etudiant said:
A two hour hiatus does not seem too bad, unless it has to take place several times each day. If memory serves, the initial thought had been a bi weekly change of the filter media, just by pulling the old skids.
Presumably the skids could be changed out very quickly, assuming appropriate water line couplings and skid handling provisions.
Does anyone know how many skid sets are available?
According to http://www.nisa.meti.go.jp/english/press/2011/06/en20110615-3.pdf the plan is to treat 230,000 m³ of contaminated water with "about 400" absorption towers during "approximately one year".
The same document also said :
The Cesium adsorption bars must be changed at a rate of 2-4 bars per day; therefore, the shielding facilities will be internal. Even if there is still some processing capacity remaining, the Cesium bars are managed by replacing them when the surface dosage is a maximum of 40mSv/h, and the exposure at the time of replacement is controlled at a maximum of 4mSv/h.
http://www.nisa.meti.go.jp/english/press/2011/06/en20110615-3.pdf
These figures don't appear to be consistent: 2 bars per day during one year makes 2*365=730 bars which is more than 400.
TEPCO is plugging holes in the roofs of the turbine buildings and stacking sandbags to prevent rain water from entering the facility.
(...)
It says it has so far processed around 2,500 tons of radioactive water with the system. On Friday, it began work to desalinate treated water with the aim of recycling it to cool down the overheating reactors.
http://www3.nhk.or.jp/daily/english/24_19.html
http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110624_01-e.pdf : a timetable with details on the volumes of contaminated water treated so far at the water treatment facility, with each processing time, flushing time, and test conditions.
http://twitpic.com/5ejt3u : a more detailed map (shown to journalists during the NISA press conference) of the water treatment facility (the reactor is the box in the top left corner. The Toshiba oil removing system is on the left, the Areva system is in the middle, the Kurion system is on the right side, and the Hitachi desalinating facility on the top ; in between the various tanks are shown)
http://sankei.jp.msn.com/region/news/110624/fks11062412310001-n1.htm The T-hawk helicopter drone made an emergency landing on the top of unit 2 reactor building. No smoke or blaze was reported. They plan to rescue it with a crane.
NISA press conference 2011.06.24 11:10 http://www.ustream.tv/recorded/15577343 : it is expected that the original primary circuit at the unit 1 SFP cooling system can be reused instead of creating a new one as was previously thought. Tepco provided a report on the safety issues concerning the cover for unit 1 : http://www.meti.go.jp/press/2011/06/20110624005/20110624005-2.pdf : the roof can bear the weight of 30 cm of snow. The average maximum wind speeds recorded during the past 10 years being 17 m/s, the structure is designed to withstand 25 m/s winds. It is a "C class building" as regards the earthquake safety. 6 air-filtering units with a 10,000m³/h capacity each will be installed, providing a total capacity of 40,000m³/h (4 units are active, 2 spare units are inactive). There will be a nozzle in the roof, that can be used to pour water into the spent fuel pool. Thermometers will measure the air temperature inside the cover. Cameras will watch the spent fuel pool. Radiation sensors and hydrogen sensors will be installed (sensor locations are shown on the figure page 8). The tsunami wall will be completed by the time the cover structure is finished. The cover sheet material respects the relevant fire resistance standard. The roof and panels could be opened for fire-fighting purposes. The walls of the reactor building will be coated with a dust fixating material beforehand. Even if the cover structure collapses, the added weight is not enough to curtail the reactor building's earthquake or wind resistance. The temperature is expected to rise inside the reactor building, and on a case by case basis spot-coolers will be installed. The humidity is not expected to rise because it will be absorbed by the air-filtering system.
http://www.meti.go.jp/earthquake/nuclear/pdf/20110624-2nisa.pdf : original fax sent by plant manager Yoshida to notify nuclear accident as required by law. It is dated 11 March 16:00 by the fax machine. It says: all AC power is lost ; all units 1~5: all diesel generators are out of order. Unit 6: only one diesel generator is safe. Generators tripped because their seawater cooling system was inundated.