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Testing No Cause For Concern at San Onofre

There has been some concern about testing being conducted at San Onore Nuclear Generating Station’s Unit 2 reactor, which is currently shut down. On Monday, as part of a plan by Southern California Edison (SCE) to test the plant’s auxiliary feedwater pumps, as well as other equipment, the plant was heated to normal operating temperature of about 535 degrees and normal operating pressure of 2,200 psi. Heat is being supplied to the system by running reactor coolant pumps, not the reactor. The heat forms steam in the steam generators, which is needed to test this equipment. During this testing, the reactor remains shutdown.

The licensee is required to perform this testing at the conclusion of a refueling outage. They expect to remain in this testing condition (Mode 3) for about one week, and then return the plant to cold shutdown conditions (Mode 5). During the extended shutdown of Unit 2, Southern California Edison plugged degraded tubes. As a preventive measure, several hundred additional tubes were plugged and removed from service because of their physical location at the top of the steam generators. This was to prevent further tube to tube wear during potential future operations.

On Sunday, October 21, 2012, craftsmen at the plant identified a small hydrogen leak coming from the hydrogen supply piping system on Unit 2. The craftsmen were checking for leaks by spraying soapy water on piping joints. This is a routine leakage check. A minute amount of bubbles were observed, indicating that a very low amount of hydrogen was leaking at a mechanical piping joint. The piping joint was tightened and the leak was stopped.

Hydrogen is used at electric power plants (not just nuclear power plants) for main electrical generator cooling. At San Onofre, the affected hydrogen piping that transports hydrogen to the generator on the non-nuclear side of the plant is outdoors near the turbine building. The small amount of hydrogen leaking from the mechanical joint did not pose a threat to the public or workers on site. Since it was outdoors, a significant amount of hydrogen at combustible concentrations could not accumulate in one area.

Victor Dricks
Senior Public Affairs Officer
Region IV

19 responses to “Testing No Cause For Concern at San Onofre

  1. Check Here July 6, 2013 at 7:17 am

    I’ve gone ahead and added a backlink back to your web page from one of my clientele requesting it. We have used your blog URL: https://public-blog.nrc-gateway.gov/2012/10/25/testing-no-cause-for-concern-at-san-onofre/ and blog title: Testing No Cause For Concern at San Onofre | U.S. NRC Blog to assure you get the correct anchor text. If you woud like to check out where your website link has been placed, please email me at: sherrisegal@inbox.com. Thanks!

  2. CaptD November 19, 2012 at 1:33 pm

    Here is additional information in reply to Mr. Dricks, comments above, about the Safety of testing at San Onofre provided by The DAB Safety Team https://docs.google.com/file/d/0BweZ3c0aFXcFUndESmhOM0JsVDA/edit

  3. HelpAllHurtNeverBaba November 16, 2012 at 8:34 pm

    According to Press Releases, Edison said it plugged six tubes in Unit 2 that had wear of better than 35 percent and plugged more than 500 other tubes preventively. The company said steam generators are built with additional tubes so they can be taken out of service, and that only 2.6 percent of the total tubes in Unit 2 were plugged. A review of the Westinghouse Operational Assessment for San Onofre Unit 2 Restart Plan Report indicates that 2 additional Active tubes in one of the Unit 2 Steam Generators had a wear rate of 28 percent, which is very close to wear of 35 percent limit for NRC plugging. Westinghouse is projecting the wear of these 2 active tubes in SG 2E089 from 28% to be ~31% by the end of 5 months assuming every thing will go as planned without any transients or MSLB. In light of SONGS Unit 3 Operating experience, and to adequately protect the Public Health & Safety from a potential nuclear accident, the projection of this number based on empirical formulas and data derived from other plants/tests is highly questionable. Furthermore, this number is too close to the NRC plugging limit of 35%. Therefore, these 2 degraded tubes present a formidable challenge to the Safe Restart of Unit 2 by making it highly vulnerable to localized steam dry-outs, 100% void fractions, fluid elastic instability, flow-induced random vibrations and cascading tube ruptures during unanticipated operational occurrences and Main Steam Line Breaks. Hence these 2 active tubes and any neighboring tubes should be plugged using the MHI Screening Criteria. By not plugging these 2 tubes and hundreds of surrounding tubes as a preventive measure, which can rupture these 2 high wear tubes due during a MSLB, Edison has not met the performance criteria specified in Appendix A, “General Design Criteria for Nuclear Power Plants,” (GDC 14, 15, 30 and 32) to 10 CFR Part 50, which establishes the fundamental regulatory requirements for the integrity of the SG tubes.

    SONGS RSGs have no in-plane protection, were designed with narrow tube pitch to diameter ratios, low tube clearances, taller tubes for more thermal heat (More Money in SCE’s Pocket), without NRC License 50.90 Amendment Approval Process, Without Public Hearings, Reluctant CPUC Approval, Opposition By SDG&E, Inadequate Industry Benchmarking, NO Research of Academic Literature on how to prevent Fluid Elastic Instability & Flow-induced Random Vibrations and no design of supports and knowledge of operational parameters to prevent potential localized steam dry-out areas. SONGS RSG design is a very unique and bad design, which is outside of the NORM of the RSGs Designs for United States, European, Spanish, Russian, Korean, Taiwanese, Indian, Chinese and Canadian Nuclear Fleet. SCE and MHI has to share the blame for this Billion Dollar Rate Payer Debacle. CPUC and NRC also believed everything SCE told them and did not use good judgment in providing independent oversight for SONGS RSG Project as required by their Charter. NRC & Atomic Safety Licensing Board really needs to follow the advice provided below before they start reviewing SCE Unit 2 Restart Plan.

    Quote No 1: A NRC Branch Chief gifted with MIT Intelligence, Intuition and a Sixth Sense said to an anonymous participant at an Industry Conference, “Sir, to resolve any complex technical problem and understand unclear regulations, you have to, ‘Read and reread in between the lines’, use, ‘Critical questioning and an investigative attitude’ and ‘Solid Teamwork & Alignment.”

    Quote No 2: Insanity: Doing the same things over and over again and expecting different results – Albert Einstein

    Observation No 1: SONGS Chronic Problem: Production Before Safety & Haste makes Waste

    Observation No 2: In Emergency Planning Space, decisions have to be Accurate and Timely. Under-conservative, rushed and profit-motivated analyses based on limited facts, biased and ambiguous operational data, untested deterministic and probabilistic risk analysis, conflicting theories and differing operational assessments of degraded equipment at even reduced power operations for 150 days with conditional monitoring along with unproven and unreliable compensatory actions represent enormous risks to public safety, the environment and our nation’s economy.

  4. HelpAllHurtNeverBaba November 16, 2012 at 1:06 am

    Mihama Tube Rupture at TSP due to MS Pressurization was estimated > 8000 psig, which is 1.5 greater than MSLB Test Pressure of 5200 Psig “in-situ” pressure used at SONGS for structural testing of 8 failed tubes. That means SIPC calculations uses under conservative formulas for calculating burst pressures.

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