Moon of Alabama Brecht quote
March 19, 2011

March 19 Fukushima Update - No. 4 Pool Fission?

More water was sprayed onto the unit no. 3 spent fuel pond and efforts are underway to connect reactor no. 2 to the power grid. Manpower at the plant was ramped up with some 130 operational staff and 320 people now clearing pathways and laying new power lines. 130 firefighter from Tokyo also joined. No other incidents or efforts from the Fukushima Daiichi plant were reported since yesterday.

But what is up with unit no. 4?

Satellite picture March 18 by Digital Globe
Unit no. 4 to no. 1 from left to right
bigger version

I have been harping on over unit no. 4 for days now. I see immediate danger there.

The Japanese authorities have said little about it. There was a fire at no. 4 on the 15th they said, at some pump, and another short fire soon after the first one was out. There were two holes in the reactor building walls they said, 26 square foot each. Yesterday they even downgraded the INES classification of no. 4 from 4 to 3 while upgrading the damage classification of the Daiichi reactors 1 to 3 from 4 to 5. Instead of a "serious accident without significant off-site risk" no. 4 is now only a "serious incident" they claim. Cooling efforts for the spent fuel pond at no. 3 were again made while no efforts are made to cool the pond at no 4.

But all of that can not be right. There ain't just two holes in the unit no. 4 walls as TEPCO initially reported.

Photos and video show all outer metal and reinforced concrete walls down to the first floor severely broken and damaged after the "fire". Between the 16th and 17th the metal roof plating above the unit vanished according to satellite pictures (see yesterday's status post). Brown smoke is coming from the building. No explanation at all has been offered for all of this to happen. The TEPCO reports ignore it. Since yesterday 16:00 local time the Japanese Atomic Industry Forum report table (update 12) says for no. 4 without any further explanation: "Hydrogen from the pool exploded". But the Kyodo News Agency now reports on no. 4:
Renewed nuclear chain reaction feared at spent-fuel storage pool

The spent fuel pond at no. 4 holds about 1,500 fuel assemblies with a total mass of some 250 tons of Uranium fuel. The reactor no. 4 was temporarily unloaded for maintenance in November 2010. Therefore most of the fuel in the pond is not spent but rather fresh and radioactive. Cooling at the pond has ended a week ago right after the quake. The building exploded despite a non-active reactor within it. Why and how did that happen if not for some nuclear incident at the fuel pond?

Usually fuel in a spent fuel pond is moderated and prevented from fission by boron plates between the stored fuel rod assemblies and/or by boron in the cooling water. But if the fuel heats up due to its continuing radioactive decay it could melt and assemble an unmoderated critical mass at the bottom of the pool. Such a mass going back into fission would generate, aside from a lot of radioactivity, enough temperature to eventually burn through the concrete below and would end up in the environment after meeting water underground and exploding it into steam. This was one of the main dangers in Chernobyl and an enormous amount of work was done and serious deadly risk was taken to prevent that.

Today the New York Times writes:

[A] senior Western nuclear industry executive said Friday that there also appeared to be damage to the floor or sides of the spent fuel pool at Reactor No. 4, and that this was making it extremely hard to refill the pool with water. [..]

Engineers said Thursday that a rip in the stainless steel lining of the pool at Reactor No. 4 and the concrete base underneath it was possible as a result of earthquake damage. The steel gates at either end of the storage pool are also vulnerable to damage during an earthquake and could leak water if they no longer close tightly.

The senior executive, who asked not to be identified because his comments could damage business relationships, said that a leak had not been located but that engineers had concluded that it must exist because water sprayed on the storage pool had been disappearing much more quickly than would be consistent with evaporation.

The head of the U.S. nuclear regulator said publicly that the pool at no. 4 was dry. The NYT report tells why that is the case. TEPCO and the Japanese government are very quiet about no. 4. They probably do not know what to do about it. But what to do is easy. Doing it is dangerous though.

A heavy slurry of sand, boron and water must be put into the pond. This would shield the environment from radiation and likely prevent any fission. Drying slurry would probably even seal some of the holes in the pond. Several hundred tons would be needed.

This can be done from helicopters, as it was done in Chernobyl. It would be very dangerous for the pilots but that can not be helped. Alternatively high reaching concrete pumps could be used to deliver the slurry into the pond from the ground below. This would probably also cost the health and even life of emergency workers working near the reactor. Again, this can not be helped.

There are signs that TEPCO and the Japanese might finally start to get it:

In a further sign of spreading alarm on Friday that uranium in the plant could begin to melt, Japan planned to import about 150 tons of boron from South Korea and France to mix with water to be sprayed onto damaged reactors, French and South Korean officials said Friday.

They "plan to import". The boron was needed and offered days ago. Spraying will not help with a leaky no. 4 pool. Slurry is needed. Get it. Get it done. Now.

Additional resources:
AllThingsNuclear Union of Concerned Scientists
Bulletin of the Atomic Scientists
Atomic power review blog
Digital Globe Sat Pictures
IAEA Newscenter
NISA Japanese Nuclear Regulator
Japan Atomic Industry Forum (regular updates)
Japanese government press releases in English
Kyodo News Agency
Asahi Shimbun leading Japanese newspaper in English
NHK World TV via Ustream
Status reports for the German Federal Government by the Gesellschaft für Reaktorsicherheit in German language

Posted by b on March 19, 2011 at 6:01 UTC | Permalink


what's to say? is this a hari kari moment?

Posted by: annie | Mar 19 2011 7:13 utc | 1

Watching NHK World TV:

They had some report saying the World Health Organization saw no problem with food exports from Japan. ...
Ten minutes later the government spokesman in a live press conference: "We have detected some contaminated fresh food, spinach and milk, that exceeds the allowed levels."

Well - that WHO spin didn't work so well it seems.

Posted by: b | Mar 19 2011 7:22 utc | 2

Asahi reported on 3/16 13:14 that Ministry of Economy, Trade and Industry ordered Tepco at 10AM on the 15th to water the tank at reactor 4. It is kind of strange to see this, as far as I can tell there haven't been any water replenishment in that tank reported. I would guess the order relates to US advice, but lack of reported execution at any time is odd.

It is also odd that tank 4 is studiously avoided, or appears such when you look for that reference. There's no question that it holds a lot of recent and partially used fuel. It does not make sense to ignore it if it poses a danger over and above the #3 structure which appears to be getting all the attention. Papers report that #4 pool will be fed by JSDF later today.

Earlier Tepco presser aside from all the power restoration (on going) details did not mention #4. Interestingly, they revealed that #5 and #6 structures had holes drilled in the roof to give hydrogen escape routes.

I can't really buy the notion that they would be rearranging deck chairs..

Posted by: YY | Mar 19 2011 7:22 utc | 3

I saw in passing that concrete pump truck is on its way. I would assume this is to pump water, and surprised it took so long since this is a fairly common tool of the construction trade.

Posted by: YY | Mar 19 2011 7:31 utc | 4

@YY - I believe they know that no. 4 is too hot to go there without very severe health risk.

But that doesn't help. Something has to be done about it. The risk of reignited fission is very real.

Posted by: b | Mar 19 2011 8:44 utc | 5

The agency also said it expects the No. 3 and No. 4 reactors to get power supply Sunday.

Posted by: annie | Mar 19 2011 11:04 utc | 6

bloomberg: Japan Unit-4 Pool’s Heat Exceeded Three-Times Normal, IAEA Says

U.S. Nuclear Regulatory Commission Chairman Gregory Jaczko said in Congressional testimony March 16 that unit had no water in its cooling pool, which sits in a side chamber above the reactor’s core. A hydrogen explosion inside the core’s containment chamber may have drained the pool, which is supposed to keep radiation in check by covering the rods with 15 meters of water.

“We believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures,” Jaczko said.

