COMMISSION STAFF WORKING PAPER Technical Summary of the national progress reports on the implementation of comprehensive risk and safety assessments of the EU nuclear power plants
Date: 2011-11-24
Institutions: European Commission
Subjects: EU Member State, Switzerland, Ukraine, international cooperation, nuclear power station, nuclear safety, nuclear test

EUROPEAN COMMISSION 

Brussels, 24.11.2011 
SEC(2011) 1395 final 

COMMISSION STAFF WORKING PAPER 

Technical Summary of the national progress reports on the implementation of 
comprehensive risk and safety assessments of the EU nuclear power plants 

Accompanying the document 

COMMUNICATION FROM THE COMMISSION TO THE COUNCIL AND THE 
EUROPEAN PARLIAMENT 
on the interim report on the comprehensive risks and safety assessments ("stress tests") 
of nuclear power plants in the European Union 

{COM(2011) 784 final} 

 
 
 
 
  
 
 
 
1. 

PROGRESS REPORTS RECEIVED 

All  14  EU  Member  States  currently  operating  NPPs  sent  their  progress  reports1,  as  well  as 
Lithuania2.  From  neighboring  countries,  Switzerland  and  Ukraine  sent  progress  reports.  All 
Member State reports were received by the given deadline (15.9.). With the exception of the 
Ukrainian report, all national progress reports are published integrally on the internet3. 

The reports are different in scope, format, length and level of detail. Despite these differences 
in the approaches chosen by Member States and participating neighbouring countries, it was 
possible  to  make  a  basic  comparison,  summarise  the  country-specific  situations  and  extract 
some first cross-country findings. 

2. 

SUMMARIES OF MEMBER STATE REPORTS  

On the basis of the national progress reports submitted, the following country-specific short 
summaries can be made: 

2.1. 

BELGIUM 

Context: Belgium has 7 reactors (all PWRs) on 2 sites (Doel, Tihange), generating more than 
half of its electricity.  

Scope of Stress Tests: Stress tests are also foreseen for nuclear facilities other than operating 
NPPs  (fuel  fabrication  plant,  waste  treatment  and  storage  facilities,  radioisotope  production 
facility, research centres), and include man-made events (terrorist attacks, aircraft crash, cyber 
attack, toxic and explosive gases, blast waves).  

Short  Summary:  Limited  amount  of  technical  details,  but  work  to  be  performed  is  defined, 
seems to correspond to the required scope, and to progress as planned. Overall, the regulator 
considers  that  the  process  engaged  by  the  licensee  to  prepare  its  stress  tests  report  is 
appropriate and efficient. Working  groups set  up are considered well suited and sufficiently 
staffed. Planned tasks are performed on schedule and a substantial amount of technical data is 
now available for synthesis in the final reports. The regulator considers the effort mobilized so 
far by the licensee well suited to successfully complete the task. The report mentions several 
improvements already implemented in the areas of additional cooling water supplies for the 
SFPs  during  SBO  and  the  reinforcement  of  the  seismic  resistance  of  some  parts  of  the 
facilities. The inspections conducted by the regulator showed that some of the improvements 
are  already  operational  and  the  formal  implementation  of  the  other  improvements  is  still 
ongoing. 

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Belgium,  Bulgaria,  Czech  Republic,  Finland,  France,  Germany,  Hungary,  Netherlands,  Romania, 
Slovak Republic, Slovenia, Spain, Sweden, United Kingdom.  

Despite closure of the last NPP unit in Ignalina in 2009 in fulfillment of the Lithuanian EU Accession 
obligations,  there  are  still  site-specific  operating  licenses  in  place  as  well  as  significant  amounts  of 
spent fuel stored on-site.  

www.ensreg.eu  

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2.2. 

BULGARIA 

Context: Bulgaria has 2 reactors (all VVER-1000) on 1 site (Kozloduy) generating about 35% 
of its electricity. Construction of a new plant in Belene is planned. 

Scope  of  Stress  Tests:  In  addition  to  the  two  operating  units  in  Kozloduy,  the  report  covers 
also Unit 3 and 4 (permanently shut down with fuel still stored in SFPs).  

