Action Plan
Fukushima2015

1 | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | ENSI

Table of contents
1

Introduction

2

2

ENSI's supervisory culture project4

3

Retrospective of 20145

4

Seismic instrumentation

5

Containment integrity during outages

6

Extreme weather conditions

6

Increase in safety margins

7

Hydrogen management

8

Severe Accident Management

8

Emergency management at Swiss national level10

EU stress tests follow-up

11

Key issues in 201513

Implementing the lessons learned on the safety and supervisory culture 13

5

6Containment integrity during outages

14

Extreme weather conditions

14

Increase in safety margins

14

The effects of non-nuclear hazardous substances

15

Severe Accident Management

15

Dispersion of contaminants in watercourses

16

EU stress tests follow-up

16

Annexes17

Annex 1: List of checkpoints from "Lessons Learned"

17

Annex 2: List of open points from the EU stress tests

25

Abbreviations

27

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1

Introduction

Immediately after the reactor accidents at the Fukushima Dai-ichi nuclear power plant in Japan on
11 March 2011, ENSI initiated measures for a renewed review of the safety of Switzerland's nuclear
power plants. The measures were contained in four formal orders issued by ENSI. The first threeformal orders (dated 18 March, 1 April and 5 May 2011) called for immediate measures andsupplementary analyses.
The immediate measures comprised the establishment of a joint external emergency storage facility
for the Swiss nuclear power plants, including the necessary plant-specific hook-up points for
Accident Management (AM) equipment, and backfits to provide external injection into the spent
fuel pools. The additional reassessments focused on the design of the Swiss nuclear power plants
against earthquakes, external flooding and a combination thereof. Screening investigations werealso requested regarding the coolant supply for the safety and auxiliary systems and the spent fuelpools.
In parallel with these investigations by the licensees, ENSI itself conducted topical inspections
during 2011, entailing reviews of the cooling systems already in place for spent fuel pools, protection
against external flooding and systems for filtered containment venting. These topical inspections
were continued during 2012: they included the plants' strategies in case of a prolonged loss of power
supply, processes for the assessment of external operating experience, and the emergency rooms
available in the Swiss plants. The radiation protection equipment available on site, which is a basic
prerequisite for coping with a severe accident, was inspected at all the nuclear power plants during
2013. Radiation protection equipment is also essential so that the emergency rooms can be used by
the emergency response organisation in the longer term.
The results of ENSI's reviews confirmed that the Swiss nuclear power plants display high levels ofprotection against the impacts of earthquakes, flooding and combinations thereof, and thatappropriate precautions have been put in place to cope with a loss of power supply and of theultimate heat sink. The safety case has been demonstrated for all the analysed accidents on thebasis of the hazard assumptions that are currently applicable. This means that compliance with thebasic statutory requirements for fulfilling the fundamental safety functions (reactivity control,
cooling of the fuel elements and confinement of radioactive substances) is guaranteed. In order tocontinue improving safety, however, ENSI has stipulated a series of additional requirements for
substantial backfits, e.g. a requirement for a flood-proof and earthquake-resistant diversified
ultimate heat sink. ENSI is supervising the work carried out by the nuclear power plants to meetthese requirements in the course of its ongoing supervisory activities, either by drawing up reviews,
issuing permits or carrying out on-site inspections and checks.
In its fourth formal order issued on 1 June 2011, ENSI requested the licensees to take part in the EU
stress tests. ENSI reviewed the documentation for the EU stress tests submitted by the licensees in
the Swiss country report on the EU stress tests (ENSI-AN-7798 dated 31 December 2011). On 10
January 2012, further formal orders were issued requiring clarification of three major open points
arising from the analysis of the final reports by the Swiss nuclear power plants for the EU stresstests. Switzerland's submissions for the EU stress tests then underwent a peer review process. The
results of the peer review at European level confirm ENSI's conclusions regarding the safety of Swiss
nuclear power plants, and they also provide an overview of the condition of plants in Europe. ENSI is3 | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | ENSI

currently implementing the two recommendations made by the peer review team for Switzerland,
which relate to scenarios beyond the design basis. In addition, ENSI is participating in the follow-up
work on the EU stress tests in order to track implementation of the recommended measures in
Europe (see sections 3.8 and 4.8), and actively collaborated on the updating of the WENRA Reactor
Safety Reference Levels. ENSI will implement the recently adopted WENRA Reactor Safety
Reference Levels during the periodic revision of its regulatory framework.
In parallel with the activities mentioned above, ENSI published four reports during 2011 in relation to
the event analysis of the Fukushima accident:--

Fukushima sequence 11032011, Event Sequences in Fukushima Dai-ichi and Dai-ni following the
Tohoku-Chihou-Taiheiyou-Oki Earthquake on 11.03.2011, ENSI-AN-7614 Rev. 1 (26 August 2011)
Fukushima analysis 11032011, In-depth Analysis of the Accident at Fukushima on 11 March 2011,
With Special Consideration of Human and Organisational Factors, ENSI-AN-7669 (29 August
2011)
Fukushima lessons 11032011, Lessons Learned and Checkpoints based on the Nuclear Accidents
at Fukushima, ENSI-AN-7746 (29 October 2011)
Fukushima impact 11032011, Radiological Effects of the Nuclear Accidents at Fukushima on
11.03.2011, ENSI-AN-7800 (16 December 2011)

The knowledge obtained from analysing the events of the accident at Fukushima was reviewed todetermine its applicability to Switzerland, and a summary of insights was compiled in the ENSI
report entitled "Lessons Learned" in the form of a series of checkpoints. Further points were addedon completion of the analyses for the EU stress tests. The current overview can be found in Annexes
1 and 2. The list of points identified is reviewed continuously on the basis of the latest findings and is
updated as necessary. Processing of the checkpoints will probably be completed by the end of 2015.
Accordingly, ENSI is planning the publication of a concluding report on the Fukushima action plans
during the course of 2016.
The Fukushima action plans serve the purpose of ensuring transparency as regards processing of theidentified points until they are implemented. They also provide an instrument for the planning ofsupervisory work and the assessment of new knowledge gained from the Fukushima accident.
Progress with processing the identified points is documented and published. The action plan itself is
updated by February of the year in progress by identifying key issues for that year. ENSI's annual
reporting also provides information about the processing status. Beyond that, the public may be
informed on specific issues should the need arise.
ENSI report

Publication date

Fukushima Action Plan

February

Oversight Report, Radiation Protection Report

April - June

Research and Experience Report
National Action Plan for Follow-Up to the EU Stress Tests (asinstructed by ENSREG)

December - January

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2

ENSI's supervisory culture project

The nuclear supervisory authority plays a pivotal role in the overall "structure" of nuclear safety as
through its supervisory work it has an influence on the safety and related safety culture of theorganisations it supervises. This correlation was emphasised once again by the accident that took
place at Fukushima. The influence exerted by the authority on those it supervises depends mainly on
the adopted supervisory approach and the authority's supervisory culture alongside the legal andinstitutional framework.
It is therefore essential for the supervisory authority to continuously question its influence on thoseit supervises and their safety cultures, and to routinely check whether the supervisory culture it lives
by is appropriate and serves the purpose of fulfilling its legislative mandate with regard to protecting
people and the environment.
Although these insights were by no means new to ENSI, the accident at Fukushima did, however,represent an additional incentive to launch a systematic process of self-reflection with regard to theauthority's supervisory culture. ENSI initiated a corresponding supervisory culture project in 2012.
The project stretched over a period of three years and was split into three phases during which theentire ENSI workforce was repeatedly and actively involved. The project was managed by a teamconsisting of representatives from all disciplines and hierarchical levels.
During the first phase, the supervisory culture at ENSI was characterised on the basis of concrete
examples of the authority's supervisory work. This enabled the identification of a number of focus
areas in relation to the supervisory culture.
This basis was used during the second phase to develop a consolidated summary of the supervisory
culture's target values and objectives (TARGET), its focus areas and recommendations for action.
The central values of the targeted supervisory culture developed jointly by ENSI's workforce weretaken into consideration and subsequently integrated in the new ENSI Mission Statement 2014.
A package of measures was developed during the third phase in 2014 for the purpose of
implementing the TARGET supervisory culture formulated during the second phase. The measures
include improvements to employee training and education, the promotion of ENSI internal andintra-departmental cooperation, project management optimisation, improvements to fundamental
supervisory principles and implementation of the ENSI Mission Statement in supervisory activities.
All of these measures are long term in nature and aimed at firmly establishing in routine supervisory
activities and in the culture at ENSI, the very process of reflection on its supervision and its impact
on the safety (culture) of the supervised organisations as launched within the scope of the project.
They serve continuous improvement in view of how ENSI fulfils its mandate and therefore represent
a contribution towards protecting people and the environment from the hazards of utilising nuclear
energy for peaceful purposes (Art. 1 Nuclear Energy Act).

