Japan State Media NHK: No.1 reactor is in a "meltdown" state

http://www3.nhk.or.jp/daily/english/13_03.html

updated at 21:26 UTC, May. 12

Tokyo Electric Power Company says the No.1 reactor at the Fukushima Daiichi nuclear power plant is believed to be in a state of "meltdown".

The utility company said on Thursday that most of the fuel rods are likely to have melted and fallen to the bottom of the reactor. Earlier in the day, it found that the coolant water in the reactor is at a level which would completely expose nuclear fuel rods if they were in their normal position.

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.

Reactor surface temp has cooled down. That means the fuel has cooled down. Sorry, is the molten core material even still in the breached reactor? Or are they cooling an empty vessel?

Tepco said so, so don't worry, they'll have it on cold shutdown by January or so, er....... And the experts said they were not surprised by this latest data. Cough, cough.


Friday, May 13, 2011

Melting of reactor 1 fuel 'no surprise'

By MINORU MATSUTANI
Staff writer

Experts were not surprised Thursday to find that most, if not all, of the fuel rods in reactor No. 1 at the Fukushima No. 1 power plant had been fully exposed, melted and fell to the bottom of the pressure vessel.


"Tokyo Electric Power Co. announced the finding Thursday after workers entered the reactor building earlier this month and fixed equipment to monitor the water level in the pressure vessel.

"It's neither a surprise nor bad news," Kunihiko Takeda of Chubu University told The Japan Times. "This means Tepco has been pumping lots of water in the reactor without knowing what exactly is happening in it, which is the best thing Tepco could do." He added that reactors No. 2 and 3 may also be in the same situation. The new finding doesn't increase the likelihood of a hydrogen explosion because the temperature in the pressure vessel is still low, experts said.

Hydrogen explosions can occur if zirconium, material used in fuel-rod casings, melts at around 1,200 degrees, said Ken Nakajima of the Kyoto University Research Reactor Institute. The temperature in the pressure vessel is 100 to 120 degrees.

Takeda said the pressure vessels and containment vessels in reactors 1, 2 and 3 are likely to have cracks where hydrogen can escape, another factor reducing the likelihood of a hydrogen explosion. The fact remains, however, that the reactors at the Fukushima plant keep leaking radioactive substances into the air and are irradiating the water cooling them as well. Thus, the most important thing, as it has always been, is to build a system to recirculate the water being used to cool the reactors, Takeda said..."


http://search.japantimes.co.jp/rss/nn20110513a8.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+japantimes_news+%28The+Japan+Times+Headline+News+-+News+%26+Business%29



Japan Reactor-Core Damage Worse Than Thought
By Joe Carroll and Michio Nakayama - May 12, 2011 8:27 AM PT

"Tokyo Electric Power Co. said one of the reactor cores at its stricken Fukushima Dai-Ichi nuclear plant is more seriously damaged than previously thought, setting back the utility’s plan to resolve the crisis...

...Melted fuel has dropped to the bottom of the pressure vessel and is still being cooled, Matsumoto said...

...Holes have been found in the base of the pressure vessel, and most of the fuel has likely melted, Kyodo News reported yesterday, citing the utility. It’s possible the fuel has leaked into the containment vessel, which was damaged in the explosion, according to the report...

...“The plan needs to be revised,” Matsumoto said. “We can’t deny the possibility that a hole in the pressure vessel caused water to leak.”

http://www.bloomberg.com/news/2011-05-12/japan-suffers-setback-at-fukushima-after-no-1-reactor-s-fuel-rods-exposed.html



Don, doesn't this sound like it has way too many "more seriously damaged," and "likely melted," and "plan needs to be revised," and "we can't deny the possibility..." type of assertions than is comfortable living with on a day to day basis.

Sounds like Amateur Hour for the nuke industry.