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Oyster Creek Nuclear Alert: As Floodwaters Fall, More Questions Arise

7:10 am in Uncategorized by Gregg Levine

Oyster Creek Nuclear Generating Station in pre-flood mode. (photo: NRCgov)

New Jersey’s Oyster Creek Nuclear Generating Station remains under an official Alert, a day-and-a-half after the US Nuclear Regulatory Commission declared the emergency classification due to flooding triggered by Hurricane Sandy. An Alert is the second category on the NRC’s four-point emergency scale. Neil Sheehan, a spokesman for the federal regulator, said that floodwaters around the plant’s water intake structure had receded to 5.7 feet at 2:15 PM EDT Tuesday, down from a high of 7.4 feet reached just after midnight.

Water above 6.5 to 7 feet was expected to compromise Oyster Creek’s capacity to cool its reactor and spent fuel pool, according to the NRC. An “Unusual Event,” the first level of emergency classification, was declared Monday afternoon when floodwaters climbed to 4.7 feet.

Though an emergency pump was brought in when water rose above 6.5 feet late Monday, the NRC and plant owner Exelon have been vague about whether it was needed. As of this writing, it is still not clear if Oyster Creek’s heat transfer system is functioning as designed.

As flooding continued and water intake pumps were threatened, plant operators also floated the idea that water levels in the spent fuel pool could be maintained with fire hoses. Outside observers, such as nuclear consultant Arnie Gundersen, suspected Oyster Creek might have accomplished this by repurposing its fire suppression system (and Reuters later reported the same), though, again, neither Exelon nor regulators have given details.

Whether the original intake system or some sort of contingency is being used, it appears the pumps are being powered by backup diesel generators. Oyster Creek, like the vast majority of southern New Jersey, lost grid power as Sandy moved inland Monday night. In the even of a site blackout, backup generators are required to provide power to cooling systems for the reactor – there is no such mandate, however, for spent fuel pools. Power for pool cooling is expected to come either from the grid or the electricity generated by the plant’s own turbines.

As the NRC likes to remind anyone who will listen, Oyster Creek’s reactor was offline for fueling and maintenance. What regulators don’t add, however, is that the reactor still needs cooling for residual decay heat, and that the fuel pool likely contains more fuel and hotter fuel as a result of this procedure, which means it is even more at risk for overheating. And, perhaps most notably, with the reactor shutdown, it is not producing the electricity that could be used to keep water circulating through the spent fuel pool.

If that sounds confusing, it is probably not by accident. Requests for more and more specific information (most notably by the nuclear watchdog site SimplyInfo) from Exelon and the NRC remain largely unanswered.

Oyster Creek was not the only nuclear power plant dealing with Sandy-related emergencies. As reported here yesterday, Nine Mile Point Unit 1 and Indian Point Unit 3–both in New York–each had to scram because of grid interruptions triggered by Monday’s superstorm. In addition, one of New Jersey’s Salem reactors shut down when four of six condenser circulators (water pumps that aid in heat transfer) failed “due to a combination of high river level and detritus from Hurricane Sandy’s transit.” Salem vented vapor from what are considered non-nuclear systems, though as noted often, that does not mean it is completely free of radioactive components. (Salem’s other reactor was offline for refueling.)

Limerick (PA) reactors 1 and 2, Millstone (CT) 3, and Vermont Yankee all reduced power output in response to Superstorm Sandy. The storm also caused large numbers of emergency warning sirens around both Oyster Creek and the Peach Bottom (PA) nuclear plant to fail.

If you thought all of these problems would cause nuclear industry representatives to lay low for a while, well, you’d be wrong:

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Alert Declared at Oyster Creek Nuclear Plant

9:45 pm in Uncategorized by Gregg Levine

Oyster Creek Nuclear Generating Station (photo courtesy of NRC)

The US Nuclear Regulatory Commission is reporting that an “alert” has been declared at the Oyster Creek Nuclear Generating Station in Ocean County, New Jersey. An alert is the second level on the four-point scale, a step above an “unusual event.”

The NRC declared the alert at 8:45 PM local time, as a combination of rising tides, wind and the storm surge from Hurricane Sandy caused water to rise above safe levels in the plant’s water intake structure. Sandy, which made landfall at around 8 PM in southern New Jersey with 90 mph winds, has caused power outages and widespread flooding along the Atlantic coast from Maryland to New York.

Oyster Creek is the oldest operating commercial reactor in the US. It is a GE boiling water reactor of similar design to the ones that failed in Fukushima, Japan during 2011′s Tohoku earthquake, though Oyster Creek is actually older. As Sandy moved up the coast, fears were raised about several nuclear facilities in the storm’s path. The NRC had issued no specific directives in advance of the hurricane, though extra inspectors were dispatched to threatened plants early on Monday.

Particular concerns were raised about Oyster Creek. The reactor is currently offline for maintenance, which means all the reactor fuel, along with generations of used fuel, is in the plant’s spent fuel pools. The plant itself is not generating any electricy, and so is dependent on external power. If the power were to fail, there would be no way to circulate cooling water through the pools.

Backup diesel generators typical to this design power the heat transfer from the reactor, but the so-called “defense in depth” backups for the spent fuel pools are the plant’s own electrical output and power from an external grid.

Flooding of the coolant intake structure further complicates matters. Oyster Creek does not have a cooling tower (like those seen in classic pictures of Three Mile Island). Safe temperatures are maintained by taking in massive amounts of water from a nearby source (in this case, Barnegat Bay). Water must continue to circulate in and out of the facility to keep temperatures at safe levels.

Another question would be whether floodwaters would carry additional radioactive contamination into Barnegat Bay as they recede.

In the NRC press release on Oyster Creek (PDF), the regulator also noted (with apparent pride) that no reactors had been shut down because of Hurricane Sandy. However, at least one reactor, Millstone 3 in Connecticut, had reduced output in anticipation of the storm. Several other reactors in the region are currently offline for refueling or maintenance.