CSNI Workshop

Specialist Meeting on the Seismic Probabilistic Safety Assessment of Nuclear Facilities

Jeju Island, Korea, 6-8 November 2006

Hosted by the Korea Atomic Energy Research Institute (KAERI) and the Korea Institute Of Nuclear Safety (KINS)
In co-operation with the International Atomic Energy Agency (IAEA)

The methodology of seismic probabilistic safety assessment (PSA) for nuclear installations was first developed in the late 1970s. Over the years it has evolved so that today it is judged to be a mature methodology for assessing the risk to nuclear installations from earthquakes. A related methodology, the seismic margin assessment (SMA) methodology developed in the mid-1980s, has also been widely used.

Seismic PSA results have enabled both plant managerial personnel and regulators to concentrate their efforts and resources where it matters most, and in the process to improve safety significantly - often at low cost. For example, seismic PSA / margin studies often identify anchorage problems with electrical equipment, pumps, large tanks, and relay chatter. These problems can usually be fixed without large expense.

The NEA sponsored a workshop on seismic risk in Tokyo in August 1999 to discuss seismic PSA and SMA methodologies for nuclear installations. It was organised by the CSNI Principal Working Group 5 that later became WGRISK. The workshop report [1] provides a valuable summary of the state of the art of seismic PSA at that time, and includes findings and recommendations to guide the future work of both researchers and analysts. The workshop itself had the benefit of a 1998 state of the art report that was commissioned by the CSNI [2]. Late, in 2002, the CSNI adopted a "Topical Opinion Paper on Seismic PSA" [3], based principally on the deliberations and conclusions from the Tokyo workshop.

In the intervening years since the Tokyo workshop, the methodology of seismic PSA has been applied widely around the world at many nuclear power plants. There have also been technical advances in several aspects of the overall methodology. A major new development is the publication, under the auspices of the American Nuclear Society, of a methodology standard for seismic PSA and SMA [4]. The time seems ripe for a specialist meeting to discuss these advances, develop new findings and recommendations and provide the community of seismic risk analysts with a forum for discussing the current status of the field. The meeting will also serve as a forum to discuss items related to two IAEA safety documents in preparation; "Seismic evaluation and upgrading of existing NPPs" and "Probabilistic seismic hazard analysis for NPP sites" [5]


Workshop objectives

The main objectives of the meeting are:

The emphasis of the specialist meeting is on exchanging ideas on effective ways of using seismic PSA and SMA, rather than on simply reporting the numerical results of studies on specific plants. However, discussion of specific results is always appropriate to the extent that general insights can be drawn from them.

Related links


1. Proceedings of the OECD/NEA Workshop on Seismic Risk, Report NEA/CSNI/R(99)28, OECD Nuclear Energy Agency, Paris (1999). www.oecd-nea.org/nsd/docs/1999/csni-r99-28.pdf.

2. State-of-the-Art Report on the Current Status of Methodologies for Seismic PSA (Probabilistic Safety Assessment), Report NEA/CSNI/R(97)22, OECD Nuclear Energy Agency, Paris (1998). www.oecd-nea.org/nsd/docs/1997/csni-r1997-22.pdf.

3. Fire Probabilistic Safety Assessment for Nuclear Power Plants Seismic Probabilistic Safety Assessment for Nuclear Facilities, CSNI Technical Opinion Papers - Nos. 1-2 (2002) . NEA 3948, ISBN: 92-64-18490-2 . 28 pages. www.oecd-nea.org/nsd/reports/nea3948-fire-seismic.pdf.

4. External Events PRA Methodology Standard, American Nuclear Society Standard BSR/ANS 58.21, R.J. Budnitz (chairman), N.C. Chokshi, W. Henries, M.K. Ravindra, J. Stevenson, and T. Yee, American Nuclear Society (2003). http://ans.org/standards/

5. Treatment of external hazards in PSA for NPPs, IAEA Safety Series No: 50-P-7 (1995)

Last updated: 20 October 2006