#Fukushima I Nuke Plant Reactor 4: Leak Continues from Reactor Well/SFP/DS

TEPCO hasn't identified the leak, but the leak is evidenced by the rapidly dropping water level of the Skimmer Surge Tank.

From Jiji Tsushin (2/3/2012):

東京電力は３日、福島第１原発の４号機原子炉建屋の原子炉と使用済み燃料プール、機器用プールに共通して張っている水が建屋内に依然として漏れ続けている とみられると発表した。水位はほぼ満水状態に維持しているが、あふれた水を受けるタンクの水位が通常の２倍のペースで低下しているため、漏出の可能性が高 いと分かった。

TEPCO announced on February 3 that the water in the Reactor Pressure Vessel, Spent Fuel Pool and DS Pool in Reactor 4 continues to leak into the reactor building. The RPV, SFP, and DS Pool are filled with water to the near-full level, but the water level of the Skimmer Surge Tank is dropping twice as fast as normal, which likely indicates a leak.

　この水は放射能汚染水で、もともと汚染水がたまっている建屋地下へ流れているとみられる。配管接続部などの凍結、損傷が考えられ、作業員が場所の特定を急いでいる。

The water is contaminated with radioactive materials, and is considered to be flowing to the basement of the reactor building where the contaminated water has already been sitting. The possible causes include the frozen or damaged pipe joints, and the workers are trying to identify the location(s).

From TEPCO's Plant Parameter data, the water levels of Reactor 4 Skimmer Surge Tank:

2/3 11AM: 3179 millimeters
2/3: 5AM: 2085 mm
2/2 11AM: 2498 mm
2/2 5AM: 2784 mm
2/1 11AM: 3223 mm
2/1 5AM: 3225 mm
1/31 11AM: 3977 mm
1/31 5AM: 4357 mm
1/30 11AM: 5416 mm
1/30 5AM: 5208 mm

The relationship of the Reactor Well (RPV), SFP, and DS Pool:

SFP and Skimmer Surge Tank:

(Graphics created by @pluredro based on TEPCO's information)

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8.5 Tonnes of Water Leaked from Reactor Well/Spent Fuel Pool of Reactor 4 According to TEPCO

In the evening press conference on February 1, 2012 (with Matsumoto), TEPCO announced the result of their calculation: 8.5 tonnes of water from the Reactor Well/Spent Fuel Pool of Reactor 4 may have leaked (Jiji News, Japanese, 2/1/2012). Other than the information of the TEPCO's calculated number and the diameter of the pipe (9 millimeters), the details seem the same as I reported in my previous post.

Just keep in mind that that's their calculation for about 29 hours from 3:50PM January 30 to 10:43PM January 31.

TEPCO also released the photographs of the jet pump test line that leaked; one pipe is totally dislocated from the joint.

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#Fukushima I Nuke Plant Reactor 4 Was Leaking Water from Reactor Well/Spent Fuel Pool, and That Was Indicated by Water Level of Skimmer Surge Tank

TEPCO announced during the February 1 morning press conference that the valve of a pipe line connected to the reactor was found broken and at least 6 liters of water from the reactor had spilled.

The Reactor Well/Reactor Pressure Vessel of Reactor 4 is filled with water even if it does not have any fuel (since it was in maintenance when the accident happened), and the water goes back and forth freely between the Reactor Well and the Spent Fuel Pool as the gate separating them has been loose since the January 1 earthquake.

It is the water co-mingled with water from the Spent Fuel Pool that was leaking, as evidenced by the relatively high radioactivity of the water.

Information gleaned out of the three bumbling TEPCO people (without Matsumoto) who didn't seem to know much at all (except one), to the irritation of the reporters who attended:

• At 10:30PM on January 31, a worker found the water leaking from the jet pump test line valve in the southwest corner on the 1st floor of Reactor 4 during the "patrol" (which is probably a lie, as you'll see later).

• There are 20 jet pumps inside the Reactor Pressure Vessel.
  

