NRC says last three Pilgrim Nuclear Power Station shutdowns were unrelated
Ten days ago it was a pump problem. Then, a few days later duck hunters came a bit too close for comfort. And Monday a valve leak set off alarms at the Pilgrim Nuclear Power Station. But, according to the Nuclear Regulatory Commission, it does not, as of now, “see any commonalities between these events as two involved different valves and one was caused by personnel error.”
From a layman’s point of view, these three events – and another shutdown in May – could appear to form a troubling pattern. The plant, after all, is more than 40 years old.
Could these events be related to the age of the plant and, if so, should residents be concerned that multiple events might occur at the same time, making a simple leak or electrical problem a potential catastrophe?
Excluding the incursion by duck hunters, there have been three unplanned shutdowns at Pilgrim in just more than six months:
- Last May: Reactor scram from degrading condenser vacuum due to a valve failure
- Jan. 10: Reactor scram due to trip of both reactor recirculation pumps due to personnel error during testing.
- Jan. 20: Reactor shutdown due to a leaking safety relief valve (These safety release valves are a new design and have been installed since the last outage in 2011.)
Nevertheless, the NRC says no, there is no connection.
“We are constantly on the lookout for any problems or issues that could impact more than one area of plant performance,” NRS spokesman Neil Sheehan said this week.
“We would describe these as cross-cutting issues,” Sheehan added. “One example would be any training program weaknesses that could contribute to plant shutdowns or other events. If we saw evidence of such problems, we would not hesitate to require the company to take action in response, and we would follow up through inspections to ensure that occurred.”
But what about the age of the plant; is that a concern?
“Entergy must investigate and evaluate each equipment failure to determine if additional preventive maintenance measures may be necessary for a given component or system,” Sheehan said.
Sheehan said the reactor scram was due to personnel error during testing and not an equipment failure, and the safety relief valves had undergone work in the not-too-distant past.
The NRC does compile with what it calls “performance indicators,” Sheehan explained. These are the records of unplanned nuclear power plant changes and shutdowns.
“If the number of power changes and/or shutdowns crosses a predetermined threshold, for example, if more than three unplanned scrams occur more than the previous 7,000 hours – about 10 months – of critical operation,” he said, “that performance indicator would cross from ‘green’ to ‘white.’ ”
If that happened at Pilgrim, according to Sheehan, Entergy would have to perform a root cause evaluation and the NRC would evaluate the cause and the corrective actions Entergy took in a supplemental inspection.
“Pilgrim is currently ‘green’ in all performance indicator categories,” Sheehan said, “including unplanned shutdowns.”
But if another scram occurs in the next month or so, it would be time for a root cause evaluation.
Follow Frank Mand on Twitter at @frankmandOCM