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Mitsubishi faulted by nuclear watchdog, over San Onofre equipment tests

Nuclear watchdog faults Mitsubishi over San Onofre equipment tests
LA Times, December 17, 2012  Federal regulators found flaws in the process followed by Mitsubishi Heavy Industries in building and testing mock-up replacement parts for the troubled San Onofre nuclear plant.

The plant has been out of service for more than 10 months because of excessive wear on tubes carrying radioactive water, one of which leaked a small amount of radioactive steam in January, prompting the plant’s shutdown.

The tubes are part of the four massive replacement steam generator assemblies manufactured by Mitsubishi for plant operator Southern California Edison.

The replacement project cost Edison and San Diego Gas & Electric, which co-owns the plant, a combined $771 million, a cost passed on to ratepayers. A warranty on the equipment is capped at $137 million.

Commission staff found flaws in Mitsubishi’s process of mock-up and
testing of redesigned anti-vibration bars that could be part of a
long-term repair plan for the plant, according to a recently released
U.S. Nuclear Regulatory Commission report. Inadequate support
structures in the steam generators have been blamed in part for
allowing the tubes to vibrate excessively, leading to the unusual
wear.

The NRC report said Mitsubishi failed to verify that the tubes used in
the mock-up conformed to requirements for outside diameter
straightness, tube bending radius and total tube length that were
outlined in the purchase order and purchase specifications for the
tubes.

It also faulted Mitsubishi for failing to properly vet calibration
services performed by another company in connection with measuring
strain on the tubes. The report, completed Nov. 30, asked Mitsubishi
to respond within 30 days……. http://latimesblogs.latimes.com/lanow/2012/12/nrc-mitsubishi-san-onofre.html

December 18, 2012 - Posted by Christina Macpherson | safety, USA