1. Licensing Aspects of new power plant EPR in Finland
NERS meeting in Vienna
September 23-24, 2004
Jukka Laaksonen
Director General
STUK-Radiation and Nuclear Safety Authority
Beijing, October 2004

2. Government decision on nuclear option
The Finnish Government made in January 2002 a Decision in Principle (DiP) which concludes that constructing of a new nuclear power plant (NPP) in Finland is in line with the overall good of the society. The Finnish Parliament ratified the decision in May 2002 with votes
DiP authorised the electricity generating company TVO to continue preparations for the construction of a new NPP unit.
Beijing, October 2004

3. Olkiluoto 3 licensing phases
Operating License
2008 ?
Construction
Construction License
first quarter 2005 ?
Technical part
Preparatory phase
Political part
Decision in Principle
Feasibility study
Environmental Impact
Assessment
Beijing, October 2004

4. Environmental Impact Assessment (EIA)
EIA is based on environmental legislation, it is not included in the Nuclear Energy Act
EIA provides useful input for the Decision in Principle which is the first step of NPP licensing according to the Nuclear Energy Act
EIA does not require specific information on plant type and technology
EIA was done separately for two alternative sites: Loviisa and Olkiluoto
Beijing, October 2004

5. Decision in Principle (1)
General criteria of approval
a new NPP is in line with the overall good of society
this is to be decided by the Government and confirmed by the Parliament
no safety issues can be foreseen that would prevent the proposed plant(s) from meeting Finnish nuclear safety regulations
this is assessed by STUK, full veto right
proposed host municipality agrees to provide the site
also municipality has full veto right
Beijing, October 2004

6. Decision in Principle (2)
General conclusions in STUK’s statement:
all alternative NPP’s mentioned in the application could probably be made to fulfil Finnish safety requirements, if certain modifications would be made
none of the plants seemed acceptable as presented, but some modifications would be needed in all designs (specific safety issues were identified for each alternative plant type)
TVO needs to develop the competence of its own organisation (taking into account the planned 60 years lifetime)
addition made at request of Ministry after September 11, 2001: it is possible to provide necessary protection even against worst plane crashes
Beijing, October 2004

7. Decision in Principle (3)
Government made its positive decision in January 2002 and sent it to Parliament for ratification. The following supporting arguments were given:
Importance for electrical power supply
Together with energy savings and increased use of renewable power sources a new NPP can keep the greenhouse gas releases within the agreed target.
STUK’s positive statement on nuclear safety
Site suitability and acceptable environmental impact
Adequate arrangements for supply of nuclear fuel and management of nuclear waste
Full private funding
Ability of the applicant to implement the construction project
Beijing, October 2004

8. Decision in Principle (4)
Parliament made a thorough assessment in 8 Committees before voting in the plenary session:
Out of the 200 Parliament members, 115 attended the work during spring 2002 in one or more committees. Each committee heard a very large number of experts (up to 85 in one committee) in order to get different views.
Beijing, October 2004

9. Arguments listed by the Parliament’s Commerce Committee in favour of a new NPP
A new plant helps to maintain multiple sources for power production, thus increasing self-sufficiency and improving preparedness for crisis
Production costs of nuclear power are smaller than costs of other alternatives
Accident risks are small
There are no releases to the atmosphere and also otherwise the environmental impact is small
From the national economics point of view, nuclear power is the best way to reduce carbon dioxide releases
Nuclear fuel supply and nuclear waste management can be arranged using the existing infrastructure
The only realistic alternative to a new NPP would be increased use of gas for power production, but this would strongly increase the dependence on import from Russia and increase the power price and the need for state support to the energy section
Beijing, October 2004

10. Public opinion after DiP ratification
A poll was conducted among the general public immediately after the Parliament ratification. A clear majority of those questioned approved the decision: 55 % were for, 31 against, and 13 undecided;
Main editorials in all larger newspapers welcomed the decision in a positive spirit. According to a study done for the Ministry for Trade and Industry, not a single main editorial took a negative position on the decision.
Discussion stopped very quickly, also opposition concluded that the final decision has been made.
nuclear power was not an issue in Parliament election in 2003
Beijing, October 2004

11. Milestones of the contracting stage
TVO started preparation of tender documents after DiP in May 2002
call for tenders out end of September 2002
tenders in end of March 2003
Vendor and site were decided in October 2003
two different plant types by vendor were still considered
site Olkiluoto
Contract was signed on the 19th of December 2003
plant vendor is Consortium Framatome ANP - Siemens, lead by FANP - Turnkey delivery
plant type is EPR MWe PWR
Beijing, October 2004