• The nature of damage of the valve is not known. It is probably not from freezing. It may have been broken when the explosion happened (last March).
  

• The jet pump test line connects to the jet pumps inside the RPV.

• The water stopped when they shut off the main line coming from the RPV, at 10:43PM.

• It is hard to tell whether the test line valve broke recently or not, as the floor is littered with debris.

• The leaked water is estimated to be about 6 liters as far as they could find on the floor full of debris.

• The water is from the Reactor Well. The reactor has no fuel inside as it was on maintenance when the accident happened, but it is filled with water.

• Radioactivity of the leaking water is 35.5 becquerels/cubic centimeter (but TEPCO couldn't say whether it was all-gamma radiation or something else). Therefore, it is the water from the Reactor Well which is connected to the Spent Fuel Pool.

• The Reactor Well and the Spent Fuel Pool are separated by the gate, but the gate got loose after the earthquake on January 1 and the water from the Spent Fuel Pool comes in to the Reactor Well.

• Actually, TEPCO knew something was amiss on January 30 when they noticed the water level of the Skimmer Surge Tank dropping rapidly at 3:50PM. The cooling system for the Spent Fuel Pool was re-started at 3:13PM that day, and they thought the Skimmer Surge Tank's level had something to do with the cooling system and decided to observe for one day and look for possible causes.

• The water level of the Skimmer Surge Tank was dropping at 60 to 90 millimeters per hour.

• Then on January 31, a worker found the broken valve at the jet pump test line. (See, it was not a routine "patrol"; they were looking for possible causes of the drop in the Skimmer Surge Tank level and found the leak.)

• When the leak was stopped, the drop in the water level of the Skimmer Surge Tank stopped.
  

• As the only person who was able to talk about anything technical explained, water goes back and forth freely between the Reactor Well and the Spent Fuel Pool, and if the water level of the Reactor Well goes down that means the water level of the Spent Fuel Pool goes down, and that is reflected in the water level of the Skimmer Surge Tank.

• The Skimmer Surge Tank water level hardly changes in the cold weather like this.

• The leak is probably confined within the reactor building, and the leaked water was probably led to the basement water.
  

Well well. When the water level drop in the Skimmer Surge Tank in Reactor 4 was first reported after the January 1, 2012 earthquake, the explanation was, as I clearly recall, that the water in the Spent Fuel Pool went into the Reactor Well when the gate got loose, and therefore not enough water went to the Skimmer Surge Tank. They also said the water level of the Skimmer Surge Tank would go down naturally due to evaporation.

Now they finally admit that the water level of the Skimmer Surge Tank is the direct indication of the water level of the Spent Fuel Pool.

6 liters of the contaminated water from the Spent Fuel Pool/Reactor Well doesn't make sense if the Skimmer Surge Tank water level was dropping 60-90 millimeters per hour for 29 hours. Several reporters pressed for a clear answer, but TEPCO said they would get back to them after calculation.

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P.S. I just read a post by Ms. Emiko Numauchi as "Numayu" writing that there was nuclear fuel inside the Reactor Pressure Vessel of Reactor 4 and it had a meltdown, as she heard from a worker she trusts, and the English translation of the post by someone else.

If the fuel melted through the RPV and now on the floor of the Containment Vessel as she claims, I have no idea how the RPV/Reactor Well is able to retain water, as it clearly does, looking at the photographs. Of course she or anyone can claim they are fake photographs.

As for me, I want to find the facts as much as possible without resorting to calling everything fake. Even from TEPCO, the reporters on February 1 press conference were able to draw out more information than what TEPCO initially presented in the beginning of the press conference.

Well of course TEPCO can be lying 100%, but it simply would not make sense for TEPCO to hide a meltdown on Reactor 4 if it happened. There are already 3 meltdowns, and part of the melted fuel has eaten into the concrete floors of the Containment Vessels. What's the point of hiding another meltdown, after 10 months?

