November 2012 home page

Faulty Towers
Don Mosier | Rimini Road


Mitsubishi Heavy Industries, who constructed the steam generators for Edison, has suggested that tube-to-tube wear in the U-bend sections at the top of the generators is due to “flowering” at the high temperature,
high pressure operating environment.
(source: same NRC report of July 18, 2012 cited in text below).


Southern California Edison (Edison) applied to the Nuclear Regulatory Commission (NRC) for permission to restart damaged Unit 2 of the San Onofre Nuclear Generating Station (SONGS) on October 4th, 2012. Lee Haydu and I attended an NRC public meeting in Dana Point on October 9th, where I participated as a panelist and stated my opposition to the restart without a full, license amendment hearing with public participation and review by independent experts, many of whom are against the restart. My comments were in line with Del Mar City Council action taken on September 24th.

Why am I so adamantly opposed to restarting Unit 2? The January leak was in the new Unit 3 steam generator, and there is no proposal to start that reactor. The proposal from Edison is to restart Unit 2 at 70% power in the hope that lower power will reduce the risk of another radiation leak. Here is what the NRC inspectors concluded in July:

“Since generator physical dimensions and design are identical, the operational parameters are basically the same between the Unit 2 and 3 steam generators; therefore, the hydraulic forcing function that caused tube-to-tube wear and accelerated anti-vibration bar and tube support plate wear should also be same. The initial inspections of the Unit 2 steam generators did not indicate significant wear except at the retainer bars (different mechanism caused this wear). However, subsequent follow up inspections in Unit 2 with a more sensitive probe confirmed the existence of minor tube-to-tube wear in two neighboring tubes but in one of the steam generators. The tube-to-tube wear that was found in Unit 2 was in a similar location as that found in both of the Unit 3 steam generators.” (page 58, SAN ONOFRE NUCLEAR GENERATING STATION – NRC AUGMENTED INSPECTION TEAM REPORT 05000, 361/2012007 and 05000362/2012007; July 18, 2012)

So Edison is willing to experiment that the identical design to a failed unit will perform better, and that no further radiation leaks will occur. This experiment ignores the root cause of the problem, which clearly is faulty design and fabrication of the new steam generators, which is described in euphemistic terms as “flowering” (see illustration). This experiment will put 8.4 million southern California residents at risk, and the proposed benefit is generation of 700 megawatts of electricity that makes a small and unneeded contribution to our regional energy needs. It is this poor risk:benefit ratio that may have prompted both the LA Times and the Union-Tribune to reach rare agreement that SONGS should not be restarted. And the risk is increased by the close proximity to active earthquake faults.



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