12. OL3 Comparison Table Type of plants N4 EPR (OL3) KONVOI
Core thermal power (MWth)
Net power output (MWe)  1400
Number of loops
N° of fuel assemblies
Type of fuel assemblies (17x17), (17x17), 25 (18x18), 24
Active length (cm)
Total F.A. length (cm)
Rod linear heat rate (W/cm)
N° of control rods
Beijing, October 2004

13. OL3 Comparison Table Type of plants N4 EPR (OL3) KONVOI
Total flow-rate (kg/s)
Primary pressure
Vessel outlet temp. (°C)
Vessel inlet temp. (°C)
S.G. heat exch. surface (m²)
Steam Pressure (bar)
Containment volume (m³)
Beijing, October 2004

14. OL3 main schedule Construction permit Construction Operating license
Trial Run
Operation
2003
2004
2005
2006
2007
2008
2009
2010
Beijing, October 2004

15. Construction Permit (CP) process (1)
Processing of the CP application, in consultation with the stakeholders, is the task of the Ministry of Trade and Industry
Construction Permit is to be granted by the Government
Government has publicly committed to take fast action after Ministry has received STUK’s statement on adequate safety
Beijing, October 2004

16. Construction Permit (CP) process (2)
Construction Permit application was submitted to the Ministry of Trade and Industry on January 8, 2004
All stakeholders except STUK have made their statements by April 30, as requested by ministry
no significant objections have been expressed against the CP
Ministry asked STUK to give its statement on safety of the plant by the end of 2004, if possible
gradually improving revisions of CP documents have been submitted to STUK between Jan-Sep 2004
Beijing, October 2004

17. Preparatory work before receiving the CP
Site works started immediately after signing the contract
Excavations m3 of soil and rock to be removed by end of 2004
Construction of site infrastructure: roads, power&water supply
Anchors for pre-stressing cables at the bottom of reactor building, installation of the reinforcing steels for bottom plate by April 2005
Reactor Pressure Vessel and SG’s were purchased already in early summer 2003 and manufacturing started in the fall 2003
Bids for subcontracts and subcontracting
Systems design, specification and purchase of equipment
First concrete to bottom plate is planned 1st May 2005
Beijing, October 2004

18. STUK activities during CP stage (1)
Review of submitted CP documentation
Auditing of activities of plant vendor
design process, project management
Independent calculations to validate accident analysis
both in-house and in co-operation with expert organisations, also contracted work
Beijing, October 2004

19. STUK activities during CP stage (2)
Meetings with license applicant and vendor
several meetings weekly on technical issues and quality management
STUK inspections on design and manufacturing of Reactor Vessel and Steam Generators started in October 2003
also other component specific inspections will start in parallel with CP application review
Beijing, October 2004

20. Support to STUK from experts organisations (1)
Finnish organisations
VTT: advice and independent analysis of several topics including PSA, water chemistry, postulated accidents, severe accidents and I&C validation, inspections of mechanical components to supplement STUK’s inspection resources
Lappeenranta Technical University: tests and assessment of approach to severe accident management
Beijing, October 2004

21. Support to STUK from experts organisations (2)
Foreign organisations
DGSRN and IRSN France: exchange of information on assessment of several design topics, in specific I&C systems
GRS Germany: assessment of Break Preclusion concept for primary and secondary systems; independent analysis and assessment of aircraft crash protection approach
ISaR Germany: independent analysis of specific accidents, assessment of the ECCS
Belgian consultant (retired from AVN ): digital I&C issues
Beijing, October 2004

22. Development of regulations in Finland (1)
The nuclear safety authority STUK has since early 1970’s developed Finnish safety regulations and kept them up to date
Safety requirements are based on national and international practices - IAEA Safety Standards are becoming increasingly important
The leading principle has been to incorporate the state-of-the-art in the nuclear safety technology into the safety requirements
operating experience
research
development of science and technology
Beijing, October 2004

23. Development of regulations in Finland (2)
Mandatory safety requirements are presented in Government Decisions
the Government Decisions are drafted and proposed for the Government by STUK
views of stakeholders are requested and taken into account in preparation of final drafts
these mandatory requirements are of the type of general safety principles
Beijing, October 2004

24. Development of regulations in Finland (3)
STUK issues detailed regulations called YVL Guides
YVL guides are rules that shall be complied with unless some other acceptable procedure or solution is presented to STUK by which the safety level laid down in an YVL guide is achieved
Currently there are 73 YVL Guides in force. The Guides are up to date - as needed for licensing of the new plant
Finnish nuclear and radiation legislation as well as Goverment Decisions and YVL Guides are available in internet,
Beijing, October 2004

25. General principles used in Finnish safety requirements for design (1)
The nuclear safety philosophy applied worldwide since late 1960’s has been 100% successful at commercial nuclear power plants
there has never been a large radioactive offsite release at plants which apply this philosophy
It is well-founded to keep safety requirements based on this successful philosophy
the core of the safety philosophy is the defence-in-depth principle
Beijing, October 2004