Short  Summary:  Limited  amount  of  technical  details  and  limited  amount  of  information  on 
actions  taken  or  preliminary  results.  Progress  report  covers  mostly  existing  design  features. 
However, work to be performed is defined, seems to correspond to the required scope, and to 
progress globally as planned even though in some areas there seems to be some delay at this 
stage  (still  ongoing  work  for  the  licensee  to  submit  the  progress  report  to  the  regulator  for 
some areas). Review of licensee's report is ongoing, both with regard to design basis events 
and evaluation of safety margins. 

2.3. 

CZECH REPUBLIC 

Context:  The  Czech  Republic  has  6  reactors  (4  VVER-440,  2  VVER-1000)  at  2  sites 
(Dukovany,  Temelín)  generating  about  one-third  of  its  electricity.  In  August  2009  a  public 
tender for contractors to build 2 new reactors in Temelín was opened, planning to bring them 
online in 2020.  

Short  Summary:  Very  limited  amount  of  technical  details,  but  work  to  be  performed  is 
defined,  seems  to  correspond  to  the  required  scope,  and  to  progress  as  planned.  So  far,  no 
immediate actions have been identified or taken.  

Specific Issues: The licensee's reports on NPP stress tests at the two sites include evaluations 
based  on  BDBA  analyses  carried  out  in  the  past,  covering  specified  accidents  caused  by 
natural  disasters  and  their  potential  impact  on  the  operability  of  important  safety  systems, 
such  as  LOOP,  SBO  and  LUHS.  According  to  the  report,  even  first  evaluations  clearly 
confirm  that  the  sites  are  not  exposed  to  extreme  natural  hazards  which  could  pose  a 
significant risk to a NPP. It is mentioned that risk of LOOP is a relevant issue in the Czech 
Republic, especially with respect to the installed output of renewable power sources. 

2.4. 

FINLAND 

Context:  Finland  has  4  reactors  (2  VVER-440,  2  BWRs)  on  2  sites  (Loviisa,  Olkiluoto) 
providing nearly 30% of its electricity. A fifth reactor (EPR) is now under construction and 2 
more are planned.  

Short Summary: Detailed and technically informative report, work to be performed is clearly 
defined,  seems  to  correspond  to  the  required  scope,  and  to  progress  as  planned.  Based  on 
evaluations  carried  out  after  Fukushima,  it  has  been  concluded  that  deficiencies  demanding 
immediate plant modifications do not exist. However, some modifications to further improve 
safe plant operation are envisaged. 

Specific Issues:  

– 

Earthquake:  The  seismic  PSA  from  2010  resulted  in  introducing  some  safety 
improvements to further decrease the risk. The latest PSA shows that only about 2% 

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of  the  CDF  is  due  to  earthquakes.  Additional  studies  on  seismic  robustness  of  the 
fuel pools and the fire water systems are being conducted.  

– 

Other: Some areas for possible improvements are already identified in some plants, 
such as measures in relation to increasing the robustness: 

– 

– 

against LOOP, SBO and LUHS (ongoing investigations namely related to the 
possible  use  of  transportable  AC  power  sources,  additional  diesel  driven 
emergency feed water pumps, analysis of alternative heat transfer means to the 
atmosphere, injection of fire fighting water into reactor pressure vessel, water 
supply from independent sources), and  

of  SFPs  (ongoing  investigations  namely  related  to  the  reliability  increase  of 
SFP  inventory  makeup  using  reliable  electric  power  and  permanent  piping, 
SAM  analysis  and  implementation  of  strategies  for  the  SFPs  including 
hydrogen  management,  enhancement  of  SFP  water  level  and  temperature 
measurements). 

2.5. 

FRANCE 

Context:  France has  58 reactors (PWRs of  3 standard types) at 19 sites  (Belleville, Blayais, 
Bugey,  Cattenom,  Chinon,  Chooz,  Civaux,  Cruas,  Dampierre,  Fessenheim,  Flamanville, 
Golfech, Gravelines, Nogent, Paluel, Penly, St. Alban, St. Laurent, Tricastin) generating over 
75%  of  its  electricity  from  nuclear  energy.  1  EPR  is  under  construction,  another  one  is 
planned.  

