Here I thought they'd been injecting water directly above the melted fuel or where the fuel had once been.
TEPCO in its daily press conference on July 26 said the cooling of the three reactors at Fukushima I Nuclear Power Plant has been done by cooling the core shrouds from outside. The shroud is a cylinder inside the Reactor Pressure Vessel (RPV) that surrounds the reactor core. (The image is from Toshiba.)
Either they tell us now, or it occurred to no one to ask in detail how the fuel was cooled.
Mainichi Shinbun Japanese (7/26/2011):
東京電力は２６日、福島第１原発３号機の原子炉内にある核燃料を効率良く冷やすため、注水方法を変更するための作業を始めたと発表した。核燃料のより近くに注水できる配管が使用できるかどうかを調べるため、国産ロボット「クインス」を原子炉建屋に入れて調査した。
TEPCO announced on July 26 that the company started the work to change the method of water injection in order to cool the fuel inside the Reactor 3 more effectively. The Japanese-made robot "Quince" went inside the reactor building to investigate whether it was possible to use the pipe that could feed water closer to the nuclear fuel.１～３号機では、炉心を囲む構造物「シュラウド」の外側に冷却水を流して核燃料の温度を下げている。１、２号機は毎時４立方メートル弱の注水で一定の効果が出ているが、３号機では効率が悪く同９立方メートルを注水している。
In Reactors 1, 2 and 3, the cooling water is being poured outside the core shroud to lower the temperature of the fuel. The method is adequate in Reactor 1 and 2 with about 4 tonnes/hour water injection, but in Reactor 3 this method of cooling is not efficient enough, and it requires 9 tonnes/hour water.
しかし、その分、汚染水が大量発生しやすく、新たな対応が必要になってきた。そこで、東電は核燃料の真上から注水する緊急炉心冷却装置 （ＥＣＣＳ）の配管などを使うことを検討。同日、建屋１、２階にクインスを入れ配管を撮影したほか、作業員が入れるかどうか周辺の放射線量の測定を始め た。
As the result, more contaminated water is being produced, and the company was looking for an alternative method of cooling. TEPCO is considering using the ECCS (emergency core cooling system) pipe which can pour water from above the fuel. On July 26, the company sent the robot "Quince" to the 1st and 2nd floors of Reactor 3 building to take pictures of the pipe, and started measuring the radiation levels to see if workers could enter the building.
As far as TEPCO is concerned, the melted core is still inside the RPV in Reactor 3.
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6 comments:
Reuters Special Report on TEPCO's safety record at Fukushima prior to the earthquake.
http://graphics.thomsonreuters.com/11/07/JapanNuclearRadiation.pdf
From the report: Over 9000 contract workers were employed annually so that international safety standards of worker radiation exposure could be met. Once threshold levels of exposure were reached by individual workers, those workers were replaced.
With a revolving door of on-site workers,I doubt that the expertise was there to handle the post quake plant emergency.
"..the cooling of the three reactors .. has been done by cooling the core shrouds from outside."
They can say that if they want to, we know the reactors aren't steaming off that much water per hour so that's the water's pathway to the basements which are flooded.
They can also say the cores are in the RPVs if they want. First they'll have to tell us how the water's ending up in the basements. They certainly haven't explored the basements, so part of this is asking you to pretend the cores are in the RPVs still. Until pictures of melt in RPVs are produced, the cores are in the basements, at best.
I don't have the link at hand, but they expected the humidity in #2 to go down when they installed the cooling system for 2's SFP. It did not go down as the temperature dropped in the pool, therefore the steam/humidity is from the core in the basement. The link mistakenly said the core was in the Suppression Pool, that would be the suppression torus they're referring to. Impossible for the core to be IN the torus if it melted thru the RPV.
The core's in the basement in 2, at least.
"Here I thought they'd been injecting water directly above the melted fuel or where the fuel had once been."
This is actually a major admission by TEPCO. They're telling us they are injecting the water inside the RPVs, while the basements are flooded.
they just dump the water in from the rafters opening in the top of the building, the water ends up in the basement where the fuel is melting through the cement. that's why they needed pure water when it existed. they are now going to send workers down into the basement so they can dump water directly onto the corium as part of STAGE 2.
water in core shrouds in 1,2, & 3
nitrogen in 1,2, & 3
basements flooded in 1,2, & 3
Newly-intalled cooling system in 2 has interesting consequences,
if steam was believed to be coming from the SFP, after the temp. in the pool dropped with the new system, was the steam observed to not be rising from the pool?
Is there 'corium' in the SFP?
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