Report: Panel at Pilgrim degrading Problem in spent fuel pool described as ‘slow to develop’ Cape Cod Times, By Christine Legere May 14, 2016
PLYMOUTH — One of the panels designed to absorb neutrons and prevent a nuclear reaction called fission from occurring in the spent fuel rods stored in the Pilgrim Nuclear Power Station’s spent fuel pool has deteriorated, according to a report submitted by Entergy Corp. to federal regulators yesterday.
Fission would cause the rods to heat up the same way they do in a nuclear reactor. The heat would cause the water in the pool to boil and evaporate. If exposed, the rods could start a fire and release radiation.
Neil Sheehan, spokesman for the Nuclear Regulatory Commission said degradation of the panels has been a known problem for decades and one experienced by a number of nuclear plants……..It takes as little as four fuel assemblies to begin a nuclear chain reaction. Currently the racks in Pilgrim’s pool hold 3,300 spent fuel assemblies……..
The storage pools at nuclear plants, particularly older ones like the 43-year-old Pilgrim, were designed to hold spent fuel rods short term. Pilgrim’s pool was designed for about 800 assemblies. Assemblies were on large racks that relied on large spacing, about 20 inches between the spent fuel assemblies to maintain sub-critical conditions.
But as the solution to long-term storage continued to be elusive, the pools had to accommodate many more rods than “Because of the federal government’s problem to provide a disposal site for irradiated fuel, tens of thousands of tons of irradiated fuel remains where it was produced,” said David Lochbaum, director of nuclear safety for the Union of Concerned Scientists. “Spent fuel pools have been re-racked with storage racks holding irradiated fuel very close together, often closer than when it is in the reactor core. In the core, there are control rods to prevent criticality. In the spent fuel pools, other methods must be used to protect against criticality.
Solutions to the problem include the use of borated water or the insertion of sleeves containing boron over defective panels.
At this point, there is no time frame for a solution at Pilgrim. http://capecodtimes.com/article/20160513/NEWS/160519684