Scope  of  Stress  Tests:  The  French  stress  tests  concern  virtually  all  the  150  nuclear 
installations and not just the power reactors, including for example the EPR reactor currently 
under construction and the La Hague fuel reprocessing plant. The final report will cover 80 
priority installations, including all NPPs. On some topics (industrial hazards, nearby roads and 
railways) the report goes beyond ENSREG specifications. 

Short  Summary:  No  technical  information  included  in  the  progress  report,  but  work  to  be 
performed is defined, seems to correspond to the required scope, and to progress as planned. 
To  ensure  full  transparency  of  the  French  stress  tests,  France  is  broadly  involving 
stakeholders (non-governmental organizations, elected officials, union representatives, etc) in 
different steps of the process. Additionally, some foreign experts from Germany, Switzerland, 
Belgium  and  Luxembourg  participated  on  their  request.  According  to  the  report,  a  large 
number  of  analyses  will  apply  generically  to  all  reactors  since  the  French  nuclear  fleet  is 
largely  standardized.  Consideration  of  specific  scenarios  for  given  sites  is  requested  by  the 
French  regulator.  An  initiative  to  establish  a  national  “Rapid  Action  Force”  in  charge  of 
bringing  in  a  timely  manner  human  and  material  support  to  the  affected  site  in  case  of  an 
accident is also under consideration.  

2.6. 

GERMANY 

Context: Germany until March 2011 obtained about one quarter of its electricity from nuclear 
energy, using 17 reactors (11 PWRs, 6 BWRs) at 12 sites (Brunsbüttel, Brokdorf, Krümmel, 
Unterweser,  Emsland,  Grohnde,  Grafenrheinfeld,  Biblis,  Philippsburg,  Neckarwestheim, 
Gundremmingen,  Isar).  The  government  formed  after  the  1998  federal  elections  had  the 
phase-out  of  nuclear  energy  as  an  element  of  its  policy.  With  a  new  government  formed  in 

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2009, the  phase-out  was pushed back by around  10  years in 2010, but confirmed for 2021–
2022 in 2011 as a direct political consequence of Fukushima. 

Scope  of  Stress  Tests:  German  stress  tests  are  broader  than  the  ENSREG  specification, 
covering  also  several  man-induced  events,  such  as  aircraft  crash,  blast  wave,  toxic  gases, 
terrorist and cyber attacks. 

Short Summary: Detailed and technically informative report, work to be performed is clearly 
defined, seems to correspond to the required scope, and to progress as planned. Germany has 
launched a domestic safety review before the start of the EU stress tests, based on the German 
Reactor  Safety  Commission  approach  using  the  concept  of  robustness  levels.  To  assess 
robustness,  three  levels  have  been  proposed  for  all  the  topics  to  be  analysed.  These  levels 
reflect the assurance of the required safety functions to prevent “cliff edge” effects. The report 
states that the stress tests are progressing according to the agreed schedule. According to the 
report, the current findings show a high level of robustness.  

Some areas for possible improvements are already identified, such as measures in relation to 
increasing  the  robustness  of  NPPs  against  SBO  and  LUHS,  and  improving  plant-specific 
SAM  and  implementing  SAMG.  Quantitative  assessment  criteria  and  their  consistency  for 
beyond  design  basis  events  and  postulated  unavailabilities  of  safety  systems  are  still  under 
development.  

2.7. 

HUNGARY 

Context: Hungary has 4 reactors (all VVER-440) at 1 site (Paks) generating more than one-
third of its electricity. New nuclear capacity is under consideration, and 2 new units for Paks 
are proposed.  

Short Summary: Detailed and technically informative report, work to be performed is clearly 
defined, seems to correspond to the required scope, and to progress as planned. Some areas 
for  possible  improvements  are  already  identified,  such  as  measures  in  relation  to  increasing 
the robustness of NPPs against BDBE, dynamic effects of flooding and SBO, increasing the 
robustness of the SFPs, and introducing plant-specific SAMG. 

Specific Issues:  

– 

– 

Earthquake:  Regarding  the  ongoing  BDBA  investigations,  some  findings  which 
require  detailed  safety  assessment  and  possibly  corrective  actions  were  already 
identified.  

