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SCE Had No Knowledge of Safety Problems, Mitsubishi Heavy Industries Letter to NRC Confirms

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By Business Wirevia The Motley Fool

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SCE Had No Knowledge of Safety Problems, Mitsubishi Heavy Industries Letter to NRC Confirms

ROSEMEAD, Calif.–(BUSINESS WIRE)– A letter from Mitsubishi Heavy Industries (MHI) to the Nuclear Regulatory Commission (NRC) proves false the latest round of allegations from activists, Southern California Edison (SCE) said Tuesday. It also confirms that SCE believed the San Onofre nuclear plant’s steam generators were safe when installed and that safety measures were not sacrificed for licensing reasons. The letter, posted on the NRC‘s website, accompanied a redacted copy of the MHI Root Cause Evaluation which has been grossly distorted by the national anti-nuclear activist group, Friends of the Earth.

“The anti-nuclear activists have called the MHI report a ‘bombshell’ which couldn’t be further from the truth,” said Pete Dietrich, SCE senior vice president and chief nuclear officer. “In fact, the MHI letter explains that SCE and MHI rejected the proposed design changes referenced in the evaluation because those changes were either unnecessary, didn’t achieve objectives or would have had adverse safety consequences.

“Our decisions were grounded in our commitment to safety. SCE did not, and would never install steam generators that it believed would impact public safety or impair reliability.”

MHI repeatedly reassured SCE that based on their testing, the steam generators met safety requirements and would function for 20 years.

The MHI letter specifically confirms that at the time the replacement steam generators were designed, MHI and SCE believed that the “replacement steam generators had greater margin against U-bend tube vibration and wear than other similar steam generators.” MHI warranted the steam generators for 20 years.

“As with all engineering evaluations, the MHI letter and report describe a technical evaluation process and need to be read in their entirety to understand the conclusions reached,” said Dietrich. “The activists are taking portions of paragraphs and sentences out of context, and using them as the basis of their allegations that SCE knew of design defects when the generators were installed, but failed to make changes to avoid licensing requirements. That is untrue.”

SCE has previously pointed to faulty computer code used by MHI as failing to predict conditions in the steam generators, along with other design defects. The NRC publicly disclosed the computer code flaws three months before MHI completed its evaluation.

SCE followed standard industry best practices in outlining general specifications for the equipment. These specifications requested MHI to design replacement steam generators that were as close as possible to the original steam generators in form, …read more
Source: FULL ARTICLE at DailyFinance

Business, Finance, Occupation & Industry

Southern California Edison Comments on MHI Evaluation of San Onofre Nuclear Plant Steam Generators

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By Business Wirevia The Motley Fool

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Southern California Edison Comments on MHI Evaluation of San Onofre Nuclear Plant Steam Generators

ROSEMEAD, Calif.–(BUSINESS WIRE)– An evaluation by Mitsubishi Heavy Industries (MHI) made public today cites ineffective tube supports, dry steam and high steam flow velocity as causes of excessive wear in the steam generators MHI supplied to Southern California Edison’s (SCE) San Onofre Nuclear Generating Station.

SCE previously disclosed these same causes based on its own investigation, and the Nuclear Regulatory Commission’s (NRC) augmented inspection team report last July found that MHI‘s use of faulty computer modeling in the design process caused MHI engineers to inadequately predict the dryness of the steam, measured by void fraction, in the replacement steam generators.

MHI repeatedly reassured SCE of the efficacy of the design. During the design phase of the project, MHI advised SCE that, based on its own review and analysis, the maximum void fraction that MHI expected to occur was acceptable, did not require additional design changes or measures, and that the replacement steam generators would perform as warranted.

“SCE‘s own oversight of MHI‘s design review complied with industry standards and best practices,” said Pete Dietrich, SCE senior vice president and chief nuclear officer. “SCE would never, and did not, install steam generators that it believed would impact public safety or impair reliability.”

In fact, MHI states in its root cause report (page 41), that its analysis of conditions in the steam generator during the design phase (which calculated void fraction and steam flow velocity) concluded that the thermal hydraulic conditions in the San Onofre steam generators were acceptable, and specifically that there was no need to reduce void fraction.1

Additionally, SCE never rejected a proposed design change to address void fraction based on its impact on compliance with 10 CFR 50.59.

“At no time was SCE informed that the maximum void fraction or flow velocities estimated by MHI could contribute to the failure of steam generator tubes,” said Dietrich. “At the time, the design was considered sound.”

SCE is disappointed that MHI decided on its own to redact some information in its evaluation about the flaws in the computer codes. However, the NRC publicly disclosed the computer code flaws three months before MHI completed its evaluation. In addition, the corrective actions and other statements included in the evaluation make it evident that there were problems with the computer modeling that failed to predict conditions that led to the tube-to-tube wear.

SCE has proposed operating Unit …read more
Source: FULL ARTICLE at DailyFinance