Storage of nuclear spent fuel: concepts and safety issues
Publication date: 05/03/2019
In March 2018, the Chair of the Parliamentary Inquiry Committee on the Safety and Security of Nuclear Facilities, set up by the French National Assembly, requested the analysis of IRSN on the nuclear safety issues associated with a strategy for managing irradiated nuclear fuel (also known as spent fuel) based on the storage of that fuel only in a pool (or underwater so called wet storage) or also in dry storage facilities.
Based on its expertise of fuel storage in France, as well as on the knowledge acquired in the framework of services that the Institute carried out abroad, IRSN has made a review of the existing concepts of spent fuel storage worldwide and in France. The Institute also made a review of the associated safety issues, taking into account the characteristics of different types of fuel and the various types of storage (wet or dry, on-site or centralized).
The French version of this report was
published in June 2018, and the English version in March 2019.
Download IRSN Report 2019-00181 « Storage of nuclear spent fuel: concepts and safety issues » (PDF, 2,78 Mo)
Overall assessment of safety at basic nuclear installations other than nuclear power plants in operation in France in 2015-2016
Publication date: 08/03/2018
Produced every two year since 2009, this report concerns 76 nuclear facilities such as plants, laboratories, facilities for the treatment, disposal and storage of waste, which are in operation or are undergoing final shutdown or decommissioning, and 9 research reactors. These facilities are operated by around twenty different licensees in France.
In 2015 and 2016, 233 and 218 significant events were respectively reported to the French Nuclear Safety Authority (ASN). This number remains similar to previous years.
For IRSN, the relative stability of the annual number of significant events, which are often due to organizational and human factors, suggests that control over day-to-day operations has reached a plateau. Progress in this area, which is desirable to enhance safety, will require improvement actions by operators.
None of the events reported had any significant consequences for workers, the public or the environment, nor did they lead to any major failure in the risk control measures applied at the facilities. In 2015 and 2016, no event was classified as Level 2 or higher on the INES scale.
In terms of progress noted in 2015 and 2016, events related to criticality risks at the FBFC plant in Romans-sur-Isère (Drôme) decreased by half compared with previous years. For IRSN, these are the first tangible results of the in-depth reorganization of the safety organization at this plant for manufacturing fuel elements for reactors, in parallel with the renovation of the industrial tool and the implementation of a series of physical improvements following the last safety review.
Four subjects still require special vigilance by licensees:
Compliance with the safety requirement that the valve on cylinders used for storing and transporting uranium hexafluoride (UF6) be protected from impacts by a metal cover. If the seal between the valve and the cylinder starts to leak, this could cause loss of containment of the UF6 and its release into the environment. Four events at the Tricastin site in 2016 involved deviations affecting the valve's protective cover.
IRSN believes that the experience feedback from these events shows reflection is required on the design of the cover in respect of impacts.
The appropriateness and adequacy of the human and organisational measures taken to carry out inspections of the HEPA filters involved in limiting radioactive releases. This vigilance must be implemented by the licensee and the subcontractors, these activities being very often outsourced.
Enforce the technical and organisational measures associated with workers putting on and removing their protective clothing when working in areas with a contamination risk. In 2016, three events have caused the internal contamination of operators following the removal of their protective clothing when leaving worksites involving alpha-emitting radionuclides (such as uranium, plutonium and americium).
Better take into account the specific features of the demobilisation phases of dismantling worksites (e.g. treatment and conditioning of waste before its removal)
which may involve specific risks (dispersion of radioactive materials, fire, etc.)
or constraints (lack of space, noise, etc.).
Download the report “Safety at civil basic nuclear installations other than nuclear power plants in operation in France - Lessons learned by IRSN from significant events reported in 2015 and 2016” (PDF, 7,06 Mo)
Summary report on the French Burnup Credit Working Group knowledge regarding PWR UOX fuel
Publication date : 22/01/2018
The "Burnup Credit" Working Group was established in 1997 to examine the various parameters, such as the irradiation conditions, the burnup profile and the nuclides (actinides and fission products), to be taken into consideration in the criticality studies that take credit from burnup.
This report offers an overview of the work that has been completed or agreed under this framework. It presents the group findings on the following topics:
- the axial distribution of nuclides or the axial burnup profile;
- methods for validating the actual burnup and its axial distribution;
- the calculation of nuclide concentrations after irradiation;
- the calculation methods that will be used to determine the effective multiplication factor for systems containing used fuel assemblies.
This document gathers together the work carried out by the French Burnup Credit Working Group; it is not a guide validating a particular method for taking burnup credit into account. All of the findings presented here may serve as a basis in industry for defining a method to take account of burnup credit in criticality studies; any industrial body effectively adopting such a method will also be responsible for defining it, based on its knowledge of the used fuel assemblies and the configuration to be addressed.
This document forms a collection of the work completed by the Working Group up to 1 January 2007 but does not necessarily reflect ongoing work in the various institutes.
