Ongoing problems of NPPs in the 21st century – dangers arising from lifetime extension

1. Ongoing problems of NPPs in the 21st century – dangers arising from lifetime extension Conference: „Possibilities for a sustainable energy future in Hungary in the 21st century“ Budapest 26.10.2007 Oda Becker Budapest 26.10.2007 Lifetime extension

2. Content • Lifetime extension • Ageing • Consequences of Ageing Processes • Counter measures • Power Uprating • Terror attacks • Possible Attack Scenarios • Consequences of an Attack on a Nuclear Power Plant • Climate Change and NPP • Natural hazards • Vulnerability of NPPs in the Case of Grid Failure • Vulnerability of NPPs in the Case of Flooding • Conclusion Budapest 26.10.2007 Lifetime extension

3. Aging • At the time of their construction it was usually assumed that the reactor would not operate beyond 40 years. • Now, in order to maximise profits lifetime extension offers nuclear operators an attractive proposition. • Over the last years there has been a general trend against ordering new reactors. • As a consequence the average age of nuclear power plants have increased continuously. Budapest 26.10.2007 Lifetime extension

4. Ageing Budapest 26.10.2007 Lifetime extension

5. Ageing • Ageing is a continuous time-dependent loss of quality of materials, caused by the operating conditions. • Failure rates generally are high after start-up of a plant, • during the ‘middle age’ of a plant, problems tend to be at a minimum. • Later, as ageing processes demand their due, there will be a gradual increase of failure rates. Budapest 26.10.2007 Lifetime extension

6. Ageing The result is a so called “bathtub-curve” Budapest 26.10.2007 Lifetime extension

7. Ageing • For a nuclear power plant, the ageing phase will begin after about 20 years of operation. • Ageing already occurs during the period usually regarded as typical commercial lifetime (30 to 40 years). • As the world’s NPP population gets older, there are efforts to play down the role of ageing. Budapest 26.10.2007 Lifetime extension

8. Ageing The most important influences leading to ageing are • Irradiation • Thermal and mechanical loads • Corrosive, abrasive and erosive processes • Combinations and interactions of the processes Budapest 26.10.2007 Lifetime extension

9. Ageing • Not all components can be examined one hundred percent. • It is necessary to rely on model calculations. • Non-quantifiable uncertainties remain. • With increasing age of plants, damage mechanisms might occur which have not been foreseen, or which had even been excluded exacerbating the ageing problems. Budapest 26.10.2007 Lifetime extension

10. Consequences of Ageing Processes • The number of incidents and reportable events at an NPP will increase • There are effects leading to gradual weakening of materials which may – with luck – be never have any consequences until the reactor is shut down, but which could also lead to catastrophic failures of components with subsequent severe radioactive releases. Budapest 26.10.2007 Lifetime extension

11. Consequences of Ageing Processes • In Probabilistic safety assessment studies (PSA),ageing is usually not taken into account. • PRAs assume that equipment failure rates are taken from the low center portion of the “bathtub curve” • This leads to underestimation of the risk. • The risk of a nuclear accident grows significantly with each year. Budapest 26.10.2007 Lifetime extension

12. Counter Measures Four levels generally can be distinguished: • Exchange of components • Reduction of loads • Intensify inspections and plant monitoring • Reduce safety margins Budapest 26.10.2007 Lifetime extension

13. Power uprating • Power uprating is an economically attractive option for NPP operators which usually goes largely unnoticed by the public. • An increase of thermal power implies more nuclear fissions and thus increases operational risk. • Also, higher loads to the reactor materials are unavoidable. • An increase of reactor power reduces operational safety margins and at the same time accelerates ageing processes. Budapest 26.10.2007 Lifetime extension

14. Terror attacks There are numerous potential targets for terrorist attacks. But a NPP could be selected as target for one of the following reasons: • Because of the symbolic character • Because of the long-term effects • Because of the immediate effects Budapest 26.10.2007 Lifetime extension

15. Possible Attack Scenarios • Attack from the air • Firing on plant from a distance • Intrusion of attackers onto plant area • Attacks involving insiders • Attacks against installations located outside Budapest 26.10.2007 Lifetime extension

