Meltdown Likely Under Way At Japan Nuclear Reactor

[webfact]

FLASH: Japan nuclear agency says radioactivity levels continue to decline at Fukushima nuclear plant /via@Reuters

[jfchandler]

Just curious... if/when they start spraying water at large into/toward the cooling pools, isn't that likely to start spreading radioactive contaminated water out of the pools and into the reactors and around the site... I'm assuming it's going to mean a lot of water being sprayed... And a water cannon from afar isn't exactly a pinpoint approach.

[Jdietz]

Right now water is boiling off at a nice clip, so I don't think it will be much worse, compared to them boiling dry and decomposing

[jfchandler]

Keep in mind that yesterday, the Japanese military had to cancel their helicopter water spraying plan because one of their helicopters measured radiation exceeding 50 millisievert per hour above the plant... One good indication on radiation will be whether they are able to proceed with helicopter operations today.

While the Japanese govt. raised the radiation limit for Fukushima plant workers to 250 millisievert the other day, apparently, the limit for their military (self defense) forces remains 50 millisievert.

FLASH: Japan nuclear agency says radioactivity levels continue to decline at Fukushima nuclear plant /via@Reuters

[Jdietz]

Well if they manage to refill the pool, the amount of direct radiation will lower significantly (they will spray water mixed with boron, inhibiting the reaction)

[Jdietz]

NHK World: Officials have arrived and spraying water with the water cannon is imminent.

- Also a helicopter has arrived again

Edited March 17, 2011 by Jdietz

[canuckamuck]

I would like to know two things

1. If the rods spill their contents and those contents(fuel pellets) amass at the bottom of the pool, could they then go critical.

2. what is required for the fuel to go critical?

[jfchandler]

No sign the water cannon spraying has started yet, but NHK says soon, with police wearing "special protective clothing."

Japan police to douse spent fuel rods with water at Fukushima plant

TOKYO, March 17, Kyodo

Tokyo police plan to use a water cannon truck to attempt to cool a spent fuel rod pool Thursday in a bid to contain the disaster at the troubled Fukushima No. 1 nuclear power station in Japan. The building housing the No. 4 reactor suffered what appeared to be a hydrogen explosion early Tuesday following the devastating earthquake and tsunami last week. A fire also broke out Wednesday there.

In the face of the unprecedented nuclear crisis, the focus is now on how to cool the possibly overheating pools that store spent nuclear fuel rods at the No. 4 as well as No. 3 reactors.

Unless the spent fuel rods are cooled down, they could suffer damage and emit radioactive materials.

The government earlier studied a plan to deploy Ground Self-Defense Force choppers to spray water over the spent fuel pools, but the Defense Ministry said Wednesday afternoon it had given up on the idea due to the high radiation level.

The U.S. military, meanwhile, will operate a Global Hawk unmanned high-altitude reconnaissance aircraft, possibly on Thursday, to take images of the inside of the building that houses the No. 4 reactor, according to Japanese government sources.

Among the six reactors at the Fukushima No. 1 nuclear plant operated by Tokyo Electric Power Co., part of the No. 2 reactor's containment vessel, key to enclosing harmful radioactive substances, suffered damage in the pressure-suppression chamber connected to the vessel following Tuesday's apparent hydrogen explosion.

An estimated 70 percent of the nuclear fuel rods have been damaged at the plant's No. 1 reactor and 33 percent at the No. 2 reactor, Tokyo Electric said Wednesday.

The cores of the No. 1, No. 2 and No. 3 reactors are believed to have partially melted with their cooling functions lost in the wake of Friday's magnitude 9.0 earthquake and tsunami.

The government's Nuclear and Industrial Safety Agency said Wednesday that the water level had dropped in the No. 5 reactor, which was not in service when the killer quake jolted northeastern Japan, posing the risk of overheating. The agency said it will closely monitor data on the reactor to prevent the problems that occurred at other reactors.

The government has set the evacuation zone covering areas within a 20 kilometer radius of the plant.

http://english.kyodo...1/03/78734.html

Edited March 17, 2011 by jfchandler

[jfchandler]

NHK showing a JSDF helicopter flying over the plant...still talking about helicopter water dropping plan.