Posted by: annie | Mar 19 2011 11:09 utc | 7

sounding very dire indeed

Posted by: annie | Mar 19 2011 11:12 utc | 8

I'm struggling to understand what's going on (thanks to all, by the way)

three questions:
1) all those intermittent fires reported in the reactors should be "zirconium cladding fires", right? could be something else?
2) what happens if the "not realistic" prospect of a nuclear chain reaction materializes? a bomb? uranium digging his way to the center of the earth? has it ever happened before in a nuclear reactor?
3) how long did it take for "martyrs" to bury the reactor at Chernobyl? could it be too late?

Posted by: claudio | Mar 19 2011 12:55 utc | 9

UK telegraph live blog

15.48 The official Twitter account of the Japanese Prime Minister's Office has just published a series of tweets addressing the possibility of radioactive rain in the Tohoku and Kanto regions.

Twitter It's possible that rain can contain a small amount of radioactive substances when it rains in Tohoku and Kanto regions. (Cont)

Twitter Even if you are exposed to rain, it doesn’t impose any threat on health. If you are concerned, follow these instructions. (Cont)

Twitter Try not to go out unless it is an emergency. Make sure of covering up hair and skin as much as possible. (Cont)

Twitter In case your clothes or skin is exposed to rain, wash it carefully with running water.

Posted by: annie | Mar 19 2011 17:27 utc | 10


to 1. likely zirkonium fire, something else is possible but nobody will know if and what for a long time.
to 2. Uranium in the plant is not highly enriched enough to have a bomb like fission. It could, under certain circumstance, reconfigure into a core like matter where some reactor like moderated nuclear fission could reappear. Saying that this is "not realistic" is like saying that a 9.0 quake and 10+ meter Tsunami at the Japanese east coast is "not realistic". You may believe that and not prepare for it or you may not believe that and be prepared.
In Chernobyl the core melted through concrete floors before it got cold enough to stop. Corium (high temperature fluid fuel and concrete) flowed lava like through high temperature steam lines into the basement picture. The emergency team there filled two underground floors with concrete as an improvised "core catcher".
to 3. It is never "too late" to bury something. In Chernobyl it took 10 days and thousands of people to stop the broken reactor to emit radioactive particles. Radiation continued of course but the wider contamination through smoke particles etc ended. It took six month and 90,000 people to build the improvised sarcophagus in Chernobyl.

Posted by: b | Mar 19 2011 18:00 utc | 11

thanks, b

Posted by: claudio | Mar 19 2011 18:06 utc | 12

“What has been done is the greatest achievement of organized science in history.”

--Harry S. Truman, 1945 statement on the bombing of Hiroshima

Posted by: Uncle $cam | Mar 19 2011 20:34 utc | 13

Alexander Cockburn has a good post on nuke-loving greens being in league with the nuclear power industry. It is an eye-opener.


Posted by: Joseph | Mar 19 2011 20:43 utc | 14

They know these things are unsafe, but, short term profits ALWAYS win the day here in the U.S.

Posted by: Ben | Mar 19 2011 23:58 utc | 15

yes, thank you b. your insights into this crises is very much appreciated.

Posted by: lizard | Mar 20 2011 0:01 utc | 16


Posted by: remembereringgiap | Mar 20 2011 1:01 utc | 17

Yes, thanks b again. I rely on your posts now - still the best info to be found anywhere.

And I agree with your analysis. What the heck are they waiting for? These things are all junk now anyways. Bury them all asap.

A large explosion spreading radiation, and dependent on wind conditions, could easily contaminate the rivers that supply drinking water. The people of Tokyo would be in a terrible situation. Here is a link detailing Tokyo's water sources.

Posted by: Rick | Mar 20 2011 2:07 utc | 18

Rick - comment 18,
How would bury them help ? In the short term it might give the impression the solution is “fixed”. It would still require long term solution - the nuclear reactions would still go on beneath the concrete, etc. There have been enough reports that Tchernobyl is leaking like a sieve, that the concrete cover is broken, etc.
see also:

Posted by: Philippe | Mar 20 2011 7:11 utc | 19

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