Safety of WWER Reactors

Wolfgang KrompInstitute of Risk Research

University of Vienna

Budapest, 23.04.2007

Tschernobyl September 1999

Nuclear revisitedPLUS• TMI-Upgradings• PSA• SAMGs

MINUS• Timeliness• Liberalized market • Aging• Lack of nuclear grade spare parts• Lack of personnel • Human factor & societal instability

Nuclear revisited

Further Questions

• Life Extension• Power Uprating• Fissile Uranium

WWER

Energy Source

Steam Generator

Turbine

Heat Sink

Generator

Electricity

Short visitors’ Loviisa plant description Mainossanoma OY / Vientipaino OY 1982

Imatran Voima OY P.O.Box 138, 00101 Helsinki 10, Finland

Nuclear Engineering International

Reactor Pressure Vessel (RPV)

Reactor with fuel

RPV-wall andwelds embrittle due to neutron irradiation

55° Cold water injection through ECCS

300° hot RPV wall

After 5 years of service already 50% of neutron induced material damage Counter measures: early shielding & annealing

Pre-Service Thermal-Shock Analysis Mochovce (IAEO 1994 old , Posar 1997 new limit):Updated Codes resulted in lower limit, Even newly calculated embrittlement graph could not entirely solve the problem

F. Horvath 2002complemented

„Events“ since 2000

• Brunsbüttel (00) – tube line leakage• Japan (02) – data falsification• Davis-Besse (90-02) – vessel lid corrosion• Koslodui (03) - LOCA• Paks (03) – fuel damage• Repro plant Sellafield (04-05) – Leekage• Kosloduy (06) – control rod jamming • Forsmark (06) – loss of off-site power etc.• …

Fig. 3: Cleaning tank temporarily installed in pool no. 1

J. Schunk et al: Fuel Assemblies Chemical Cleaning, Framatome ANP GmbH, Germany, (2001)

Warnings

• IAEO-Generaldirektor El Baradei, New Orleans , Nov. 03:

– „We cannot afford another accident“

• WANO Chair Hajimu Maeda, Okt. 03:– “a terrible disease that originates within the

organization”– “a major accident” … “destroy the whole

organization“

Extension of Operational Life-Time: WWER-Related Aspects

Main focus on ageing at VVER–plants:

• Reactor vessel [1]

• Ageing of components

• Confinement tightness

• Internals, Piping

• Concrete

RPV Embrittlement

• VVER 440/ 213 End of Life depends on weld Radiation Embrittlement

• Radiation Embrittlement depends on P and Cu contents

[1] Control of permanent set structures state at definition of nuclear power plants lifetime Ya. I. Shtrombakh

Extension of Operational Life-Time: Paks-Related Aspects

Systematic preparatory work for long-term operation of Paks NPP WWER-440/213 units had started in 2000 and is on going [2]

Ageing Management (AM) measures concentrated for Paks NPP on:- RPV embrittlement- Leaking of confinement due to liner degradation,- Seismic resistance of bubbler condenser )- Corrosion of SG heat exchange tubes (magnetite problem)- etc.

[2] KEY ELEMENTS OF LONG TE M OPE ATION OF WWE -440/213 UNITS AT PAKS NPP T. Katona, S Rátkai Nuclear Power Plant Pak, Hungary

Extension of Operational Life-Time: Paks-Related Aspects

Additional Questions: •International programms & experiences from RPV embrittlement studies e.g. Rovno 1 and 2, Kola NPP sufficietly considered?

• Different studies are focused on the RPV base materials and weldings: The condition of metal of the RPV is known as essential for VVER-440 life time [3]

[3] THE EXPERIENCE OF ERVICE LIFE PROLONGATION OF NPP UNIT OF THE FIRST GENERATION, M. Kakirov, V. Potapov, A. Kann, A. Dementev, V. Levchuk, E. akhus, S. C ubarov, V. Ilyn, E. Mamaeva, A. Mazepa, Centre of Materials Researches and Lifetime Management, Moscow, Russia, Rostechnadzor, Novovoronezh, Russia Concern “Rosenergoatom”, CNIITMASH, Moscow, Russia

Timeliness

Limits:

• Construction capacity • Availabilty of financial resources• Availability of trained personnel

Lead Time

Uranium production and demand

Energy Watch Group 2006

Far more Uranium used than produced!

Resources

• WEC 2000: 62.000 t/a -> 2015 80.000t/a

• 4Mio t U235 reasonably assured + estimated additional -> 41a

• 10Mio t U235 highly speculative -> 95a

Present & Future Plants

• Generation 2• Generation 3 u. 3+• Generation 4

Up to Generation 3+ based on fissile U235

Generation 4 mainly based on dangerous Plutonium or Uranium 233

U238 -> Pu239 or Th232 -> U233

Generation 4

• No severe accident• No long lived waste• No matter for proliferation • Cheap

Ordinary fast breeder! „Pu economy“

Generation 4

• “We have not found and, based on current knowledge, do not believe it is realistic to expect that there are new reactor and fuel cycle technologies that simultaneously overcome the problems of cost, safety, waste, and proliferation”

MIT (2003), op. cit., p. 76.

NPP – attractive target

• Radioactivity & energy inventory• Key components of electricity networks• Structures visible at large distance

Example of insuccessful terror defence at RBMK Smolensk

• Simulated terror attack early eighties • 14 days pre-warning• Security guards prepared• Safety barriers overcome by intrudor• Alarm went on• Intrudor disappeared among personnel• Intrudor communicated with personnel

of main circulation pump control room

Radiant Inheritance • Plutonium 239, Technetium 99

HLT 24.000 and 211.000 ys 9 kg per t spent fuel • Neptunium 237, Cerium 93, Cesium 135,

Palladium 107, Iodine 129 HLT 1,5 to 15 million ys

3,5 kg per t spent fuel

• Globally 436 NPPs 10.500 t heavy metal / a 265 000 t spent fuel up to date

> 3 300 t long time radio nuclids up to date

Interim storage – anthropogenic threat

• Attacke on spent fuel pit Circonia fire • Could be „well beyond Chernobyl“(Sensintaffar 2005)

„Main stream“ deep geological structures?

Geological Deep Repository

Search – AkEnd (Germany)

•1 Mio Years

•300 to 1200m deep

•Preferably one site

•Sooner or later closed

and unaccessible Detlev Ipsen (AkEnd):

global societal & political mega experiment

Summary

• Remarkable Efforts to be Acknowledged

• Old and New Constraints• Persistent „Near Misses“• Threat of Severe Accident• Unresolved Waste Issue• Daughtful Future Developments• To Small & Late for Climate Change

and Fossiles‘ Shortage