The DAB Safety Team Agrees With Newly Released MHI Data:
Plug All Of SONGS Unsafe Tubes, Not Just Some
The DAB Safety Team along with the support of an ever-growing number of SONGS Concerned Insiders and Whistleblowers, prepared the following analysis, which is consistent with the conclusions presented in the publicly available reports provided earlier on this subject by:
1. Fairewinds Associates Internationally Known Nuclear Consultant Arnie Gundersen and his team of Anonymous Industry insiders, who have had lengthy careers in the design, fabrication, and operation of nuclear steam generators.
2. Professor Daniel Hirsch and Internationally Known Nuclear Consultant Dale Bridenbaugh.
3. Publicly available posted documentation by Dr. Joram Hopenfeld, a retired engineer from the Office of Nuclear Regulatory Research and NRC's Advisory Committee on Reactor Safeguards (ACRS) report issued in February 2001, which substantiated many of Dr. Hopenfeld's concerns,
4. David A. Lochbaum, Director of the Nuclear Safety Project for the Union of Concerned Scientists (UCS).
MHI Part 21 (10/05/2012) - Steam Generator Tube Wear Adjacent To Retainer Bars: The following information was received via email: "Mitsubishi Heavy Industries, LTD (MHI) has identified steam generator tube wear for San Onofre Nuclear Generating Station. "The Steam Generator tube wear adjacent to the retainer bars was identified as creating a potential safety hazard. The maximum wear depth is 90% of the tube thickness. The cause of the tube wear has been determined to be the retainer bars' random flow-induced vibration caused by the secondary fluid exiting the tube bundle. Since the retainer bar has a low natural frequency, the bar vibrates with large amplitudes. This type tube wear could have an adverse effect on the structural integrity of the tubes, which are part of the pressure boundary. The plugging of the tubes that are adjacent to the retainer bars was performed. MHI has recommended to the purchaser to remove the retainer bars that would have the possibility of vibration with large amplitude or to perform the plugging and stabilizing for the associated tubes."
SCE Unit 2 Restart Plan, Attachment 4, Page 9, Line 13, MHI States, "In order to ensure the structural integrity of the tubes after restarting the plant, all tubes which have a potential for losing their integrity during the next operating period should be plugged and thermal power output of the plant should be decreased. Plugging for the Type 1 wear should include not only the tubes with the Type 1 (tube-to-tube) wear but also tubes which are susceptible to the Type 1 wear, for preventative reasons." Attachment 4, Page 82, Section 8.1.3, MHI states, “ Tubes with wear indications adjacent to the retainer bars should be plugged regardless of the wear depth. Furthermore, all tubes that have a possibility to come in contact with the retainer bars should be preventatively plugged.” SONGS Technical Specification states, “Structural integrity performance criterion: All in-service steam generator tubes shall retain structural integrity over the full range of normal operating conditions (including startup, operation in the power range, hot standby, and cool down and all anticipated transients included in the design specification) and design basis accidents.” General design criteria (GDC) 14, “Reactor Coolant Pressure Boundary (RCPB)” of Appendix A to United States Code of Federal Regulations 10 CFR Part 50, “Domestic Licensing of Production and Utilization Facilities,” states “The RCPB shall have “an extremely low probability of abnormal leakage…and gross rupture.”
Even at 70% power operations, if a steam line break outside containment were to occur in Unit 2, the depressurization of the steam generators with the failure of a main steam isolation valve to close would result in 100% void fraction in the entire U-Tube bundle. This condition of ZERO Water in the steam generators would cause fluid elastic instability (FEI) and flow-induced random vibrations. This adverse condition, in turn would result in hundreds of SG tube failures/ruptures due to tubes hitting each other because of extremely low tube clearances, NO in-plane support protection, and movement of retainer bars with large amplitudes due to low natural frequencies. With an undetermined amount of tube leaks/ruptures, approximately 60 tons of very hot high-pressure radioactive reactor coolant would leak into the secondary system. The release of this amount of radioactive primary coolant, along with an additional approximately 200 tons of steam in the first five minutes from a broken steam line would EXCEED the SONGS NRC approved safety margins and result in a nuclear meltdown like Fukushima in Southern California.
Many steam generator tube ruptures and steam line break events have occurred in the last 30 years at nuclear power plants throughout the world (See DAB Safety Team’s SONGS MSLB Analysis). In light of the Unit 3 Replacement Steam Generators (RSGs) unprecedented eight tube failures due to 99.6% steam voiding, narrow tube pitch to tube diameter ratio, low tube clearances and NO Designed "In-plane Fluid Elastic Instability support protection" and other tube ruptures/steam line break events, the DAB Safety Team agrees with MHI that all the Unit 2 Tubes would be susceptible to the Type 1 (tube-to-tube) failures/ruptures due to 100% steam voiding of the entire U-Tube Bundle in case of a Main Steam Line Break (MSLB). Therefore, to meet the SONGS Technical Specifications and GDC 14 of Appendix A to 10 CFR Part 50 for a MSLB and prevent a nuclear accident and reactor meltdown in California from cascading tube ruptures, all Unit 2 RSG’s Tubes should be preventatively plugged before Unit 2 Restarts. In other words, the Unit 2 RSG’s in the “As Designed and Degraded Configuration” cannot be OPERATED at any “Power Levels” due to the substantial risk of nuclear meltdown described above.
The DAB Safety Team: November 21, 2012
Media Contact: Don Leichtling (619) 296-9928 or Ace Hoffman (760) 720-7261