Overall assessment of safety and radiation protection of the French nuclear power plant fleet in 2015

Publication date: 09/03/2017

IRSN publishes its report on the operation, in 2015, of the 58 nuclear reactors of EDF in France. It is based on an overall review of significant events, which brings out global lessons as well as trends in evolution and identifies topics requiring special attention.

In its report, the Institute presents the overall assessment of the significant events reported by EDF to the Nuclear Safety Authority (ASN) and highlights the most noteworthy events of the year.

Safety: a decrease in the number of events but still a significant number of non-compliance with the technical operating specifications

604 significant safety-related events in 2015: the decline observed since 2013 in the number of events continued. This decrease is 7% compared to 2014 and 18% compared to 2012. Also, for the third consecutive year, no event was rated at or above 2.

In 2015, half of the safety-related events originated from non-compliance with technical specifications. In addition, the quality of maintenance activities was not at the expected level, due in particular to a risk analysis that was often incomplete. Improving the control of these activities remains an important objective for EDF.

Finally, the inspections carried out in 2015 showed a habituation to deviation which requires a rigorous response from EDF to keep the plants in compliance.

Radiation protection: a decrease in the number of events but three events of workers’ skin contamination

After a first decline of 8% in 2014, the number of significant events concerning radiation protection of workers decreased by 5% in 2015.

However, in 2015, three cases of skin contamination of plant workers led to exceedances of the regulatory limits for skin-equivalent dose. They were responsible for the three events described as incidents on the INES scale: an event classified at level 2 and two events classified at level 1. The setting up by EDF of organizational measures, particularly during the phases of undressing, could reduce the risk of skin contamination.

Moreover, the number of events linked to failures in the application of basic rules of radiation protection has increased strongly over the last two years. This is particularly the case for forgetting to wear a dosimeter with 22 events in 2015, as opposed to 17 events in 2014 and 11 events in 2013. Finally, as in 2014, deviations associated with access and stay in controlled area decreased significantly, although they still represent the largest number of events. The implementation by EDF of operational action plans seems to have a positive effect.

Expertise on specific issues in 2015

In its report, IRSN also presents its main conclusions on specific issues that were the subject of an assessment in 2015:

• Guidelines of the periodic review associated with the fourth ten-yearly reactor safety reviews for the 900 MWe reactors;
  
• The optimization of the radiation protection of workers in EDF plants, and particularly the adequacy and sufficiency of organizational arrangements;
  
• The control by EDF of the risks associated with the subcontracted maintenance activities.

Download the report “IRSN's Position on Safety and Radiation Protection at Nuclear Power Plants in France in 2015” (PDF, 4 Mo)

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Overall assessment of safety and radiation protection of the French nuclear power plant fleet in 2014

Publication date: 23/03/2016

In 2014, none of the significant events reported affected reactor safety. The number of significant radiation protection events fell by 8% compared to 2013 and few of them had any impact on the plants' workers’ health, the public’s health or the environment.

IRSN’s point on view on safety and radiation protection of the 58 French  nuclear power reactors currently operated by electric utility company EDF. This report is based on the Institute’s scientific and technical expertise of significant events, and its analysis of several events that it found to be the most noteworthy for the year.

In 2014, the number of significant safety events reported by EDF dropped by 8% compared with 2013, confirming the decrease already observed in 2013 compared with 2012.

Early detection by EDF teams of anomalies may have contributed to the fact that none of the events reported in 2014 had a very significant impact on safety. In 2014, ASN did not class any of the events reported on Level 2 on the INES Scale. 

IRSN points out organisational improvements made by EDF regarding maintenance activities and equipment changes. Nevertheless, half the significant safety events reported by EDF were caused by maintenance errors. Noteworthy, the number of anomalies affecting safety-related equipment in reactors was generally lower in 2014 than in 2013.

In 2014, the number of significant radiation protection events fell by 8% compared to 2013, and was just below the number of similar events reported in 2012. Among the factors contributing to this decrease:

• the number of events related to gamma radiography inspections for checking welds was halved, despite a nearly identical number of interventions;
  
• the number of non-compliances related to the access to or time spent in radiologically controlled areas is falling, although these non-compliances  still represent the largest number of reported events.

The most notable trend compared to previous years concern worker dosimetry, with 18 events reported in 2014 (against 11 events in 2013), including 17 events due to failure to wear a dosimeter. However, these figures should be compared to the important number of entries in radiologically controlled areas.

In 2014, the vast majority of events have not resulted in any significant consequences for the plant workers and the environment. No event was classified as Level 2 or higher on the INES scale (one Level 2 event in 2013) and three events were classified at Level 1 (two events in 2013).

Read the flipbook version of the report “IRSN's Position on Safety and Radiation Protection at Nuclear Power Plants in France in 2014”

Download “IRSN's Position on Safety and Radiation Protection at Nuclear Power Plants in France in 2014” (PDF, 5,6 Mo)

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Methodology used in IRSN nuclear accident cost estimates in France

Publication date: 16/11/2015

This report - produced in 2013 in its French version and 2014 in its English version - describes the methodology used by IRSN to estimate the cost of potential nuclear accidents in France.

It concerns possible accidents involving pressurized water reactors leading to radioactive releases in the environment. These accidents have been grouped in two accident families called: severe accidents and major accidents. Two model scenarios have been selected to represent each of these families.

The report discusses the general methodology of nuclear accident cost estimation. The crucial point is that all cost should be considered: if not, the cost is underestimated which can lead to negative consequences for the value attributed to safety and for crisis preparation. As a result, the overall cost comprises many components: the most well-known is offsite radiological costs, but there are many others. The proposed estimates have thus required using a diversity of methods which are described in this report.

Download the report IRSN/PRP-CRI/SESUC/2014-00132 "Methodology used in IRSN nuclear accident cost estimates in France" (pdf)

Considerations concerning the strategy of corium retention in the reactor vessel

Publication date: 10/07/2015

Third-generation nuclear reactors are characterised by consideration during design of core meltdown accidents. More specifically, dedicated measures or devices must be implemented to avoid basemat melt-through in the reactor building. These devices must have a high level of confidence. The strategy of corium retention in the reactor vessel, if supported by appropriate research and development, makes it possible to achieve this objective.

IRSN works alone or in partnerships to address all the issues associated with in-vessel corium retention. This document describes the in-vessel corium retention strategy and its limitations, along with the research programmes conducted by IRSN in this area.

Download the document “Considerations concerning the strategy of corium retention in the reactor vessel"

IRSN’s Position on Safety and Radiation Protection at Nuclear Power Plants in France in 2013

Publication date: 23/05/2015

This report does not find any notable change in significant safety-related events from the previous report in 2012. Nevertheless, it confirms the increase in the number of significant radiation protection-related events observed since 2010. IRSN notes that the overwhelming majority of events that occurred in 2013 had no significant impact on plant safety and no consequences for the health of workers and the public.

The analysis confirms that EDF's efforts appear to be successful in handling the main causes of certain types of events such as periodic tests that had been increasing in recent years. Nevertheless, vigilance over organizational and human aspects is still necessary during a period of significant staff turnover.

IRSN has highlighted the considerable progress protecting nuclear plants from internal and external hazards that led or will lead EDF to implement modifications to its reactors. Finally, IRSN continues to pay particular attention to EDF's efforts to improve reactor safety as a result of stress tests performed after the disaster at the Fukushima-Daiichi Nuclear Power Plant in Japan on 11 March 2011.

In the report, IRSN also provides its analysis of several events and anomalies that it considered the most significant in 2013.

Download IRSN report « IRSN's Position on Safety and Radiation Protection at Nuclear Power Plants in France in 2013 » (pdf)

Download the infographic with key figures and analysis (PDF)

IRSN’s Position on Safety and Radiation Protection at Nuclear Power Plants in France in 2012

Publication date: 16/06/2014

After working a year to consolidate the data, the annual report on the radiation protection and safety of nuclear power plants in France gives the IRSN's independent point of view on all progress and problems concerning safety and radiation protection encountered in the French nuclear power plant fleet in 2012. 

The first part of the report presents the main trends that emerge from IRSN's overall assessment of the radiation protection and safety performance of currently operating nuclear power plants for the year 2012. The year 2012 has witnessed an increase in the total number of significant events. However, IRSN notes the absence in 2012 of incidents with a potentially significant impact on nuclear power plant safety, the surrounding environment or nearby communities in a context of large-scale personnel renewal.

This increase can mainly be explained by EDF's implementation of an improved nonconformance detection and handling procedure which led to the identification, in 2012, of various nonconformances presumably present for several years but previously undetected.

With regard to radiation protection, IRSN notes that the effective dose received by the majority of exposed workers over a period of 12 consecutive months is below the annual public radiation dose limit. 

Faults may occur with nuclear power plant equipment or reactor monitoring systems. Given the standardisation of EDF nuclear power plant reactors, such faults may affect an entire reactor series or even the entire reactor fleet. A few examples deemed particularly significant by IRSN are presented in the second part of this report.

French nuclear reactors are subject to modifications throughout their operating lives, particularly with a view to ensuring continuous safety improvement, this is the subject of the third part of the report. Most of these modifications are the result of studies conducted within the framework of ten-yearly safety reviews, leading to the definition and implementation of new safety requirements and associated changes. Certain issues analysed in parallel with said safety reviews may also lead to changes. This is the case, for example, with the new guidelines document for the protection of basic nuclear installations against external flooding (prepared as part of the response to a nationwide storm that caused partial flooding of the Blayais site in late 1999) or the intense heatwave baseline requirements document (based on lessons learned from the drought period of 2003). The relevance of such an approach has been clearly demonstrated during the definition of NPP protection measures against natural hazards exceeding design-basis levels ('hardened safety core'), as part of the post-FUKUSHIMA review process.

Download IRSN report DG/2013-00005-EN « IRSN's Position on Safety and Radiation Protection at Nuclear Power Plants in France in 2012 » (pdf)

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)

IRSN's viewpoint on the safety and radiation protection on French nuclear power plants in 2007

Publication date : 16/03/2009

The regular annual dissemination of information about nuclear reactor safety, outside any context of media coverage associated with current events, can help ensure a better understanding b​y the stakeholders – and more widely by the public – of the real safety issues associated with the operation of nuclear installations, the progress made in terms of safety as well as the identified deficiencies.

The IRSN safety assessment of the French nuclear power plants is based on data transmitted by operators and its own research. It is organized around the following points: first, an overall examination confirms that no event had serious consequences in the fields of either safety or radioprotection in 2007. This good result must however be tempered by the persistence, or even the increase in unanticipated events and operating difficulties, caused essentially by human factors, organizational aspects and certain shortcomings in terms of operating rigour.

Download the report “IRSN's viewpoint on the safety and radiation protection on French nuclear power plants in 2007" (PDF File)

Evaluation guide for the radiological impact study of a basic nuclear installation (bni) as a support for the authorization application of releases 

Publication date : Octobre 2002

At the time of a licence application of effluent releases and water pumping of basic nuclear facilities (BNI), the operator of the installation must in particular provide a radiological impact study of the radioactive effluent releases coming from the installation on the environment and on pubic health. By definition, it is about an assessment (in principle called an impact study) corresponding with the future activity of the installation, even if such licence applications relate mostly to existing facilities taking into account the Regulatory requirements.

An impact study of the radioactive releases represents technical and conditional specifications. It was for this reason that the French Safety Authority (ASN then DSIN) and the Directorate-General of Health Services (DGS) requested IRSN (then IPSN), in April 1999, to develop a guide facilitating the review of such a study, as well for the services implied in the examination of the licence applications, as for all the concerned parties in this field.

A first version of this guide was issued (in the form of a project) in August 2001 by the ASN. The present version takes into account all comments collected.

Download the evaluation guide (PDF file)