bodies and in the operational arena. There is today, however, a growing opinion among experts that more attention should be given to achieving optimum allocation of efforts and resources in order to improve protection in relatively neglected areas, such as in medicine and certain sectors of industry and research, rather than to continue to expend disproportionate resources for the sake of achieving marginal improvements in areas where the standard of protection is already very high.

5.1.1. Nuclear Power and the Nuclear Fuel Cycle

This is the area where, because of the magnitude of the safety and protection problems involved, the largest efforts have been made. These efforts have not only provided a high level of protection in nuclear power facilities, but have made substantial contributions to the field in terms of principles and criteria for radiation protection, development of assessment methods, techniques and equipment, and resolution of complex ethical and technical issues.

The most notable achievement of radiological protection in the nuclear fuel cycle, both from the point of view of worker protection and the protection of the public and the environment, has been the progressive implementation of the optimisation (or ALARA) principle as complement to the more traditional dose limits to control exposure. The objective of maintaining or reducing exposures as low as reasonably achievable, economic and social factors being taken into account, is now recognized as the cornerstone of radiological protection programmes, although in some cases minimization of dose rather than optimisation of protection has been applied. The result is that most nuclear power plants and other nuclear fuel cycle installations in OECD Member countries are operating far below regulatory limits for worker exposure and environmental releases.

The degree of formalization and systematisation of the optimisation programmes remains quite different among countries and among utilities and companies within a given country. In many cases, implementation of the "ALARA thinking" is still based on a simple, non quantified common sense approach, combining sound engineering techniques and judgements about the practicability of protection actions with the acceptability of residual levels of exposure. However, the feasibility of implementing structured and quantified approaches has now been demonstrated in many areas related to the control of sources, e.g., the sizing of shielding and the selection of remote tooling and robotics, or the management of working conditions. An increasing number of utilities are adopting formalized ALARA programmes. It is now widely recognized that a management approach based on predictions, measurement of performance and analysis of past experience is the most effective way to integrate optimisation of protection into the general objectives of production and quality. A large set of computer based systems for dose prediction and analysis as well as operational dose tracking is available allowing for routine application of optimisation of protection.

The creation of systems for the exchange of information on past experience is facilitating the spreading of the ALARA culture and the promotion of cost-effective solutions for the protection of workers and the public all over the world. The NEA has played an active role in this area by developing the international information system on occupational exposures at nuclear power plants (ISOE) and a similar effort should be envisaged to cover other types of practices, although in a simplified form to make it cost effective consistent with the complexity and size of the practice.

Among the different steps in the nuclear fuel cycle, waste disposal offers difficult protection challenges from, both, a technical and ethical standpoint. These challenges are mainly due to the very long term commitment to present decisions. Waste disposal is seen as the principal protection issue by a large segment of the public, which is concerned about the risk to those living near disposal sites and the long term potential impact of disposal on future populations and the environment. The public is sensitive to the fact that disposal decisions have been made in past decades, particularly decisions related to early radium and uranium recovery, without much thought about environmental consequences. Poor management of radioactive waste disposal has sometimes resulted in an undesirable level of environmental contamination and will need extensive remedial efforts, particularly, but not exclusively, in some Eastern European countries.

Whereas environmental remediation programmes are being developed where needed, it should be noted that waste management standards have improved substantially and optimised technology can provide a high degree of protection now and in the future. Sound engineering technologies and good management practices are well developed and applied in OECD countries to achieve very low discharges of radioactivity in effluents. Also, it can be demonstrated that the disposal of low level short-lived waste can be accomplished with minor impact on the environment.

As far as high activity level and other wastes containing long lived radioisotopes are concerned, there is an international consensus among experts that disposal can be accomplished safely. Taking into account the fact that the decay of the radioactive waste spans extremely long periods of time, much longer than the expected duration of any human institution, the central strategy favoured for the disposal of such wastes is their isolation within passive multi-barrier systems located in deep and stable geological formations. The objective is to ensure isolation for timescales sufficient to render the eventual release of the residual activity into the biosphere relatively trivial, under safety conditions equivalent for, both, present and future populations. Safety assessment techniques have been developed for this purpose, showing the appropriateness of the above strategy. However, one of the main problems is to satisfactorily demonstrate to the public that performance objectives can be met, particularly performance in the far distant future.