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3

Retrospective of 2014

Seismic instrumentation
The subject of earthquakes has come under renewed scrutiny from different angles due to theevents that took place at Fukushima. The issues under discussion included the advantages anddrawbacks of an upstream automatic scram by means of seismic instrumentation.
The seismic instrumentation currently installed in the plants was summarised and documented in areport. The systems in place serve to assess whether a seismic event fulfils or exceeds the criteria of
an OBE or SSE. Corresponding alarm notifications are displayed in the control room. The measuresand procedures based on these notifications are documented in the corresponding operating andemergency documentation. The seismic instrumentation in place today does not directly trigger ascram. However, a scram can be triggered by other signals or by the operator.
On an international level, it emerged that an upstream automatic scram by means of seismic
instrumentation (on-site) is only used in areas with increased seismic activity. Early warning systems(off-site) are not used in these locations.
In 2012, the licensees of Switzerland’s nuclear power plants demonstrated deterministically in theirsafety cases that the plants can cope with seismic accelerations with an exceedance frequency of
10-4 per year. The advantage of an upstream automatic scram by means of seismic instrumentation
therefore lies primarily in increasing existing safety margins.
Triggering and completing a scram before the arrival to the plant of the seismic waves prevents thecomponents involved in the scram from being subjected to the seismic loads while performing theirfunctions. In order to evaluate the safety gain, the potential reduction in core damage frequency(CDF) was estimated on the basis of available probabilistic safety analyses. The reduction lies
between 0.1 and 2 % of the total CDF, depending on the plant in question. The potential for false
alarms triggered by a new upstream automatic scram by means of seismic instrumentation would,
however, also result in a slight CDF increase that is slightly less than the mentioned reduction.
Systems for implementing an upstream automatic scram by means of seismic instrumentation areunable to guarantee scram completion prior to the maximum ground acceleration for seismic events
taking place less than 20 kilometres away. That is why the advantage of such a system depends on
the seismic hazard at the location in question. According to recent seismic studies, the seismic
hazard at the Swiss sites is mainly due to earthquakes taking place less than 20 kilometres away.
This in turn lowers the possible reduction of CDF.
On the basis of the conducted investigations it can be concluded that backfits of this nature are notmandatory from a deterministic and probabilistic viewpoint and on account of similar backfits to
European plants.

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Containment integrity during outages
Fairly large containment openings are present for a specified period during shutdowns in connection
with the annual refuelling and maintenance outages in order to transport material and equipment or
to allow access by individuals. ENSI has identified a need for clarification with regard to this plantstate. It involves a review of the measures in place to restore containment integrity in the event ofan accident with a prolonged loss of power (Station Blackout, SBO). ENSI has substantiated thescope of the clarifications needed on the basis of reviews of probabilistic safety analyses, technicalspecifications, emergency operating procedures and Severe Accident Management Guidance.
Corresponding letters with plant-specific requests for additional information were sent to plant
licensees. All licensees submitted their responses within the specified period (by the end of October2014). The information provided by licensees comprises the required and available time for action
with regard to reclosing the containment under SBO conditions as well as identified potential for
improvement.

Extreme weather conditions
In 2012, ENSI defined the requirements for the probabilistic hazard analyses and safety case needed
to demonstrate adequate protection of plants against extreme weather conditions. Quantitative
analyses are required for the hazards posed by extreme winds, tornadoes, extreme air and watertemperatures, heavy rainfall on the plant site and snow levels. In contrast, qualitative analyses are
suitable for the following hazards: hail, freezing rain, drought, forest fires, freezing conditions andcombinations of exceptionally arduous winter conditions and extremely severe summer conditions.
The design-basis values for buildings and equipment required to cope with the hazard in question
must be presented as proof of adequate plant protection. It is also necessary to demonstrate thatthese values can withstand the anticipated loads. The margin in relation to the design basis mustalso be stated.
The hazards to be reviewed within the scope of extreme weather conditions can be divided into
instantaneously occurring hazards, which comprise wind, tornadoes, heavy rainfall, hail and freezing
rain. These loads occur within a very short period of time and must coped with by the plant’s design(mainly that of its buildings). The lead time for action with regard to the remaining hazards ranges
from a number of hours to a few days so that the plant can be properly and timely shut down as aprecaution and other measures to control the hazards can be executed.
The licensees have submitted hazard studies for the hazards named above as well as evidence ofadequate plant protection to ENSI. The task of drawing up hazard analyses was assigned to
specialists in mathematical and statistical evaluation. An assessment of historical data and climatechange was carried out by swissnuclear itself.
A review of the submitted hazard analyses has been delayed as ENSI considers more in-depth
clarification necessary in certain areas (e.g. with regard to the plausibility of hazard results andregional evaluations). This is also the reason why the review of the safety case submitted in 2014
(i.e., related to all hazards except air and water temperatures) has also been delayed.

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Increase in safety margins
The analyses relating to the increase in safety margins (ERSIM) were submitted to ENSI on time by
30 April 2014. The analyses cover the events of “earthquake” and “external flooding”.
One of the project’s purposes is to provide a systematic summary of the safety margins for the threesafe shutdown paths ascertained in previous studies. The three shutdown trains are theconventional safety systems, the special emergency safety systems and the Accident Management(AM) systems. A particular focus was placed on the third shutdown train of “AM measures” and their
inclusion in the plants’ overall safety concept. The summary is also be used to highlight any weak
points that may exist and to develop recommendations for improvements.
In the analyses for increasing the safety margins it was required to use the current hazard
assumptions accepted by ENSI for the events of “earthquake” and “external flooding” with anexceedance frequency of 10-4/year as a reference.
The safety margin for the event of “earthquake” is defined as the ratio of the seismic capacity of theunit under consideration (component, shutdown path, plant) to the Peak Ground Acceleration (PGA)
from the PRP Intermediate Hazard (PRP-IH) with an exceedance frequency of 10-4/year.
The safety margin for the event of "external flooding" is defined as the difference between thecritical flood height leading to the failure of the unit under consideration and the reference floodheight with an excess frequency of 10-4/year.
ENSI initially subjected the reports submitted by the licensees to a cursory review. Due to a numberof additional demands, the licensees were required to provide supplementary information and, in
one case, a thoroughly revised analysis by the end of October 2014. Contrary to the originalschedule, detailed reviews have therefore not yet been completed for all plants and no decisions on
the continuation and expansion of the ERSIM project have been made as yet.
In the case of KKG, ENSI drew an initial overarching evaluation on the basis of the analysis results
relating to the safety margins for "earthquake" events by giving due consideration to the extensive
backfits that KKG proposed in view of long-term operation. In its analysis, KKG did not reference thehazard assumptions based on PRP-IH as preliminarily accepted by ENSI, and instead opted toreference stricter values from the latest hazard assumptions based on the PEGASOS Refinement
Project (PRP) that have not yet been confirmed by ENSI. In view of the possible long-term operationof KKG for more than 40 years, ENSI has concluded that at least the shutdown path 2 (special
emergency safety systems) must provide a significant safety margin with regard to the seismic
hazard and that the scope of special emergency safety functions must be extended.
The evaluation of the results of the ERSIM analyses of other plants will be completed by the end of
the first quarter of 2015.
A review of the requirements for emergency equipment is another issue that was addressed within
the scope of “increasing safety margins”. The requirements for emergency equipment wereincorporated into the draft of Guideline ENSI-G02 "Design principles for existing nuclear power
plants". The draft is currently under discussion at ENSI and will subsequently be made available forexternal consultation. The specifications for emergency equipment take into consideration thelessons learned from Fukushima together with the subsequent backfits in Switzerland and othercountries and updates to the requirements of international regulations (especially to the WENRA
Safety Reference Levels, the IAEA and the NRA [Japan], etc.).

