Risk-Informed Regulation and Applications in Taiwan
Volume 3, Number 1, January 2007 - Paper 5 - pp. 47 - 59
TSU-MU KAONuclear Engineering Division, Institute of Nuclear Energy Research, P.O. Box 3-3, Longtan Township, Taoyuan County 32546, Taiwan, R.O.C
(Received from the Guest Editor on July 31, 2006)
The Probabilistic Risk Assessment (PRA) group of Institute of Nuclear Energy Research (INER) has developed and maintains the PRA models of all the nuclear power plants (NPPs) for Taiwan Power Company over 20 years since PRA was first introduced to Taiwan's NPPs. These PRA models cover internal and external events, power operation and shutdown mode, with LERF (Large Early Release Frequency) calculation modules. The PRA group has also completed a dedicated risk monitor with indigenous model solver engines, which are now adopted by the domestic three NPPs to monitor daily operation risks. The second generation of the risk monitor, TIRM-2 (Taipower Integrated Risk Monitor-2) with calculation capabilities of LERF has been developed successfully in Taiwan. A window-based tool with the Significance Determination Process (SDP) context to help the resident inspectors of Taiwan's nuclear regulatory body to perform the Phase 2 SDP assessment of the Reactor Oversight Process (ROP) has also been completed. Recently, the approval of on-line maintenance of Residual Heat Removal (RHR) systems and acceptance of PRA peer review reports on all of the three Taiwan's operating NPPs have created a basis of risk-informed applications in Taiwan. A table-based SDP of the ROP has been provided by the USNRC to determine the safety significance of resident inspection findings. After a preliminary screening (the Phase 1 of SDP) of inspection findings, an assessment process is conducted to obtain a risk approximation and to help the inspectors determine the risk significance (the Phase 2 of SDP). INER has developed a window-based tool with the SDP context to help the resident inspectors perform the Phase 2 SDP assessment at power and obtain the associated results more quickly and precisely. In addition to the progress of the TIRM-2 and the window-based SDP tool, on-line maintenance of RHR systems for current three operating NPPs of TPC has been approved in October 2003. Dedicated PRA models mentioned above were established for all of the three nuclear plants by 1992. The third party, ABS Consulting of the United States and Professor George Apostolakis of MIT have reviewed the accomplished living PRA reports on all of the three Taiwan's operating NPPs in 2002. Taiwan's regulatory body has accepted the associated peer review reports in December 2003 and is well satisfied with the PRA quality. Other subsequent risk-informed applications will be proposed soon. A new era of risk-informed regulation and applications has been initiated in Taiwan's nuclear society.
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