Fukushima nuclear plant: Murphy wins, TEPCO stops ‘water entombment’ experiment on Reactor 1

By arevamirpal::laprimavera
29 April 2011 After the pressure inside the Containment Vessel of the Reactor 1 dropped down very, very close to the atmospheric pressure, TEPCO decided to stop the experiment of pumping extra water into the Pressure Vessel of the Reactor 1. The idea was to pump extra water into the Pressure Vessel, which then would leak extra water into the Containment Vessel, which then would be filled with water to the level that’s high enough to cool the fuels inside the Pressure Vessel. For now, the idea of turning the “unintended” water entombment into the “intended” is out. Snippets from Asahi Shinbun (9:58PM JST 4/29/2011):

東京電力は２９日、福島第一原発１号機の格納容器に水を充填（じゅうてん）する「水棺」の試験のため毎時１０トンに増やしていた注水量を元の６トンに戻した。温度や圧力が下がったためで、引き続き様子をみる。 On April 29 TEPCO reduced the amount of water being injected to the Reactor 1 [Pressure Vessel] from 10 tonnes/hr back to 6 tonnes/hr for the “water entombment” experiment to fill the Containment Vessel with water, because the temperature and the pressure dropped [more than expected]. TEPCO will continue to observe the changes. …

It was good that the temperature dropped, but the pressure drop was the Murphy. Here are the precise numbers for the Containment Vessel dry well pressure (from the Plant Parameter sheets from NISA, the latest is linked). It did come awfully close to the atmospheric pressure:

1 atmospheric pressure = 0.1013 MPa
April 29 11:00AM: 0.105 MPa
April 28 5:00AM: 0.125 MPa
April 27 5:00AM: 0.155 MPa (when the experiment started)

#Fukushima I Nuke Plant: Murphy Wins, TEPCO Stops “Water Entombment” Experiment on Reactor 1