ID :
191398
Mon, 06/27/2011 - 19:07
Auther :
Shortlink :
http://m.oananews.org//node/191398
The shortlink copeid
Key water circulation cooling system for troubled reactors hits snag
Kyodo - Tokyo Electric Power Co. said Monday it has started cooling the crippled nuclear reactors at the Fukushima Daiichi power complex by using decontaminated water from newly installed water treatment devices, but operation of the system was suspended shortly after the announcement due to a water leak.
The latest development highlights the difficulties of smoothly operating what the plant operator calls ''circulating injection cooling,'' which is seen as a key step to achieve the stable cooling of the Nos. 1 to 3 reactors.
The company plans to check Tuesday for the cause of the water leak from a hose installed to carry decontaminated water into the reactors from a storage tank.
The leak was found only around 90 minutes after the utility known as TEPCO started to send the cleaned water into the three reactors from about 4:20 p.m.
Getting to the point of commencing the circulating injection cooling had already been troublesome because TEPCO had to deal with water leaks and other problems to fully activate on Monday the water treatment devices designed to remove radioactive substances from highly contaminated water accumulating inside the plant's premises.
The devices have been developed by such companies as Kurion Inc. of the United States and France's Areva SA with the aim to largely reduce radioactive cesium, and eliminate oil and salt. Full operation of the devices initially started on June 17, but test-running of the system followed because of the problems that were found.
About 1,850 tons of clean water had been produced in trial runs of the devices by Monday morning and stored in a tank for injection into the reactors.
Under its plan, TEPCO would inject a total of 13 tons per hour using the decontaminated water, while also getting 3 tons per hour of water taken from a nearby dam, a source of water that the reactors are now using as a coolant.
Around 110,000 tons of highly contaminated water, including coolant liquid leaking from damaged reactors, is estimated to have accumulated inside the plant's reactor turbine buildings and nearby areas as a side effect of the current emergency step of injecting coolant water from outside.
But there are fears that the water could overflow or leak out to the Pacific Ocean and elsewhere unless the amount of contaminated water is reduced by using the water treatment system.
Hit by the magnitude 9.0 earthquake and tsunami waves on March 11, the six-reactor nuclear complex lost nearly all of its power sources, causing the cooling functions of the reactors and spent nuclear fuel pools at the Nos. 1 to 4 units to fail.
The Nos. 1 to 3 reactors' cores are assumed to have suffered meltdowns, although it is believed that the melted fuel is being kept cool at the bottom of each reactor pressure vessel because of the current water injection measure.
The latest development highlights the difficulties of smoothly operating what the plant operator calls ''circulating injection cooling,'' which is seen as a key step to achieve the stable cooling of the Nos. 1 to 3 reactors.
The company plans to check Tuesday for the cause of the water leak from a hose installed to carry decontaminated water into the reactors from a storage tank.
The leak was found only around 90 minutes after the utility known as TEPCO started to send the cleaned water into the three reactors from about 4:20 p.m.
Getting to the point of commencing the circulating injection cooling had already been troublesome because TEPCO had to deal with water leaks and other problems to fully activate on Monday the water treatment devices designed to remove radioactive substances from highly contaminated water accumulating inside the plant's premises.
The devices have been developed by such companies as Kurion Inc. of the United States and France's Areva SA with the aim to largely reduce radioactive cesium, and eliminate oil and salt. Full operation of the devices initially started on June 17, but test-running of the system followed because of the problems that were found.
About 1,850 tons of clean water had been produced in trial runs of the devices by Monday morning and stored in a tank for injection into the reactors.
Under its plan, TEPCO would inject a total of 13 tons per hour using the decontaminated water, while also getting 3 tons per hour of water taken from a nearby dam, a source of water that the reactors are now using as a coolant.
Around 110,000 tons of highly contaminated water, including coolant liquid leaking from damaged reactors, is estimated to have accumulated inside the plant's reactor turbine buildings and nearby areas as a side effect of the current emergency step of injecting coolant water from outside.
But there are fears that the water could overflow or leak out to the Pacific Ocean and elsewhere unless the amount of contaminated water is reduced by using the water treatment system.
Hit by the magnitude 9.0 earthquake and tsunami waves on March 11, the six-reactor nuclear complex lost nearly all of its power sources, causing the cooling functions of the reactors and spent nuclear fuel pools at the Nos. 1 to 4 units to fail.
The Nos. 1 to 3 reactors' cores are assumed to have suffered meltdowns, although it is believed that the melted fuel is being kept cool at the bottom of each reactor pressure vessel because of the current water injection measure.