Severe  accident  management  &  emergency  management:  In  Unit  1,  technical 
modifications  have  already  been  completed,  and  the  introduction  of  SAMGs  will 
begin  at  the  end  of  2011.  Technical  modifications  and  introduction  of  SAMGs 
regarding  the  other  units  will  be  completed  by  2014.  The  report  highlights  some 
areas  for  improvement  under  evaluation,  mainly  concerning  the  containment 
integrity through:  

– 

– 

Installation of passive autocatalytic recombiners by end of 2011 at all 4 units; 

Installation of a containment filtered venting system; 

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– 

– 

Analyses  of  hydrogen  generation  and  distribution  when  a  nuclear  accident 
involves several reactors and/or SFPs simultaneously; 

Analysis of possible mitigation measures after a severe accident in the SFP. 

2.8. 

LITHUANIA 

Context: As part of its EU Accession commitments, Lithuania closed the last of its 2 reactors 
(all RBMK) at the Ignalina site at the end of 2009. Despite closure of Ignalina, there are still 
several  site-specific  valid  licenses,  for  example  to  operate  the  storage  facility  for  the 
significant  amounts  of  spent  fuel.  Plans  for  a  new  plant  with  or  without  involving 
neighbouring countries are in place. 

Short  Summary:  Limited  amount  of  technical  details  and  reference  to  the  final  report,  but 
work to be performed is defined, seems to correspond to the required scope, and to progress 
as planned. Some areas for possible improvements are already identified, such as measures in 
relation to increasing the robustness of the SFPs against BDBE. 

Several potential corrective measures are identified, such as the provision of alternative means 
to  makeup  water  inventory  to  Unit  2  reactor  core  and  the  SFPs,  means  to  supply  neutron 
absorbers to the SFPs, and alternative power supply in case of SBO. A number of preliminary 
conclusions and recommendations identified for the new interim spent fuel storage include the 
analysis of BDBE, scenarios of cask turnover and tightness failure during transportation, cask 
blockage  by  debris  after  collapse  of  the  storage  hall,  and  cracks  or  collapse  of  the  hot  cell 
while spent fuel is being handled. The possible installation  of  new  mobile diesel generators 
has been identified as a preliminary recommendation. 

2.9. 

NETHERLANDS 

Context: The Netherlands has 1 reactor (PWR) at 1 site (Borssele) generating about 4% of its 
electricity. A large new unit is proposed.  

Scope of Stress Tests: The scope of the Dutch stress tests has been broadened to cover also 
other  nuclear  facilities  in  addition  to  the  NPP.  Research  reactors  in  Petten  and  Delft,  the 
URENCO enrichment plant in Almelo, and the COVRA radioactive waste storage facility in 
Vlissingen  will  be  covered  as  well.  However,  the  results  on  these  facilities  will  not  be 
presented  in  the  final  report.  The  implementation  of  the  stress  test  is  also  enhanced  by 
bilateral collaboration with the Belgian regulator. The scope of the stress tests has also been 
extended  to  include  additional  initiating  events,  such  as  large  grid  disturbances,  airplane 
crash,  explosion  pressure  wave,  electromagnetic  pulse,  toxic  gasses,  running  aground  of  a 
ship, cyber attack and biological phenomena. 

Short Summary: Limited amount of technical details, no details about the preliminary results, 
but  work  to  be  performed  is  defined,  and  seems  to  progress.  The  regulator  informed  the 
licensee that the progress report contains too little information and requested complementary 
information  about  the  adopted  scenarios  and  methodologies,  the  progress  so  far  and  the 
quality assurance. Further, it was noted that the licensee's progress report only considers the 
NPP as it is built and operated on 30.6.2011, i.e. with only U-fuel. Since a license has already 
been given for the use of MOX-fuel, regulator informed licensee that also MOX-fuel should 
be included in the analysis. Further, it is stated that actions will follow-up on the short term 
measures undertaken by the licensee immediately after Fukushima, including verification of 

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the NPP's capability to cope with BDBA, SBO, internal and external flooding, as well as its 
capability to mitigate fire and flooding after a seismic event.  

