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Nuclear clean up plan criticised

A blueprint for ending radiation leaks and stabilising reactors at Japan’s crippled Fukushima nuclear plant drew a lacklustre response today as polls showed diminishing public support for the government’s handling of the country’s recent disasters.

Nine-month plan

Plant owner Tokyo Electric Power Company (Tepco) this week unveiled its plan to get the reactors under control, which it expects to take up to nine months. Tepco’s work is part of the overall plan to let some of tens of thousands evacuees from near the plant return home.

The exclusion zone remains over a 20km radius around the Fukushima plant, extending beyond that to the communities of Iitate and Kawamata.

The firm has come under fire previously for not offering clear assurance over the extent of the problems in the aftermath of the 11 March earthquake and tsunami, as well as in previous incidents (NCE 17 March).

In addition, independent nuclear expert Tony Roulstone believes that Tepco’s measures are a demonstration of “managing expectations” and is conservative in its ambitions.

“The levels of radiation in some areas of the exclusion zone are low, so it may take less than nine months for the local population to be let back in”

Independent nuclear expert Tony Roulstone

He said it would be better for officials to overestimate the time it will take to reopen areas in the exclusion zone, than to under estimate them.

“The levels of radiation in some areas of the exclusion zone are low, so it may take less than nine months for the local population to be let back in,” he said.

The first phase is aimed at getting the “radiation level in steady decline” will take about three months. At this point officials hope to reduce the energy from the heat of each of the four damaged reactors down from between 6MW and 7MW to 2MW to 3MW.

It also needs to create adequate storage for contaminated water.

Second phase

The second phase will be a cold shutdown on each reactor using temporary covers, likely to be formed mostly from concrete covering the entire reactor buildings.This should be completed within three to six months after phase one.

“Looking at the evidence, it appears officials have almost completed phase one now,” said Roulstone.Following cold shutdown, Tepco will then turn its attention to decommissioning the reactors.

“There may be a period of reduced activity while engineers decide what the best way is to clean up the plant,” added Roulstone.

He said that the first thing engineers will do is put a camera in each reactor to accurately assess the extent of the damage.

Water method

In the meantime engineers are attempting to cool the reactors by putting water around the containment vessel and using heat exchangers to remove the heat. This is possible because engineers have managed to reconnect another power line to the station.

This method reduces the amount of contaminated water in the cooling operation (NCE 7 April). Previously, engineers were using a “feed and bleed” system, where water was continually pumped into and drained from the reactors.

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