In mid-November, the embattled utility is preparing to remove 400 tons of spent fuel from the damaged reactor 4, 2½ years after a hydrogen explosion damaged the structure’s exterior.Extraordinary claims have been made about the level of risk of removing the spent fuel from unit 4 calling it potentially "apocalyptic". Those claims have been disputed by nuclear industry representatives. Although I left the USNRC many years ago, I think I have the expertise and independence to provide a good independent assessment of the situation.
According to the Nuclear Regulation Authority, there are 1,533 spent and unused fuel rod bundles in the cooling pool that contain radiation equivalent to 14,000 times the amount released in the atomic bomb attack on Hiroshima in 1945.
To remove the rods, Tepco has erected a 273-ton mobile crane above the building that will be operated remotely from a separate room.
Up to 22 spent fuel rods will be pulled from the racks they are stored in and inserted one by one into a heavy steel chamber while the assemblies are still under water. Once the chamber is removed from the pool and lowered to the ground, it will be transported to another pool in an undamaged building on the site for storage.
As long-time anti-nuclear activist Harvey Wasserman explained, theThe upper level of unit 4 suffered structural damage from a hydrogen explosion. Workers have reinforced the structure since, but its seismic safety is a concern.
Spent fuel rods must be kept cool at all times. If exposed to air, their zirconium alloy cladding will ignite, the rods will burn and huge quantities of radiation will be emitted. Should the rods touch each other, or should they crumble into a big enough pile, an explosion is possible.
"In the worst-case scenario," RT adds, the pool could come crashing to the ground, dumping the rods together into a pile that could fission and cause an explosion many times worse than in March 2011. Wasserman says that the plan is so risky it requires a global take-over, an urging Gunter also shared, stating that the "dangerous task should not be left to TEPCO but quickly involve the oversight and management of independent international experts."
Wasserman told Common Dreams thatThe conclusions made in the Common Dreams article are strongly disputed by multiple experts associated with the U.S. nuclear power industry. Tom Kauffman of the Nuclear Energy Institute (NEI) wrote "These claims are false and irresponsible".
The bring-down of the fuel rods from Fukushima Unit 4 may be the most dangerous engineering task ever undertaken. Every indication is that TEPCO is completely incapable of doing it safely, or of reliably informing the global community as to what's actually happening. There is no reason to believe the Japanese government could do much better. This is a job that should only be undertaken by a dedicated team of the world's very best scientists and engineers, with access to all the funding that could be needed.
The potential radiation releases in this situation can only be described as apocalyptic. The cesium alone would match the fallout of 14,000 Hiroshima bombs. If the job is botched, radiation releases could force the evacuation of all humans from the site, and could cause electronic equipment to fail. Humankind would be forced to stand helplessly by as billions of curies of deadly radiation pour into the air and the ocean.
As dire as Wasserman's warning sounds, it is echoed by fallout researcher Christina Consolo, who told RT that the worst case scenario could be "a true apocalypse." Gunter's warning was dire as well.
"Time is of the essence as we remain concerned that another earthquake could still topple the damaged reactor building and the nuclear waste storage pond up in its attic," he continued. "This could literally re-ignite the nuclear accident in the open atmosphere and inflame it into hemispheric proportions," said Gunter.
Wasserman says that given the gravity of the situation, the eyes of the world should be upon Fukushima:
This is a question that transcends being anti-nuclear. The fate of the earth is at stake here and the whole world must be watching every move at that site from now on. With 11,000 fuel rods scattered around the place, as a ceaseless flow of contaminated water poisoning our oceans, our very survival is on the line.
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The following is a guest post written by NEI's Tom Kauffman. Though Tom works in NEI's media relations shop. He also spent 23 years working at Three Mile Island, seven of those as a licensed reactor operator.A spent fuel expert added a comment to Tom Kaufmann's post to clarify questions about criticality at unit 4. Blog comments are generally poor sources of information but this comment demonstrates specialized expertise with spent fuel management.