16. Consequences of Terror Attack • It is likely that the reactor building will be the primary target in case of an attack. • If the reactor is operating as the attack occurs, and if the cooling is interrupted, a core melt can result within a very short time (about 2 hour). • A core melt accident of the most hazardous category results: Rapid melting with open containment. • The resulting radioactive releases will be particularly high, and occur particularly early. Budapest 26.10.2007 Lifetime extension

17. Consequences of Terror Attack • The consequences amount to a catastrophe with effects over a large region: Up to 10.000 km2 have to be evacuated in the short term. • There will be up to 15.000 acute radiation deaths and up to 1 million cancer deaths, as well as uncounted cases of genetic damage. • The area which will be contaminated in the long term to a degree necessitating relocation of the population can measure up to 100.000 km2. • The economic damage has been estimated at about 6 trillion Euros. Budapest 26.10.2007 Lifetime extension

18. Climate Change and NPPs • Reduction of greenhouse gases needed to attain the Kyoto aims necessitates compensation for about 380 GWe by 2030.If these capacities were supplied exclusively from nuclear energy about 425 NPP • To maintain the present share of nuclear (16 %) in the rising world electricity production about 15 plants per year would need to be built additionally • The losses through shut downs of plants must be compensated additionally. Budapest 26.10.2007 Lifetime extension

19. Natural Hazards • It is to be feared that extreme events will have increasingly grave consequences in the future. • The potential threat climate change constitutes for nuclear power plants can be illustrated by looking at events which have already taken place at NPPs. • Such events has to be regarded as precursors of worse incidents and accidents yet to come. Budapest 26.10.2007 Lifetime extension

20. Vulnerability in Case of Grid Failure • NPP are dependent on a continuous electric power supply to operate, particularly for the instrumentation and safety systems, even when they are shut down. • Heavy storms can lead to multiple damage of the transmission lines, and hence to loss of off-site power. • A natural disaster that disables the incoming power lines to a nuclear power station coupled with the failure of on-site emergency generators can result in severe accident. Budapest 26.10.2007 Lifetime extension

21. Vulnerability of NPP in Case of Flooding • Cooling needs of nuclear reactors dictate a location at the sea or at a large river. • Flooding is possible due to natural causes such as runoff resulting from precipitation or snow melt, high tide, storm surge, and wind waves • It appears likely that in the decades to come, the hazards associated with flooding will increase for many NPP world-wide • It is highly questionable whether NPP operators and regulatory authorities are fully aware of this problem. Budapest 26.10.2007 Lifetime extension

22. Conclusion • Life extension (and power uprating) exacerbate the hazards of ageing and increase the risk of a nuclear catastrophe • Reactors cannot be sufficiently protected against terrorist threat. Several scenario’s could lead to a severe accident. • Climate change impacts, such as flooding, seriously increase nuclear risk. Budapest 26.10.2007 Lifetime extension

23. References • H. Hirsch et al.: Nuclear Reactor Hazards – Ongoing Dangers of Operating Nuclear Technology in the 21st Century, Report Prepared for Greenpeace International, Amsterdam, April 2005 • Federal Ministry of Agriculture and Forestry, Environment and Water Management of Austria: Nuclear Power, Climate Policy and Sustainability An Assessment of the Nuclear Option with regard to Climate Policy and Sustainable Development; January 2007 Viennawww.lebensministerium.at Budapest 26.10.2007 Lifetime extension

24. Oda Becker • Professor at the University of Applied Science and Arts, Hanover; • freelance scientific consultant for energy and the environment; • studied physics and education science at the University of Hanover. • working as an independent scientific consultant in the field of nuclear safety and security for many years. • clients include the Austrian Federal Government as well as NGOs. • Recent work includes: • Studies of the hazards of spent fuel cask storage facilities; studies of the vulnerability of the German NPP to terror attacks; • studies of the ongoing dangers of NPP in the 21st century; • study of the situation at the NPP Chernobyl site. Budapest 26.10.2007 Lifetime extension