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

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 107-92. DiP authorised the electricity generating company TVO to continue preparations for the construction of a new NPP unit. Beijing, October 2004

Olkiluoto 3 licensing phases Operating License 2008 ? Construction Construction License first quarter 2005 ? Technical part Preparatory phase Political part Decision in Principle 2000-2002 Feasibility study Environmental Impact Assessment 1998-2000 Beijing, October 2004

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

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

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

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

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

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

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

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 - 1600 MWe PWR Beijing, October 2004

OL3 Comparison Table Type of plants N4 EPR (OL3) KONVOI Core thermal power (MWth) 4250 4300 3850 Net power output (MWe) 1475 1600  1400 Number of loops 4 4 4 N° of fuel assemblies 205 241 193 Type of fuel assemblies (17x17), 25 (17x17), 25 (18x18), 24 Active length (cm) 427 420 390 Total F.A. length (cm) 480 480 483 Rod linear heat rate (W/cm) 179 155 163 N° of control rods 73 89 61 Beijing, October 2004

OL3 Comparison Table Type of plants N4 EPR (OL3) KONVOI Total flow-rate (kg/s) 19714 22135 18800 Primary pressure 155 155 158 Vessel outlet temp. (°C) 329.1 327.2 324.5 Vessel inlet temp. (°C) 292.1 295.9 292.5 S.G. heat exch. surface (m²) 7308 7960 5400 Steam Pressure (bar) 72.5 78 64.5 Containment volume (m³) 73000 80000 70000 Beijing, October 2004

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

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

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

Preparatory work before receiving the CP Site works started immediately after signing the contract Excavations - 500 000 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

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

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

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

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

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

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

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, www.stuk.fi Beijing, October 2004

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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