(UPDATED with Photos) #Fukushima I NPP: TEPCO Thinks Someone Opened the Wrong Valve, Causing the Leak of 100 Tonnes of RO Waste Water with 23 Terabecquerels of All-Beta

(UPDATE) One of the local papers in Fukushima Prefecture shares my suspicion that someone (possibly plural) tried to hide the mistake. Fukushima Minyu (2/22/2014; part):

実際は最大９時間は開いていたとみられることを明らかにした。弁の操作を誤った可能性があり、さらに、現場でミスを隠そうとした可能性も出てきた。発覚後の２０日未明の現場確認では問題の弁は閉まっていたが、前日の１９日午前１１時ごろの写真では弁が開いた状態で、通常は外しておく開閉操作用レバーが取り付けられていた。

[TEPCO] disclosed [on February 21] that the valve in question was in fact open for 9 hours at the maximum. There is a possiblity that someone made a mistake in operating the valve. Further, there is a possibility that they [those in the section in charge of the water transfer operation] tried to hide the mistake. In the early hours of February 20 after the leak was discovered, the valve in question was confirmed to be closed. However, in the photo taken around 11AM on the previous day (February 19) the valve was open, and the lever to open and close the valve was attached to the valve, which is normally removed.

From TEPCO's photos and videos library, 2/21/2014:

The valve in question (V347) on February 19, 2014 morning, "open" position, as it shouldn't:

The same valve on February 20, 2014, "closed" position, as it should, but after the leak:

==========================

That's what increasingly the government public relations broadcaster aka NHK says. NHK also says TEPCO has dispatched investigators from the TEPCO headquarters (in Tokyo) to Fukushima I Nuclear Power Plant and started interviewing the plant workers.

It is rather difficult to grasp what NHK is trying to say (they do talk like TEPCO's PR), but I think they are saying:

1. The RO waste water was to be transferred to a storage tank that was NOT the tank it subsequently went and overflowed.

2. Someone opened the wrong valve, and the water went to the wrong tank which was almost full. The water leaked from the top of the tank.

3. AFTER the water leaked from the wrong tank, he realized his mistake; he closed that valve, and opened the valve that should have been opened to transfer the contaminated water to the correct tank.

A gross human error (I hope), which caused (at least) 100 tonnes of extremely contaminated (230 million Bq/L of all-beta, or 23 trillion Bq (terabecquerel) in 100 tonnes) water to leak (see my post on 2/20/2014).

According to Mainichi Shinbun, the Nuclear Regulation Authority has said it is speaking with IAEA on whether to have an INES event scale assigned to this particular incident. The last year's leak of 300 tonnes of the same RO waste water from the storage tanks into the surrounding soil was INES Level 3 "incident". (Level 4 and above are "accidents".)

From NHK News (2/22/2014; emphasis is mine):

汚染水流出 誰かが配管の弁を開けたか

Contaminated water leak: Did someone open the valve?

東京電力福島第一原子力発電所で、山側のタンクから高濃度の汚染水およそ１００トンが流出した問題で、東京電力は本来、閉じている配管の弁を誰かが開けたのが原因とみて、本店の調査の担当者を派遣して作業員への聞き取りを進めています。

Regarding the 100 tonnes of highly contaminated water that leaked from a tank at Fukushima I Nuclear Power Plant, TEPCO has dispatched investigators from the TEPCO headquarters to the plant who are interviewing the workers. TEPCO suspects someone opened the valve that should remain closed, causing the leak.

福島第一原発では今月１９日から２０日にかけて４号機の山側にあるタンクに水が入りすぎ、汚染水およそ１００トンが敷地内の地面に流出しました。

At Fukushima I Nuclear Power Plant, about 100 tonnes of contaminated water leaked into the surrounding ground in the plant compound in February 19 and 20 when too much water was poured into a tank on the mountain-side (west) of Reactor 4.

当初、東京電力は、汚染水の処理設備から問題のタンクにつながる配管の途中の弁の１つが、閉じた状態になっていたにもかかわらず、水が流れていたとして、この弁が故障していた疑いがあると説明していました。

Initially, TEPCO explained that one of the valves [there are three] on the pipe that goes to this tank may have malfunctioned, as it let the water flow even if it was closed.

ところが、別の作業で弁を撮影した写真が見つかり、水を断続的に移送していた今月１９日の午前の時点では、故障の疑いがあるとされた弁は開いた状態になっていたことが分かりました。

However, a photograph was found that captured the same valve on a different job; the photo showed that the valve, suspected of malfunctioning, was open as of the morning of February 19 when the water was being transferred intermittently.

一方、本来、汚染水を送る予定だったタンクにつながる配管の弁は１９日の午前の時点では閉じられ、水が流れないようになっていて漏えいが見つかったあとには開いていました。

On the other hand, the valve on the pipe that goes to the tank where the contaminated water was supposed to go remained closed as of the morning of February 19, blocking the water flow. However, after the leak was found, this valve was open.

東京電力はこの２つの弁を誰かが開け閉めしたことが汚染水が漏れた原因とみています。

TEPCO thinks someone opened and closed these two valves, causing the leak of the contaminated water.

弁が操作された理由や詳しい経緯を明らかにするため、東京電力は本店の調査の担当者を派遣して作業員から聞き取りを進めています。

In order to find out the details of how the incident happened and why the valves were operated, TEPCO has sent investigators from the headquarters to the plant who are interviewing the workers.

今回の問題で東京電力は弁を操作した際のタンクの水位の監視が徹底されておらず、弁の開け閉めに使う器具がふだん誰でも使える状態で置かれていたことから管理の見直しを検討しています。

TEPCO is considering a review of the maintenance/operation procedure, as the water level monitoring procedure when valves were operated was not strictly followed and the tools to open and close the valves were readily available to anyone.

(Hmmm. So TEPCO does suspect someone may have done it on purpose?)

For now, it looks like some worker made a mistake, and after the leak corrected the mistake without saying anything to anyone, hoping no one would notice.

Too bad TEPCO found the photos...

Tweet