2.10.  ROMANIA  

Context: Romania has 2 reactors (CANDU 6) at 1 site (Cernavoda) generating almost 20% of 
its  electricity.  Plans  are  advanced  for  completing  2  more  units  at  Cernavoda.  The  regulator 
agreed that any potential design changes resulting from the stress tests will be implemented in 
the designs of Cernavoda Units 3 and 4. More plants are proposed at different sites.  

Short Summary: The report shows good progress, provides preliminary results and technical 
design  information,  and  mentions  possible  safety  improvements.  Several  concrete  areas  for 
improvement are identified in order to increase the robustness of the plant, such as measures 
against hydrogen build up and slow containment over-pressurisation. Installations of passive 
autocatalytic hydrogen re-combiners and containment emergency filtered venting systems are 
planned.  The  report  highlights  also  technical  improvements  in  the  field  of  SAM  that  are 
already  in  place,  such  as  the  procurement  of  mobile  diesel  generators  and  specific  EOP  to 
cope with SBO and loss of SFP cooling events. Special attention has been paid to improve the 
existing SAM communication systems. Improvements are also planned for the survivability of 
key instrumentation in BDBA conditions. 

Specific Issues:  

– 

– 

Earthquake: First, a seismic design basis review was performed, and both the level 
of  earthquake  against  which  the  NPP  is  designed  and  the  methodology  used  to 
evaluate the DBE have been found adequate. Preliminary seismic margin assessment 
showed that in comparison with the original DBE of 0.2 g (at 10-3 per year), all SSCs 
which  are  part  of  the  safe  shutdown  path  after  an  earthquake  would  continue  to 
perform  their  safety  function  up  to  0.4  g  (at  5×10-5  per  year).  This  margin  is 
considered adequate by the regulator. 

Severe  accident  management  &  emergency  management:  The  main  challenges 
identified  are  due  to  hydrogen  build  up,  slow  containment  over-pressurization  and 
molten  core–concrete  interaction.  Safety  improvement  measures  already  planned 
comprise,  among  other,  hydrogen  re-combiners,  containment  emergency  filtered 
venting systems and mobile diesel generators.  

2.11. 

SLOVAKIA  

Context: Slovakia has 4 reactors (all VVER-440) on 2 sites (Bohunice, Mochovce) generating 
about  half  of  its  electricity  and  2  more  under  construction  in  Mochovce.  The  2008  national 
Energy Security Strategy aims to maintain the proportion of electricity generated by NPPs at 
around  50%  by  means  of  power  uprates  and  construction  of  a  new  reactor  at  Bohunice  in 
addition to completing Mochovce 3-4. 

Short  Summary:  Limited  amount  of  technical  details,  but  work  to  be  performed  is  defined, 
seems  to  correspond  to  the  required  scope,  and  to  progress  as  planned.  Although  the  report 
does  not  identify  any  needs  for  immediate  actions,  additional  safety  upgrades  are  being 
studied to increase the existing safety margins against beyond design basis events. Although 
with  a  focus  on  the  two  units  currently  under  construction  in  Mochovce,  some  areas  for 
improvement  possibly  relevant  also  for  other  units  have  already  been  identified,  such  as 
measures to increase the robustness of plants against BDBE and external flooding.  

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Specific Issues:  

– 

– 

Earthquake: Earthquakes are relevant safety issues considered in the plant design at 
both  sites  (max.  horizontal  acceleration  in  Mochovce  is  0.143 g  and  0.344 g  in 
Bohunice  at  10-4  per  year).  Seismic  margin  assessment  is  ongoing  and  will  be 
summarized in the final national report. 

Severe  accident  management  &  emergency  management:  The  progress  report 
highlights  that  some  improvements  have  already  been  implemented  in  the  last  few 
years to extend the capabilities of the NPPs to cope with severe accidents. Additional 
safety improvement measures are currently under evaluation, such as: 

– 

– 

– 

– 

Adoption of measures to flood the reactor cavity in order to ensure the outside 
cooling of the reactor pressure vessel; 

Protection  of  the  containment  against  uncontrollable  hydrogen  burning  by 
means of passive autocatalytic recombiners and igniters; 

Protection  of  the  containment  against  overpressure  and  high  temperature  by 
containment spray using a dedicated borated water tank; 

Setting up an offsite plant control center for SAM. 