Besides deep geological disposal, other concepts, such as separation and transmutation of long-lived radionuclides, notably actinides, and long-term retrievable storage options are also being considered. The results of these programmes need to be carefully assessed so as to compare their feasibility, costs and worker exposures versus reduction of risk to future generations. Also, considerations wider than radiation protection may play a role in this field, safety being only one though essential element of the debate.

5.1.2. Industry and Research

During normal operations, the level of radiation protection for the spectrum of current industrial and research practices is generally good. Radiation doses are usually well below limits. Many research programmes use small amounts of radioisotopes with few problems related to radiation protection in practices such as tracer studies. For these practices, the most serious problems result from isolated instances of carelessness which result in contamination. However, the consequences are usually minor. Other research, and most industrial practices, involve the use of large sealed sources or electrically generated ionizing radiation sources, such as those employed in food irradiation and industrial radiography. Protection of workers and members of the public from these sources in normal operation is generally satisfactory; however, accidents connected with these types of sources have caused serious injury and death. While any single accident is usually confined to one or a few individuals, the ubiquitous nature of the practices requires increased attention to accident prevention. Accounting for the complete human-machine system in safety evaluations to reduce potential exposure risk is a current challenge for radiation protection in industry and research. Some industrial activities which do not use radiation sources can also require attention from the radiation protection viewpoint. This is the case, for example, of industries such as those producing fertilizers, where raw materials containing natural radionuclides are processed on a large scale and give raise to the production of large quantities of wastes highly enriched in natural activity.

5.1.3. Medical Uses of Radiation

The situation in the field of medical uses of radiation is rich in contrasts. There are, in fact, several competing trends which act to increase and decrease doses, and may be accompanied by increased benefit or harm. One trend has been an increase in the use of medical radiation, whether measured by frequency of diagnostic examinations and therapeutic treatments, by collective dose or by other indicators such as the introduction of new techniques. Set against this has been a gradually developing pressure to eliminate unjustified procedures, and to reduce individual doses from particular examinations or treatments. Such pressure may need to be intensified for vulnerable groups, in particular children, who may be exposed at rather higher frequency and dose levels than generally realised. Other areas of similar concern are the continuation in some countries of certain mass screening procedures that are of questionable justification, and the increased use of computed tomography which tends to give larger doses than examinations by conventional radiography.

These competing trends illustrate a difficult grey area where the interests of radiation protection can impinge on the practice of medicine and medical decisions about what is best for overall patient care. For many medical diagnostic procedures there is no other reasonable alternative to achieve the desired result, whereas for most industrial processes there usually is. Benefit to the patient is highlighted in radiation medicine while risk is often highlighted in the nuclear industry, e.g., nuclear power. The result has been a tendency for less vigorous dose reduction measures in medicine than in industry. This situation is improving, but there is still opportunity for further advances towards "retaining the benefit but recognising the harm". For example, there is still opportunity for improvement in dose reduction for radiodiagnostic procedures, where the range of exposures given to patients to obtain similar diagnostic information is unduly wide, up to a factor of ten or more.

Mistakes or accidents in radiation medicine have resulted in serious injury and death of patients. As stated in the discussion about industrial and research practices utilizing large sources, there is a need to improve ability to assess and manage risks from potential exposure. This is an even greater challenge for radiation therapy, because the margin for error is small when treating patients with high radiation doses. Also, devices and procedures used in radiation medicine are constantly evolving, which makes keeping current with understanding and managing potential exposure risk particularly difficult. While we learn from accidents, an important objective in radiation protection is to develop an assessment methodology which enables better identification of vulnerability of new therapy systems to accidental exposure of patients.

5.1.4. Developing and new practices

Some practices are in a constant state of evolution with new technologies and procedures replacing the old ones. As already discussed, the use of radiation in medicine is an example of such a situation. In addition, there are a number of practices that are currently being developed and are expected to reach a full operational status only in the next few decades. Although it is felt that in many cases the present principles, criteria and techniques will be adequate to deal with the radiation protection problems associated with these evolving practices, some of these developments may well raise new issues of protection or exacerbate problems that are at present of minor importance. A few examples may suffice to give an idea of the kind of issues the near future might hold.

