Cooling system for fuel storage pool at Fukushima reactor fails

The cooling system for a storage pool for fuel at one of the reactors at the tsunami-damaged nuclear plant in Japan failed today for the second time in a month, although the breakdown had no immediate safety implications.

According to Nuclear Regulation Authority spokesman Takahiro Sakuma, an alarm went off in the afternoon about the problem at reactor No 3. The cause continued to remain under investigation.

According to Tokyo Electric Power Co, or TEPCO, the utility that runs Fukushima DaiIchi in northeastern Japan, the cooling system could be turned off for two weeks ibefore temperatures approached dangerous levels at the spent fuel storage pools.

However, according to experts, if the water were to run dry, the fuel rods, even spent ones, would spew enormous levels of radiation,

Following the failure of the tsunami-damaged backup generators and all cooling systems, in March 2011, the plant went into multiple meltdowns. The plant is being decommissioned, but work continues to be hit by glitches.

A power outage last month, led to a non-functioning cooling system for two days, with TEPCO later saying it had found a dead rat near a switchboard. It suspected that to be the cause for the power trip and the reason for loss of power at nine facilities at Fukushima Daichi.

Meanwhile, BBC said in a report that while it would be reassuring to think that the world's worst nuclear disaster since Chernobyl had been contained, and the Fukushima Daiichi nuclear power plant was in stable shut-down, a look inside the Fukushima plant suggests otherwise.

BBC's Rupert Wingfield-Hayes, was part of a group taken in to the Fukushima plant last week, only the second time foreign TV journalists were allowed in after the disaster two year ago. He writes that there was little about that about the brief two-hour tour that  was reassuring. The team's first stop was reactor building number four which was potentially the most worrying.

Inside devastated building, over 1,500 spent fuel rods still sat inside a cooling pool. These were still highly radioactive and the pool lay outside the reactor's steel and concrete containment vessel, perched high on the third floor.

Around 3,000 nuclear workers were still trying to clean up the site, according to Wingfield-Hayes.

A race was now on to get the fuel rods out, with a huge steel structure under erection around building four that would be used to raise the spent fuel out.

However, Wingfield-Hayes says the operation would not start until the end of this year, and would then take two more years to complete. In the event of  another large earthquake striking during that time there was real concern about the building collapsing.