2.12. 

SLOVENIA 

Context:  Slovenia  has  1  reactor  (PWR)  at  1  site  (Krško)  generating  about  40%  of  its 
electricity. New nuclear capacity is under consideration.  

Short  Summary:  The  report  is  very  comprehensive,  well-structured  and  provides  valuable 
technical  details.  It  indicates  that  the  stress  test  is  well  ahead  of  schedule,  as  most  of  the 
specified  requirements  have  already  been  dealt  with.  The  work  to  be  performed  is  clearly 
defined and seems to correspond to the required scope. Some areas for possible improvements 
are  already  identified,  such  as  measures  in  relation  to  increasing  the  robustness  of  the  NPP 
against  BDBE,  flooding,  LOOP  and  LUHS.  Several  safety  improvements  are  already 
implemented  as  result  of  the  stress  tests.  Critical  disruption  of  plant  supplies  due  to 
infrastructure destruction has been considered.  

Specific Issues:  

– 

– 

– 

Earthquake - NPP: According to the report, a number of measures have already been 
implemented  at  the  plant  to  increase  its  seismic  robustness  –  no  need  for  further 
work/measures mentioned.  

Earthquake  -  SFP:  SFP  was  not  evaluated  in  the  context  of  the  Krško  SPSA,  only 
NPP. For earthquakes up to about 0.9 g, it is considered that SFP integrity would not 
be  challenged.  For  earthquakes  >0.9  g,  gross  structural  failures  of  SFP  cannot  be 
excluded. It is considered likely that fuel uncovery would then occur (i.e. at ≤10-5 per 
year). No further work mentioned.  

Severe  accident  management  &  emergency  management:  SAM  evaluations  were 
performed  (for  NPP  and  SFP)  as  well  as  emergency  management  evaluations. 
Updated SAMG are in place. No further work/measures mentioned in the report.  

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2.13. 

SPAIN  

Context: Spain gets about one fifth of its electricity from nuclear energy, using 8 reactors (6 
PWRs,  2  BWRs)  at  6  sites  (Almaraz,  Ascó,  Cofrentes,  Sta.  Maria  de  Garoña,  Trillo, 
Vandellós). By government decision Sta. Maria de Garoña has been granted a life extension 
of 2 years and will be shutdown in 2012, although the regulator had accepted the extension for 
10 years as submitted by the operator. 

Scope of Stress Tests: Stress tests are also foreseen for a nuclear fuel manufacturing facility.  

Short Summary: Detailed and technically informative report, work to be performed is clearly 
defined, seems to correspond to the required scope, and to progress as planned. All sites have 
addressed  almost  all  points  of  the  stress  test  requirements,  and  the  regulator  considers  the 
progress  reports  as  complete  and  appropriate.  Some  areas  for  possible  improvements  are 
already  identified,  such  as  measures  in  relation  to  increasing  the  robustness  of  the  NPPs 
against BDBE, flooding, LOOP and LUHS, as well as SAM.  

Specific Issues:  

– 

– 

Earthquake:  According  to  the  report,  the  existing  DBEs  were  re-assessed  for  all 
sites, and seismic margins are being reviewed for a horizontal acceleration of 0.3 g, 
from 1.5 to 3 times the design basis.  

Severe  accident  management  &  emergency  management:  The  licensees  propose  to 
set up a common support centre for all the plants equipped with all necessary human 
and material resources to intervene in any plant within a maximum of 24 hours. 

2.14. 

SWEDEN  

Context: Sweden has 10 reactors (7 BWRs and 3 PWRs) at 3 sites (Oskarshamn, Forsmark, 
Ringhals)  providing  over  40%  of  its  electricity.  In  June  2010,  the  abolishment  of  the  act 
banning  construction  of  new  reactors  was  approved  by  Parliament,  with  construction  being 
possible at existing sites and to replace the present 10 units. This is part of the government's 
climate  program,  which,  among  other  targets,  stipulates  that  the  country  should  be  carbon-
neutral by 2050. 

