Tokyo Electric Power Co. arrested an unexpected rise in temperature at Fukushima Daiichi unit 2 this week and also scheduled the shutdown of the company's last operating reactor.
Recent developments at the nuclear plant blacked out by the earthquake and tsunami last March include:
Unit 2 Temperature Falls
Following pipe repair and concurrent adjustments to cooling water at the unit 2 reactor, temperature readings inside began rising from 45 C after Jan. 26. Readings varied among gauges placed at different locations in the reactor pressure vessel, with a TEPCO spokesman telling Bloomberg that one reached 72.2 C Monday morning. TEPCO increased the volume of water injected into the reactor by about a third and also injected boron Tuesday as a precaution. No increase in Xenon has been detected that would suggest recriticality. A TEPCO release placed the RPV temperature at 66.8 C as of Thursday morning.
Last TEPCO Reactor Scheduled to Go Offline
Unit 6 at the Kashiwazaki-Kariwa plant will shut down for maintenance March 26, TEPCO announced Thursday, leaving the company with none of its 17 reactors in service. Kyodo reported TEPCO hopes to restart reactors at Kashiwazaki-Kariwa in 2013 at the earliest. As with plants across the country, the ability of the units to gain local government approval to restart remains an open question. The Daily Yomiuri quoted unnamed officials as saying government plans called for the restart of two reactors at Kansai Electric Power Co.'s Ohi plant by the end of April, but the country’s trade minister later disavowed the report. Unless units idled over the last year for inspections and maintenance are restarted, all 54 of Japan’s reactors will be offline in April.
Tsunami Likely Higher Than First Thought
The first survey of its kind in Fukushima Prefecture since the accident suggests the tsunami that hit the plant on March 11, 2011, was even taller than originally thought. The waves that topped the plant’s defenses were originally estimated at 15 meters high. The Daily Yomiuri reported Thursday that researchers from the University of Tokyo found evidence the waves near Fukushima may have topped that. At one point 8 kilometers south of the plant, researchers said waves reached 21.1 meters high.