#Fukushima I Nuke Plant: Amount of Water Being Injected into RPVs Temporarily Dropped Below Necessary Amount, Cause Unknown

The amount of treated water being constantly injected into the Reactor Pressure Vessels of Reactors 1, 2 and 3 has fluctuated often for no reason that TEPCO cares to identify, but on August 30 that amount temporarily dropped below the levels specified by the NISA's safety regulations.

Cause is still unknown, but unlike in the past, TEPCO's Matsumoto says the company will conduct investigation to identify the cause.

If you want to check the temperature readings of the RPVs, here's TEPCO's page (English).

From Kyodo News (8/31/2012):

福島１～３号機注水量が一時低下　第１原発

Amount of water injected into Reactors 1 through 3 at Fukushima I Nuke Plant dropped temporarily

東京電力は３０日、福島第１原発１～３号機の原子炉への注水が、保安規定に定められた冷却に必要な量より一時低下したと発表した。同日午後に注水量が下がり、バルブ操作で一度回復したが、夜になって再び下がった。同日午後１０時半時点では必要量は確保できている。

TEPCO announced on August 30 that the amount of water injected into the Reactors 1, 2 and 3 at Fukushima I Nuclear Power Plant temporarily dropped below the amount specified in the safety regulation as the amount necessary for cooling the reactors. The amount dropped in the afternoon of August 30, and though it recovered after adjusting the valves [that control the flow] it dropped again in the evening. As of 10:30PM on August 30, the amount necessary for cooling is maintained.

　原子炉圧力容器の温度に変化はない。２台ある注水用ポンプの異常の可能性もあることから、予備ポンプを起動して、原因を調べる。

There are no changes in temperature of the Reactor Pressure Vessels. It is possible that the water injection pumps (there are two) have some problems, and TEPCO will start the backup pump[s] to investigate the cause.

　東電によると、同日午後３時に注水量を監視していた社員が低下に気付いた。１号機には毎時４・９トン、２、３号機には７・０トンを注水していたが、１号機は４・０トン、２号機は５・５トン、３号機は５・６トンに低下していた。原子炉の冷却に最低限必要な量を０・３～０・６トン下回った。バルブの調整で水量を増加させ、間もなく回復した。

According to TEPCO, an employee who was watching the amount of water injected noticed the drop at 3PM on August 30. Normally, 4.9 tonnes/hour of water is injected into Reactor 1, and 7.0 tonnes/hour of water into Reactors 2 and 3. However, [at 3PM on August 30], the amount for Reactor 1 dropped to 4.0 tonnes/hour, for Reactor 2 to 5.5 tonnes/hour, and for Reactor 3 to 5.6 tonnes, which were below the minimum necessary amount [as specified in the safety regulations] to cool the reactors by 0.3 to 0.6 tonnes[/hour]. TEPCO adjusted the valves to bring the amount back up to the normal levels.

　その後、注水量は不安定な状態で、午後８時に再び必要注水量を下回った。バルブ操作で午後１０時半ごろまでに回復した。

However, the amount of water being injected continued to fluctuate, and at 8PM it dropped below the required amount again. It recovered by 10:30PM after valve adjustment.

　１～３号機の注水はこれまでも低下したことがあり、その都度、バルブを微調整して流量を確保していたが、必要量を下回ったのは初めて。漏えいなどは確認されていないという。

The amount of water into Reactors 1, 2 and 3 has dropped in the past. In each occasion, TEPCO adjusted the valves to maintain the flow. But it was the first time on August 30 that the amount dropped below the required amount. TEPCO says no leaks have been found.

　東電の松本純一原子力・立地本部長代理は「冷却に一番大事なシステムで、注水量が極端に下がった原因を慎重に調べたい」と話している。

TEPCO's Junichi Matsumoto says, "It is the most important system for cooling the reactors, and we would like to carefully investigate the cause of sudden drop in the amount of water."

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