Fukushima #4 reactor update

9-16-13    fuelrod removal from reactor #4 process will begin in November and Tepco expects to take about a year removing the assemblies, spokesman Yoshikazu Nagai told Reuters by e-mail. It’s just one installment in the decommissioning process for the plant forecast to take about 40 years and cost $11 billion.

Each fuel rod assembly weighs about 300 kilograms (660 pounds) and is 4.5 meters (15 feet) long. There are 1,331 of the spent fuel assemblies and a further 202 unused assemblies are also stored in the pool, Nagai said…

Spent fuel rods also contain plutonium, one of the most toxic substances in the universe, that gets formed during the later stages of a reactor core’s operation…

“There is a risk of an inadvertent criticality if the bundles are distorted and get too close to each other,” Gundersen said.

He was referring to an atomic chain reaction that left unchecked could result in a large release of radiation and heat that the fuel pool cooling system isn’t designed to absorb.

“The problem with a fuel pool criticality is that you can’t stop it. There are no control rods to control it,” Gundersen said. “The spent fuel pool cooling system is designed only to remove decay heat, not heat from an ongoing nuclear reaction.”

The rods are also vulnerable to fire should they be exposed to air, Gundersen said. http://islandbreath.blogspot.com/2013/09/fukushima-reactor-4-fuel-pond.html
…………………………………………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………..
Title: #117: Olympic Insanity + If Gundersen were in Charge at Fukushima
Source: Nuclear Hotseat
Host: Libbe HaLevy
Date: Sept. 10, 2013
INTERVIEW: Former nuclear industry insider Arnie Gundersen of Fairewinds Energy Education paints a clear picture of the current state of problems at Fukushima Daiichi… and then explains what he would do if he were in charge of the disaster site.
Arnie Gundersen, Fairewinds Energy Education: Think of a fuel rack as a pack of cigarettes and you try to pull a cigarette out, you pull the cigarette out, it will come out just fine. But if the pack is distorted and you pull the cigarette out, it breaks. Well that’s the problem they’re going to encounter on Fukushima Daiichi Unit 4. The racks are distorted from the earthquake — oh, by the way, the roof has fallen in, which further distorted the racks.
The net effect is they’ve got the bundles of fuel, the cigarettes in these racks, and as they pull them out, they’re likely to snap a few. When you snap a nuclear fuel rod, that releases radioactivity again, so my guess is, it’s things like krypton-85, which is a gas, cesium will also be released, strontium will be released. They’ll probably have to evacuate the building for a couple of days. They’ll take that radioactive gas and they’ll send it up the stack, up into the air, because xenon can’t be scrubbed, it can’t be cleaned, so they’ll send that radioactive xenon up into the air and purge the building of all the radioactive gases and then go back in and try again.
It’s likely that that problem will exist on more than one bundle. So over the next year or two, it wouldn’t surprise me that either they don’t remove all the fuel because they don’t want to pull too hard, or if they do pull to hard, they’re likely to damage the fuel and cause a radiation leak inside the building.  So that’s problem #2 in this process, getting the fuel out of Unit 4 is a top priority I have, but it’s not going to be easy. Tokyo Electric is portraying this as easy. In a normal nuclear reactor, all of this is done with computers. Everything gets pulled perfectly vertically. Well nothing is vertical anymore, the fuel racks are distorted, it’s all going to have to be done manually. The net effect is it’s a really difficult job. It wouldn’t surprise me if they snapped some of the fuel and they can’t remove it.
…………………………………………………………………..
Radio Ecoshock interview you said that the Japanese should start unloading nuclear fuel bundles from Reactor 4 as a priority before that building collapses. Are they doing it?
Arnie Gundersen, Nuclear expert with Fairewinds Energy Education: Well, they’re planning as of November to begin to do it, so they’ve made some progress on that. I think they’re belittling the complexity of the task. If you think of a nuclear fuel rack as a pack of cigarettes, if you pull a cigarette straight up it will come out — but these racks have been distorted. Now when they go to pull the cigarette straight out, it’s going to likely break and release radioactive cesium and other gases, xenon and krypton, into the air. I suspect come November, December, January we’re going to hear that the building’s been evacuated, they’ve broke a fuel rod, the fuel rod is off-gassing. […]
I suspect we’ll have more airborne releases as they try to pull the fuel out. If they pull too hard, they’ll snap the fuel. I think the racks have been distorted, the fuel has overheated — the pool boiled – and the net effect is that it’s likely some of the fuel will be stuck in there for a long, long time.
Smith: I should point out to listeners that you were a fuel rack expert in the nuclear industry, so you know what you’re talking about.
………………………………………………………………………
Arnie Gundersen, Chief Engineer at Fairewinds Energy Education:
Tokyo Electric has admitted that the boron between these fuel cells — there’s a boron wafer in between the fuel to prevent something called an inadvertent criticality, you can have a nuclear chain reaction in the fuel pool, and that’s not a good thing — but they’ve admitted that all the boron has disintegrated.
So the only thing preventing a chain reaction from occurring […] in the fuel racks themselves, is the fact they put all sorts of boron in the water.
But if the rods get too close to each other, they can still fire up again and create a chain reaction in the nuclear fuel pool.
…………………………………………………………………………………………….……………………………….
 
