MEHB 513 Introduction on nuclear technology assignment GROUP MEMBERS:ID: SEEH CHONG CHIN ME YEE QIAN WAHME TING DING PINGME LIM JIA YINGME POO CHUAN HANME087568

Introduction on Fukushima accident  Occurred at 12 march 2011  Start with 9.0 earthquake at 11 march 2011  Caused 11 reactor to shut down (9377MWe) but 3 reactor at Fukushima failed to shut down (2 BWR-4 and 1 BWR-3).  Following with15m tsunami flooded disabled 12 of 13 backup diesel generator and also heat exchanger.  The reactors SCRAMmed but still continue to release 6.5% decay heat  battered-powered cooling system used but can only last till 12 march 2011  On day 4 to 6 of the event total of 940PBq radioactive release, which lead to the event rated 7 on INES scale.  The purpose of this assignment was to identify the changes in nuclear industry occurred after the accident.

Reactor Site Selection  Protection against natural disaster  Away from sea to protect against tsunami  Control tower to activate cooling system was destroyed  Distance of nuclear reactor from residential area  Reduce the radioactive exposure into public  Large evacuation cause great impact on economy

Reactor Site Selection  Increase height of the site level  Fukushima built at low sea level, easily attacked by tsunami  Reduce damage from floods  Geometrical conditions  Should build on hard rock foundations  Reduce impact from earthquake

Reactor Design Generation III+ Nuclear Reactor Passive Safety System

EPR Passive Cooling System Natural Convection

AP1000 Passive Cooling System

ESBWR Passive Cooling System

Plant Design

OSART (operational safety review team)  To evaluate the safety features of the NPP  Focus on operational procedures and cultures of management  42 missions done after Fukushima accident, 21 missions planned in the future

IRRS (Integrated Regulatory Review Service)  To review the nation regulation of safety  Advice and suggestion will given to the nation to improvised on the NPP conducting regulation  Follow up after 4 years  15 missions and 6 follow up is done.

INIR (Integrated nuclear infrastructure review mission)  evaluate the progress of development NPP of member states and the safety of existing NPP in terms of infrastructure  Service upon request  NPP expert will sent to requested member states to evaluate their infrastructure status by interview, site visit and document studies

EPREV (emergency preparedness review)  Review on how well a NPP can response to a emergency event such as natural disaster  Experts give services upon request.  Providing a basis to the member states so that they can come out with a long-term programme to strengthen their respond ability.

Mitigation Strategies to Prevent Nuclear Disasters

Prevention of AC Power Loss  AC Power is important to the safety of the nuclear power plant:-  To cool the nuclear fuels in the reactor and spent fuel pools.  To maintain radioactive containment systems.  To provide ventilation systems to minimize release of radioactive materials.  Will cause Station Blackout (SBO) if AC power is stopped.

Prevention of AC Power Loss  To prevent damage to nuclear reactor by SBO:-  Maintain a highly reliable AC electric power system.  Develop procedures / training to restore offsite and onsite emergency AC power when unavailable.  Ensure that the nuclear power plant can cope with SBO for a period of time and capability of restoring AC power on site as soon as possible.

Providing Cooling to Nuclear Fuel without on site AC Power  Pressurized Water Reactors (PWRs)  Additional sources of coolant water for the reactor and steam generators.  Methods to reduce pressure in and feed cooling water to the steam generators  Methods to cool the reactor core and minimize release of radioactive materials from containment.

Providing Cooling to Nuclear Fuel without on site AC Power  Boiling Water Reactor (BWRs)  Additional sources of coolant water for the reactor.  Methods to reduce reactor pressure and feed cooling water to the reactor.  Methods to cool the reactor core and reduce releases of radioactive materials from containment.

Providing Cooling to Nuclear Fuel without on site AC Power  For spent fuel pools:  Additional sources of coolant water for and methods to inject or spray to the spent fuel pools  Methods to control leakage from damage to the spent fuel pools  Methods to reduce releases of radioactive materials from the spent fuel pools

Conclusion Three changes in reactor site selection:  Position of nuclear plant  Ground height  Geometrical condition Changes in plant and reactor design:  Introduction of Generation III/III+ reactor  Plant anti-tsunami safety increased from 8 meter to 15 meter Effort in safety by IAEA:  Various group form with specific roles which were OSART, IRRS, INIR, EPREV and DSARS.

Conclusion continues.. Mitigation of accident  Effort from TEPCO in filter contaminated cooling water and delivery of water tank to store contaminated water during cooling down the hot nuclear fuel. The changes moving NPP toward better future with enforcing new safety rules and higher safety qualification.