There has been a spate of online posts and articles claiming that the failure of the used fuel storage pool at Fukushima Daiichi Unit 4 could result in: “a big explosion, a meltdown in the pool, or a large fire,” that could have widespread health effects all over the world. These claims are false and irresponsible. Consider the facts:
If for any reason there was a rapid loss of water from the Unit 4 storage pool exposing all of the used fuel to air, the used fuel can’t catch fire or melt because it has been cooled for more than two and-a-half years and no longer generates enough heat to damage itself. The used fuel in the pools at the other three damaged Fukushima units is even older and colder.
By design, it is physically impossible for the fuel in any commercial reactor in Japan or the U.S. to explode like a nuclear weapon. It’s impossible because the concentration of uranium in the fuel is far too low to cause a nuclear explosion. And there’s nothing that can be done at a site to change that.
dean4fukushimahelp said...The U.S. Nuclear Regulatory Commission had concerns about the safety of spent fuel pools at BWRs in the U.S. with the same design as Fukushima unit 4. To address these concerns, the NRC sponsored a research project to determine what might happen if a BWR spent fuel pool lost its cooling water. In June, 2000 the NRC published the results of this research in NUREG-1726 Predictions of Spent Fuel Heatup After a Complete Loss of Spent Fuel Pool Coolant
I am with SimplyInfo.org and function as a Fukushima Nuspent fuel pool nuclear research specialist. My career spanned 35 years in the nuclear industry. There have been many articles on presumed dangers with fuel in the unit 4 spent fuel pool. I have written articles on the pool and the fuel assemblies which is found on the web link. I agree with the statements in this article and in addition, want to dispel factless information being spread the if one fuel assembly touches another in the unit 4 pool, a criticality accident will happen with no control capability. To set the record straight, it takes 12 BWR fuel assemblies configured geometrically in water to reach a condition where criticality is possible. The water is needed to act as a moderator. Our concern in fuel handling is focused on damaged fuel assemblies which may loose fuel pellets what could be fractured and release the fission fragment isotopes into the building and atmosphere.
October 28, 2013 at 8:20 AM
Predictions are made at each of the four decay times using best-estimate parameters. These parameters include an overall wall heat transfer coefficient of 2 W/m2-K and a ventilation rate of 2 building volumes per hour. These results represent the best estimate of the fuel temperatures and the convective flow fields, given the assumptions and limitations of this model. ...
The primary result is the decay time sensitivity given in Figure 19. The data from cases f2v2h2, f3v2h2, f4v2h2, and f6v2h2 are plotted. Critical decay times of 26 and 35 months are noted on the figure for temperature limits of 800 0C and 600 °C, respectively. Critical decay time is defined as the post shutdown time required to ensure fuel temperatures don't rise above predefined temperature limits after a complete loss of fuel pool coolant. The 26 month decay time, associated with the 800 0C temperature limit, has significant uncertainty due to the model limitations at elevated temperatures discussed earlier.
Based on the worst case curve developed by the NRC research, the spent fuel pool at unit 4 could run out of water now and temperatures would stay below 700 Celsius, given that over 2.5 years have passed since the spent fuel was removed from the reactor. The spent fuel is presently generating a little over a thousandth of the heat it was producing per rod the day it was removed from the reactor.
Assertions that individual spent fuel rods could catch fire upon removal are not credible.
However, if the structure of Unit 4 collapsed in a major earthquake and a large mass of rods piled up in the wreckage, the NRC's cooling model no longer applies. The spent fuel does not contain enough fisssionable material to explode like a weapon, but it could get very hot if a number of rods piled up. Hydrogen would be generated in the hypothetical mass so the possibility of hydrogen explosions cannot be precluded in a collapse scenario. Moreover, rainwater and groundwater could act as a moderator increasing the risk of localized criticality events.
Update The spent fuel pool apparently contains 200 assemblies of brand new fuel. This fuel is cool but it contains more fissionable U-235 than spent fuel so it has a greater risk of accidental criticality than spent fuel.
Note: there is confusion in the terminology about spent fuel components used in the various articles. The graphic below by the USNRC shows the correct terminology.
