Long-awaited assessments of a damaged reactor at Japan's Fukushima Daiichi nuclear plant have cast doubt on Tokyo Electric Power Co's plans to flood its containment.
Initially, TEPCO said it would inundate the containment vessel of the unit 1 reactor with cooled water to bring the pressure vessel and the damaged core within to cold shutdown temperatures. After crews late week calibrated a water-level gauge, though, TEPCO realized much of the core was fully exposed to air, had likely melted and accumulated in the bottom of the pressure vessel. Small holes in the bottom of that stainless steel structure indicated much of the water pumped into the core to cool it in the weeks since the March 11 earthquake and station blackout had been leaking. Worse, TEPCO in recent days has said it suspects the containment has sprung leaks in the joints of pipes connecting the GE Mark I containment vessel to its suppression pool.
On Friday, TEPCO said its workers found an estimated 3,000 tons of water in the basement of the reactor. Lower floors of the plant's reactors are connected through a series of tunnels and conduits, and operators are fearful of additional leaks of irradiated water into the ocean. Because of these problems, TEPCO this weekend said it is considering using the leaked water to cool the reactor core, adding an additional layer of complexity to a situation already made difficult by high dose levels and damaged equipment.
Also over the weekend, a worker in his 60s died. The Daily Yomiuri newspaper quoted a Japanese hospital as confirming that his death was caused by heart problems and was not related to radiation exposure. He had collapsed on the job at Fukushima on Saturday morning, Japan time.