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Hydrogen management
With regard to the management of hydrogen, licensees were required to investigate the impact ofhydrogen combustion in relation to beyond design-basis accidents in containment and the spread ofhydrogen into adjacent rooms. Furthermore, plants with non-inerted containment (i.e. all plants
except KKM) had to develop an approach to equipping the containment with passive autocatalytic
recombiners (PARs) or to review the existing PAR design concept. The plants are currently equippedwith different hydrogen management systems, including active igniters, active recombiners andactive/passive mixing systems. KKM is equipped with an inerted containment system. All plants areequipped with a filtered venting system.
All licensees have submitted the required documents regarding the hydrogen hazard in case of
severe accidents. CFD codes and system codes were used for the, in some cases, highly detailed
numerical simulations. In summary, ENSI's review confirmed that hydrogen management in Swiss
nuclear power plants is of a high standard, but that safety can be increased still further by taking
appropriate measures. KKG will equip its containment with PARs. KKL will provide for a solution
with passive igniters and PARs. KKB will increase its hydrogen reduction capacity through PARs.
Following the implementation of ENSI’s requests or backfits, all Swiss nuclear power plants will haveinstalled passive systems to tackle the hydrogen hazard. Ignitable hydrogen concentrations inrooms outside of containment are not anticipated in the event of a severe accident if the tightness(integrity) of the containment is as per design and the Accident Management (AM) measures inplace are implemented successfully. Additional reviews and enhancements to the corresponding
provisions will be considered on a plant-by-plant basis. For instance, KKM is required to develop asolution for measuring the concentration of hydrogen in the reactor building and to assure thesupply of water to the outer torus by means of an AM measure. This completes the measuresagainst the hydrogen hazard within the scope of the Fukushima action plan. The next steps are apart of ongoing supervision.

Severe Accident Management
ENSI completed its review of the reports submitted by nuclear plant licensees on the deployment
strategy for their emergency response organisation in 2014. These reports set out the deployment
strategy for the working locations of the emergency staff and supporting elements, with a view to alengthy deployment lasting days or weeks. ENSI established that licensees have further improved
emergency preparedness inside the plants. Extensive consideration of the radiological impact on
personnel inside the plant was made together with indications for potential improvements.
Despite differences in the degree of detail and scope, all plants face similar challenges under thestricter boundary conditions of a severe accident as specified by ENSI. ENSI has therefore defined
the emergency rooms, the availability of equipment and material, the protection of employees, thenumber of employees and their management and coordination as focal review points with regard tointernal plant emergency preparedness.
ENSI considers it a necessity for emergency staff to have at least two options with regard to
emergency rooms: one set of rooms should be located on the plant site and another at a distance to9 | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | ENSI

the plant that allows for safe and effective action by the emergency staff even under the more
adverse boundary conditions outlined by ENSI. Nuclear power plant licensees have realised that it
would be beneficial to choose from a number of pre-evaluated external emergency rooms. In themeantime, all nuclear power plant licensees have evaluated suitable external premises for thoseparts of the emergency organisation that do not have to be located on site. ENSI considers it anecessity to include external emergency centres as a fixed option in emergency plans and to
document them accordingly in the emergency documentation. The corresponding plans should go
as far as necessary to enable the licensee to fulfil his obligatory tasks at any time and allow theexternal emergency centre to be used as a point of contact by the entire emergency organisation. It
is already clear that this will require a high degree of preparation and coordination. ENSI hasrequested nuclear power plant licensees to plan and make provisions for the installation of an
external emergency centre of this nature.
Furthermore, ENSI considers it a necessity to ensure access to equipment that would be needed inan emergency under the anticipated conditions, including radiation protection equipment as well as
supplies for the emergency teams. According to reports from the plant licensees, the emergency
teams would initially be left to their own devices under the specified conditions as they would nothave immediate access to equipment from the external storage facility in Reitnau. However, thestorage facility in Reitnau offers additional options for supplying teams with essential equipment
and materials. For this reason, the nuclear power plants have meanwhile acquired additional mobile
equipment and made it available on site. Whilst access to technical equipment under accident
conditions has been of course studied in detail , access to work and protection equipment and, inparticular, to the supplies available to the emergency teams is not yet at the same level at every
plant. ENSI includes these among the "suitable means" for managing accidents. As part of its review
and in view of this issue, ENSI has required licensees to provide adequate on-site storage to allmeans that would be needed for emergency preparedness under the specified stricter boundary
conditions until such time as means from the external facility in Reitnau or neighbouring power
plants become available.
Personnel protection has also gained greater international significance since the accident at
Fukushima. Through suitable measures, the licensee must ensure that the effective dose to which
the personnel deployed to manage an accident (i.e. plant employees and external personnel) are
exposed is limited. This requires the effective doses to which all personnel are exposed to beevaluated and documented. In the event of an accident, the skin and incorporation dose must be
reliably ascertained alongside direct radiation (whole body dose). The potential development of
respiratory toxins must also be considered in relation to personnel protection. ENSI therefore
required licensees to introduce and report on the technical and organisational provisions that makeit safe to stay at the plant under consideration of the quality of air in the rooms used.
As means of communication are essential for the effective management and coordination ofnecessary measures in the event of an accident, a failsafe fall-back level for communication withemergency response partners must be provided for. This point was not scrutinised in detail during
the review as communications between emergency response partners are currently undergoingevaluation in a separate project.

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Emergency management at Swiss national levela) IDA NOMEXThe report by the working group on the review of the reference scenarios (IDA NOMEX measure 14)
was forwarded by ENSI to the Federal NBCN Crisis Management Board (BST ABCN) together withthe consultation report in the second quarter of 2014. BST ABCN has acknowledged the reports andhas tasked the project committee for the emergency preparedness concept (concept for emergency
preparedness in the vicinity of nuclear power plants) with recommending a reference scenario basedon the reports. The recommendation developed as a result was presented to and approved by BST
ABCN in the fourth quarter of 2014.
The report by the working group on the review of the emergency planning zone (EPZ) concept (IDANOMEX measure 18) was submitted in mid-2014 to the Federal government and the cantons for
consultation. The consultation report and the report by the working group were presented to the
BST ABCN during the fourth quarter of 2014 and approved by way of acknowledgement.
The results of these two IDA NOMEX measures will be incorporated in the emergency preparedness
concept that is currently undergoing a review under the guidance of the FOCP. They also have an
influence on the ongoing overall review of the Radiological Protection Ordinance and the planned
amendments to the NBCN Operations Ordinance and the Emergency Preparedness Ordinance.
Thus, ENSI has concluded the four measures for which it was responsible as project leader within the
IDA NOMEX framework. BST ABCN routinely informs the Federal government on theimplementation status of IDA NOMEX; it is anticipated that the conclusion of IDA NOMEX will bepossible in 2015.

b) Dispersion of contaminants in watercourses
On the basis of the Fukushima Action Plan, ENSI reviewed the existing procedures and measures todetermine their effectiveness in protecting drinking water. In 2013, ENSI collaborated with theFederal agencies involved in emergency preparedness (the National Emergency Operations Centre(NEOC), the Federal Office of Public Health (FOPH) and the Federal Office for the Environment(FOEN)) and the cantons concerned to carry out a situation analysis on this aspect. The analysis
showed that the statutory regulations and the existing emergency response procedures andmeasures are basically suitable for protecting people and the environment. However, a need forverification was ascertained with regard to a few points that were summarised in four work
packages. ENSI has taken over the project leader role for two of the packages. At the end of 2014,
the status of completion of the work packages was as follows:
Work package 1: Review of accidents with regard to liquid releases and the development of aconcept for dealing with large quantities of contaminated water.
At the end of 2013, all four nuclear power plants had described in reports the radioactive liquid
releases into watercourses to be expected in the event of operational occurrences and design-basis
accidents. ENSI has reviewed these reports and is in agreement with the nuclear power plants thatdesign-basis accidents would only lead to low radioactive discharges into the groundwater or river inthe order of magnitude of a few multiples of the long-term discharge limits.

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Additionally, the GSKL (Group of Swiss Nuclear Power Plant Managers) has submitted a basic
concept for dealing with large quantities of contaminated water to ENSI, including a schedule forthe next steps. ENSI has reviewed the basic concept and formulated additional requirements. The
GSKL submitted a revised concept at the end of June 2014. Following a comprehensive review, ENSI
then declared its agreement with the revised basic concept. It does, however, expect its comments
to be taken into due consideration in the plant-specific studies to be submitted by the end of
November 2015.
Work package 2: Review of reporting channels
A meeting with relevant cantons chaired by the National Emergency Operations Centre (NEOC)
took place on 16 December 2014. During the meeting, it was ascertained that the reporting channels
between nuclear power plants, ENSI, NEOC and the cantons will be just as effective in the event ofan accident involving the discharge of contaminated water into the environment. It was agreed thatthe cantons will review and, where necessary, improve their internal reporting channels to the water
treatment plants by the end of the third quarter of 2015.
Work package 3: Review of radiological criteria for alarm initiation and the introduction of
immediate measures by the end of 2014.
In cooperation with the FOPH and the NEOC, ENSI has developed the radiological criteria for alarm
initiation and the introduction of immediate measures in the event of a discharge of radioactive
substances into the Aare and Rhine rivers and documented them in a memo. As a result of thisreview, ENSI will define more precisely the obligation to notify the non-routine discharges into theenvironment defined in section 4.4 of Guideline ENSI-B03.
Furthermore, ENSI has developed rules of thumb for estimating the activity concentration levels andflow times following a nuclear power plant accident involving the discharge of radioactive
substances into the Aare or Rhine rivers.
Work package 4: Review and supplementation of the environmental monitoring programme
The FOPH has reviewed the existing environmental monitoring programme with the result that fourcontinuous measuring stations for monitoring the gamma activity of river water downstream fromthe nuclear power plants will be installed by FOPH before the end of 2015. Two measuring stations
are currently in trial operation.

EU stress tests follow-up
The so-called stress tests were carried out at European level following the accident at the Fukushima
Dai-ichi nuclear power plant in Japan on 11 March 2011. They were ordered by the European
Commission and took place in every member state with nuclear power plants. Switzerland
participated voluntarily. In 2012, a European peer review process took place on the basis of thereports from the 17 participating countries. This complex review process resulted inrecommendations both for individual countries and for the EU as a whole. The national
recommendations were listed in a peer review report. The general recommendations for the EU

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were published in the "Compilation of stress tests peer review recommendations and suggestions"(shortened to "Compilation of Recommendations").
At the end of 2012, the participating countries submitted a "National Action Plan" (NAcP) to the EUthat reported on the current implementation status of all recommendations (both on national andEuropean level) from the stress tests peer review process. In the spring of 2013, the NAcPs were
subjected to a peer review within the framework of an international workshop, whereby
Switzerland's NAcP received a positive evaluation. Questions from the general public were also
answered during the course of the process.
The European Nuclear Safety Regulators Group (ENSREG) called for an update to all NAcPs by theend of December 2014 in view of a renewed peer review to be held during a workshop in the springof 2015. The Swiss NAcP http://static.ensi.ch/1419332464/swiss-nacp-2014-final.pdf was submitted
to ENSREG on time on 22 December 2014. The report summarises the status of Switzerland’s
implementation of the recommendations formulated by ENSREG and adopted by various
international committees. The latest version of the Swiss NAcP lists the international
recommendations in a cross-reference table together with national checkpoints (see section 5.1) andopen points (see section 5.2).
All documents relating to the EU stress tests and its follow-up are accessible via the ENSREG web
site. The web page http://www.ensreg.eu/EU-Stress-Tests can be used as start page. The reports foreach country including the results of the peer review can be found under http://www.ensreg.eu/EUStress-Tests/Country-Specific-Reports.

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4

Key issues in 2015

The following key issues were specified for ENSI's post-Fukushima activities during 2015, based on
their safety significance and on synergies with ongoing projects:
1. Implementing the lessons learned on the safety and supervisory culture
2. Containment integrity during outages
3. Extreme weather conditions
4. Increase in safety margins
5. The effects of non-nuclear hazardous substances
6. Severe Accident Management
7. Dispersion of contaminants in watercourses
8. EU stress tests follow-up

Implementing the lessons learned on the safety and supervisory culture
The accident at Fukushima made it clear once again that the safety of nuclear power plants cannot
be seen merely as a technical issue but rather one that calls for an integrated view of the overallsocio-technical system, i.e. the human, technological and organisational elements of a nuclear
power plant and their complex interaction with one another. The safety culture that the plant lives
by plays a pivotal role, i.e. the values, world views, behaviours and characteristics of the physicalenvironment that define or show how the plant licensees deal with nuclear safety and theimportance they accord to it. ENSI sets great store by the safety culture within the framework of its
regulatory supervision. After the accident at Fukushima, the safety culture became a focal point ofattention in the context of supervisory measures with a specific reference to Fukushima.
However, the accident at Fukushima also made it clear that the focus must not concentrate solely on
the plant licensee but rather on the entire "structure" of nuclear safety and all the actors involved init (licensees, manufacturers and suppliers, authorities, political institutions, the media and thegeneral public, etc.). The latter interact with each other in many different ways and mutually
influence each other through their respective roles, behaviours and cultures. Accordingly, they
influence nuclear safety and the safety culture of nuclear power plant licensees. One of these actors
is the supervisory authority that must endeavour to achieve and maintain a positive safety culture("supervisory culture") and critically question its influence on nuclear power plant licensees. In lightof the events at Fukushima, ENSI established a three-year project aimed at initiating a process of
self-reflection on the authority’s supervisory culture and deriving concrete measures from it (seesection 2).
The activities ENSI has derived from the lessons learned from the accident in Fukushima will be
discussed in a report.

ENSI | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | 14

Milestones:
4th quarter of 2015

ENSI: Compilation of a report on implementing the lessons learned withregard to the safety and supervisory culture.

Containment integrity during outages
Fairly large containment openings are present for a specified period during shutdowns in connection
with the annual refuelling and maintenance outages in order to transport material and equipment or
to allow access by individuals. ENSI identified the necessity for additional studies on the measures inplace to restore containment integrity with regard to SBO accidents during this plant configuration.
At ENSI’s request, licensees submitted additional analyses which included identified potential for
improvement. Licensee statements will be reviewed by ENSI during the course of 2015.
Milestones:
2nd quarter of 2015

ENSI: Review of the documents submitted by licensees.

Extreme weather conditions
The review related to extreme weather conditions has been delayed due to the increased efforts
ENSI has to undertake to evaluate the hazard analyses. ENSI will conclude its review of all hazard
analyses during the second quarter of 2015. The review of the safety cases related to all hazards will
be completed in the fourth quarter of 2015.
Milestones:
2nd quarter of 2015

ENSI: Review of hazard analyses.

4th quarter of 2015

ENSI: Review of the safety case in cases related to extreme weather
conditions.

Increase in safety margins
ENSI intends to conclude its review on the submitted analyses on the increase in safety margins by
the end of the first quarter of 2015. Any backfits derived therefrom will be followed up in the courseof ongoing supervisory activities. The insights gained during the first quarter of 2015 will be used asa basis to determine which events the ERSIM project will be extended to include. Analysis will focus
in particular on the events linked to extreme weather conditions.
Milestones:
1st quarter of 2015

ENSI: Evaluation of analyses on the increase in safety margins (earthquakes
and extreme flooding).

15 | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | ENSI

1st quarter of 2015

ENSI: Decision on the continuation and extension of the ERSIM projectthrough additional analyses relating to the increase in safety margins

4th quarter of 2015

ENSI: Review of the additional analyses relating to the increase in safetymargins.

The effects of non-nuclear hazardous substances
The deployment strategies developed by nuclear power plants frequently provide for manualintervention by their staff in the event of nuclear accidents that exceed the design basis. Flammableand explosive liquids and gases as well as caustic or hazardous chemicals are present on every power
plant site. The question arises to what extent conventional hazardous substances could interferewith managing beyond design-basis accidents and what countermeasures are available. In early
2015, ENSI will specify the scope of the clarifications needed and require the nuclear power plants tosubmit their considerations. The reports provided by the licensees will then be reviewed by ENSI.
Milestones:
1st quarter of 2015

ENSI: Specification of the scope of the clarifications needed.

3rd quarter of 2015

NPPs: Submission of answers and documents regarding the specified scopeof the clarifications.

4th quarter of 2015

ENSI: Review of the documents submitted by licensees.

Severe Accident Management
Pursuant to the Emergency Preparedness Ordinance, the authorities involved in an emergency(including nuclear power plant licensees, ENSI and the cantons) must ensure that adequate
personnel and equipment are available to manage emergencies. This applies in particular toqualified radiation protection personnel on the plant site. ENSI will verify the availability of adequate
personnel, in particular in view of emergencies.
Milestones:
2nd quarter of 2015

ENSI: Request of information from the NPPs in relation to the minimum
personnel levels during normal operation and for dealing with severe
accidents.

3rd quarter of 2015

NPPs: Submission of documents on minimum personnel requirements.

4th quarter of 2015

ENSI: Review of the documents submitted by licensees.

ENSI | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | 16

Dispersion of contaminants in watercourses
The work packages presented in section 3.7 (Retrospective of 2014) will be further processed andconcluded during 2015.
Work package 1: The nuclear power plants will conclude their plant-specific studies on dealing withlarge quantities of contaminated water and submit corresponding reports by the end of November
2015. ENSI will then review the studies.
Work package 2: The cantons will conclude their internal reviews of reporting channels by the end of
the third quarter of 2015.
Work package 3: The review of the radiological criteria for alarm initiation and the introduction of
immediate measures under ENSI’s lead is virtually complete and documented in two reports. It is
intended to bring the amendment to Guideline ENSI-B03 described in section 3.7 (Retrospective of2014) into force during 2015.
Work package 4: The FOPH intends to conclude the installation of the new measuring system forcontinuous radiological monitoring of river water downstream from nuclear power plants by the endof 2015.
Milestones:
4th quarter of 2015

NPPs: Submission of plant-specific studies on dealing with large quantities
of contaminated water.

4th quarter of 2015

ENSI: Amendment to the obligation to notify non-routine discharge into theenvironment as defined in section 4.4 of Guideline ENSI-B03.

EU stress tests follow-up
ENSREG is organising a new international workshop on the updated NacPs for April 2015 as a part offollow-up activities to the EU stress tests. The NAcPs will be subjected to a peer review. The process
also provides the general public with an opportunity to pose questions relating to the NAcPs via the
ENSREG website http://www.ensreg.eu/node/3762. The results of the review will again besummarised in a so-called rapporteurs report. The report will present the activities by theparticipating countries that have taken place since Fukushima as well as those implemented since
the last workshop. Switzerland will actively participate in the review and concluding workshop.
Milestones:
2nd quarter of 2015

ENSI: Participation in the peer review of NAcPs and the concludinginternational ENSREG workshop.

17 | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | ENSI

5

Annexes

Legenda to column 3 (status/action plan)
2015 Key issue of the action plan for 2015
LA
Issue has been incorporated into ongoing supervisory activities
NI
Issue yet to be initiatedB
Issue dependent on IDA NOMEX

Annex 1: List of checkpoints from "Lessons Learned"
No.

1

Designation Status /action plan

PP1

2015

Description

The hazard assumptions for earthquakes and external flooding, and also for
extreme weather conditions, must be re-evaluated to take account of the latest
knowledge.

Implementation text

Earthquakes: the first review of the seismic safety case based on intermediate hazard
assumptions was completed in June 2012. At the end of 2013, the operators handed in to
ENSI a final report on the PEGASOS Refinement project (PRP). ENSI will issue a final
assessment of the PRP in 2015 and will redefine the hazard assumptions for each of the
NPP locations.
External flooding: hazard assumptions were reviewed in 2011. Combination ofearthquakes/earthquake-induced flooding was covered in 2012.
Extreme weather conditions: New studies have been compiled by the operators for therequired hazards, and proof of adequate protection was submitted to ENSI in 2014. The
information from the operators is currently under review at ENSI.

2

3

PP2

PP3

LA

LA

The control strategies for a prolonged loss of electric power supply must be reevaluated on the basis of knowledge gained from Fukushima.

The strategies were reviewed during topical inspections in all NPPs at the end of 2012: theplants have effectively continued to develop their existing strategies on a targeted basis
and adequate resources for AM are available in order to prevent core damage after an
SBO.

It should be checked whether the coolant supply for the safety systems and theassociated auxiliary systems is guaranteed from a diverse source which is safe
against earthquakes, flooding and contamination.

Screening analyses of coolant supply were completed in 2012; at all plants except
Mühleberg, adequate redundancies are available in order to guarantee the coolant supply.
KKM must backfit a diverse coolant supply. The applications for alternative back-fitting
measures (if any) which KKM must implement in order to operate until 2019 were
submitted in mid-2014. ENSI reviewed these applications and issued its safety evaluationin January 2015 (report ENSI 11/1999).

ENSI | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | 18

No.

Designation Status /action plan

4

PP4

LA

Description

Implementation text

It should be checked whether the requisite tightness of buildings containing
important safety equipment is guaranteed in case of flooding of the site.

The safety cases for the 10,000-year flood were accepted by ENSI in 2011. Other additional
requirements were incorporated and followed up in the course of the project ERSIM and of
the ongoing supervisory activities.

5

PP5

LA

On the basis of experience gained from the Fukushima accident, it should bechecked whether the availability of the instrumentation required to assess thecondition of the plant is guaranteed adequately even in extreme situations.

6

PP6

LA

It should be checked whether control of leaks and the long-term cooling of the
spent fuel pools are guaranteed in case of severe accidents.

7

8

PP7

PP8

LA

LA

It should be checked whether tests and inspections regarding the prevention ofhydrogen explosions should be extended to additional areas of the plants
beyond the primary containment.

The design and operation of the systems for filtered venting of the containment
must be addressed again.

Backfitting of instrumentation to monitor the spent fuel pools was required in the formal
order dated 05.05.2011. Backfitting projects for this purpose are in progress in all NPPs;
permits for these have been issued by ENSI, which also supervises the implementation.
Activities in connection with accident instrumentation were covered in section 3.7 of the2014 Fukushima Action Plan. The requirements for emergency equipment wereincorporated into the draft of Guideline ENSI-G02 "Design principles for existing nuclear
power plants" (see section 3.4).
Reviews took place in 2011 and 2012. Permits for backfitting projects at the Beznau andMühleberg NPPs are being issued by ENSI, which also supervises the implementation.
In 2013, ENSI required a reconsideration of various aspects of the hydrogen hazard in caseof severe accidents in the reactor. Topics are: analyses of the hydrogen hazard, including
propagation of hydrogen from the containment into other buildings of the nuclear power
plant, robustness and scope of the measuring equipment, measures and procedures inplace, review of the containment venting path.
The operators submitted the installation-specific studies promptly by the end of June
2014. After a detailed review, ENSI has concluded that each plant has adequate preventive
measures in place against the hydrogen hazard in case of beyond design basis accidents.
Nevertheless, appropriate measures could further increase safety in all the plants. One of
ENSI's requests was for all the nuclear power plants to have suitable passive means ofcounteracting the hydrogen hazard at their disposal. ENSI will continue to track theimplementation of the measures and/or backfittings in the course of ongoing supervision.
The filtered venting system was examined both in the EU stress tests ("Measures anddesign to protect containment integrity") and in the course of topical inspections by ENSI
which relate specifically to knowledge gained from the accident at Fukushima Dai-ichi. The
reviews have confirmed the suitability of these systems.
Aspects of hydrogen management related to the filtered venting systems are considered
under PP7.

19 | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | ENSINo.

Designation Status /action plan

Description

Implementation text

9PP9

It is necessary to carry out a new review of the earthquake and flood design ofthe monitoring network for automatic dose rate measurement in the vicinity of
nuclear power plants (MADUK), in relation to experience gained from the
Fukushima accident.

ENSI has reviewed the specific requirements on the basis of knowledge acquired through
IDA NOMEX. This knowledge was taken as the basis for a study to derive the requirements
for redundant and reliable measurement and forecasting systems used in the emergency
response organisation (see PP5).

It should be checked whether the emergency control center (ECC) and thesubstitute ECC at the Swiss nuclear power plants still meet the requirements,
based on the experience gained from the Fukushima accident.

Requirements for technical emergency preparedness equipment at nuclear installations
are stipulated in ENSI guideline B12. Inspections were conducted at all NPPs in 2012 and2013 covering the emergency rooms and the radiation protection equipment that could be
deployed in case of an event. The review report on the deployment strategies for the
emergency response organisations submitted by the NPPs was issued in 2014. In thisreview report, ENSI concluded that external emergency centres must be included in theemergency plans as a fixed option (also see section 3.6). The work will continue to be
tracked by ENSI in the course of its ongoing supervisory activities.

10 PP10LALA

The access control system for nuclear power plants and the associatedarrangements must be reviewed to determine the accessibility of rooms

11 PP1112 PP12LA

LA

where intervention is required in case of severe accidents, while maintaining
appropriate plant security. Monitoring of radiation protection must continue tobe guaranteed in this context.

The emergency measures for heat removal in case of a complete failure of thecooling water supply must be reviewed and verified under conditions resulting
from the disruption of the infrastructure and the power supply.

This issue was initially addressed in the course of existing supervisory activities taking into
consideration the additional knowledge gained from the Fukushima accident.
Follow-up will continue in the course of ongoing supervisory activities.

After the construction of the Reitnau external storage facility, resources were alreadymade available in June 2011 for use in a situation of this sort in order to maintain thecooling function independently of the permanently installed safety systems. In addition,
this issue was analysed as part of the EU stress tests. Topical inspections were carried out
on the issue of a complete loss of the AC power supply, and improvements were
implemented in the plants.
The comprehensive review of the deployment of resources from the Reitnau external
storage facility took place in 2013 in connection with an alarm exercise and the 2013
general emergency exercise.

13 PP13LA

It should be checked whether the alternative supply of water and power for
emergencies is ensured.

Operational resources have been held in readiness at a central point at the Reitnau storage
facility since 2011; in addition, storage facilities with appropriate emergency resources
have been set up at the NPP sites. Hook-up points at the NPPs have been backfitted asnecessary. The plants' provisions for water injection in case of an SBO were successfully
reviewed by ENSI on the basis of inspections. Periodic reviews are conducted as part of theregular emergency exercises.

14 PP14LA

It is necessary to examine the water resources that can be made available tosupply the reactor pressure vessel, the spent fuel pools and the containment.

Available reserves of water have already been reviewed and are already documented in theexisting emergency procedures. This topic will be reconsidered again as part of the"Increase in safety margins" key issue (see section 3.4).

ENSI | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | 20

No.

Designation Status /action plan

Description

Implementation text

Implementation is taking place under the auspices of IDA NOMEX, e.g. as part of IDANOMEX measure 4 "Personnel and materials" and IDA NOMEX measure 24 "Obligations
on individuals". The resultant specific requirements for nuclear installations are being
supervised by ENSI. Reporting on the complete package of IDA NOMEX measures isundertaken by the Federal NBCN Crisis Management Board.

15 PP15

B

Emergency management must be reviewed to determine further potential for
improvement.

IDA NOMEX measures 14 ("Review of reference scenarios") and 18 ("Review of the zone
concept") for which ENSI was tasked with the lead, were also completed in 2014 (seesection 3.7).
In addition, the deployment strategies for the NPPs' emergency response organisations
were reviewed in 2014 to determine their potential for improvement (see PP10 and
section 3.6).

ENSI has identified the following issues for improving emergency planning andemergency exercises:a

The decision-making guidance for emergency management in case of severe
accidents (SAMG) at nuclear power plants, including the newly planned
checkpoints to deal with severe accidents, must be reviewed on the basis ofknowledge gained from the Fukushima accident. In this regard, it isparticularly necessary to check:-

16 PP16

LA-

whether adequate consideration is given to a prolonged Station
Blackout (SBO) and the simultaneous occurrence of events in multipleunit plants;
whether there is any need for measures, auxiliary resources andequipment that must be available to ensure subcriticality in the longterm in case of severe accidents.

b

Consideration given to accidents involving a prolonged SBO in the planningof emergency exercises.

cExamination of whether the procedures are trained often enough during
emergency exercises. Particular attention should given here to a functioning
inter-organisation chain of communication across the various organisations.

The Swiss NPPs have a comprehensive system of accident and emergency procedures,complemented by the SAMG. ENSI considers that a new assessment in the light of events
at Fukushima would serve the interests of safety. In the course of ongoing supervisory
activities, there will be re-assessments of the regulatory requirements(ENSI-B12) and the implementation of the SAMG in the plants.
In connection with the implementation of ENSI's formal order dated 18.03.2011, an
external emergency storage facility (Reitnau) for all NPPs in Switzerland was alreadyestablished on 01.06.2011. Among other items, stocks of boron compounds are kept inreadiness here to ensure the long-term maintenance of subcriticality.
Guideline ENSI-B11 has been amplified since 2011 so that, as a new feature, the planningmust also include recurring emergency exercises focusing on the deployment of the firebrigades and the security forces. In addition, the option of conducting longer exercises
has been incorporated into ENSI-B11. The cross-organisational and cross-bordercommunication chain is especially being examined during general emergency exercises.

Implementation will take place under the auspices of IDA NOMEX. The resultant specificrequirements for nuclear plants will be supervised by ENSI.

17 PP17B

It should be checked whether and to what extent the communication facilities
are designed with adequate redundancy and diversity.

In 2013, the Swiss POLYCOM security radio network was introduced at ENSI as analternative communication system. The option of satellite-based communication is under
examination (see section 3.7 of the 2014 Fukushima Action Plan). Furthermore, the FOCP
is working on a solution for secure communication for civil protection purposes, with theparticipation of the KKM SVS (Consultation and coordination mechanism of the Swiss
safety network) and in collaboration with the Army.

21 | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | ENSINo.

Designation Status /action plan

Description

Implementation text

Implementation will take place under the auspices of IDA NOMEX (also see PP15).

B
18 PP182015

19 PP19LA

It must be ensured that adequate staff is available at all times to accomplish allnecessary emergency management activities.

Measures that increase the organisation's ability to react to unexpected events
must be reviewed again on the basis of experience gained from Fukushima.

The resultant specific requirements for nuclear plants will be supervised by ENSI. The
review report on the deployment strategies for the emergency response organisations
submitted by the NPPs was issued in 2014 (also see section 3.6). For 2015, ENSI will carryout a special review of the staffing level for qualified radiation protection personnel
during an emergency in the NPPs (see section 4.6).
Actions related to this issue are followed up by the Human and Organisational Factors
section in the course of ongoing supervisory activities.

20 PP20

LATransmission of plant parameter data must be re-evaluated with respect to analternative, independent means of data transmission.

The specific requirements have been drawn up by ENSI on the basis of knowledge
acquired through IDA NOMEX. The FOCP is working on a solution for securecommunication for civil protection purposes, with the participation of the KKM SVS(Consultation and coordination mechanism of the Swiss safety network) and incollaboration with the Army.

21 PP21B

The evacuation concepts must be reviewed, taking account of knowledge
gained from the Fukushima accident.

Implementation will take place under the auspices of IDA NOMEX by the FOCP.

22 PP22

B

Coordination with other international partners is required to determine whether
and how an international network for central international emergency support
can be set up.

Implementation will take place under the auspices of IDA NOMEX. The resultant specificrequirements for nuclear plants will be supervised by ENSI. Switzerland specified
arrangements for collaboration with RANET (Response and Assistance Network) in 2013,
and it has been a member since March 2014. Since September 2013, the FOPH has been amember of REMPAN, the Radiation Emergency Medical Preparedness and Assistance
Network within the WHO (World Health Organization).

23 PP23LA

It should be checked whether the necessary information regarding forecasts ofreleases and radiation exposure is provided in a timely and continuous mannerin case of accident.

