Union of Concerned Scientists has serious concerns about Southern California Edison’s (SCE) restart plans for San Onofre Unit 2. In a 10/12/2012 letter submitted to the Nuclear Regulatory Commission (NRC), David Lochbaum, Director, Nuclear Safety Project, identified the following issues:
- Unit 2 replacement steam generator 2SG89 has significantly more wear indications per number of supports than does [Unit 2] replacement steam generator 2SG88. Until the reason for this marked difference between the wear degradation for the Unit 2 replacement steam generators is understood, the operational assessment performed for future operation is suspect. [See graph in Lochbaum letter].
- Since all four replacement steam generators came from the same manufacturer, were of the same design, made of the same materials, assembled using the same procedures, and operated under nearly identical conditions in twin reactors, the reason for this marked difference is unclear… [the] explanation is not well documented and therefore appears to be more convenient than factual.
- The document states that the owner will “administratively limit Unit 2 to 70% reactor power prior to a mid-cycle” outage to inspect the replacement steam generators. What are the legal consequences if the reactor power were to increase to 75%, 85% or 100% power? The NRC has licensed San Onofre Unit 2 to operate at 100% power. What would legally prevent the owner from restarting Unit 2 and increasing its output to the NRC licensed limit? The NRC’s enforcement program includes sanctions when its regulations are violated, but nothing for broken promises. If the NRC agrees that reactor operation at less than 100 percent power is warranted, it should enforce that reduction with an order or comparable legally-enforceable document.
- Table 8-1 of Enclosure 2 and its accompanying text attempt to explain how operating Unit 2 at 70% power will prevent the tube-to-tube wear (TTW) experienced on Unit 3 by comparing it to an anonymous reactor (called Plant A). ..reliance on one suspect data point (Plant A) is hardly solid justification for operation and 70% power being acceptable.
- There is no justification in this 80-plus page document for an operating duration of 150 days.
- … there are no legal means compelling the plant’s owner to shut down Unit 2 after 150 days of operation at or above 15% power.
- ...a temporary nitrogen-16 radiation detection system will be installed prior to the Unit 2 startup. However, there is no commitment to use it after startup, or to keep it in service should it stop functioning. The detection system is proposed as a defense-in-depth measure, but there is no assurance it will be operated.
- Attachment 6 to Enclosure 2 has proprietary information redacted. Section 1.4 of Enclosure 2 states that the owner used AREVA, Westinghouse Electric Company LLC, and Intertek/APTECH to review the operational assessment. At least one of these companies manufactures replacement steam generators and would therefore be a competitor to Mitsubishi Heavy Industries (MHI), which made the replacement steam generators for San Onofre. If the owner did not withhold the proprietary information from MHI’s competitors, why withhold it at all? If SCE did withhold the proprietary information from these reviewers, what is the value of their independent, but limited, review?
Nuclear Regulatory Commission (NRC) Confirmatory Action Letter (CAL) dated March 27, 2012, (ADAMS Accession No. ML12087A323). required the owner of the San Onofre nuclear plant to submit to the NRC its report on the root cause of degradation to the replacement steam generator tubes and to keep both reactors shut down until the NRC reviewed and agreed with the root cause determination.
SCE submitted an 80-plus page report dated October 3, 2012, describing the causes of the steam generator tube degradation and proposing compensatory measures if the NRC permits Unit 2 to restart.
However, Lockbaum questions whether the root cause has been properly identified. He states
“…when reactor safety problems rise to the point where an owner must submit a formal root cause report to the NRC, it is a prudent public health practice that these reports be submitted prior to restarting the affected reactors. If the cause of the degradation has not been properly identified, then the solutions applied to the wrong cause may not adequately protect the public.”
The issues raised by Lockbaum must be address by the NRC. Restarting a broken nuclear reactor is unacceptable.