Download the report IRSN PSN-EXP/SNC n°2017-000177 "Summary report on the French Burnup Credit Working Group knowledge regarding PWR UOX fuel" (PDF)
Addressing Cultural Aspects of Organisations in High Risk Industries
Publication date : 22/06/2017
IRSN presents the results of a study carried out by its research laboratory in human and social sciences aimed at defining guidelines for the use of the "culture" and "safety culture" dimensions in safety assessments of nuclear facilities. The different contributions and limitations of the safety culture concept are discussed, and an analysis grid of cultural aspects of risk organisations is provided.
The concept of Safety Culture is a key element of many initiatives aimed at improving the safety of nuclear facilities. In particular, the IAEA has focused its development strategy on taking into account human and organisational factors. In this context, the IRSN has mainly devoted its evaluations and research to theoretical lines arising from ergonomics and the sociology of organisations. Although this orientation has helped to formulate documented assessments, it is necessary to better take into account cultural aspects, because some of these contribute to risk management. They can, for example, be an important part of provisions to promote cooperation between different professions (maintenance and operation, operation and decommissioning, operation and research, etc.), between project organisation and daily organisation (outage management, change implementation, dismantling worksites, etc.), between companies (relations between customers and service providers).
IRSN thus conducted a study aimed at defining guidelines for the use of the "culture" and "safety culture" concepts in safety assessments of nuclear facilities. First, the contributions and limitations of the safety culture concept are identified, leading as a second stage to a review of the main works on culture that have been conducted in anthropology, sociology, management science and ergonomics. These studies show that taking into account cultural aspects can give access to phenomena that are difficult to deal with using other organisation analytical frameworks. On this basis, four analysis plans were defined, which provide a breakdown of the overall "culture" topic: organisational cultures, professional cultures, social cultures and relations, and national cultures. In the fourth part of the document, these analysis plans are used to revisit safety assessments performed in the past. In doing so, the relationship between cultural aspects and safety are specified and the interest in taking them into account is confirmed.
Download the report IRSN/PSN/SRDS/SFOHREX n°2017-005 "Addressing Cultural Aspects of Organisations in High Risk Industries” (PDF)
Overall assessment of safety at basic nuclear installations other than nuclear power plants in France in 2013-2014
Publication date: 23/03/2016
Produced every two year since 2009, this report concerns 73 facilities such as plants, laboratories, facilities for the treatment, disposal and storage of waste, and facilities which have been decommissioned, and 9 research reactors, operated by around twenty different licensees in France.
IRSN publishes the lessons learned from its analysis of significant events which have occurred in 2013 and 2014 at
82 civil basic nuclear installations (INBs) other than nuclear power plants (NPPs).
Produced every two year since 2009, this report concerns 73 facilities such as plants, laboratories, facilities for the treatment, disposal and storage of waste, and facilities which have been decommissioned, and 9 research reactors,
operated by around twenty different licensees in France.
210 and 227 significant events were respectively reported in 2013 and 2014 to the French Nuclear Safety Authority (ASN).
This number remains similar to previous years and tends to "stabilize" at around 200 to 220.
On the one hand, among the improvements observed in 2013 and 2014, IRSN found two subjects of particular interest:
Efforts made by the licensees to increase reliability of organisational and human measures related to handling operations, in particular at the spent fuel reprocessing plant of AREVA NC La Hague and in the radioactive waste storage facilities operated by the CEA.
Important improvement program deployed by the licensee of the FBFC plant in Romans-sur-Isère (Drôme) to enhance operating practices, particularly regarding management of criticality risks (prevention of uncontrolled chain reactions).
On the other hand, three subjects still require special vigilance by licensees:
Ensuring full control over the safety documentation of facilities. IRSN’s cross-cutting analysis of events reveal a large number of cases for which parts of the safety documentation are not fully understood at the facilities, are not applied, are inaccurate or not applicable to the situation.
Ensuring in-depth and comprehensive planning of installation clean-up and dismantling operations. Risks of worker exposure to ionising radiation are higher during these operations which may require personnel to work in close proximity to radioactive materials.
Ensuring more rigorously that personnel observe access conditions to controlled areas and comply with the radiological zoning implemented.
Read the flipbook version of the report “Safety at civil basic nuclear installations other than nuclear power plants in France - Lessons learned by IRSN from significant events reported in 2013 and 2014”
Download the PDF of the report “Safety at civil basic nuclear installations other than nuclear power plants in France - Lessons learned by IRSN from significant events reported in 2013 and 2014” (PDF, 11,4 Mo)
Safety at basic nuclear installations other than nuclear power plants: Lessons learned from significant events reported in 2011 and 2012
Publication date: 16/06/2014
The third report on the safety of basic nuclear installations in France other than power reactors presents an IRSN's analysis of significant events reported to the Nuclear Safety Authority in the years 2011 and 2012. It covers plants, laboratories, research reactors and facilities for the treatment, storage or disposal of waste.
This report aims to contribute to a better understanding by stakeholders and more widely by the public of the safety and radiation protection issues associated with the operation of nuclear facilities, the progress made in terms of safety as well as the identified deficiencies.
The main trend shows, once again, the significant role of organizational and human factors in the significant events that occurred in 2011 and 2012, of which the vast majority are without noteworthy consequences. Aging mechanisms are another major cause of equipment failure and require special attention.
The report also provides IRSN's analysis of specific events that are particularly instructive for facility safety and a synthesis of assessments performed by IRSN on topics that are important for safety and radiation protection. IRSN also includes an overview of its analysis of measures proposed by licensees for increasing the safety of their facilities after the March 2011 accident at the Fukushima Daiichi nuclear power plant in Japan, which consist of providing a "hardened safety core" to confront extreme situations (earthquake, flooding, etc.) that are unlikely but plausible and can bring about levels of hazards higher than those taken into account in the design of the facilities.
Download IRSN report DG/2013-00006-EN « Safety at basic nuclear installations other than nuclear power plants. Lessons learned from events reported in 2011 and 2012 » (pdf)
Safety of laboratories, plants, facilities being dismantled, waste
processing, interim storage and disposal facilities: Lessons learned from events reported in 2009 and 2010
Publication date: 10/04/2012
France has 72 civil basic nuclear installations (BNI) falling under the category "Laboratories, plants, facilities being dismantled, waste processing or interim storage facilities or disposal facilities" (LUDD).
To promote the dissemination of lessons learned from these very different kinds of facilities, IRSN has carried out a transversal analysis of the events occurred in 2009 and 2010. This analysis is a continuation of the one conducted in 2009, which covered the
period from the years 2005 to 2008. It presents the general lessons learned and especially the main developments over the past two years, whatever it is: improvements, areas for improvement and points to watch.
The analysis showed improvements on some issues important to safety although the efficiency in time has to be checked. Points of care were identified regarding particular risks such as internal contamination of workers by injury, especially during cleanup or decommissioning operations. Finally, with regard to organizational and human aspects that remain prominent in the events reported to the ASN, efforts by the operators need to be continued.
Download the report "Safety of laboratories, plants, facilities being dismantled, waste processing, interim storage and disposal facilities: Lessons learned from events reported in 2009 and 2010" (PDF File)
Analyses guide : Nuclear criticality risks and their prevention in plants and laboratories
Publication date: 16/09/2011
This report is intended to provide support for the implementation or assessment of a criticality risks analysis. After a brief description of these risks and the principles of prevention in plants and laboratories, and a reminder of the French Basic Safety Rule (BSR) No. I.3.c, it presents in diagrammatic form (i) the methodology recommended by this BSR, and (ii), for the reference fissile medium and for each criticality control mode, the parameters to be considered in the analysis, the failures to be investigated, and the typical scenarios associated with these failures without claiming to be exhaustive.
Download the report "Analyses guide : Nuclear criticality risks and their prevention in plants and laboratories" (PDF File)
Research and development with regard to severe accidents in pressurised water reactors : Summary and outlook
Publication date: 22/03/2011
This report was produced conjointly by the French Institute for Radiological Protection and Nuclear Safety (IRSN) and the French Atomic Energy Commission (CEA). The French electric utility EDF also contributed to Section 8.2.
Download the report "Research and development with regard to severe accidents in pressurised water reactors : Summary and outlook" (PDF File)
Nuclear fuel cycle facilities, laboratories, irradiators, particle accelerators, under-decommissioning reactors and radioactive waste management facilities safety. Lessons learned from events notified between 2005 and 2008
Publication date : 12/05/2010
France has more than 70 civil basic nuclear installations (BNI) falling under the category "Laboratories, plants, facilities being dismantled, waste processing or interim storage facilities or disposal facilities" (LUDD). To encourage the diffusion of operating feedback, IRSN has produced a report concerning events notified to the Nuclear Safety Authority (ASN) by operators of LUDD facilities between 2005 and 2008. The main objective is to make general lessons for safety in this type of facility available based on a cross-disciplinary analysis of notified events and noted evolution trends.
Download the information report (PDF File)
Risks of explosion associated with "red oils" in reprocessing plants
Publication date : 10/06/2008
As new countries are considering the development of reprocessing plants, the IRSN publishes a technical note regarding the risks of explosion associated with "red oils".
This note presents the risks of explosion associated with reactions between TBP (tributylphosphate), its degradation products and nitrates derived from nitric acid or associated with heavy metals (uranium and plutonium), leading to the formation of unstable compounds known as "red oils". Feedback from explosions associated with the formation of these compounds, occurring in reprocessing plants around the world, is dealt with concisely. The main measures for controlling these risks implemented in the French plants concerned are also presented.
Download the technical note (PDF file)