Guidelines for Nuclear Data Requestors

HPRL Main High Priority Requests (HPR) General Requests (GR) Special Purpose Quantities (SPQ) New Request SGC/HPRL Documents

The following material is provided to guide requesters in preparing their requests using the online nuclear data request submission template. Co-operation from data requesters in adhering to the present guidelines will insure that their requests are well received by the data provider community and will contribute to enhancement of the credibility of the Nuclear Data Request List (the “List”).

Motivation for the present request list

The basic philosophy of the present List is similar to that of earlier lists, namely, to stimulate nuclear research that will lead to improved quantitative knowledge of important nuclear processes based on requests received from the nuclear science community.

Categories of requests

The requests found in the List of accepted requests fall into three broad categories: high priority requests, general requests and special purpose quantity requests.

Nature of a request

An individual request for nuclear data should be sufficiently limited to enable a well-focused research activity to be initiated. Generally, this will mean that a request should involve a single target nucleus, one reaction process, and a well defined energy range. Requests that are too broad will not be included in the List.

Example of a reasonable request

Measure the neutron fission cross section for 238U from 0.5 MeV to 8 MeV to an accuracy of 5% from 0.5-2 MeV, 3% from 2-5 MeV, and 4% from 8-10 MeV (other details need to be included as requested by the template).

Example of an unreasonable request

Measure the neutron fission cross sections of 235U, 238U, and 239Pu from thermal to 100 MeV to 1%. The latter request is unreasonable for several reasons. It involves more than one target isotope. The energy range is so broad that a number of distinct measurement techniques would need to be used. Finally, the requested accuracy of 1% is probably unreasonable, especially when applied to such a broad energy range. In this example, the request should be broken up into several distinct requests corresponding to different isotopes and energy ranges, and more realistic target accuracies should be specified.

Who can submit requests?

Requests for improved nuclear data may be submitted by any members of the broad nuclear science community who possess knowledge of the data issue that gives rise to the request, and who can provide the information required to complete the data request submission template. It is anticipated that most of the requests will be from the data user community, and that these requests will be associated with specific contemporary nuclear science and technology projects. However, data evaluators are also in a good position to identify data needs and deficiencies because, by its nature, the evaluation process requires detail review of the status of the database for the evaluated physical quantities. Most evaluators are familiar with at least a few of the important contemporary nuclear science and technology projects, and thus are qualified to offer reasonable justification for requested data. Requests from evaluators are more likely to be considered as general request candidates unless the request can be further substantiated by data user input. Requests from data measurers may be considered; however, because of the potential for a conflict of interest, such requests are likely to be referred to data evaluators and potential users for comments prior to seriously considering the request for acceptance into the list.

Important notice

Each request is submitted by an individual who will be considered as the "owner" of the request and the person to be contacted on all matters related to this request. Multiple requestors are permitted, but one individual will be considered the owner. Orphaned requests will automatically be eliminated from the List if no one can be found to adopt the request as a new owner.

How should requests be submitted?

Requests for improved nuclear data should be submitted using the data request template provided at this website.

How will a submitted request be processed?

Submission of a request does not automatically insure that the request will ultimately be included in the list

Requests that are properly prepared using the data request template will be reviewed by Subgroup C of the NEA Working Party for International Nuclear Data Evaluation Cooperation (WPEC). This standing subgroup consists of nuclear data specialists from each of the major data evaluation projects. Subgroup C has the sole discretion as to how received requests are to be handled. When a final decision has been made by Subgroup C concerning a particular request, then that request will either be rejected or included in the List with a designation of either High Priority, General or Special Purpose Quantity.

Stewardship of the request list

The List will be subject to periodic review. Requests that have been satisfied will be transferred to the category of satisfied requests. Requests that are no longer relevant will be removed entirely. It is also the responsibility of the data requester to monitor the status of his particular request(s) and to inform Subgroup C of any changes in the status of any requests for which he (or she) is responsible. Closer cooperation and communication between requesters and Subgroup C will insure that the List maintains currency and credibility, and serves its purpose to stimulate research aimed at satisfying requests.


The NEA has established an e-mail communications list to facilitate communication between data users, data requesters, data providers, staff members of the NEA, and members of Subgroup C. Messages can be posted to this list by sending e-mail to Communications addressed in this manner will be received by the NEA and distributed to a mailing list that includes Subgroup C members as well as several other interested individuals.

Components of a data request

When a request is submitted using the online template, specific instructions related to individual fields of the entry form can be obtained by clicking on the field title. This includes codes and other details to help the requestor to prepare his (or her) request in accordance with the established formats and procedures. This section discusses the various components of an individual request to aid the requester in understanding the underlying context of the information requested by the request template. Only those components marked with an asterisk ("*") need be supplied by the requester. Other information that appears in an accepted request in the List is provided by the NEA or Subgroup C.

Request identification (ID)

This is a unique number that identifies an individual request. This number will be assigned by the NEA upon receipt of the request via the online request template. The number will remain with the request throughout the review and listing process. If the request is denied, the number will automatically be retired. Similarly, a request number will be retired if a List request is deleted later for any reason. The data requester need not worry about supplying or managing this number.


Each request should be "owned" by a single individual. Multiple requesters can be permitted, but one will be the main contact person. Organizational affiliation, contact details (mailing address, telephone, e-mail address) must be entered in the request template.

Country/International Organisation*:

The country or international organisation from which the request is initiated is specified, e.g., France, IRMM, IAEA, etc.

Isotope, Z, A*:

Each request should address a single target isotope, e.g., 12C, with atomic number Z=6 and mass number A=12.


This field defines the physical reaction or process which is of concern to the requester. This might include fission, capture, delayed neutron emission, etc. Examples of codes are provided in the request template. Quantity* This field defines the reaction quantity. This might include cross section (SIG), spectra (DE), angular distribution (DA), multiplicity (nubar), etc. Examples of codes are provided in the request template.

Energy range*:

This field establishes the energy range of interest. This corresponds to the energy of the incident particle in the laboratory system. It is important that the appropriate units be included as well, e.g., 10-150 keV.

Outgoing energy/Angle*:

If differential or double-differential data are requested, then the energy and angular ranges for the emitted particle need to be specified, e.g., 0.5-5 MeV emitted laboratory neutron energy over the laboratory angular range 0-135 degrees.


If a particular request involves specifying a collection of energy and/or angular ranges (possibly with varying accuracy requirements), that taken together comprise the whole request, then uncertainty correlation information may be required. If so, then the requester should state that covariance data are to be included in the request. If there is no request for covariance information, then it will be assumed that knowledge of the variances (or standard deviations) alone is adequate.


A check-box allows the requester to tell if the request is intended to be of high priority, a general request or a request associated to a special purpose quantity, e.g. activation, decay data, fission yields...

Application area*:

Due to the limited resources of the data provider community, worldwide, priority consideration will be given to requests that are known to be important for specific contemporary application areas, e.g., Generation IV reactor development, nuclear fusion, LWR pressure vessel surveillance, criticality safety, etc. For this reason, the requester is asked to provide this information in the appropriate field of the data request template. This is mandatory for requests intended to be of high priority.


A request from a data user will most likely be associated with a specific project. The relative importance and currency of such a project will be a factor in deciding whether a request should be general or high priority. In other cases, a request may originate for a more fundamental reason, e.g., an evaluator determines that he (or she) will be able to better define particular nuclear model parameters if certain experimental data that currently do not exist were available. This might constitute a legitimate request that is not associated with any specific technology project but that is nevertheless important for fundamental reasons.

Impact documentation*:

The justification for a request establishes the need for the requested data. However, the impact that having such information - if indeed it is possible to satisfy the request - must be established by impact documentation submitted along with the request. The requirement for detailed quantitative information on impact to support a particular request for data is again much more severe for high priority requests than for general requests. Generally, impact deals with matters such as safety, reliability, and cost. For example, if the requester can make a case that better knowledge of a neutron activation cross section (to within specified accuracy limits) could lower the cost of storing radioactive waste by significant amounts, this would qualify as strong support for the request on the basis of cost impact.

Requested accuracy*:

This is the requested accuracy (in %) for the physical quantity to determined. A reasonable request for data over a fairly wide energy range should include a list of accuracy specifications in tabular form that correspond to distinct sub-components of the overall energy range of the request.

Justification documentation*:

This is the heart of any request for nuclear data. The requester is expected to make a strong case as to why the request is being submitted. The need for these data, inadequacy of existing information, etc., should be clearly established. In the case of requests that are to be considered as general, a few sentences (or paragraphs) with reference to documents that establish the current status of these data would probably be sufficient. In the case of requests that are intended to be high priority, much more extensive documentation is required to justify a high status for the request. This documentation might be a report or journal article that clearly shows the importance of the requested data, in quantitative terms, and establishes the lack or inadequacy of such data. Requests will be included in the high priority category only if there is a firm consensus by experts that this would be appropriate. Quantitative support for a request, especially for specified accuracy levels, can usually result only from sensitivity studies. To requestors who might object to such stringent requirements for high priority requests, Subgroup C responds by noting that if a request is really to be of high priority, and the need for the information is great, then it is likely that the project requesting the data will have already performed such analyses and reached conclusions concerning the importance of the data from this work. If these analyses have not been performed, then Subgroup C must conclude that the requirement is not sufficiently strong to motivate such an investigation and therefore is probably not of very high priority.

General comments*:

Any general comments can be given here. That can for example be if references or documents are to be attached as justification of the request.


The date when the request was initially submitted via the template as well as the date posted on the List following review and approval will both be established by the NEA for each individual request.

Additional fields

The submitter of a request need not be concerned with these fields, so it is not part of the request form.


All ancillary information related to this request will be included here, or there will be links or references to such information if it can be found elsewhere. This provides a mechanism for the nuclear science community to comment on requests found in the List and to have these comments made available to the public via the website.

Status (present accuracy, on-going activities, etc.):

In its review of a particular request, Subgroup C may generate comments that are pertinent to this request. These will be included in the website.

Subgroup C assessment:

Comments from Subgroup C concerning the prognosis for satisfying the listed request will be included in this field. Again, there may be links or other references to supportive information.