Published on January 15th, 2014 | by Sandy Dechert11
Fukushima Fuel Transfer Reaches 10% Milestone
Tokyo Electric Power Company has reached a minor milestone in cleaning up the mess that started at its Fukushima nuclear power station on Friday, March 11, 2011 (March 12, U.S.). A subsea earthquake off the Pacific coast of Tōhoku, the resulting tsunami, and an unfortunate series of human miscalculations have dogged the ruined facility for almost three years.
The Fukushima Daiichi plant originally comprised six boiling water reactors of a half-century-old General Electric design. The installation was one of the world’s 25 largest nuclear power stations. TEPCO currently believes that after the tsunami, units 1-3 suffered meltdowns, perhaps even through the floors of the buildings and into the soil.
However, the situation in unit 4 merited the most immediate attention. There, the building had partly collapsed. New and spent (used) fuel rods stored in temporary containment 100 feet above ground level were emitting radiation to the atmosphere.
In danger of internal collision due to seismic events or spillage from the damaged secondary containment, this exposed fuel has threatened Japan with a massive uncontrollable nuclear chain reaction. After completing precautionary activities, on November 18, 2013, the company began a delicate task of rearrangement. Plant workers started moving the assemblies of nuclear fuel rods racked in the upper-story pool to safer ground-level storage in a centralized pool common to all the damaged reactors.
As well as the hazard of spontaneous explosions, spent fuel rods can release considerable heat and quickly lethal levels of radiation. Robot cranes and other human-directed machinery are necessary to move these very hazardous materials. The unit 4 cooling pond contains 1,533 fuel assemblies, of which 1,331 have been used and 202 are unirradiated (fresh) ones. Some of the fuel assemblies are known to be damaged.
Today, TEPCO plant personnel completed 10% of the transfers that must be done to stabilize the fuel from reactor unit 4. TEPCO describes the operations being undertaken as follows:
- Relocate the fuel assemblies stored in the fuel rack inside the spent fuel pool, one by one, into a transportation container (cask) underwater using a fuel handling machine.
- Lift up the cask from the spent fuel pool using a crane.
- Conduct, on the floor as high as the operating floor, such works as closing the lid of the cask and decontaminating the cask.
- Lift down the cask toward the ground using the crane to lay it on a trailer.
- Transport the cask to the common pool using the trailer.
TEPCO expects it will take about a year to make all the Unit 4 transfers. Hundred-ton casks of fuel have now been transported to ground-level storage seven times, for a total of 154 transferred assemblies. Those who have doubted TEPCO’s capability find some reassurance in the apparently smooth progress of this work and about the 90% of transfers still to be made. Too, it bodes well that TEPCO has been able to extract both spent and new fuel assemblies during this time. The company can plan further withdrawals of both from a position of greater certainty.
The plan for unit 4 generated confidence in some observers initially, but considerable doubt in others. Among those urging caution were scientists of both Japan and other nations and some highly placed Japanese officials, including a former prime minister. The United States has expressed support and dispatched both official and unofficial observers. Internally, it appears that the Japanese people are uncertain and divided about the company’s future use of nuclear power. Political wrangles over the issue have become commonplace, and the population has not reduced its distrust of both TEPCO and (to a lesser degree) the inconsistent government.
The other three damaged reactors at Fukushima hold additional dangers. Serious leaks from the plant to groundwater and the Pacific have already been discovered. These have apparently resulted from small ruptures within the many tanks and pipes used to hold radioactive cooling water. Recent reports of Fukushima-originated radiation currently endangering the west coastal and interior United States have been debunked. A new meltdown in unit 3, also reported by some news outlets, has apparently not occurred, although emissions to the air from that reactor have been noted. Further explosions seem unlikely at present.
As we noted here and in our sister publication, Planetsave, earlier on the operation,
“The company is proceeding from what nuclear experts agree is the easiest task to the most difficult: safely coping with the molten fuel released by the other three affected reactors somewhere below the ground’s surface.”
Units 5 and 6 of the power station suffered no critical damage from the 2011 storm and TEPCO initially hoped to restart them, but Japan’s government views them as part of the general disaster area and has closed them down completely. Both a large and powerful offshore wind farm and a capacious Toshiba-backed solar photovoltaic field near Fukushima are in the works and can be expected to offset some of the crushing burden of Japan’s recent oil and gas expenditures needed to replace lost nuclear power. Also, since the first of the year, major solar players have just announced two far-reaching partnerships in Japan. TEPCO expects it will take 40 years to decommission the entire Fukushima Daiichi nuclear plant.