| inbluevt | Date: Monday, 2013/07/29, 9:39 AM | Message # 1 | DMCA |
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Earlier this spring, workers at Reactor Unit 3 of the Indian Point nuclear power plant, 40 miles north of New York City, undertook a routine procedure vital to the operation of any such plant in the United
States: they replaced the reactor’s “spent” nuclear fuel rod assemblies with fresh ones, transferring the older assemblies to a cooling pool adjacent to the reactor core.
Back in 1976, when Unit 3 was first licensed, the Nuclear Regulatory Commission (NRC) authorized its cooling pool to hold a maximum of 264 spent fuel assemblies. Now, however, 1,218 assemblies are packed into the pool like giant radioactive sardines in a large underwater tin.This is not only more than four times the number of spent fuel assemblies for which the pool was initially designed, but also close to the maximum 1,345 permitted by the NRC¾a reality that no doubt presents a
headache for Indian Point’s corporate owner, Entergy. After all, as Entergy spokesperson Jerry Nappi notes, “A reactor cannot continue to operate unless there is room in its cooling pool for its spent fuel.”
Of course crowded cooling pools represent more than an inconvenience for the nuclear industry. As UCS Nuclear Safety Project Director Dave Lochbaum explains, “Densely packed cooling pools represent an undue risk to the public because they are unacceptably vulnerable to accidents,
natural disasters, or terrorist attack.”
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The Simpler, Safer Choice
Why nuclear waste should be moved to dry casks.
After five years in a cooling pool, spent fuel assemblies are cool enough to
be moved into dry casks: concrete and metal containers that are filled
with inert gas, then placed on concrete pads or in large concrete silos
at the reactor site. Unlike cooling pools that require mechanically
driven water circulation, dry casks employ “passive” cooling: air enters
an opening at the bottom of the cask, absorbs heat from the spent fuel,
then rises and exits through an opening at the top, creating a “chimney
effect” that pulls more air into the bottom of the cask.
Passive cooling makes dry casks less likely to lose their cooling capacity than “active” systems like cooling pools, which are vulnerable to mechanical failure, technical or human error, terrorist attack, and natural disaster. In addition, maintaining safety is simpler with dry casks, involving such mundane tasks as ensuring that birds have not built nests that block the chimney’s air flow.
It is worth noting that some of the spent fuel from Japan’s Fukushima Daiichi plant had already been stored in dry casks prior to the 2011 earthquake and tsunami. The safety of
this radioactive waste was never a concern during the subsequent crisis.
Message edited by inbluevt - Monday, 2013/07/29, 9:53 AM |
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