In the field of fission nuclear power, several models of power reactors based on new safety concepts are currently being developed. These developments are not expected to raise significant new problems from the radiation protection viewpoint. However, in view of the fact that the protection provisions in the existing plants are generally redundant if compared with the more cost-effective solutions suggested by optimisation of protection, it will be appropriate in the future to put greater effort into this optimisation in the design of the new plants in order to achieve more effective use of available resources. Also, it is recognised that the public often demands more than optimal protection, and this should be reflected in the social factors that go into the decision.

In the case of the truly new practice represented by nuclear fusion, this kind of concern is compounded by the fact that radiation protection objectives and constraints for the design and operation of the future commercial fusion plants appear currently to be developed by the community of fusion experts without sufficient consideration and application of the principle and procedures of optimisation of protection. This approach is leading to the establishment of design constraints which may be extremely restrictive and perhaps not justified in the light of the general principles and requirements of radiation protection. This kind of development is not in the right direction and might unduly affect the prospects for success of the fusion technology.

On the other hand, it is felt that the establishment of firm design constraints at this early stage might be premature in view of the significant uncertainties still existing on some aspects of the operation of the future fusion machines, for example on the potential relevance of the radioactive waste management aspects. All this suggests the need, in the near future, for a dialogue to be started between the fusion experts and the radiation protection experts on the way in which the basic radiation protection principles should be applied to establish design and operational standards for a new technology such as fusion.

There is also a feeling that the emphasis, which is currently put in statements aimed at the public, on the triviality of radiological risks in fusion plants in comparison with fission nuclear power plants, particularly in relation with radioactive waste production and hazards, may be misleading in view of the uncertainties still existing in these areas. The need for a more balanced assessment of the radiological risk associated with fusion is another reason for suggesting closer interaction between the fusion and the radiation protection communities.

Another area which is expected to reach an industrial dimension in the next few decades is decommissioning of commercial nuclear plants. The basic techniques for safe dismantling of plants have been developed. In the next few years the emphasis should focus on the elaboration of optimised strategies and project management approaches which take into account the requirements of protection of workers and members of the public. The need for further development of methods and techniques aimed at optimising protection, both, during dismantling operations and the management of wastes resulting from decommissioning, should be emphasized. Of particular interest is the application of the protection principles for exemption of wastes associated with huge amounts of slightly contaminated scrap materials and valuable metals. However, no conceptual or fundamental emerging problems in this area are anticipated from the radiation protection viewpoint.

The recently increased risk factor, the higher altitude of commercial flights and a general increase in air transport continue to raise questions about in-flight exposure to cosmic radiation. Although aircrews for long haul air travel could be treated as radiation workers, it is unlikely that the ICRP dose limits would be exceeded, with the possible exception of exposure resulting from exceptional solar flare events. The main issues would seem to be protection of the embryo/foetus of pregnant aircrew members. Some countries provide information about the radiation risks from cosmic rays, and there are some restrictions on the participation of pregnant women in air crews for other reasons. Problems that might arise from in-flight exposure to cosmic radiation require continuing attention.

In the area of space flight, it appears that much remains to be done in the dosimetric estimations and the assessment of radiation risks for long missions. There may be also a need to develop internationally agreed criteria and standards for the protection of the crew members of space missions, especially since considering that increasing numbers of missions may involve crews of mixed nationalities.

5.2 Interventions

5.2.1. Chronic exposure situations

Natural radiation in its multiple forms (cosmic rays, radon and the other naturally occurring radionuclides) is widely recognised as the most significant contributor to human exposure. Because of its pervasive nature, steps to reduce exposure to large segments of the population have been taken only in the last decade.

There are few, if any, practical methods to reduce exposure of large populations to certain types of natural radiation, such as exposure to cosmic radiation at the terrestrial level, nor is there a compelling need to do so. However, exposure to indoor radon ranks high on the list of contributors to large population exposure and cost-effective steps can often be taken to reduce the exposure. Surveys to evaluate the average exposure of the general public to radon have been carried out in many countries. A major effort has been undertaken in recent years to assess exposure in a sample of dwellings which are representative from a statistical point of view. Studies are also being carried out in a number of countries to identify areas with high radon levels and to characterise the parameters leading to high indoor radon concentrations.

