BRATTLEBORO — Federal regulators have approved yet another change in Entergy Nuclear’s inspections of the Vermont Yankee nuclear plant.
In the most recent change approved by the Nuclear Regulatory Commission, Entergy was given permission to change the way it performs tests of the reactor head for seal leaks during its upcoming refueling outage.
“It is not uncommon for plant owners to seek relief from system and equipment surveillance (testing) requirements,” said NRC spokesman Neil Sheehan via email. “However, there needs to a be a well-articulated and valid justification before the NRC would grant such relief.”
In the most recent case, Entergy sought relief from the requirements set by the American Society of Mechanical Engineers boiler and pressure vessel code for the fourth, 10-year in-service inspection. Entergy told the NRC that to comply with the established code “would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.”
Entergy Nuclear spokesman Robert Williams said Monday “whenever there are tests involved, we look for the best way of doing things. Occasionally we can make the case there’s an alternate way of doing things.”
“We do thousands of inspections based on codes and standards established by organizations such as ASME (American Society of Mechanical Engineers) and overseen by NRC.” Williams said.
“Those codes and standards are designed for a typical plant, so allow for alternate means for inspections where the code method is impractical or a hardship or where it doesn’t increase in the level of quality of safety.”
Williams said that the tests will now be done during a plant shutdown, with the standing head of water as the source of pressure for the leak test, instead of normal water conditions.
Just before Christmas, the NRC gave Entergy permission to inspect the problem-prone steam dryer less often, but said if an inspection of the dryer during Yankee’s upcoming refueling outage revealed any changes in any of the dozen small cracks that are already documented in the dryer, the inspection schedule will remain the same.
He said Entergy made modifications to the steam dryer using new hardware with low carbon stainless steel material that is more resistant to intergranular stress corrosion cracking, which is the source of the cracks.
Williams said there was no connection between the granting of the steam dryer request on Dec. 20, and the latest request, which was submitted the next day, Dec. 21, 2012.
Sheehan said that in the testing of the reactor head for seal leaks, Entergy made the case that it could do it safely and with less radiation exposure to its workers.
“After a thorough review, the NRC staff determined that the proposed Entergy approach was consistent with the ASME,” Sheehan said.
Sheehan said that Entergy has made a commitment to visual inspections of the lines involved during Yankee’s upcoming refueling and maintenance outage.
Yankee is already starting the “coasting down” process of reducing power output in preparation for shutting down for its regularly scheduled refueling outage. The plant was listed at 91 percent power Monday morning with the NRC.
Williams refused to say when the shutdown would occur, saying that was proprietary, market-sensitive information.
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