26. General principles used in Finnish safety requirements for design (2)
Systematic application of the defence-in-depth principle requires that well specified accidents are postulated as design basis of
the reactor core,
the release barriers, and
the safety systems
Traditional deterministic approach to safety is thus followed
Safety margins and protection against a wide spectrum of other less specific accidents are provided by overlapping design basis accidents
this has proven to ensure the safety also in unforeseen situation
Beijing, October 2004

27. General principles used in Finnish safety requirements for design (3)
As a necessary complement to the deterministic safety design, a probabilistic risk analysis (PRA) is required to verify the reliability of all vital safety functions in a systematic manner
PRA results indicate the balance of the design features from the safety point of view, and help to identify the weakest points that possibly need to be strengthened
experience has shown that insights from the PRA have increased the understanding of the safety factors, and helped to remove risks that have gone unnoticed in the previous engineering assessment
Risk informed approach to safety strengthens the traditional design practice
Beijing, October 2004

28. General principles used in Finnish safety requirements for design (4)
All calculations in the safety analysis have to be made with models that simulate the physical reality with the best possible manner
safety margins must be used in the model parameters to account for estimated inaccuracies in simulation of the real situation
failures in the safety systems have to be postulated as specified in detail in the YVL Guides
conservative unphysical assumptions should be avoided in order not to give a distorted picture of the course of accidents
Beijing, October 2004

29. General principles used in Finnish safety requirements for design (5)
Acceptance criteria for the safety analysis are connected with the actual estimated probability of each accident category
acceptance criteria take into account what might actually be tolerable consequences (releases, doses, physical “cliff-edge” limits implying a potential change of an accident process)
no physically meaningless limits are used, such as the traditional acceptance criteria for LOCA analysis: maximum fuel temperature of 1204°C and maximum cladding oxidation 17%
Beijing, October 2004

30. Technical requirements specified by the utility (in call for tender, contract, and PSAR)
The technical requirements were specified by using the European Utility Requirements (EUR) document as a reference
The application of EUR document represented a new approach that had not yet been used earlier
The EUR document represents a European set of requirements compiled by the utilities
EUR needs to be complemented with the safety requirements set by the national regulatory bodies
TVO’s specifications deviated from EUR mainly in those points where Finnish requirements are more stringent than EUR
Beijing, October 2004

31. Example of defense-in-depth based deterministic approach: loss of coolant accidents (1)
Postulated loss-of-coolant accidents are important for defining the design targets for the fuel, reactor core, mechanical structures, and safety systems, as well as for setting respective operational limits for them.
Unambiguous assumptions on design basis accidents help
to estimate available safety margins and
to avoid gradual reduction of the margins as a consequence of small successive design modifications
Beijing, October 2004

32. Example of defense-in-depth based deterministic approach: loss of coolant accidents (2)
Design basis requirements based on postulated LOCA’s take into account
experience from the safety systems at the existing plants: do not remove the protective features that are proven to be feasible (e.g., fuel and core design limits, ECCS, containment)
development of technology: make safety improvements that are reasonably achievable
need to provide protection against unforeseen events or events left outside the design basis
Beijing, October 2004

33. Example of defense-in-depth based deterministic approach: loss of coolant accidents (3)
1) Eliminate the possibility of sudden large breaks of the reactor coolant circuit by applying Break Preclusion (BP) principle
2) Postulate a sudden guillotine break of the largest pipeline, but limit the physically possible maximum break flow areas (and consequent fluid transients in the reactor coolant circuit) by means of pipe whip restraints
use the maximum estimated break flow as the design basis for specific mechanical structures
3) Postulate a loss of coolant accident that is equal to a free flow from both ends of the broken pipe
use the large break LOCA as the design basis for safety systems, thus providing protection also for unforeseen events
study the actual strength of mechanical structures under influence of dynamic forces, by using best estimate assumptions for physical phenomena
Beijing, October 2004

34. Break Preclusion principle to eliminate possibility of sudden large breaks
Break Preclusion (BP) principle used to eliminate the possibility of sudden large breaks of the reactor coolant circuit must involve:
qualified construction (materials, fabrication, QA), operation (loadings, chemistry), and surveillance to prevent major cracking throughout plant life
strength analysis to demonstrate adequate safety margins in all design-basis load conditions
effective in-service inspections of welds and other stressed areas
effective leak detection and verification of the leak-before-break principle
Beijing, October 2004

