Since there are many experts who urge removing the spent fuel assemblies from the Reactor 4 Spent Fuel Pool at Fukushima I Nuclear Power Plant and into dry cask storage as soon as possible, I checked what the US regulatory agency of the nuclear power industry says about spent fuel storage to find out how soon is "as soon as possible".
The minimum the NRC has authorized is 3 years, 5 years normal, industry norm 10 years.
From NRC's webpage "Spent Fuel Storage in Pools and Dry Casks: Key Points and Questions & Answers" (part):
1. All U.S. nuclear power plants store spent nuclear fuel in “spent fuel pools.” These pools are robust constructions made of reinforced concrete several feet thick, with steel liners. The water is typically about 40 feet deep, and serves both to shield the radiation and cool the rods.
2. As the pools near capacity, utilities move some of the older spent fuel into “dry cask” storage. Fuel is typically cooled at least 5 years in the pool before transfer to cask. NRC has authorized transfer as early as 3 years; the industry norm is about 10 years.
3. The NRC believes spent fuel pools and dry casks both provide adequate protection of the public health and safety and the environment. Therefore there is no pressing safety or security reason to mandate earlier transfer of fuel from pool to cask.
The Reactor 4 Spent Fuel Pool contains fuel assemblies that were removed from the reactor core when the unit went into regular maintenance that included replacing the core shroud on November 30, 2010. The maintenance was to last until September 24, 2011 (299 days). There were 548 fuel assemblies in the reactor core at that time. (Information from TEPCO's press release, 11/29/2010)
Assuming that the fuel assemblies were removed from the core soon after the start of the maintenance and put into the SFP, say sometime in December 2010, they have been cooled in the SFP for about one and a half years by now. Another one and a half years to go, then, to reach the minimum that the NRC would authorize the removal from the SFP to dry casks.
TEPCO/Japanese government's current plan seems to be to move the older fuel assemblies in the Common Spent Fuel Pool into dry casks to make room for the Reactor 4 SFP fuel assemblies.
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8 comments:
Can they use an external crane to move the newest SPF bundle back into the #4 reactor ?
Can they remove the Japanese government and then put it on that elevator to space scientists were planning to build, and take them along with the EU commissioners and put them out into space, safely?
Just kidding!
Well, the urgency of the matter is that IF A BIG EARTHQUAKE happens the consequences will be extremely dire. So going according to the "normal" schedule is irrelevant. Not only that, the normal schedule does not apply in such a disaster zone. We need a Manhattan Project otherwise Japan may end up contaminating most of the world with massive radiation. Don't people get this, or is this no big deal? The entire time this is going on people are being terrorized by the possibility of it occuring and Tipco has ZERO credibility, technical ineptitude rating of infinity and we are supposed to follow the normal schedule? Gimmee a friggin' break ExSKF.
OMG! Ultra man is back! I am so happy. Swatch!!!
Laprimavera,
I believe the "experts" all know that the fuel has to be cooled for another 18 months before it can be transferred to dry cask storage.
The current pressure on TEPCO is meant to ensure that TEPCO hastens the groundwork so as to be fully prepared to begin the process of dry cask storage by the end of 2013.
In other words, the "experts" want to be certain that TEPCO doesn't wait 5-10+ years to mitigate the threat that's currently posed by the extraordinary radioactive inventory of the unit 4 spent fuel pool.
anon above, if that's the case, none of the "experts" have done the decent explanation of that to "lay" people, that it takes at least 18 months to move the hottest fuel to dry cask storage.
US Spent Fuel -> Salt Mine
Fort Calhoun is loaded w/ spent fuel rods but you can't talk about it anymore as it is under DHS & NDAA
FYI, the BfS (Bundesamt fuer Strahlenschutz) says typical wet storage is 5 years, like NRC.
But, unlike NRC the BfS says that minimum obligatory wet storage/cooldown time is 1 year.
(see http://www.bfs.de/bfs/druck/broschueren/dezentr_zwischenlager.pdf , page 24)
Probably we can interpret these (differing) information in the way that the burn-up rates of the individual fuel cartridges determines the necessary wet storage time.
Obviously lesser-burnt-up cartridges earlier reach the threshold of about 1 kilowatt maximum heat production per fuel cartridge that the casks can dissipate.
And, reading the BfS document, one can note that the German view is that "wet storage" (in NRC view) actually is "cooldown" temporary storage, and "dry storage" (in NRC view) represents the actual "storage".
So the German nuclear authorities actually consider the storage methods not equal.
Wet storage in today's German policy view is just necessary for cooling down and can be extended only until the nuke plant dismantling starts (and the latter is another topic for itself, of course...).
This leading to big concrete halls to hold the casks being built near the German nuclear plants, as to avoid unnecessary transports until a final storage has been found.
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