The Nuclear Energy Agency (NEA) Committee on the Safety of Nuclear Installations (CSNI) Working Group on Fuel Cycle Safety (WGFCS) held an international workshop on Developments in Fuel Cycle Facilities (FCFs) after the Fukushima Daiichi Nuclear Power Station (NPS) Accident. The workshop was be hosted by the Japan Nuclear Regulation Authority, from 15-18 November 2016 in Aomori City, Japan. The workshop was planned for four days, including a one day site visit.
Working under the mandate of the CSNI, the objective of the WGFCS is to advance the understanding of relevant aspects of nuclear fuel cycle safety for regulators, technical support organisations (TSO) and operators from OECD countries but also from non-OECD countries with FCFs.
The objective of this workshop were to review and discuss national activities, plans and regulatory approaches by member countries in light of the lessons learnt from the Fukushima Daiichi nuclear power station (NPS) accident, in terms of new safety requirements and operational issues of FCFs.
Within this framework, various characteristics, particularities and a wide range of hazards from FCFs compared to nuclear power plants (NPPs) were be taken into account, considering specific aspects of FCFs such as radiological and chemical risks. The application of a graded approach was also taken into account.
In September 2011, considering the impacts of the March 2011 events at the Fukushima Daiichi NPP on FCFs in general, the working group carried out an exchange of information on the early actions taken, as well as the preliminary lessons learnt thus far. This was done in a special session included in the workshop, Safety Assessment of Fuel Cycle Facilities – Regulatory Approaches and Industry Perspectives, which was held in Toronto, Canada.
Besides nuclear reactors, many NEA member countries have also conducted safety reviews (e.g. comprehensive risk and/or safety assessments, so called "stress tests") of the design and safety of their FCFs with respect to protection of the facilities from extreme natural hazards (earthquakes, floods, tornados). The safety reviews aim to challenge the sites under natural hazardous phenomena, exceeding the levels taken into account by the design basis and current safety requirements applicable to the facilities.
These assessments led, in many cases, to the identification of improvements to maintain and/or strengthen the facilities' capabilities for the prevention and/or mitigation of accidents and consequences under extreme natural hazards. These assessments were performed with consideration of the defence-in-depth concept, fundamental safety functions of the plant and emergency capabilities. Regarding FCFs, it had to take into account the large number and diversity of facilities, among which those with specific features (multiple FCFs sites with "domino effects" risks, FCFs sites with nuclear/chemical hazards).
It is important for member countries with FCFs, existing or planned, to share the lessons learnt from the Fukushima Daiichi NPS accident and the improvement actions used to maintain and enhance the safety level of their facilities.
Within the context of the workshop, the following aspects were presented and discussed by the participating countries:
The workshop was centered on the following technical focus areas:
Session 1: Feedack of post-Fukushima safety reviews performed for FCFs
This session aimed to present methodologies, scope and feedback of the stress tests or alternative reviews performed for FCFs in terms of:
Session 2: Implementation of post-Fukushima regulatory improvements on FCFs
This session presented the changes and/or enhancements, made or planned, to regulatory framework, in order to address rare initiating events (like natural hazards) that may lead to common-cause failures, "threshold effects" ("cliff-edge effects") and consequential hazards, regarding:
Session 3: Implementation of post-Fukushima technical and operational improvements of FCFs
This session addressed technical and operational changes and/or enhancements implemented or planned for FCFs and FCFs sites to withstand severe external hazards:
Session 4: Future challenges for new FCFs
This session presented future developments for FCFs in the context of long-term planning on post-Fukushima feedback actions:
The workshop included an introductory session, four technical sessions devoted to presentations by participants on the topics drawn above and a final session. The final session summarised the discussions and developed conclusions and recommendations for possible further CSNI action.
All participants were expected to take part in the discussions and in the formulation of conclusions in the final session.
A site visit to FCFs of Japan Nuclear Fuel Limited in Rokkashomura, Aomori prefecture was included.
Participation was open to experts from FCF operating organisations, regulatory authorities and their technical support organisations, FCF designers and vendors, and industry associations and observers from NEA member countries.
All presentations and discussions were in English.
In addition to the full technical papers, the workshop proceedings will include the conclusions and recommendations based on the workshop presentations and discussions.
The workshop was held in Aomori City, Japan and organised by the NRA.
The workshop organising committee organised the sessions and the final program for the workshop. The following persons formed the organising committee of the workshop: