Oct 22, 2013

    Heavy rain causes leak at Fukushima

    HEAVY rain at the Fukushima nuclear plant caused a leakage of radioactive water containing a cancer-causing isotope, possibly into the sea, its operator said yesterday, as a typhoon approaching Japan threatened further downpours.

    It is the latest in a long line of setbacks at the site, further undermining agreements between operator Tokyo Electric Power (Tepco) and the government, which limit the level of radioactive contamination in water that goes outside the plant.

    Tepco said a barrier intended to contain radioactive overflow was breached in one spot by water contaminated with strontium-90 at 70 times the legal limit for safe disposal.

    Strontium-90 is produced during nuclear reactions. It accumulates in bones and remains potent for many years, and causes several types of cancer in humans.

    The admission came as a team of experts from the United Nations' nuclear watchdog wrapped up their review of Japan's progress in cleaning up the worst atomic disaster in a generation.

    Tepco has poured thousands of tonnes of water on badly damaged reactors at Fukushima to keep them cool and prevent them from melting down again.

    This huge volume of water has to be stored in large tanks until it is cleaned of the radioactive substances that it picks up in the cooling process.

    Rain exacerbates the problem because, as it hits polluted surfaces, it becomes contaminated, meaning Tepco needs to scoop it all up for storage and treatment.

    While the storage tanks all appeared to have survived the battering from heavy rain on Sunday, the concrete overflow barriers around them were not high enough to contain the rainwater runoff in several places.