A crane accident at Fukushima Daiichi, evidence of fission in one of its units and the first restart of an idled reactor elsewhere in the country were among the news from Japan this week.
Developments at the Tokyo Electric Power Co. plant damaged by the March earthquake and tsunami include:
TEPCO: Not enough xenon to suggest recriticality
The utility reported that testing Tuesday revealed radioactive xenon in unit 2’s containment. The isotopes of the noble gas detected and their short half-lives raised fears that some of the damaged fuel in the reactor recently achieved criticality. On Thursday, though, TEPCO officials quoted by the Daily Yomiuri said the amounts of xenon-133 and xenon-135 detected were an order of magnitude smaller than what would be present following a criticality incident. Instead, the utility believes spontaneous fission of radioactive curium explains the xenon’s presence. Nonetheless, the International Atomic Energy Agency reported TEPCO injected 10 metric tons of boric acid solution into the unit. Its temperature and radiation levels have not changed significantly in recent days.
First of idled plants restarts
A reactor at Japan’s Genkai plant returned to service Tuesday – the first shut-down unit in the country granted permission to restart following the Fukushima accident. The move had the backing of the Japanese prime minister and the previously reluctant governor of Saga prefecture. Their support is significant because it may hint at the future of the country’s nuclear program. Only 10 of Japan’s 54 reactors are operating, the New York Times reported, because local governments prevented units from restarting after maintenance and inspection outages in the months following the Fukushima crisis.
Crane accident injures two
An accident Saturday injured two workers as they helped assemble a crane at Fukushima Daiichi. Crews were using a crawler crane to assemble a second crane when a set of slings slipped and dropped a back mast onto the men. While their status has not been released, both were transported to hospitals.