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#Fukushima Reactor 4 Skimmer Surge Tank Latest: Earthquake Caused the Water to Go from SFP to Reactor Well Instead, Says TEPCO

TEPCO admits the January 1, 2012 earthquake caused it, and no it wasn't a leak but the water from the Spent Fuel Pool went the other way to the Reactor Well, instead of going to the Skimmer Surge Tank.

(For the last announcement from TEPCO, see my post here.)

I started reading the Mainichi Shinbun article, but it was very short on details, and knowing TEPCO couldn't have held a press conference on January 2 I went to look for TEPCO's own words somewhere. It was in the handout for the press on January 2, 2012.

The handout is in Japanese only for now, so the following is my translation. It was clearly written over time as new information came in. (I will put up the English reference handout when TEPCO issues one.)

１月１日午後５時30 分頃、４号機使用済燃料プールのスキマサージタンク＊１の水位が午後２時から午後５時までの３時間で約240mm 低下していることを確認（これまでの運転実績では３時間で約50mm 程度の低下）。その後、現場確認を行った結果、４号機原子炉建屋外廻りおよび同号機使用済燃料プール代替冷却システムの一次系配管接続部や設置エリア等に、漏えいは確認されなかった。

At 5:30PM on January 1, it was observed that the water level of the Skimmer Surge Tank of the Spent Fuel Pool of Reactor 4 dropped by 240 millimeters during the 3 hours from 2PM to 5PM (while the normal decline is 50 millimeters in 3 hours). Later we surveyed the facilities, but found no leak outside the reactor building, at the pipe joints of the SFP cooling system or at the location where the cooling system was installed.

なお、１月１日午後５時現在の４号機使用済燃料プール水の温度は23℃（１月２日午前５時現在22℃）であり、現在も使用済燃料プール代替冷却システムは運転しているため、同プールの冷却に問題はない。また、使用済燃料プールの水位も維持されており問題はないものの、スキマサージタンクの水位低下は継続しているため、１月１日午後10 時27 分から同日午後11 時13 分にかけてスキマサージタンクの水張りを実施。現在のスキマサージタンク水位低下は１時間あたり約90mm で継続中であり、スキマサージタンクの水位確認を３時間に１回から１時間に１回に強化する等の監視強化を継続。なお、現時点では建屋外への漏えいは確認されておらず、建屋内の滞留水の水位にも顕著な変化は確認されていない。

As of 5PM on January 1, the temperature of the water in the Reactor 4 SFP was 23 degrees Celsius (as of 5AM on January 2 it was 22 degrees Celsius). The SFP cooling system is in operation and there is no problem in cooling the pool. While the water level in the SFP remained the same, the water level in the Skimmer Surge Tank continued to drop. From 10:27PM to 11:13PM on January 1, we filled the water in the Skimmer Surge Tank. Currently the water level is declining at about 90 millimeters per hour. We are monitoring the water level every hour instead of every 3 hours. As of now there is no leak outside the building, and there is no noticeable change in the water level of the contaminated water inside the [reactor] building.

その後の調査により、スキマサージタンクの水位低下に相当する減少量と原子炉ウェル＊２の水位上昇に相当する増加量がほぼ同等であること、および原子炉ウェル水位が使用済燃料プール水位より低いことを確認。これらのことから、１月１日午後２時30 分頃に発生した地震の影響で原子炉ウェルと使用済燃料プール間のゲートの隙間の状態が変化し、使用済燃料プールから原子炉ウェル側への水の流入量が増加したことにより、使用済燃料プールからスキマサージタンクへのオーバーフロー量が低下し、スキマサージタンクの水位低下が通常よりも多くなったことが原因であると推定。

Later inspection revealed that the amount of water decreased in the Skimmer Surge Tank was about the same as the amount of water increased in the Reactor Well, and that the water level in the Reactor Well was lower than that in the SFP. Therefore, our hypothesis is that: the earthquake on January 1 at 2:30PM tweaked the space in the gate between the Reactor Well and the SFP; water flowed from the SFP to the Reactor Well, and the overflow water to the Skimmer Surge Tank decreased, causing the water level of the Skimmer Surge Tank to decrease more than normal.

