TOKYO — Nuclear workers at the crippled Fukushima power plant raced to inject boric acid into the plant’s No. 2 reactor early Wednesday after telltale radioactive elements were detected there, and the plant’s owner admitted for the first time that fuel deep inside three stricken plants was probably continuing to experience bursts of fission.
But the urgent injection of boric acid underscored that the company was operating on the assumption that the measurements were valid. A naturally occurring element, boron soaks up the neutrons released when an atom is split so that those neutrons cannot go on to split other atoms in the process of fission. Nuclear power plants harness the energy released in the form of heat to produce electricity.
Junichi Matsumoto, a Tokyo Electric spokesman, acknowledged episodes of fission, telling a news conference: “There is a possibility that certain conditions came together temporarily that were conducive to re-criticality,” and that the measurements indicated a burst that occurred at a slightly higher rate than prior cases. “It’s not that we’ve had zero fission until now,” Mr. Matsumoto said. “But at this point, we do not think there is a large-scale and self-sustained re-criticality.”
The engineer, who has worked at all three nuclear power complexes operated by Tokyo Electric, spoke on condition of anonymity because he did not want to be identified by his former employers. He said that tiny fuel pellets could have been carried to different parts of the plant, like the spaces under the reactor during attempts to vent them in the early days. That would explain several cases of lethally high radiation readings found outside the reactor cores.
“If the fuel is still inside the reactor core, that’s one thing,” he said. But if the fuel has been dispersed more widely, then we are far from any stable shutdown.”
Continue reading at Fears of Fission Rise at Stricken Nuclear Plant in Japan