Research work aimed at a better understanding of the ingress pathways of radon in buildings is under way in some countries where residential buildings, offices and schools are studied. An increasing number of practical and cost-effective methods to reduce radon concentration indoors is becoming available in most industrialized countries. However, further efforts should be made to better identify high risk areas and to develop "radon proof" building construction techniques. It seems desirable to focus intervention on dwellings with high radon concentrations, while a reduction of exposures which are closer to average could be obtained more gradually through changes in building practices. A distinction in action levels for existing and new dwellings and workplaces seems appropriate. This approach would be similar to the common practice in fields other than radiation protection, where more stringent safety regulations apply to new structures and products. However, it should also be noted that applying different action levels to existing and new structures can be a source of confusion and not particularly helpful if the difference between the action levels is small.

There are several other challenging issues related to indoor radon. The need for epidemiology studies aimed at obtaining reliable information on the radon exposure risk to members of the public in order to replace utilization of the risk coefficients derived from mine worker studies is one challenge. Another one is the possible interaction, or even synergism, of radon exposure with smoking and whether this should be taken into account in intervention decisions. A third issue is whether or not indoor radon should be considered in a broader context, i.e. as one of several hazardous substances affecting indoor air quality for intervention decisions.

During the last few years some attention has been given to thoron exposure originating from building materials. In some circumstances, exposure from this source could be significant. Further study of this potential problem should be encouraged.

Moreover, some groups of individuals and populations receive chronic exposure as a result of previous practices and accidents. Contamination resulting from past uranium mining and milling, nuclear weapons testing and the Chernobyl accident are obvious examples, but there are others, although, perhaps, not on as large a scale. A key problem confronting radiation protection is arriving at appropriate levels of decontamination for suitable land use, e.g., habitation and agriculture, and achieving public acceptance of proposed solutions. As discussed earlier, in the case of catastrophic accidents such as Chernobyl, this problem is complicated by the social disruption caused by a large-scale and long-term land contamination.

5.2.2. The Management of Accident Situations

Publications such as the recent ICRP Publication 63, which updates the ICRP publication 40, and IAEA Safety Series No. 109, set out usable principles for planning and deciding interventions to cope with a radiological emergency. The comparison of international guidance before and after the Chernobyl accident shows that many lessons were learned from the accident. For example, it is now quite clear that the main criterion for deciding on an intervention is the mean individual dose which is expected to be avoided by the intervention. It is also accepted that any intervention should be justified by the fact that it will produce more good than harm. And finally, when several intervention strategies are available, the choice of the best strategy needs to be made on the basis of optimisation, which includes consideration of the "non-intervention" option since it could emerge in some cases as the optimised solution.

At the time of the Chernobyl accident, the inconsistent and confusing answers of radiation protection experts to questions concerning the delayed effects of the accident on the population worried a general public unable to understand why an accurate prediction of future consequences could not be given. A better system must be available for rapidly identifying all the populations affected by an accident, assessing exposure of such populations and providing a subsequent estimate of the delayed effects. It should be noted that substantial progress has been made in this direction.

In the field of management of accident consequences, emergency planning and preparedness has improved considerably and is now supported by impressive monitoring networks, by well prepared intervention teams, and by rapid communication systems. The NEA is making a significant contribution to continuing effectiveness and enhancement in this area with its INEX Programme of international emergency exercises and studies.

6. Radiation Protection Technology

A fundamental component of operational radiation protection is the availability of adequate measurement equipment and techniques as well as modelling and assessment methods and software. These are well developed for most situations.

Monitoring systems for the work place and the environment continue to be updated and refined, especially in the nuclear facilities. Computerization of measurement data has been introduced to set up centralized data bases. Survey meters have been well developed for routine monitoring, but improvement should be considered for easy handling and compactness. Quality control of measurement equipment and techniques as well as modelling and assessment methods and software continue to improve. The social-legal aspects of personal exposure and environmental monitoring data are one of several reasons for continuing the pursuit of good quality assurance. Effluent monitoring and effluent treatment technologies for most nuclides are well established, and, when properly employed, very low discharges of radioactive materials to the environment can be achieved. However, these techniques are expected to be updated and refined in an on-going effort.