Title: Bridging the News Gap
Source: Fairewinds Energy Education
Date: Sept. 26, 2013
At 22:30 in
Arnie Gundersen, Fairewinds’ Chief Engineer: The Unit 4 fuel pool has 200 bundles of brand new fuel. Brand new fuel, while cold as a cucumber, runs the risk of starting a nuclear chain reaction. The nuclear fuel in the new portion of the pool is more likely to undergo what we call an inadvertent criticality, a nuclear chain reaction that nobody wants.
I build fuel racks, and I know that the gap between the fuel is really, really critical. If the fuel gets too close together you will get a chain reaction. That’s not something you want to happen in the fuel pool. As they’re pulling this fuel out, they have to be very, very cautious that they don’t get the fuel too close together.
…………………………………………………..
Title: Interview with Nils Bøhmer, Bellona.org
Source: TRU News
Date: August 10, 2012
At ~38:00 in
Nuclear Physicist Nils Bøhmer: Should there be a new earthquake in the region, you could have a dramatic situation once again. You could have new cracks, water entering into reactor core, you could maybe have a nuclear chain reaction starting in the fuel, which means you could have a lot of radioactivity released again
[…]
I’m most concerned that a nuclear chain reaction could start in the fuel if you have a lot of water in there because that will be very difficult to control and that will have a lot of heat there that you don’t have control over
[…]
If there is a new earthquake, there is leakages, the rain, a lot of rain, that water will get in contact with the fuel and act as a moderator and you will have a nuclear reactor starting again without any control mechanism, and that will be very, very [inaudible] […]
So that is the main thing now, to keep the water out, to keep the cooling running, and build the buildings around the reactors […]………………………..
9-2-13      but the most dangerous thing is the cooling pool of unit 4. Now it is terribly dangerous because the entire hot core of reactor 4 had been removed and put in this cooling pool shortly before the tsunami. So, there was a hot core in this cooling pool the entire superstructure building was blown off in a hydrogen explosion.
0The entire area is weakened and there is a great risk of an aftershock. Now this pool contains something on the order of 400.000 kg of hot plutonium. So, the thing that people should be aware of is that TEPCO is going to begin attempting to remove these rods from this pool to some other type of storage. This has never been done with plutonium rods that have been out of a core for such a short period of time.
0There is a great danger of a thermonuclear reaction if these rods become exposed to the air and the cooling pool itself is just barely containing the temperature levels of the core as it is.
0When you are saying about international effort, how could other countries help with that?
0I think it is imperative that this is not looked at as a contracting opportunity and opportunity to make money out of this situation. This has to be dealt with something like a space race, like with the funding of a space program and all the technology and resources brought there for that kind of an effort. The inertia that we have seen with this, we are not seeing that kind of focus internationally. That needs to be brought to bear.
0The media coverage of the situation has been almost non-existent. The public must become engaged and the governments must become engaged because this is a global threat. They say that one microgram of plutonium could theoretically kill a person.
0There are billion micrograms in a kilogram and there are 400.000 hot kilograms in this pool. So, if these rods combust, if the set of rods begins a thermonuclear reaction, it will vaporize the water in the pool and the entire pool can become an uncontrolled nuclear reaction open to the air. These particles will be spread through the northern hemisphere.
Advertisements
This entry was posted in Uncategorized and tagged , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s