Some spent fuel rods at Fukushima were damaged before 2011 disaster

TOKYO Thu Nov 14, 2013 6:20am EST

TOKYO Nov 14 (Reuters) - Three of the spent fuel assemblies due to be carefully plucked from the crippled Japanese nuclear plant at Fukushima in a hazardous year-long operation were damaged even before the 2011 earthquake and tsunami that knocked out the facility.

The plant's operator, Tokyo Electric Power Co, or Tepco, said the damaged assemblies - 4.5 metre high racks containing 50-70 thin rods of highly irradiated used fuel - can't be removed from Fukushima's Reactor No. 4 using the large cask assigned to taking out more than 1,500 of the assemblies.

One of the assemblies was damaged as far back as 1982, when it was mishandled during a transfer, and is bent out of shape, Tepco said in a brief note at the bottom of an 11-page information sheet in August.

In a statement from April 2010, Tepco said it found two other spent fuel racks in the reactor's cooling pool had what appeared to be wire trapped in them. Rods in those assemblies have pin-hole cracks and are leaking low-level radioactive gases, Tepco spokesman Yoshikazu Nagai told Reuters on Thursday.

The existence of the damaged racks, reported in a Fukushima regional newspaper on Wednesday, came to light as Tepco prepares to begin decommissioning the plant by removing all the spent fuel assemblies from Reactor No. 4.

"The three fuel assemblies ... cannot be transported by cask," Tepco spokeswoman Mayumi Yoshida said in an emailed response to queries on Thursday, referring to the large steel chamber that will be used to shift the fuel assemblies from the pool high up in the damaged reactor building to safe storage.

"We are currently reviewing how to transport these fuel assemblies to the common spent fuel pool," she said.

Tepco is due within days to begin removing 400 tonnes of the dangerous spent fuel in a hugely delicate and unprecedented operation fraught with risk. Each assembly contains radiation equivalent to around 10 times that of the atomic bomb dropped on Hiroshima in 1945.

Having to deal with the damaged assemblies is likely to make that task more difficult and could jeopardise a 12-month timeframe to complete the removal that many have already called ambitious.

RISKY, COMPLEX OPERATION

Three reactors suffered core meltdowns at the Fukushima Daiichi plant north of Tokyo after the March 2011 disaster that triggered explosions and forced the evacuation of 160,000 people from nearby towns and villages.

Tepco, which has floundered in trying to bring the plant under control in the two and a half years since the disaster, is now moving to full decommissioning at the six-reactor facility.

The most urgent task is to remove the fuel assemblies from the unstable Reactor No. 4, which due to their height - about 18 metres above ground level - are more vulnerable to any new earthquake. The operation is seen as a test of Tepco's ability to move ahead with decommissioning the whole facility - a task likely to take decades and cost tens of billions of dollars.

Lake Barrett, a former U.S. nuclear regulator who is advising Tepco, visited the Fukushima site on Wednesday and endorsed preparations for the removal of the assemblies.

"While removal of the fuel is usually a routine procedure in operating a power plant, the damage to the reactor building has made the job more complex," he said, adding he was "genuinely impressed by the thoroughness of the effort and Tepco's contingency planning."

Tepco has said the assembly removal process will begin around mid-November, but has not given an exact date, citing what it says are security reasons.

The assemblies must first be lifted from their storage frames in the pool and individually placed in a steel cask - kept all the while under water to prevent overheating. The cask, weighing around 90 tonnes when filled, will then be hoisted by crane from the pool, lowered to ground level and transported by trailer to a common storage pool about 100 metres away.

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Comments (4)
jayjay1980 wrote:
Ok so these same idiots that realized they had problems in the 1980′s and failed to fix them, and again more recently, are the morons who are moving 1600 fuel rods? The international community needs to stop this fiasco now and have Europeans and Chinese move them before they let these dorks try it!

Nov 14, 2013 8:54am EST  --  Report as abuse
wannmann wrote:
59 Total Thyroid Tumors In Fukushima Children
November 13th, 2013 SimplyInfo
New data has been released from the government study of thyroid abnormalities and cancer in Fukushima children. Of those screened 59 have been found to have tumors. The health survey examined 289,960 children total.
This becomes 1 cancer per 5000 people. This is far higher than the pre-disaster levels. This raises big questions about the claims that these are increased just due to more screening. The more these numbers grow the harder it is to dismiss the findings are some version of normal.

Nov 14, 2013 1:00pm EST  --  Report as abuse
Que surtin amb el Seu propòsit¡i que expliquin el que van fen.

Nov 15, 2013 1:39pm EST  --  Report as abuse
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