The rapid progress of solid state physics, electronics and computer science has allowed radiation protection personnel to utilise a vast array of equipment and techniques for highly sensitive and accurate measurements and sophisticated assessments of exposures. There are, however, specific fields where further improvement is desirable or even necessary in order to increase the accuracy or the reliability of measurements and assessments, or to satisfy to particular requirements such as easy handling, compactness and maintenance. Radiation sensors need to be developed to meet the requirements of the new ICRP recommendations and the new dosimetric quantities. In the area of dosimetry and monitoring, the need for improvements concerns, for example, the development of individual dosimeters for high dose/dose-rate gamma radiation. Instruments to measure low doses and dose-rates for neutron dosimetry are particularly important. In addition, there are developing needs for ambient monitoring instrumentation characterized by a wider range of detection and measurement and real time dosimeters with alarm characterized by easy handling, compactness and maintenance. Also, these new instruments should make it possible to determine the type, the energy distribution, and the direction of the incoming radiation in complex mixed fields with sufficiently high sensitivity.

If the present trend of exploitation of microelectronics in radiation protection technologies continue, the radiation monitors in the year 2000 will be characterized by easy operation, compactness, low power requirement, extensive self- checking and performance control features. The present passive personal monitors will be replaced by real-time individual dosimeters, in which the radiation sensor and microelectronic circuit are derived by a single piece of semiconductor material (typically silicium). Both, hand-held instrumentation and individual monitors will achieve characteristics typical of consumer-type products, such as low cost, ruggedness, high reliability and long battery life. In general, these improvements can be characterized as increased "convenience of use".

Accelerators are being widely used in physics research and medicine. Radiation protection for accelerator operations requires specialised instrumentation to measure high energy and high pulse-rate radiation. Technology enhancement in this area should be pursued.

In the area of environmental monitoring, analytical methods using gamma spectrometry appear to be well established. Sampling and measurement procedures for radionuclides present in the environment are becoming standardized, although widespread differences among countries and institutions still exist. Intercomparison exercises and/or scientific exchange programmes are expected to help standardization. Quicker methods for the analysis of certain radionuclides such as long-lived nuclides of plutonium and other transuranic nuclides in environmental samples around nuclear facilities, especially in accident situations, are desirable.

The importance of rapid monitoring systems to measure things such as large stocks of food-stuffs, live animals, people, building materials, import and/or export products, vast surfaces of land and high altitude clouds will likely increase. A demand for a new generation of instruments to meet these various needs is to be foreseen. In the area of dose assessment models and computer codes and of sampling and measurement protocols for environmental contamination, there are widespread differences between solutions adopted in different countries and institutions. This situation calls for substantial criticism in view of its potential for damaging confusion and discrepancies, and also in view of the relatively little technical difficulties to be faced in order to significantly attenuate these differences. There is here a potential and a real need for a better qualification and harmonisation, both nationally and internationally.

In the area of worker protection, various techniques have been introduced to reduce occupational exposure. However, to implement the new ICRP recommendations, further improvement such as increased radiation shielding and use of remote handling techniques for radioactive sources, improved decontamination techniques and chemical removal of corrosion products may be required. Robotics technology may be necessary in some instances to achieve dose reduction objectives. Sophisticated confinement techniques may be also required in certain applications depending on the physical and chemical forms of radiation sources.

7. Conclusions

The conservative concepts and models used today provide a suitable basis for achieving adequate protection. The standard of radiation protection across the OECD area appears good and sometimes excellent. A similar conclusion can be drawn for some, but not all, countries throughout the rest of the world.

However, radiation protection is a dynamic field. It has undergone a significant evolutionary period during the past few decades and general improvement of protection techniques and technology is expected to continue. Further progress in the practical application of protection principles and concepts such as optimisation and dose constraints will contribute to balanced protection. In addition, much is going on in fundamental research, particularly in the biology area, which could improve the scientific foundation upon which today's protection is based. Further epidemology studies might also contribute to this improvement. All of this could lead to more efficient use of resources allocated to protection, as well as other benefits.

Meanwhile, there continues to be a number of challenges for protection specialists. One, for example, is better adaptation of the protection concepts to cope with situations of chronic exposure from natural radiation and long-term contamination resulting from accidents or past practices. Another is finding practical ways to apply the concept of potential exposure to a variety of practices. Also, satisfactorily addressing radiation protection and long-term safety aspects of waste disposal will require continuing attention, notably to improve public understanding through a well focused effort of information.

Because of the dynamic nature of the protection field, the prospect of new radiation practices, and changing public attitudes toward risk, it is important that the wealth of expertise and resources for protection and related fields which has been accumulated so far is preserved in order to guarantee adequate and cost-effective protection.