In 2013, the requirements for redundant and reliable measurement and forecasting
systems were specified in connection with IDA NOMEX measure 10 (see section 3.7). The
transmission of forecasts was reviewed again in the course of the 2013 generalemergency exercise.

ENSI | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | 22

No.

Designation Status /action plan

Description

The following improvement measures were identified regarding information
provided to the general public:

24 PP24

B

a It must be ensured not only that the requisite infrastructure and thenecessary individuals and/or organisations and equipment are available
for crisis communication, but also that the necessary means ofcommunication are in place. The relevant precautions must be taken.
Regular training must be provided on the associated procedures. This
point also includes a functioning network of experts who are available tothe media to supply neutral and objective information.
b It should be checked whether the organisational responsibilities for
informing the public as well as the local authorities and support staff areclearly stipulated, and are uniformly understood by all involved parties.
It should be checked whether the timely communication of radiological effects,
including calculated forecasts, is also ensured beyond Switzerland's borders.

25 PP25

26 PP26

27 PP27

Implementation text

Implementation will take place under the auspices of IDA NOMEX (e.g. in connection with
IDA NOMEX measure 116 "Information agreement, information in the event of an NPP
accident within Switzerland", which is being handled by the FOCP). In 2013, ENSI
introduced the Swiss POLYCOM security radio network as an alternative communication
system. The option of satellite-based communication is under examination (see section
3.7 of the 2014 Fukushima Action Plan). Prompt transmission of information onradiological effects, including forecasts, is examined on a recurring basis in the course ofgeneral emergency exercises. The last examination of this sort took place during the 2013
general emergency exercise.
The FOCP is working on a solution for secure communication for civil protection
purposes, with the participation of the KKM SVS (Consultation and coordination
mechanism of the Swiss safety network) and in collaboration with the Army.

2015

It is necessary to examine the extent to which the release of non-nuclear
hazardous substances in case of beyond design basis accidents could exert an
additional influence on the accident sequence, and which counter-measures are
required.

The issue of "Impacts of non-nuclear hazardous substances in case of events beyond thedesign basis" is a key point for 2015 (see section 4.5).

LA

The process of evaluating and examining the applicability of national andinternational operating experience must be optimised on the basis ofknowledge gained from the Fukushima accident.

ENSI has continued to optimise the relevant internal structures. The internal processes
have been adapted on the basis of operating experience feedback from international
events. The effectiveness of these optimisation measures will be reviewed during theperiodic audits of ENSI's management system.

LA

It must be guaranteed that the knowledge gained from national andinternational operating experience (event analysis) in the licensees'organisations reaches all the relevant individuals and units (including those atgroup level).

Inspections of this aspect were carried out by ENSI at all NPPs in the fourth quarter of2012. The plants have processed the requirements derived. ENSI will follow this issue up
in the course of its ongoing supervisory activities.

23 | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | ENSINo.

Designation Status /action plan

Description

Implementation text

Switzerland collaborates continuously in the Safety Standards Groups (SSC) and otherimportant IAEA bodies.

28 PP28LA

It must be ensured that internationally harmonised assessment criteria for
nuclear safety are established at the highest level of safety.

Under the auspices of WENRA, ENSI advocates the development of harmonised Safety
Reference Levels (SRL) and their implementation in European countries that use nuclear
energy. In 2013, six new working groups within the RHWG (Reactor Harmonisation
Working Group) drew up proposals for the integration of new knowledge from the EU
stress tests into the SRLs. The revised SRLs were adopted by WENRA after the public
consultation in 2014. When revising its regulatory framework, ENSI will implement the
newly adopted WENRA Reactor Safety Reference Levels.
An OSART mission was carried out at KKM in October 2012. The OSART follow-up
mission was completed in June 2014, after which the report on the results was published.

29 PP2930 PP30

LA

2015

Greater importance should be accorded also at international level to therecommendations resulting from international reviews (IRRS, OSART) and fromthe regular Periodic Safety Reviews (PSR). The transparency of ENSI's
supervision and of the operators' safety-related activities must be increased.

ENSI is reviewing the significance of the lessons from the Fukushima accident
for its supervisory activities.

By the end of 2012, ENSI had drawn up an action plan for the proposed improvements
arising from the IRRS mission in 2011, with a view to the Follow-Up Mission. The IRRS
Follow-Up-Mission will take place in April 2015.
The sixth Review Meeting on the Convention on Nuclear Safety (CNS) took place inMarch/April 2014. Switzerland achieved good results at this meeting. The Swiss proposal
to amend the CNS (Article 18) was discussed on this occasion, and was forwarded to a
Diplomatic Conference. In February 2015, the conference decided to adopt the "Vienna
Declaration on Nuclear Safety" by consensus, instead of the proposed amendment. Thisdeclaration incorporated Switzerland's original requests.
Long before the accident in Japan, ENSI endeavoured to adopt a questioning attitude
towards its own supervisory strategy. By the end of 2014, ENSI had completed an internal
project for this purpose on the subject of supervisory culture (see section 2). The
knowledge gained from this project, and findings concerning the plants' safety culture,
will be summarised by ENSI in a report during 2015 (see PP37 and section 4.1).
The regulatory framework is being reviewed in the course of ongoing supervisory
activities. Specific issues are covered in other checkpoints.

31 PP31LA

Additional operational resources must be kept in readiness for radiation
protection in case of severe accidents.

Additional radiation protection equipment has been held at the Reitnau external storage
facility since 2011. Reviews to determine the adequacy of the resources held in readinessare conducted at regular intervals. In 2013, inspections of the radiation protection
equipment stored at the NPP sites were carried out.

ENSI | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | 24

No.

Designation Status /action plan

Description

Implementation text

32 PP32

LA

It is necessary to examine whether the emission and immission measurements
in place on the power plant sites in order to determine the activity releases areguaranteed in case of loss of offsite power or loss of normal emergency power.

The review is being carried out as part of the Periodic Safety Reviews (PSR). KKM met therequirement for the high dose rate sensor in the stack, which is used as incident
instrumentation, at the start of 2014. Work on the required improvements is under way at
KKL. For KKB, ENSI will carry out the assessment during the current PSR. For KKG, thereview was carried out in the course of an inspection in 2014, with the result that thepreventive measures taken are adequate.

33 PP33

LA

It is necessary to examine the extent to which the availability of themeteorological data required for dispersion calculations is guaranteed in case of
extreme natural events.

In 2013, the requirements for redundant and reliable measurement and forecasting
systems were specified in connection with IDA NOMEX measure 10. Implementation willtake place in the course of ongoing supervisory activities and as part of the FOCP projecton secure communication for civil protection purposes.

B

It is necessary to stipulate arrangements for dealing with contamination in thearea surrounding nuclear installation following severe accidents.

The specific requirements for the implementation of this checkpoint are being defined on
the basis of knowledge acquired from IDA NOMEX, in connection with the total revisionof the Radiological Protection Ordinance; this is taking place under the lead managementof the Federal Office of Public Health (FOPH). The public consultation is planned during
2015.

35 PP35

2015

It is necessary to examine how to deal with large volumes of contaminatedwater, radioactive waste or environmentally hazardous substances in case of
severe accidents.

At the end of 2013, the NPPs submitted a concept for dealing with the input of radioactive
contaminants into groundwater and watercourses in case of beyond design basis
accidents. ENSI carried out its review and issued its comments in 2014 (also see section
3.7). Work on this topic will continue in four "work packages", and it will also be a key
point in 2015 (see section 4.7).

36 PP362015

As part of the emergency planning for severe accidents, it must be ensured thatsufficient radiation protection staff is available on site.

This issue will be followed up as a key point in 2015 (also see section 4.6).

2015

Knowledge gained from the accident at Fukushima was integrated into the activities
The knowledge gained from the Fukushima accident must be taken into account related to safety culture at the NPPs and at ENSI during 2012, and this will be continued
in the programmes to foster and develop the safety culture in Swiss nuclear
in subsequent years as part of the regular activities related to safety culture. The
power plants.
knowledge gained from activities related to safety culture and supervisory culture will besummarised by ENSI in a report during 2015 (see PP30 and section 4.1).