Short Summary: Detailed and technically informative report, work to be performed is clearly 
defined, seems to correspond to the required scope, and to progress as planned. Some areas 
for  possible  improvements  are  already  identified,  such  as  measures  in  relation  to  increasing 
the  robustness  of  NPPs  against  BDBE  and  flooding,  as  well  as  to  further  improving  some 
SAM measures. Assessment of hydrogen accumulation and combustion needs further studies. 

Specific Issues:  

– 

Earthquake:  According  to  the  report,  assessments  are  proceeding  according  to 
schedule.  Remaining  work  includes  renewed  verification  of  plant  design  against 
DBE  and  BDBE  analysis.  DBE  characterized  by  a  set  of  ground  response  spectra 
corresponding  to  an  exceedance  frequency  of  10-5  per  site  and  year.  The  8  oldest 
NPPs  were  initially  not  analyzed  and  designed  to  withstand  a  specified  earthquake 
and  are  thus  not  fully  verified  against  DBE.  Analyses  will  be  limited  to  a  seismic 
load level of 10-7 per site and year.  

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2.15.  UNITED KINGDOM 

Context:  The  UK  has  18  reactors  (MAGNOX,  AGR,  PWR)  at  9  sites  (Oldbury,  Wylfa, 
Dungeness,  Hartlepool,  Heysham,  Hinkley  Point,  Hunterston,  Torness,  Sizewell)  generating 
about  15%  of  its  electricity,  and  all  but  one  will  be  shut  down  by  2023.  The  government 
assumes that there will be a requirement of 60 GWe of net new generating capacity by 2025, 
of  which  35  GWe  is  to  come  from  renewables  and  the  expectation  is  for  "a  significant 
proportion" of the remaining 25 GWe to come from new nuclear. 

Short  Summary:  Limited  amount  of  technical  details,  but  work  to  be  performed  is  defined, 
seems to correspond to the required scope, and to progress as planned. The report describes 
the progress of the licensees’ reassessments, the organization set up by those licensees and the 
works still to be done by both licensees and the regulator. The report provides only very little 
information  about  the  contents  and  the  preliminary  results.  Some  areas  for  possible 
improvements are already identified, such as measures in relation to increasing robustness of 
NPPs against flooding and LUHS.  

Specific Issues:  

– 

– 

Earthquake:  Work  is  ongoing.  The  exact  nature  of  modifications  and  additional 
equipment  to  further  improve  resilience  where  reasonably  practicable  has  not  yet 
been fully developed for any of the licensees or sites. 

Flooding: Work is ongoing. As an example, one licensee has indicated that resilience 
enhancements  under  consideration  include  provision  of  additional  local  flood 
protection to key equipment and provision of further emergency back-up equipment 
to  provide  cooling  and  power.  Additional  studies  are  being  prepared  to  re-consider 
flood modelling for specific sites and to review recent climate change information. 

3. 

SUMMARIES OF NEIGHBOURING COUNTRIES' REPORTS 

Several neighbouring countries expressed an interest to participate in the stress tests. So far, 
Switzerland and Ukraine sent their progress reports. 

3.1. 

SWITZERLAND  

Context:  Switzerland  has  5  reactors  (3  PWRs,  2  BWRs)  on  4  sites  (Beznau,  Leibstadt, 
Gösgen,  Mühleberg)  generating  about  40%  of  its  electricity.  Two  large  new  units  were 
planned.  A  national  vote  had  recently  confirmed  nuclear  energy  as  part  of  Switzerland's 
electricity  mix.  However,  following  Fukushima,  in  June  2011  parliament  resolved  not  to 
replace any reactors, and hence to phase out nuclear power by 2034.  

Short Summary: Detailed and technically informative report, work to be performed is clearly 
defined, seems to correspond to the required scope, and to progress as planned. Some areas 
for  possible  improvements  are  already  identified,  such  as  measures  in  relation  to  increasing 
the robustness of the NPPs against BDBE and flooding.  