Says first helicopter likely monitoring radiation, while two other helicopters reportedly are en route with water dropping capacity...ability to drop 7.5 tons of water per trip.

Saying helicopters likely to target No. 3 reactor pool first.Saying likely easier access to No.3 because the prior explosion ripped away more of the roof structure vs. Reactor 4.

Edited March 17, 2011 by jfchandler

[jfchandler]

NHK reporting CH-47 helicopter just dropped first water load on Reactor No. 3 at 9:48 am Japan time.

Edited March 17, 2011 by jfchandler

[jfchandler]

Reporting second helicopter just made its water drop.

Edited March 17, 2011 by jfchandler

[jfchandler]

SDF chopper drops water on No. 3 nuke reactor at Fukushima plant

TOKYO, March 16, Kyodo

A Self-Defense Forces helicopter dropped water on the troubled No. 3 reactor of the Fukushima nuclear power plant on Wednesday as it is feared the reactor may have released radioactive steam due to damage to its containment vessel.

Jfc note - recall that Reactor No. 3 also is the one with the mixed plutonium fuel source..considered more dangerous than the other reactors' fuel sources.

Edited March 17, 2011 by jfchandler

[jfchandler]

Black dot shows helicopter and white spot underneath shows water drop in process.

NHK also reporting helicopters beginning to drop water on Reactor 4 as well.

NHK reporting helicopters are using sea water, picking it up from the ocean immediately adjacent to the nuclear plants.

Edited March 17, 2011 by jfchandler

[jfchandler]

NHK reporting helicopter crews wearing protective gear and helicopters equipped with lead plates.

NHK now saying 11 police water canon trucks are "headed" for the reactors plant. Saying authorities believe the water cannon spraying may be more effective.

Edited March 17, 2011 by jfchandler

[jfchandler]

NHK saying helicopter crews are wearing radiation dose meters... that can be checked in live time..

Also saying JSDF forces, for the emergency, have raised their radiation exposure limit to 100 millisievert...vs. the normal limit of 50 millisievert.

Saying helicopter operations will be limited to 40 minutes per helicopter due to radiation exposure.

Now saying initial two helicopters have completed their air drops.... Other helicopters may be en route.

Edited March 17, 2011 by jfchandler

[Jdietz]

NHK world:

- 4 water dumps have been completed.

- 40 minutes max mission duration

- More helicopters on their way to relieve current ones

Edit: JF got it, no need for me to double up, I'll sit back and read.

Edited March 17, 2011 by Jdietz

[atsiii]

In watching the heli-dumping on NHK TV, the choppers are trying to keep moving and not hover... so it seems difficult to be on target. I can't imagine it (refilling cooling pools) will be successful in this way. It seems like now the choppers have been pulled away. Maybe the water cannons will be more effective.

Edited March 17, 2011 by atsiii

[jfchandler]

Just to recap, the initial two helicopters completed four total water drops...then departed....

NHK showing image of police water cannon truck, saying they carry four tons of water...

Actually, NHK now saying there will be fire trucks and police water cannon truck...

The above image almost looks more like a fire truck than a police truck... Anyone know? NHK originally showed this when talking about the police water cannon truck.

Edited March 17, 2011 by jfchandler

[Jdietz]

As long as the helicopters get at least -some- water in, the radiation level at the site will drop enough to get the fire engine crews closer.

The storage pools are described as being 'twice the size of an Olympic pool, and stacked 10 high'

They normally hold 15 meters of water, so some serious refilling needed.

Edited March 17, 2011 by Jdietz

[jfchandler]

Thanks Jd... Glad I woke up early today...

[Jdietz]

NHK showing image of police water cannot truck, saying they carry four tons of water...

Funny accurate typo though ( cannot truck )

Edit: Saved original quote so this keeps making some sense

Edited March 17, 2011 by Jdietz

[jfchandler]

NISA official on NHK saying a priority today will be work to begin restoring emergency power supply to the plant, with work supposed to begin this afternoon...

Plan to provide power to eventually use sea water pumped in for cooling. But because the original pumps were contaminated by tsunami sea water...they're going to need work.

Edited March 17, 2011 by jfchandler

[brahmburgers]

Some thoughts: let's hope, with multiple copters flying in hazardous and smoky areas, that they don't collide.

question: if a fuel rod is sitting dry on its own, will it heat up and emit radioactivity?

How much less problematical is a spent U rod compared to a relatively new rod?

As mentioned earlier, at least some of the fuel at #3 is plutonium - more dire than U.

Spraying water may be much more difficult in #4, where supposedly exposed fuel rods lie, as it sounds as though the containment structure is only partially breached (a small area?). This might sound extreme, but I wonder if authorities there have considered using tank rounds to blow off more of the covering, in order to get cooling water to the danger areas. Some reports here have said the outer containment structure is steel, but I would guess it's more likely reinforced and hardened concrete, don't know?

There was mention yesterday that #1 had a partial meltdown. If there's no coolant going in there, then it would seem the meltdown in #1 is continuing (and worsening?), as there would seem to be nothing to slow it down.

[canuckamuck]

Getting sufficient electricity would be a Godsend at this point.

[jfchandler]

Forgive me for being a cynic...but I can't believe four helicopter water drops alone ( we'll have to see if more and how many are forthcoming) would have had much effect on the situation on the ground....even in terms of any temporary relief...

They're moving in the air...the water gets spread thru the air... part of reactor 4 still has the roof in place, etc etc..

I almost get the feeling, the exercise was as much one in public relations (trying to show people the government is actually doing something) as anything else.

PS - What about the supposed U.S. military delivered generators... No one's popped in with any authoritative reference about that supposed development...

Edited March 17, 2011 by jfchandler

[JulianLS]

According to NHK, all four water dumps were targeted at unit 3. Seems the storage pools are the main concern.

Edit> sorry, correction, now they are saying the third dump was aimed at unit 4.

Edited March 17, 2011 by JulianLS

[Jdietz]

At this time it looks like the situation inside the reactor cores is pretty much under control. Don't forget the reaction has been stopped at the moment of the quake, and it has been cooling down ever since. With sufficient cooling this should have taken 4 to 5 days.

If they now get at least some water in the pools, this will lower the ambient radiation level enough so some work can be done around the sites.

Also they plan to finish AC power hookup today, and install new sea water pumps.

I would say, 6 days in, no *kaboom*, very low levels of radiation outside the plant, that they are doing a marvelous job all considering.

[jfchandler]

NHK:

More people evacuating to avoid radiation

An additional 28,000 people have been forced to evacuate from their homes to other areas to avoid possible radiation from a nuclear power in Fukushima Prefecture, northeastern Japan. Friday's earthquake and tsunami crippled the nuclear plant.

NHK has learned that as of Wednesday, 31municipalities in Fukushima Prefecture accepted at least 28,152 evacuees, in addition to those who had already taken shelter in those municipalities.

But many temporary shelters set up in the prefecture were already too crowded to accept the newcomers.

At a shelter about 100 kilometers from the Fukushima Daiichi nuclear power plant, 295 evacuees joined the 38 people who had already been staying there since the earthquake. Some of them say they were forced to move there because the first shelter they went to was overcrowded. They also say some of them have not yet received any radioactive screening tests.

The number of Fukushima people trying to evacuate to other prefectures is increasing.

Neighboring Niigata Prefecture says it has booked another 17 hotels in Niigata City and elsewhere for evacuees from Fukushima to stay since it expects the number to rise. About 2,700 people from Fukushima have already taken shelter in Niigata.

Yamagata Prefecture has started providing screening tests and health counseling services at 4 health centers for the Fukushima evacuees. At least 1,600 Fukushima residents have already moved to that prefecture.

By Wednesday evening, Tochigi Prefecture had also received 320 people. They were divided among 3 shelters after getting a health check and radioactive screening test.

Thursday, March 17, 2011 01:59 +0900 (JST)

http://www3.nhk.or.jp/daily/english/17_01.html

[jfchandler]

Actually, NHK was reporting they dropped on Reactor 4 as well... Hard to see visually whether that was correct or not.

According to NHK, all four water dumps were targeted at unit 3. Seems the storage pools are the main concern.

Edit> sorry, correction, now they are saying the third dump was aimed at unit 4.

[Lopburi99]

Am I the only one feeling some signs of optimism for the first time in days?

Edited March 17, 2011 by Lopburi99