34 PP34

37 PP37

25 | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | ENSI

Annex 2: List of open points from the EU stress tests
Status /action plan

Description

Implementation text

38 OP2-1

LA

ENSI will follow up on the question as to whether in the Swiss nuclear power
plants automatic scrams should be triggered by the seismic instrumentation.

An upstream automatic scram by means of seismic instrumentation has not yet been
implemented in Swiss nuclear power plants. A working group was set up at ENSI in 2013.
A report on the advantages and drawbacks of an upstream automatic scram via theseismic instrumentation was completed at the start of 2015 (see section 3.1).

39 OP2-2

LA

In respect of seismic proof that has still to be supplied, ENSI will follow up on amore detailed examination of the seismic robustness of the isolation of thecontainment and the primary circuit.

Proof was submitted by the licensees in 2012 and the cursory review by ENSI wascompleted. The subsequent detailed review by ENSI was completed by mid-2013.

ENSI will follow up on measures to improve the seismic stability of thecontainment venting systems in case of beyond design basis accidents for KKG
and KKL.

Proof was submitted by the licensees in 2012 and the cursory review by ENSI wascompleted. The subsequent detailed review by ENSI was completed by mid-2013.

No.

Designation

40 OP2-3

LA

Based on the positive results from the review, it was possible to close OP2-2.

Based on the positive results from the review, it was possible to close OP2-3.
Proof was submitted by the licensees (KKB, KKG and KKM) in 2012. For KKB and KKM,ENSI determines that no cliff-edge effects from debris blockage are to be expected. At
the end of 2013, the licensees (KKB, KKG and KKM) submitted refined analyses based on
2D model calculations in combination with the transport of solid matter. ENSI reviewed
the refined analyses in 2014.

41 OP3-1

LA

ENSI will follow up on the impacts of a total debris blockage of hydraulicengineering installations.

42 OP4-1

2015

ENSI will follow up on the proofs of protection against extreme weather
conditions, including combinations thereof.

Requirements were defined by ENSI in 2012. In 2014, the operators submitted newhazard studies for this purpose, together with corresponding proof of the adequate
safety of the installations. ENSI will review this documentation in 2015.

LA

ENSI will follow up on the development of a comprehensive strategy for thetargeted deployment of the mobile accident management emergency diesels inorder to secure selected direct current and/or alternating current consumers in
the long term under total SBO (or an SBO) conditions.

Inspections of this aspect were carried out by ENSI in the fourth quarter of 2012. The
results were assessed in the first quarter of 2013. Follow-up measures will continue to besupervised by ENSI in the course of its ongoing supervisory activities.

From the point of view of risk minimisation, ENSI will follow up on the extent towhich the current deployment strategies for the venting systems in severe
accidents should be retained.

The deployment strategy for the containment venting systems in case of severe
accidents was re-examined during 2014 in connection with the issue of hydrogen
management. ENSI's review confirmed that hydrogen management in the Swiss nuclear
power plants is of a high standard, but that safety can be increased still further by taking
appropriate measures. One of ENSI's requests was for all the nuclear power plants tohave suitable passive means of counteracting the hydrogen hazard at their disposal.
Implementation of the requested backfitting measures is tracked in the course ofongoing supervisory activities.

43 OP5-1

44 OP6-1

LA

ENSI | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | 26

No.

Designation

45 OP6-2

46 PRT-1

47 PRT-2

Status /action plan

Description

2015

ENSI will follow up on whether restoring containment integrity during shutdown ENSI specifically defined the need for clarification at the start of 2014, and all theoperators submitted their responses promptly (by the end of October 2014). The
in case of a total SBO represents a time-critical measure.
information submitted by the operators will be reviewed in 2015.

2015

LA

The peer review team recommends considering the assessment of margins withrespect to extreme weather conditions exceeding the design bases, e.g. byextending the scope of future PSRs.

It is recommended that the regulator assesses the opportunity of requiring morereliance on passive systems for hydrogen management for severe accident
conditions. It is also recommended that the regulator considers further studies
on the hydrogen management for the venting systems.

Implementation text

ENSI specified detailed requirements for the probabilistic hazard analyses and the proofof adequate protection of plants against extreme weather conditions in 2012. In 2014, thelicensees submitted their safety cases to ENSI, including an appreciation on theavailability of safety margins. ENSI will complete its review of the operators' informationin 2015.
In 2013, ENSI required a reconsideration of various aspects of the hydrogen hazard incase of severe accidents in the reactor. The topics are: analyses of the hydrogen hazard,
including the propagation of hydrogen from the containment into other buildings of thenuclear power plant, robustness and scope of the measuring equipment, measures andprocedures in place, and review of the containment venting path.
The operators submitted the installation-specific studies promptly by the end of June
2014. After a detailed review, ENSI has concluded that each plant has adequate
preventive measures in place against the hydrogen hazard in case of beyond design basis
accidents. Nevertheless, appropriate measures could further increase safety in all theplants. One of ENSI's requests was for all the nuclear power plants to have suitablepassive means of counteracting the hydrogen hazard at their disposal. ENSI will continue
to track the implementation of the measures and/or backfittings in the course of ongoingsupervision.

27 | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | ENSI

6

Abbreviations

AM

Accident Management

BST ABCN

Federal NBCN Crisis Management Board(Bundesstab für ABCN-Ereignisse)

CDF

Core Damage Frequency

CNS

Convention on Nuclear Safety

ENSI

Swiss Federal Nuclear Safety Inspectorate(Eidgenössisches Nuklearsicherheitsinspektorat)

ENSREG

European Nuclear Safety Regulators GroupERSIM

Increase in Safety Margins

EU

European Union

FOCP

Swiss Federal Office for Civil Protection

FOEN

Federal Office for the Environment

FOPH

Federal Office of Public Health

GSKLGroup of Swiss Nuclear Power Plant Managers(Gruppe der schweizerischen Kernkraftwerksleiter)

IAEA

International Atomic Energy Agency

IDA NOMEXInterdepartmental Working Group to Review Emergency Preparedness Measures incase of Extreme Events in Switzerland(Interdepartementale Arbeitsgruppe zur Überprüfung derNotfallschutzmassnahmen bei Extremereignissen in der Schweiz)

IRRS

Integrated Regulatory Review Service

KKM SVS

Consultation and Coordination Mechanism of the Swiss Safety Network(Konsultations- und Koordinationsmechanismus Sicherheitsverbundes Schweiz)

MADUK

Monitoring network for automatic dose rate measurement in the vicinity of nuclear
power plants(Messnetz zur automatischen Dosisleistungsüberwachung in der Umgebung der
Kernkraftwerke)

NAcP

National Action Plan

NEOC

National Emergency Operations Centre

NPP

Nuclear Power Plant

ENSI | F u k u s h i m a A c t i o n P l a n 2 0 1 5 | 28

NRA

Nuclear Regulation Authority

OBE

Operating Basis Earthquake

OP

Open Point

OSART

Operational Safety Review TeamPAR

Passive Autocatalytic Recombiner

PEGASOSProbabilistic Seismic Hazard Analysis for Swiss Nuclear Power Plant Sites(Probabilistische Erdbebengefährdungsanalyse für die KKW-Standorte in der
Schweiz)

PGA

Peak Ground Acceleration

PP

Checkpoint(Prüfpunkt)PRP

PEGASOS Refinement Project

PRP-IH

PRP Intermediate Hazard

PSR

Periodic Safety Review

RANET

IAEA Response and Assistance Network

REMPAN

WHO Radiation Emergency Medical Preparedness and Assistance Network

RHWG

WENRA Reactor Harmonisation Working Group

SAMG

Severe Accident Management Guidelines

SBO

Station Blackout

SRL

Safety Reference Level

SSE

Safe Shutdown Earthquake

WENRA

Western European Nuclear Regulators’ Association

WHO

World Health Organisation

Issued by
Swiss Federal Nuclear Safety Inspectorate ENSI
Industriestrasse 19
CH-5200 Brugg
Phone +41 (0)56 460 84 00
Fax+41 (0)56 460 84 99
info@ensi.ch
www.ensi.ch
ENSI-AN-9106
Published 28.02.2015