Radiation Watch 2013

Originally posted by MariaLida
Insight: After disaster, the deadliest part of Japan's nuclear clean-up

(Reuters) - The operator of Japan's crippled Fukushima nuclear plant is preparing to remove 400 tons of highly irradiated spent fuel from a damaged reactor building, a dangerous operation that has never been attempted before on this scale.

By Aaron Sheldrick and Antoni Slodkowski
TOKYO | Wed Aug 14, 2013 3:16am BST

Containing radiation equivalent to 14,000 times the amount released in the atomic bomb attack on Hiroshima 68 years ago, more than 1,300 used fuel rod assemblies packed tightly together need to be removed from a building that is vulnerable to collapse, should another large earthquake hit the area.

Tokyo Electric Power Co (Tepco) is already in a losing battle to stop radioactive water overflowing from another part of the facility, and experts question whether it will be able to pull off the removal of all the assemblies successfully.

"They are going to have difficulty in removing a significant number of the rods," said Arnie Gundersen, a veteran U.S. nuclear engineer and director of Fairewinds Energy Education, who used to build fuel assemblies.

The operation, beginning this November at the plant's Reactor No. 4, is fraught with danger, including the possibility of a large release of radiation if a fuel assembly breaks, gets stuck or gets too close to an adjacent bundle, said Gundersen and other nuclear experts.

“There is a risk of an inadvertent criticality if the bundles are distorted and get too close to each other,” Gundersen said. He was referring to an atomic chain reaction [...]

“The problem with a fuel pool criticality is that you can’t stop it. There are no control rods to control it,” Gundersen said. [...]

“Previously it was a computer-controlled process [...] It has to be done manually so there is a high risk that they will drop and break one of the fuel rods,” [Toshio Kimura, a former Tepco technician, who worked at Fukushima Daiichi for 11 years] said. [...]

The process will begin in November and Tepco expects to take about a year removing the assemblies, spokesman Yoshikazu Nagai told Reuters by e-mail. It's just one installment in the decommissioning process for the plant forecast to take about 40 years and cost $11 billion.

uk.reuters.com...

enenews.com... u-cant-stop-it-no-control-rods-to-control-it-consulta

Three hundred tons of highly contaminated water has leaked from a storage tank at the ravaged Fukushima Daiichi Nuclear Power Plant on Japan’s Pacific coast, its operator said Tuesday, prompting regulators to declare a “radiological release incident” for the first time since disaster struck there in 2011 and adding new fears of environmental calamity.

Workers raced to place sandbags around the leaking tank to stem the spread of the water, contaminated by levels of radioactive cesium and strontium many hundreds of times as high as legal safety limits, according to the operator, Tokyo Electric Power, or Tepco. The task was made more urgent by a forecast of heavy rain for the region later in the day

Japan will raise the severity rating of a recent toxic water leak at the destroyed Fukushima nuclear plant to level 3, or "serious incident", on an international scale for radiological releases, underlining the deepening sense of crisis at the site.

Contaminated water with dangerously high levels of radiation is leaking from a storage tank at Fukushima, the plant's operator said on Tuesday, the most serious setback to date for the clean up of the worst nuclear accident since Chernobyl.