原子炉ウェルと使用済燃料プールの水位差を低減させるため、１月２日午前11 時50 分から午前11 時59 分にかけて原子炉ウェルへの水張りを実施したところ、午後４時現在、スキマサージタンクの水位低下は確認されていない。今後も引き続きスキマサージタンク水位の監視を実施予定。

In order to decrease the difference in the water levels between the Reactor Well and the Spent Fuel Pool, water was poured into the Reactor Well from 11:50AM to 11:59AM on January 2. As of 4PM, there is no decrease in the water level in the Skimmer Surge Tank observed. We will continue to monitor the water level in the Skimmer Surge Tank.

＊１ 使用済燃料プールからオーバーフローした水を受けるため設置されているタンク。使用済燃料プールの水は、通常、燃料集合体の冷却および水の不純物を取り除くため、スキマサージタンクへオーバーフローさせ、熱交換器およびフィルタを通した後、再び使用済燃料プールへ戻している。

Skimmer surge tank is a tank set up to collect the overflow from the Spent Fuel Pool. In order to cool the spent fuel bundles and to remove impurities from the water, the water in the Spent Fuel Pool is overflowed into the skimmer surge tank, and goes through the heat exchanger and the filter before it goes back into the Spent Fuel Pool.

＊２ 原子炉ウェルは、原子炉圧力容器および原子炉格納容器の蓋を収納している空間で、定期検査中はこの空間を満水状態にし、燃料交換などを行う。

The Reactor Well is a space to store the Reactor Pressure Vessel and the Containment Vessel Lid. During the regular maintenance [which Reactor 4 was undergoing at the time of the accident], this space is filled with water to conduct work such as exchanging the nuclear fuel.

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#Fukushima Reactor 4 Skimmer Surge Tank Water Level Update

（UPDATE: Again, it is NOT about the water level of the Spent Fuel Pool. There are blogs and tweets that either deliberately or by ignorance blur the distinction between the SFP and the skimmer surge tank and create an impression that the SFP is leaking. As of now, that is simply not true, with what little information available.)

(UPDATE 2: By the way, TEPCO doesn't have a press conference until January 4. So much for "emergency" email notification.)

(Update 3: TEPCO says the earthquake sent the water from SFP to Reactor Well instead to the Skimmer Surge Tank. See my latest post.)

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TEPCO's emergency email notification, as posted on Twitter by one of the freelance journalists:

東京電力からのご連絡
Notice from TEPCO
────────────────────────────────────
報道関係各位
To the Press

・本メールは、事前に「深夜・早朝における連絡先」の登録のお申し込みをいただいた方にお知らせしています。
This mail is sent to those who have registered for "Notification in late night and early morning".

・本日（１月１日）午後５時30分頃、免震重要棟でプラントデータの確認を行っていた当社社員が４号機使用済燃料プールのスキマサージタンク（※）の水位が比較的早い速度で低下していることを確認しました。

Today (January 1) 5:30PM, our employee monitoring the plant data found the water level of the skimmer surge tank was falling at a relatively rapid pace.

・スキマサージタンクの水位については、自然蒸発などにより低下しますが、これまでの運転実績において、３時間で50ｍｍ程度（１時間あたり約17ｍｍ）の低下であったものが、本日午後２時～午後５時までの３時間で約240ｍｍ程度（１時間あたり約80ｍｍ程度）の低下が確認されました。

The water level of the skimmer surge tank goes down due to natural evaporation. In the past normal operation, the rate was 50 millimeters in 3 hours (or 17 millimeters per 1 hour). However, in 3 hours from 2 to 5PM today it dropped about 240 millimeters (or 80 millimeters per hour).

