Friday, February 7, 2014

Nuclear Power and Earthquakes:

A Contribution to the Dialogue

When I studied nuclear engineering in grad school, I thought that nuclear power was an intersection between different science and engineering disciplines--nuclear, mechanical, chemical, electrical, systems, etc.

At the time, that scope seemed plenty broad to me.  Little did I realize that, over the years, I would find my work affected by international and domestic politics, the electricity market, regulation of all types, public perception of risk, and a variety of other external factors.  While I can't claim to have become an expert in all of these areas, I have tried to develop at least a rudimentary understanding, and I do try to keep up with the news.

Therefore, I was very pleased to get a message from Woody Epstein providing me with a recent article he co-authored on an analysis of active faults and nuclear power plants.  Earthquakes, of course, are yet another external factor that is important to nuclear power.

Woody lives and works in Japan and has been active on a number of risk assessment issues.   The paper he sent me, which is entitled Active Faults and Nuclear Power Plants, was co-authored by Neil Chapman (MCM Switzerland), Kelvin Berryman (GNS Science, New Zealand), Woody Epstein (Lloyd’s Register, Japan) and Hideki Kawamura (Obayashi Corporation, Japan).  (This is a submission version of a paper for  Eos Transactions, American Geophysical Union.  That version indicates two additional authors, Pilar Villamor and Lloyd Cluff.) 

Although the title is generic, the article primarily covers the geology and seismic vulnerability of the site of the Tsuruga Nuclear Power Plant.  For me, it provided a very useful and understandable tutorial of how a major fault is analyzed to determine when it was last active and what other considerations are important.  Understanding such arguments is critical to understanding the discussions now underway in Japan that underlie the decisions on whether some of the currently closed nuclear power plants will be permitted to restart. 

In the case of Tsuruga, the paper briefly walks the reader through the steps that lead to the conclusion that the Japan Atomic Power Company (JAPC) was correct when it determined that there was no evidence of movement at the site in the last 120,000-130,000 years.  The paper also briefly addresses other issues, such as the presence of smaller faults.  And although the authors don't go into specific detail, they do note that the earthquake issue should not be viewed as a simple "guilty or not guilty" issue.  Likewise, they point out that, where active faults are found nearby, there can be consideration of whether and how the risk can be mitigated. 

Japan, of course, is not the only country that faces serious seismic concerns.  Therefore, at least some of the discussion in this paper may be useful to understanding the situation elsewhere as well.  Of course, we must keep in mind that different locations around the globe have very different geologic and seismic characteristics.  Furthermore, the authors point out that different countries have different definitions of "active faults."  Nevertheless, for those of us who struggle to understand the basis for some of the discussion going on in Japan, this paper makes a useful start.

Thus, Woody and his colleagues have not only contributed to the analysis of the particular situation at Tsuruga, but they have produced an assessment that can help more of us become familiar with the issues involved.  While one paper can't turn a nuclear engineer into a seismologist, I certainly think it will help me understand better the reports I am hearing from Japan on their seismic assessments, as well as reports I may hear from elsewhere.


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