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Sunday, 29 September 2013

The REAL Fukushima Danger : Story 101

[snip]

The Real Problem …

The fact that the Fukushima reactors have been leaking huge amounts of radioactive water ever since the 2011 earthquake is certainly newsworthy.  As are the facts that:
But the real problem is that the idiots who caused this mess are probably about to cause a much biggerproblem.
Specifically, the greatest short-term threat to humanity is from the fuel pools at Fukushima.
If one of the pools collapsed or caught fire, it could have severe adverse impacts not only on Japan … but the rest of the world, including the United States.   Indeed, a Senator called it a national security concern for the U.S.:
The radiation caused by the failure of the spent fuel pools in the event of another earthquake could reach the West Coast within days. That absolutely makes the safe containment and protection of this spent fuel a security issue for the United States.
Nuclear expert Arnie Gundersen and physician Helen Caldicott have both said that people should evacuate the Northern Hemisphere if one of the Fukushima fuel pools collapses. Gundersen said:
Move south of the equator if that ever happened, I think that’s probably the lesson there.
Former U.N. adviser Akio Matsumura calls removing the radioactive materials from the Fukushima fuel pools “an issue of human survival”.
So the stakes in decommissioning the fuel pools are high, indeed.
But in 2 months, Tepco – the knuckleheads who caused the accident – are going to start doing this very difficult operation on their own.
The New York Times reports:
Thousands of workers and a small fleet of cranes are preparing for one of the latest efforts to avoid a deepening environmental disaster that has China and other neighbors increasingly worried: removing spent fuel rods from the damaged No. 4 reactor building and storing them in a safer place.
The Telegraph notes:
Tom Snitch, a senior professor at the University of Maryland and with more than 30 years’ experience in nuclear issues, said  “[Japan officials] need to address the real problems, the spent fuel rods in Unit 4 and the leaking pressure vessels,” he said. “There has been too much work done wiping down walls and duct work in the reactors for any other reason then to do something….  This is a critical global issue and Japan must step up.”
The Japan Times writes:
In November, Tepco plans to begin the delicate operation of removing spent fuel from Reactor No. 4 [with] radiation equivalent to 14,000 times the amount released by the Hiroshima atomic bomb. …. It remains vulnerable to any further shocks, and is also at risk from ground liquefaction. Removing its spent fuel, which contains deadly plutonium, is an urgent task…. The consequences could be far more severe than any nuclear accident the world has ever seen. If a fuel rod is dropped, breaks or becomes entangled while being removed, possible worst case scenarios include a big explosion, a meltdown in the pool, or a large fire. Any of these situations could lead to massive releases of deadly radionuclides into the atmosphere, putting much of Japan — including Tokyo and Yokohama — and even neighboring countries at serious risk.
CNBC points out:
The radioactive leak at Japan’s Fukushima nuclear plant is far from under control and could get a lot worse, a nuclear energy expert, who compiles the annual “World Nuclear Industry Status Report” warned.
***
The big danger – and it was identified by Japan’s atomic energy commission – is if you lose water in one of the spent fuel pools and you get a spent fuel fire.
CNN reports:
[Mycle Schneider, nuclear consultant:]  The situation could still get a lot worse. A massive spent fuel fire would likely dwarf the current dimensions of the catastrophe and could exceed the radioactivity releases of Chernobyl dozens of times. First, the pool walls could leak beyond the capacity to deliver cooling water or a reactor building could collapse following one of the hundred  of aftershocks. Then, the fuel cladding could ignite spontaneously releasing its entire radioactive inventory.
Reuters notes:
The operator of Japan’s crippled Fukushima nuclear plant is preparing to remove 400 tons of highly irradiated spent fuel from a damaged reactor building, a dangerous operation that has never been attempted before on this scale.
Containing radiation equivalent to 14,000 times the amount released in the atomic bomb attack on Hiroshima 68 years ago, more than 1,300 used fuel rod assemblies packed tightly together need to be removed from a building that is vulnerable to collapse, should another large earthquake hit the area.
Tokyo Electric Power Co (Tepco) is already in a losing battle to stop radioactive water overflowing from another part of the facility, and experts question whether it will be able to pull off the removal of all the assemblies successfully.
“They are going to have difficulty in removing a significant number of the rods,” said Arnie Gundersen, a veteran U.S. nuclear engineer and director of Fairewinds Energy Education, who used to build fuel assemblies.
The operation, beginning this November at the plant’s Reactor No. 4, is fraught with danger, including the possibility of a large release of radiation if a fuel assembly breaks, gets stuck or gets too close to an adjacent bundle, said Gundersen and other nuclear experts.
That could lead to a worse disaster than the March 2011 nuclear crisis at the Fukushima plant, the world’s most serious since Chernobyl in 1986.
No one knows how bad it can get, but independent consultants Mycle Schneider and Antony Froggatt said recently in their World Nuclear Industry Status Report 2013: “Full release from the Unit-4 spent fuel pool, without any containment or control, could cause by far the most serious radiological disaster to date.”
***
The utility says it recognizes the operation will be difficult but believes it can carry it out safely.
Nonetheless, Tepco inspires little confidence. Sharply criticized for failing to protect the Fukushima plant against natural disasters, its handling of the crisis since then has also been lambasted.
***
The 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. [The pools have already boiled due to exposure to air.]
***
Tepco has shored up the building, which may have tilted and was bulging after the explosion, a source of global concern that has been raised in the U.S. Congress.
***
The fuel assemblies have to be first pulled from the racks they are stored in, then inserted into a heavy steel chamber. This operation takes place under water before the chamber, which shields the radiation pulsating from the rods, can be removed from the pool and lowered to ground level.
The chamber is then transported to the plant’s common storage pool in an undamaged building where the assemblies will be stored.
[Here is a visual tour of Fukushima's fuel pools, along with graphics of how the rods will be removed.]
Tepco confirmed the Reactor No. 4 fuel pool contains debris during an investigation into the chamber earlier this month.
Removing the rods from the pool is a delicate task normally assisted by computers, according to Toshio Kimura, a former Tepco technician, who worked at Fukushima Daiichi for 11 years.
“Previously it was a computer-controlled process that memorized the exact locations of the rods down to the millimeter and now they don’t have that. It has to be done manually so there is a high risk that they will drop and break one of the fuel rods,” Kimura said.
***
Corrosion from the salt water will have also weakened the building and equipment, he said.
And if an another strong earthquake strikes before the fuel is fully removed that topples the building or punctures the pool and allow the water to drain, a spent fuel fire releasing more radiation than during the initial disaster is possible, threatening about Tokyo 200 kilometers (125 miles) away.
ABC Radio Australia quotes  an expert on the situation (at 1:30):
Richard Tanter, expert on nuclear  power issues and professor of international relations at the University of Melbourne:
***
Reactor Unit 4, the one which has a very large amount of stored fuel in its fuel storage pool, that is sinkingAccording to former prime Minister Kan Naoto, that has sunk some 31 inches in places and it’s not uneven. This is really not surprising given what’s happened in terms of pumping of water, the aftermath of the earthquake and the tsunami, the continuing infusions of water into the groundwater area. This is an immediate problem, and if it is not resolved there is an extraordinary possibility we really could be back at March 2011 again because of the possibility of a fission accident in that spent fuel pond in Unit No. 4.
Xinua writes:
Mitsuhei Murata, a former Japanese ambassador to Switzerland has officially called for the withdrawalof Tokyo’s Olympic bid, due to the worsening crisis at Fukushima, which experts believe is not limited to storage tanks, but also potential cracks in the walls of the spent nuclear fuel pools.
Japan Focus points out:
The spent-fuel pool … was damaged by the earthquake and tsunami, and is in adeteriorating condition. It remains vulnerable to any further shocks, and is also at risk from ground liquefaction.
***
If a fuel rod is dropped, breaks or becomes entangled while being removed, possible worst case scenarios include a big explosion, a meltdown in the pool, or a large fire.
***
This is literally a matter of national security – another mistake by TEPCO could have incredibly costly, even fatal, consequences for Japan.
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http://www.washingtonsblog.com/2013/09/the-real-fukushima-danger.html 
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