Specific Issues:  

EN 

10 

   EN 

 
– 

– 

– 

in  accordance  with 

Earthquake: Regarding seismic risk, in 1999 the operators were requested to perform 
including 
re-evaluations 
comprehensive  quantification  of  uncertainties.  It  was  shown  that  in  the  past  the 
seismic  hazard  had  been  underestimated.  On  the  basis  of  this  insight,  the  regulator 
required  the  PSAs  of  all  NPPs  to  be  reassessed.  The  new  PSA  results  demonstrate 
that all Swiss plants satisfy the IAEA criterion on CDF. 

the  most  advanced  methods, 

Flooding: It is stated that several hazard levels for external flooding are considered. 
Regarding analysis of safety margins, a need for harmonization of procedures for all 
operators has been identified. Furthermore, it is considered necessary that sensitivity 
studies on potential cliff-edge effects are undertaken. 

Other: In June 2011, an external storage facility for emergency equipment shared by 
all NPPs was set up as requested by the regulator.  

3.2. 

UKRAINE 

Context:  Ukraine  has  15  reactors  (all  VVER)  in  operation  at  4  sites  (Khmelnitski,  Rovno, 
South  Ukraine,  Zaporozhe)  generating  about  half  of  its  electricity.  Completion  of  2  VVER 
units at Khmelnitski as well as construction of new nuclear capacity is planned.  

Short  Summary:  Very  limited  amount  of  technical  details,  but  work  to  be  performed  is 
defined,  and  seems  to  progress  according  to  the  agreed  schedule.  For  the  operating  plants, 
preliminary  results  are  available.  Walkdowns  in  all  plants  performed.  Ukraine,  as  a 
neighbouring country, has adopted a different timing for the stress tests, with progress reports 
to be presented by the licensees to the regulator by 15.10.2011.  

Specific Issues:  

– 

– 

– 

External  initiating  events:  Based  on  the  preliminary  assessments,  the  NPPs  must 
continue  improving  seismic  qualification  of  SSCs  important  to  safety.  As  for 
flooding, the implementation of technical and organizational measures to cope with 
possible  damages  of  dams  at  the  Dnieper,  mostly  for  Zaporozhe  site,  is  one  of  the 
priority actions. Regarding extreme weather conditions, the report states that specific 
measures have to be implemented to strengthen NPP resistance to tornadoes. 

Severe  accident  management  &  emergency  management:  The  following  areas  for 
improvement have been identified at this stage: Absence of mobile devices to supply 
power to equipment and water, absence of design features for containment protection 
against overpressure, as well as absence of hydrogen concentration control features 
under severe accident conditions.  

Other:  Priorities  for  safety  enhancement  defined.  Shortcomings  in  electrical  power 
supply  identified.  Evaluations  on  hydrogen  hazards  and  containment  overpressure 
performed, impact analysis ongoing.  

EN 

11 

   EN 

 
•  GLOSSARY 

•  AC Alternating Current 

•  AGR 

Advanced Gas Cooled Reactor 

•  BDBA 

Beyond Design Basis Accident 

•  BDBE 

Beyond Design Basis Earthquake 

•  BWR 

Boiling Water Reactor 

•  CANDU  Canada Deuterium Uranium (Pressurised Heavy Water) Reactor 

•  CDF 

Core Damage Frequency  

•  DBE 

Design Basis Earthquake 

•  ENSREG  European Nuclear Safety Regulators Group 

•  EOP 

Emergency Operating Procedure 

•  EPR 

Evolutionary Power Reactor 

•  LOOP 

Loss Of Offsite Power 

•  LUHS 

Loss of Ultimate Heat Sink 

•  NPP 

Nuclear Power Plant 

•  PSA 

Probabilistic Safety Assessment 

•  PWR 

Pressurised Water Reactor 

•  SAM 

Severe Accident Management 

•  SAMG 

Severe Accident Management Guidelines 

•  SBO 

Station Blackout 

•  SFP 

Spent Fuel Pool / Pit 

•  SPSA 

Seismic Probabilistic Safety Assessment 

•  SSC 

Structures, Systems and Components 

•  UHS 

Ultimate Heat Sink 

•  VVER 

(Russian) Water Water Energetic Reactor 

EN 

12 

   EN