Is Containment Holding?

Mar 14th, 2011 2:32pm CST

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While many experts continue to reassure us that the critical core containment structures involved in the Fukushima Dai-Ichi complex are not breached, the latest pronouncements from NISA don't make me feel any better. From The Guardian:

"On Monday evening, Ryohei Shiomi, an official at Japan's Nuclear and Industrial Safety Agency (Nisa), said reactors 1 and 3 appeared stable for the time being, but that reactor two, where fuel rods were most exposed, was still a concern. "Unit 2 now requires all our effort and attention," he said.

 

The day began with an orange flash and a violent blast that destroyed most of the containment building around reactor 3, with debris falling back inside and onto the structure housing the reactor. The blast was caused by a buildup of hydrogen that was produced when superheated steam in the core reacted with the zirconium alloy cladding that surrounds the reactor's fuel rods.

 

Tepco said 11 people were injured in the accident, one seriously. A similar explosion blew the top off the reactor 1 building on Saturday morning.

 

Despite earlier assurances from Tepco that the steel containment vessels surrounding the reactors were undamaged in both explosions, Naoki Kumagai, a Nisa official, said "It's impossible to say whether there has or has not been damage."

More Core Uncertainty

Mar 14th, 2011 1:56pm CST

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For every reassuring statement we hear regarding the situation at Fukushima, there is an equally disturbing set of new releases. 

From the Sydney Morning Herald:

 

"Engineers had begun pumping seawater into the reactor at the facility, the third reactor to receive the last-ditch treatment, after the plant's emergency cooling system had failed and the fuel rods 

had been partially exposed to the air.

 

But apparently something went wrong and the injection of water failed. Workers were scrambling to re-immerse the fuel assembly before more damage is done to the reactor core.

 

No one knows how much damage has been done to the fuel rods, either in this reactor, No.2, or in reactors No.1 and No.3, where engineers began pumping in seawater over the weekend.

 

Officials have called the situation a partial meltdown because they have detected minute quantities of radioactive caesium and iodine - byproducts of the nuclear fission that powers the reactor - outside the plant.

 

That may mean simply that the zirconium cladding that sheathes the uranium fuel pellets has cracked due to heat from being exposed to the air, allowing small quantities of the radionuclides to escape, or it may mean that the fuel pellets themselves have partially melted.

 

As long as the reactor containment vessel remains intact, however, no one will know until workers can physically examine the fuel rods for damage."

BREAKING - Reactor #2 Fuel Rods "Fully Exposed"

March 14th, 2011 6:18am CST
UPDATE 3/14/11 7:10am CST Please CLICK HERE to find information to donate to Japanese relief efforts.

UPDATE: 8:03am CST 
From Wexford:
 "The fuel rods in one of Japan's damaged nuclear reactors have been temporarily fully exposed from their coolant, raising the risk of overheating and a meltdown.

A spokesman at the Fukushima plant said that Unit 2's rods were briefly exposed.

Sea water has been channelled into the reactor to cover the rods again.

Unit 2 of the Fukushima Dai-ichi plant is the latest reactor to lose its ability to cool down. The other two reactors at the plant are facing a meltdown and authorities are racing to cool them with sea water."

JUST IN from Reuters:
"Nuclear fuel rods at a quake-stricken Japanese nuclear reactor are now fully exposed, Jiji news agency said, quoting the plant's operator, Tokyo Eletcric Power Co. 

The report referred to the Fukushima Daiichi complex's No.2 reactor, where levels of water coolant around the reactor core had been reported as falling earlier in the day. 

The Jiji report said a meltdown of the fuel rods could not be ruled out. A meltdown raises the risk of damage to the reactor vessel and a possible radioactive leak, experts say."