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Toshinobu Miyajima, commanding general of the Ground Self-Defense Force (GSDF) Central Readiness Force when it was desperately trying to bring the crippled Fukushima nuclear plant under control, thought at one point that Japan was done for, he recalled in a recent interview with the Mainichi.
However, Miyajima pointed out that the highly risky mission demonstrated to the world that Japan was truly serious about containing the crisis, which led the United States and other countries to extend major assistance to disaster areas. Excerpts of the interview follow:
Question: When were you ordered to serve as the commander of the response to the disaster at the Fukushima No. 1 nuclear plant?
Originally posted by GhostR1der
reply to post by zworld
What units are these in? Millibecquerels?
Originally posted by Human0815
can you overlay the Safecast.org Map?
Originally posted by zworld
reply to post by Aircooled
From Fukushima Diary fukushima-diary.com...
I can't believe they are going to take the top trusses and support structure apart before offloading the SFP. This is insane. The engineers tweeting are concerned that without the over head support holding the walls together as one structure, an EQ could cause the walls to go split apart.
Not sure what Tepco is thinking, but I dont like it. Theyre rolling the dice again. This is all that is going to be keeping the walls from disjoining.
Does looking at that flimsy design that is holding up enough uranium and plutonium to damn near end life on this planet if it all went critical give you warm and fuzzy feelings. I didn't think so.
Originally posted by zworld/AC
I don’t know if it’s because they gave sea water to cool down or because it’s brackish area, if natrium (sodium salt) of sea water made a chemical reaction with calcium carbonate in the concrete to become diuranate natrium (sodium diuranate) or not, it looks yellow as yellow cake.
Originally posted by zworld
You gotta love a public agency that uses public money to monitor things that directly affect the public but doesn't want the public to know. That is so fugging EPAish that its scary.
Originally posted by qmantoo
Unit 4 was shut down and had been in an outage since November 30, 2010. All the fuel was in the spent fuel pool to facilitate reactor pressure vessel shroud work. The cavity gate was installed, isolating the spent fuel pool from the upper pools...
Could you tell us which press releases these quotes are taken from please?
Our Mission . . . to promote the highest levels of safety and reliability – to promote excellence – in the operation of commercial nuclear power plants.
4.4 Unit 4 Narrative
[color=FDD017]Unit 4 was shut down and had been in a refueling outage since November 30, 2010. All of the fuel had been removed from the reactor and placed in the spent fuel pool to facilitate shroud work. The reactor was disassembled with the head off at the time of the earthquake. The cavity gates were installed, isolating the spent fuel pool from the upper pools. Spent fuel pool temperature was approximately 80.6*F (27*C).
Following the earthquake and tsunami, the operators in the Units 3-4 control room focused the majority of their efforts on stabilizing Unit 3. Because of the low decay heat load in the Unit 4 spent fuel pool, operators may not have been immediately concerned with taking action to fill or cool the spent fuel pool.
On March 15, however, a hydrogen explosion occurred in the Unit 4 reactor building. This was unexpected, as workers did not believe there was enough decay heat in the pool to result in overheating and the subsequent high-temperature interaction of zirconium and water to produce hydrogen gas.
After the explosion, however, some people suspected that the spent fuel was overheating, and they became concerned about subsequent hydrogen explosions caused by the fuel in the spent fuel pools on other units. Some resources may have been diverted from attempts to stabilize the reactors, as extensive actions - such as helicopter water drops and the use of water cannons - were taken in an attempt to refill the pools.
[color=00FFFF]Subsequent analysis and inspections determined that the water level in the Unit 4 spent fuel pool never dropped below the top of fuel and that no significant fuel damage had occurred.
There are various theories regarding the cause of the hydrogen explosion in Unit 4. Hydrogen water chemistry was used at Fukushima Daiichi, and hydrogen was also used to cool the main generators. Both of these sources of hydrogen were reviewed, and it appears that neither source caused the Unit 4 explosion.
The most widely accepted theory is associated with the backflow of gases from Unit 3 during venting. The containment vent exhaust piping from Unit 3 is connected to the Unit 4 exhaust piping. The dampers on the Unit 4 standby gas treatment system (SGTS) are air-operated and fail open on a loss of power or air (except the cross-connect between SGTS filter trains).
Additionally, the system does not have a backflow damper installed in the piping that connects to Unit 3. With no power or air, and no fans in service to direct the gases from Unit 3 up the exhaust stack, the exhaust gases from Unit 3 would be directly aligned to the Unit 4 SGTS filters. This piping arrangement may have allowed gases from the Unit 3 containment to be vented to the Unit 4 reactor building via reverse flow through the Unit 4 standby gas treatment system.
To confirm this theory, on August 25 TEPCO personnel performed radiation surveys on the Unit 4 SGTS filters. The survey results, shown in Figure 4.4-2, revealed higher radiation levels at the locations closer to Unit 3.
These survey results support the conclusion that there was backflow from Unit 3 to Unit 4. Further inspections are needed to confirm this theory; but based on this information, it is postulated that the hydrogen explosion in the Unit 4 reactor building was caused by hydrogen from Unit 3.
As shown, the spent fuel pools (SFPs) for units 1-4 contained different amounts of spent fuel at the time of the event, generating different heat loads. [color=Cyan]The Unit 4 SFP had the greatest heat load because the entire core had been offloaded into the SFP to support ongoing outage work.
Approximately 60 percent of the spent fuel on site is stored in a separate building in a common spent fuel pool. This pool contained 6,375 fuel assemblies (about 80 percent of pool capacity), but the heat load was very low because the assemblies were stored in their respective units’ SFPs for 19 months or longer before being set in the common pool.
[color=Chartreuse]Calculations determined that cooling can be lost to this pool for 30 days before it becomes a concern. The common spent fuel pool uses fans and air for cooling, so cooling is maintained if the seawater ultimate heat sink is lost; however, AC power is required to power the fan motors and circulating pumps.
Dry cask storage is also used for spent fuel. [color=FDD017]At the time of the event, the station had nine casks containing 408 spent fuel assemblies.
[color=00FFFF]There are no mixed-oxide fuel assemblies in any of the spent fuel pools or in the dry cask storage facility.
The first two units, Genkai-3 and Ikata-3, began operations with MOX fuel in November 2009 and March 2010 respectively. Use of MOX fuel in light-water power reactors is part of Japan's "pluthermal" program, which plans to have 16-18 reactors using MOX fuel by 2015.
Shaun Burnie, an independent nuclear energy consultant and former head of nuclear campaigns at Greenpeace, said the presence of a percentage of fuel core loaded with plutonium Mox fuel in the No 3 reactor posed a grave threat to the surrounding area.
“Plutonium Mox fuel increases the risk of nuclear accident due the neutronic effects of plutonium on the reactor,” Burnie told the Guardian. “In the event of an accident – in particular loss of coolant – the reactor core is more difficult to control due to both neutronics and higher risk of fuel cladding failure. In the event of the fuel melting and the release of plutonium fuel into the environment, the health hazards are greater, including higher levels of latent cancer.”
Spent fuel pool cooling flow was lost for all pools because of the loss of off-site power and was not restored after the emergency diesel generators started. [color=Cyan]The existing water inventory in the spent fuel pools provided sufficient cooling to remove decay heat, as long as the fuel remained covered. Unconfirmed reports were that sloshing of the water in the SFPs during the earthquake resulted in a loss of some inventory; however, this has not been verified. After the tsunami impacted the site, operators were able to use the 6B emergency diesel generator (EDG) to provide power to cooling systems for the Unit 6 spent fuel pool. After installing temporary cables, the 6B EDG provided power to Unit 5 spent fuel pool cooling.
Hydrogen explosions in the Units 1, 3, and 4 reactor buildings, coupled with the loss of the blowout panel in Unit 2, resulted in the SFPs of all units being exposed to atmosphere.
[color=Chartreuse]The explosions may have also caused additional inventory to be lost from the pools. After the explosion on Unit 4, a concern arose that the SFP may have boiled dry and resulted in fuel damage and hydrogen generation. In response to this concern, station personnel took numerous actions to ensure the spent fuel had sufficient cooling.
Fire engines from the surrounding area, including water cannons from the Japan Self-Defense Force, were brought to the site to spray water into the SFPs to keep the fuel assemblies covered. The water cannons could only reach the floor surrounding the SFP, so little water got into the pool. On March 17, helicopters attempted to drop large loads of water into the SFPs. Because of high radiation levels, the helicopters needed to maintain a high altitude; and that, coupled with the prevailing winds, resulted in this effort not being successful.
Concrete pumping trucks were flown to Japan for use in pumping water into the SFPs. These trucks, which have long, articulated booms normally used for transferring concrete, were lined up to pump water into the spent fuel pools on March 18. This operation was successful; however,
the trucks did not start refilling the SFPs until several days after the event began. [color=Cyan]The delay in refilling the SFPs may have contributed to increased radiation levels in the area around the spent fuel pools because less shielding was provided with the reduced water level.
The exact impact, however, was not known because radiation levels were not monitored as the pools were refilled.
An inspection of the dry cask storage facility revealed that, while the building was damaged by the tsunami, the dry storage casks do not appear to be damaged. The casks were wetted by the tsunami, but they were not moved from their storage locations by the force of the waves or debris. The fuel stored inside the dry casks has not yet been inspected.
7.6 Operator Training
Initial operator training programs for reactor operators and above are provided by BWR Training Center Corporation (BTC), which is located close to Fukushima Daiichi. TEPCO is one of the shareholders of the company. The site superintendent certifies initial qualifications for senior operators, main shift operators, and auxiliary operators on site. By law, shift supervisors are required to be licensed. The licensing process includes an evaluation of their knowledge and skills. The Japan Nuclear Technology Institute (JANTI) performs this evaluation and issues the license.