35. Limitation of maximum break flow in connection with primary circuit breaks
Limitation of the break flow area after a potential guillotine break by restricting the pipe motion is required in order to limit dynamic forces on mechanical structures. Vital structures that need to preserve their integrity after a sudden (1 msec) limited break with adequate margin are among others
support and anchoring structures of the main components
reactor pressure vessel internals, including fuel (mechanical strength) and control rod drive systems
steam generator tubes and other internals
main coolant pump flywheels
reactor containment internals
Beijing, October 2004

36. Loss of coolant accidents, beyond design studies
Beyond design studies are made to demonstrate the actual mechanical strength under the influence of dynamic forces that would result from the maximum free leak from both ends of the broken main coolant pipe
best estimate assumptions can be used for physical phenomena such as break opening time
items to be looked at are the fuel, reactor vessel internals, steam generator tube bundle and its supports, steam generator primary side manhole and main coolant pump flywheel
Beijing, October 2004

37. Example of defense-in-depth based deterministic approach: design basis for Containment
1) Large break LOCA
adequate capacity to carry pressure loads and to limit radioactive releases must be shown in conditions expected after a LB LOCA
this gives a sound basis to manage also severe accidents
2) Severe accidents
all foreseeable loads threatening the containment integrity in connection with a severe core damage must be identified, and necessary protection (prevention or mitigation) must be provided against each load
3) External events
potential external events must be identified and protected against
Beijing, October 2004

38. Severe accidents
Severe accident management strategy is mandated in containment design
high pressure failure of reactor vessel prevented by dedicated depressurization system
hydrogen management with autocatalytic recombiners to prevent detonation
low pressure melt arrested in a core catcher, with passive long-term cooling
containment integrity against dynamic loads
containment pressure management in long term
containment leak tightness criteria from release limits
AC power supply systems and I&C systems dedicated to support severe accident management are required
For systems dedicated for protection against severe accidents, single failure criterion applies
Beijing, October 2004

39. Protection against external threats
After September 11, 2001: political and public will was expressed to improve protection against terrorist actions
Reconsideration of aircraft crash design basis
consider large passenger and military aircrafts
no immediate release of significant amount of radioactive substances
initiation and maintenance of key safety functions in spite of the direct consequences of the event (penetration of structures by impacting parts, vibration, explosion, fire)
Microwave and biologic weapon consideration
Beijing, October 2004

40. System design requirements
Safety classification
N+2 failure criterion for systems that deal with design basis events (redundancy, diversity, segregation)
Proven technology
properly evaluated operational experience
experimental demonstration & analysis (novelties, such as “passive” systems)
Performance / safety margins required
Beijing, October 2004

41. Event classification for setting fuel damage and radioactive release criteria
Event categories
anticipated transients
postulated (design basis) accidents - “minor and major”
severe accidents
Single SG tube rupture is considered as an anticipated transient
Some low-probability high consequence events are postulated accidents
large primary-to-secondary leak: no major discharge to atmosphere is wanted
ATWS: good confidence in adequate reactivity control
LB LOCA remains within Design Basis
Beijing, October 2004

42. Acceptance criteria for preventing / limiting fuel damage
Anticipated events, f > 10-2/a
95/95 confidence with respect DNB or dry-out, no (internal) fuel melting, nor damage due to pellet-cladding mechanical interaction.
“Minor” postulated accidents, 10-2/a > f > 10-3/a
number of rods in heat transfer crisis < 1%, PCT < 650 °C, and extremely low probability of fuel damage by the mechanical interaction between fuel and cladding
”Major" postulated accidents, f < 10-3/a
the higher the frequency of a postulated accident, the smaller the number of damaged fuel rods. Number of damaged fuel rods < 10%. Enthalpy limit 140 cal/g for failure (230 cal/g not be exceeded). No danger to long-term coolability
Beijing, October 2004

43. Acceptance criteria for radioactive releases / max doses to general public
Normal operation
radiation dose limit 0,1 mSv / year for the entire site
Anticipated events
radiation dose limit 0,1 mSv
Design basis accidents
radiation dose limit 5 mSv
Severe accidents
release < 100 TBq Cs-137 equivalent
no acute health effects
can be fulfilled only if containment integrity is guaranteed
Beijing, October 2004

44. Fire protection High importance to lay-out
systematic and complete division of the whole plant into fire areas housing separate redundancies
Separation with structures, and reliable fire suppression within fire zones is emphasized
cable channels
cables spreading areas
reactor building
Beijing, October 2004

45. Fuel burn-up
YVL Guide
Limit of 40 MWd/kgU is given for fuel assembly average burn-up
this is used unless higher burn-up is not supported with adequate experimental evidence
Operating plants in Finland
45 MWd/kgU has been approved with experimental evidence
EPR burn-up target
The licence applicant has indicated target value of 50 MWd/kgU for burn-up; no regulatory position at this stage
Beijing, October 2004