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....end update
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.
The huge inventory of radionuclides at unit 4 would be at risk of further contaminating the Pacific ocean if a major earthquake brought down the spent fuel pool. In my opinion, the spent fuel needs to be removed from the damaged structure. We already have 3 melted-down reactor cores contaminating water that is partially reaching the Pacific.
Multiple investigations by journalists have revealed severe labor problems at Fukushima, including the involvement of the Japanese Mafia, the Yakuza, in subcontracting the labor supply. Serious concerns about TEPCO's ability to manage the decommissioning and decontamination at Fukushima, have been documented in many reports. Hitachi/GE the contractor that handled spent fuel removal dry run may be an exception to the cases identified by journalists, but the concerns about the quality of TEPCO's management are valid, in my opinion.
Blogger exSKF, who has been reliably reporting from Japan on the situation at Fukushima Daiichi since the tsunami hit, translated anonymous interviews from a Japanese magazine that portray horrific labor conditions on site. These workers have been dealing with the large amounts of contaminated water around the damaged reactor units 1, 2 and 3. The anonymous interviews cannot be directly verified, but they are consistent with other investigations including a major Reuters report.
Worker C: Some of TEPCO's affiliate companies put in the bid with ridiculously low price and caused the deflation of labor cost at Fukushima I. Workers include people sent here by yakuzas for their debts and down and out yakuzas themselves. The site is full of yakuzas and rank amateurs...The report translated by blogger exSKF is completely consistent with a recent Reuters special report that involved interviewing over 80 personnel involved in the Fukushima clean up.
Worker B: A journalist who smuggled himself into the plant wrote in his book that "10% of workers are yakuza". I do see more yakuzas. I have met workers with tattoo. They may be sending cheap workers and skimming the wages, or sending young yakuzas simply as means to make money. On the other hand, it's a fact that they can't secure workers unless they rely on yakuza.
Worker D: To begin with, it is a mistake to let a company handle the accident when that company didn't even have countermeasures in case of an accident. They are too proud to admit they can't do it under the current condition. Contaminated water keep increasing, workers keep decreasing. There is a law for supporting children and disaster victims, but there is nothing for radiation-exposed workers. Soon, not even yakuza nor amateurs will remain at Fukushima I Nuke Plant.
In reviewing Fukushima working conditions, Reuters interviewed more than 80 workers, employers and officials involved in the unprecedented nuclear clean-up. A common complaint: the project's dependence on a sprawling and little scrutinized network of subcontractors - many of them inexperienced with nuclear work and some of them, police say, have ties to organized crime.The shortage of qualified workers has been an opportunity for the yakuza. Gangsters have stepped in to supply labor to subcontract to TEPCO's contractors. The yakuza's labor pool is the most desperate men in Japan. They are poorly trained, suffer from wage theft, and are over-worked and demoralized. TEPCO is enabling the yakuza because management is unwilling to cut profits to pay competitive wages.
Tepco sits atop a pyramid of subcontractors that can run to seven or more layers and includes construction giants such as Kajima Corp and Obayashi Corp in the first tier. The embattled utility remains in charge of the work to dismantle the damaged Fukushima reactors, a government-subsidized job expected to take 30 years or more.
The unprecedented Fukushima nuclear clean-up both inside and outside the plant faces a deepening shortage of workers. There are about 25 percent more openings than applicants for jobs in Fukushima prefecture, according to government data.
Raising wages could draw more workers but that has not happened, the data shows. Tepco is under pressure to post a profit in the year to March 2014 under a turnaround plan Japan's top banks recently financed with $5.9 billion in new loans and refinancing. In 2011, in the wake of the disaster, Tepco cut pay for its own workers by 20 percent.
TEPCO is involved in criminal mismanagement of the Fukushima clean up, in my opinion. The activists' concern's about TEPCO's incompetence are valid, in my opinion.
We are depending on desperate men working for gangsters to protect the Pacific ocean from contamination by massive inventories of radioactivity.