While efforts to cool spent fuel at Fukushima Daiichi have made progress in recent days, crews also discovered some of the highest radiation readings at the plant to date.Among the developments in the last week at the Tokyo Electric Power Co. reactors damaged by the March earthquake and tsunami:Water Treatment System Lowers Spent-Fuel TemperaturesThe Nuclear
Energy Institute reported Monday that a recirculating cooling system
has successfully brought down the temperature in unit 4’s spent-fuel tank, with
measurements expected to decline to 40 C. Separate reports quoted a
TEPCO spokesman as saying two large concrete-pumping trucks used to pour
water onto units’ spent fuel were replaced earlier with piping and
recirculation systems. They have been installed outside units 2, 3 and 4 and are in the
works for unit 1. Radiation Readings Topping 10 Sieverts (1,000 Rem) DetectedGamma-radiation imaging taken by a robot Sunday led TEPCO to detect radiation at potentially lethal levels in an exhaust system.Further measurements on Monday confirmed radiation levels exceeding 10 sieverts per hour in a pipe connecting the containment of units 1 and 2 to an exhaust stack – the highest reading at the plant since measurements exceeding 4 sieverts were taken inside the unit 1 reactor building several weeks ago.The Daily Yomiuri also quoted TEPCO officials as saying Tuesday that another 10-sievert reading and a 5-seivert reading were taken at two different locations at unit 1 near the same pipe.Japanese Ministry Heads DismissedOn Thursday Japan’s Trade and Industry Minister Banri Kaieda, who himself plans to resign over the handling of the Fukushima crisis, announced he will replace three of the country’s top regulators.The Asahi Shimbun reported that he will replace Nuclear and Industrial Safety Agency Director General Nobuaki Terasaka, Agency for Natural Resources and Energy Director General Tetsuhiro Hosono and Vice-Minister of Economy, Trade and Industry Kazuo Matsunaga.
(Photo: Bottom of the main exhaust stack for units 1 and 2. Source: TEPCO)
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