・現在、漏えいを想定した現場確認を行っているところでありますが、４号機の使用済燃料プール循環冷却システムが設置されている廃棄物処理建屋１階ならびに原子炉建屋外廻りにおいて漏えいは確認されておりません。原子炉建屋内の配管の接続部の健全性確認など、現場調査を引き続き行い、原因調査を行ってまいります。

We are conducting the survey of the area with the expectation that there is a leak somewhere. So far, there is no leak on the 1st floor of the Waste Product Process Building where the cooling system for the Reactor 4 SFP is installed, and no leak outside the reactor building. We will investigate the pipe joints inside the reactor building for any leaks, and identify the cause.

・本日午後５時現在の使用済燃料プール水の温度は23℃であり、現在も同プールの冷却を継続しており、使用済燃料プール自体の水位に変動はありません。今後、準備が整い次第、スキマサージタンクの水張りを実施し、水位を監視してまいります。

As of 5PM today, the temperature of the SFP is 23 degrees Celsius. Cooling of the SFP continues, and there is no change in the water level of the SFP. As soon as ready, we will fill the skimmer surge tank with water and monitor the water level.

・本メールには返信できませんのでご了承ください。
Do not reply to this mail.

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　以　上


（※）使用済燃料プールからオーバーフローした水を受けるため設置されているタンク。使用済燃料プールの水は、通常、燃料集合体の冷却および水の不純物を取り除くため、スキマサージタンクへオーバーフローさせ、熱交換器およびフィルタを通した後、再び使用済燃料プールへ戻している。

Skimmer surge tank is a tank set up to collect the overflow from the Spent Fuel Pool. In order to cool the spent fuel bundles and to remove impurities from the water, the water in the Spent Fuel Pool is overflowed into the skimmer surge tank, and goes through the heat exchanger and the filter before it goes back into the Spent Fuel Pool.

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(UPDATED) #Fukushima I Nuke Plant Reactor 4's Skimmer Surge Tank Water Level Going Down At 5 Times the Normal Pace

UPDATE: translation of TEPCO's email to the members of the press who have signed up to receive notification of emergencies is posted in this post. It's not for so-called "mass media", it is for any journalist who has signed up for the notification from TEPCO." In fact, I got the link from an independent news media.

Again, it is NOT the water level of the SFP but of the skimmer surge tank, as some people are clearly confused that SFP's water level is dropping.

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From ANA (Asahi TV) News (1/1/2012):

【原発】福島第一4号機プール隣接施設で水漏れか

Water leaking in the facility adjacent to the Spent Fuel Pool in Reactor 4 in Fukushima I Nuclear Power Plant?

福島第一原発4号機の使用済み燃料プールに隣接するタンクで、水位が通常の5倍近い速さで低下しているのが確認されました。東京電力は、原因の特定を急いでいます。

It has been confirmed that the water level is getting lower in the tank adjacent to the 4 Spent Fuel Pool in Fukushima I Nuclear Power Plant at a pace 5 times faster than normal. TEPCO is trying to identify the cause as soon as possible.

　 1日午後5時30分ごろ、4号機の使用済み燃料プールに隣接する「スキマサージタンク」の水位が比較的速く低下しているのが見つかりました。普段でも蒸発などで低下しますが、その5倍の速さでした。これまでに、プールの循環冷却システムや原子炉建屋の周辺で水漏れは見つかっていません。プール自体の冷却は続いていて、温度や水位に変化はないということです。東京電力では、配管の接合部などの調査を行い、タンクの水位低下の原因の特定を急いでいます。

At 5:30PM on January 1, the water level of the "skimmer surge tank" next to the Spent Fuel Pool in Reactor 4 was found to be going down at a relatively rapid pace. The water level goes down due to evaporation, but the speed was 5 times faster than the rate of evaporation. No leak has been discovered in the SFP's cooling system or around the reactor building. The cooling of the SFP continues, and there is no change in the temperature and the water level [in the SFP]. TEPCO is conducting the inspection of the pipe joints, trying to identify the cause of the dropping water level in the skimmer surge tank.

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