NHK Reports Fukushima Reactor 1 Is Melting Down
The company believes the melted fuel has cooled down, judging from the reactor’s surface temperature.
But it suspects the meltdown created a hole or holes in the bottom of the reactor causing water to leak into the containment vessel.
It also suspects the water is leaking into the reactor building.
The company is planning to fully fill the containment vessel with water by increasing the amount injected.
The company says, however, it must review the plan in light of the latest finding.
And this from Reuters:
One of the reactors at Japan’s crippled Fukushima nuclear power plant has a hole in its main vessel following a meltdown of fuel rods, leading to a leakage of radioactive water, its operator said on Thursday.
The disclosure by Tokyo Electric Power Co (TEPCO) is the latest indication that the disaster was worse than previously disclosed, making it more difficult to stabilize the plant.
Workers at the Fukushima Daiichi nuclear plant have been pumping water into at least three of the six reactors on the site to bring their nuclear fuel rods to a “cold shutdown” state by January.
But after repairing a gauge in the No. 1 reactor earlier this week, TEPCO discovered that the water level in the pressure vessel that contains its uranium fuel rods had dropped about 5 meters (16 ft) below the targeted level to cover the fuel under normal operating conditions.
“There must be a large leak,” Junichi Matsumoto, a general manager at the utility told a news conference.
“The fuel pellets likely melted and fell, and in the process may have damaged…the pressure vessel itself and created a hole,” he added.
The finding makes it likely that at one point in the immediate wake of the disaster the 4-meter-high stack of uranium-rich rods at the core of the reactor had been entirely exposed to the air, he said. Boiling water reactors like those at Fukushima rely on water as both a coolant and a barrier to radiation.
U.S. nuclear experts said that the company may have to build a concrete wall around the unit because of the breach, and that this could now take years.
“If it is assumed the fuel did melt through the reactor, then the most likely solution is to encapsulate the entire unit. This may include constructing a concrete wall around the unit and building a protective cover over it,” W. Gene Corley, senior vice president of CTL Group in Skokie, Illinois, said on Thursday.
“Because of the high radiation that would be present if this has happened, the construction will take many months and may stretch into years,” Corley said.
Arnie Gundersen, Chief Engineer at Fairewinds Associate, who many have called an insane crackpot, has gotten the recognition he deserves:
TEPCO should consider digging a trench around reactors 1-3 all the way down to the bedrock, which is about 50 feet below the surface, said Arnie Gundersen, Chief Engineer at Fairewinds Associates Inc of Burlington, Vermont, who once worked on reactors of similar design to the Fukushima plant.
He said this should be filled with zeolite, which can absorb radioactive cesium to stop more poisons from leaking into the groundwater around the plant.
The truth is that the situation is getting worse, not better, with each passing day:
“TEPCO seems to be going backwards in getting the situation under control and things may well be slowly eroding with all the units having problems,” said Tom Clements with Friends of the Earth, a U.S.-based environmental group.
“At this point, TEPCO still finds itself in unchartered waters and is not able to carry out any plan to get the situation under control,” he said.
Matsumoto said the utility would study whether to increase the amount of water it was injecting to overcome the leak and raise the level of water covering the fuel, at the risk of allowing more radioactive water to leak out of the facility.
Nearly 10,400 tonnes of water has been pumped into the reactor so far, but it is unclear where the leaked water has been going. The high radiation levels makes it difficult for workers to check the site, Matsumoto said.
Brilliant: and all the newly pumped water is about to seep either into the groundwater or the ocean.
As usual, we urge any Japanese readers who live in proximity to the reactor to study the immediate plume dispersion forecast: