Flashes of extremely intense radioactivity have become a serious problem, he said. Tokyo Electric’s difficulties in providing accurate information on radiation are not a result of software problems, as some Japanese officials have suggested, but stem from damage to measurement instruments caused by radiation, the executive said. It’s at the end of this NY Times article:
Still, concerns about the plant remain high. The Nuclear Regulatory Commission speculated Wednesday that some of the core of the No. 2 reactor had flowed from its steel pressure vessel into the bottom of the containment structure. The theory implies more damage at the unit than previously believed.
While a spokeswoman for Tokyo Electric dismissed the analysis, a spokesman for the Nuclear and Industrial Safety Agency of Japan agreed that it was possible that the core had leaked into the larger containment vessel.
The possibility raised new questions. The Nuclear Regulator Commission said that its speculation about the flow of core material out of the reactor vessel would explain high radiation readings in an area underneath, called the drywell.
But some of the radiation readings at Reactors Nos. 1 and 3 over the last week were nearly as high as or higher than the 3,300 rems per hour that the commission said it was trying to explain, so it would appear that the speculation would apply to them as well. At No. 2, extremely radioactive material continues to ooze out of the reactor pressure vessel, and the leak is likely to widen with time, a western nuclear executive asserted.