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
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