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| SONGS - aerial view |
The utility, Mitsubishi, which supplied the steam systems, and the NRC are crawling all over them to figure out why there is unusual wear on so many tubes in the steam generators for both reactors.
While they are doing that, state energy officials are making contingency plans to supply replacement power to heavily urbanized southern California as summer heat drives up electricity demand from air conditioning. SONGS Unit 2 has been out of service since January 9, 2012, for a planned outage and Unit 3 was safety removed from service January 23, 2012, when plant operators detected a leak in one of the tubes.
Problems with the tubes are safety issues for two reasons. First, broken tubes can result in the release of radiation, Second, if too many tubes break, it could compromise cooling of the reactor core.
NRC letter to SCE
For its part SCE, says it has identified two possible sources of excessive wear. These causes include tubes that are rubbing against adjacent tubes and against support structures. Vibration may also play a role in causing the unusual wear and tear. The steam generators were installed in 2009 and show much more wear on nearly 900 tubes (10%) for the steam generator at Unit 3 than is expected given the short time the units have been producing steam.
The NRC is requiring SCE to plug all tubes in the steam generators for Units 2 & 3 for which testing indicates excessive wear relative to industry guidelines. Also, it is requiring SCE to plug tubes likely to experience excessive wear because of their location in the steam generator.
Additionally, the NRC is requiring SCE to figure out the causes of excessive tube-to-tube wear and to provide for a mid-fuel cycle shut down to inspect the tubes. The purpose of the inspection is to insure that tube wear doesn't get to the point where a damaged tube could cause a safety issue.
Some history about steam generator tube wear and tear
In 1995 the Department of Energy published a paper on steam tube problems Titled, "Steam Generator Degradation and Its Impact on Continued Operation of Pressurized Water Reactors in the U.S," author Kenneth Chuck Wade wrote in the Energy Information Administration Electric Power Monthly for August 1995 that there are eight types of degradation of steam generators. Causes include vibration, various forms of internal and external corrosion, and cracking and thinning of tubes.
Wade's paper, written more than a decade before Mitsubishi manufactured the San Onofre steam generators, does not take into account the new alloy used by the company to combat corrosion. Also, during the ensuring ten years other forms of wear may have been identified by nuclear utilities and the Electric Power Research Institute (EPRI).
What is significant about the paper is that it provides a starting point, or a framework, to think about why wear occurs in steam generators and what utilities have done in the past to deal with the problem. Also, the paper offers some general advice on how to deal with the problem including improvements to water chemistry, cleaning the tubes, and plugging the ones that are excessively degraded.
Readers wondering what types of factors the teams from SONGS, Mitstubishi, and the NRC are considering to assess the causes of excessive wear, and how to address them, will benefit from a review of the paper despite its age.
Anti-nuclear whistle blower weighs in
Arnie Gundersen, a long time critic of the commercial nuclear energy industry, was hired by FOE to prepare the report. He said in it the tube alloy was changed, support bracing was changed, and more tubes added to the units. Gundersen alleges these changes took place to increase the amount of steam, and thus power, the reactors could produce to make electricity.
In response Jennifer Manfre, a spokesperson for SONGS, told wire services that SCE has "provided open and transparent information" to the NRC. At the agency, NRC spokesman Scott Burnell said that the agency is aware of the changes SCE made to the steam generators. Burnell added that the company "showed by analysis that their design was acceptable . . . [and] would meet our requirements for safe operation."
Who watches the whistle blowers?
Manfre declined to speak with a nuclear blogger, but did send out a tweet last week asking "who watches the whistle blowers."
Perhaps it would be useful to note here that three nuclear bloggers got together last Saturday (March 31) here in Cleveland, OH, and spent several hours discussing the situation at San Onofre.
The group includes myself at Idaho Samizdat, Will Davis of Atomic Power Review and Leslie Corrice who has a blog and web site Hiroshima Syndrome. Nuclear bloggers are an independent lot so when three of them team up to follow an issue, it is, as they say, a "critical mass."SCE may have its reasons for limiting what it says to the news media even in the face of provocative allegations by an anti-nuclear group. Perhaps once the utility has a diagnosis of the causes of the excessive wear of the steam tubes, and a path forward to restart both reactors accepted by the NRC, it will be willing to be more interested in public communication.
Top executives at nuclear utilities, with billions in physical assets to worry about, have an unfortunate tendency to adopt a "bunker mentality" when faced with a combination of technical problems and criticism from a frightened public.
Experts in crisis communication will tell you that just the opposite strategy is the best response. Explaining what you know, and don't know, builds public confidence that the utility and the regulators know what they are doing and serves as a buffer against the most obvious scare tactics of anti-nuclear groups.
As a side note it is possible Ms. Manfre's management is not familiar with the social media infrastructure on the pro-nuclear side of the house? The door is open for a dialog any time.
Hot summer in the city
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| Conceptual diagram of a brownout; change in amplitude over time |
These long-duration under-voltage conditions can cause in a transmission and distribution system, damage motors in industrial equipment, create power quality problems for medical equipment in hospitals, such as centralized oxygen systems, and disrupt highway traffic control devices, aviation and ground control electronics at airports, and other major systems that require reliable electrical power to sustain a large urban region.
Meanwhile, another coalition of anti-nuclear groups is seeking to collect 550,000 signatures to put an initiated referendum on the November ballot to close San Onofre and the Diablo Canyon reactors. While the results of the current unplanned outage at SONGS could be a real crisis for southern California, it could also become an object lesson for the rest of the state about where its electricity comes from and what happens when a major power source is lost to the grid.
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