Today's Coming Crisis Movie

Friday, August 24, 2012

 TEPCO to check for active faults beneath Kashiwazaki-Kariwa nuclear plant

Tokyo Electric Power Co. (TEPCO) will survey the earth beneath the Kashiwazaki-Kariwa nuclear power plant in Niigata Prefecture to check if two fault lines there are active, the utility announced on Aug. 23.

The two faults, labeled alpha and beta, run directly under the plant's No. 1 reactor. TEPCO had previously judged that they were inactive, and the central government accepted this conclusion after conducting its own examination.

However, as all of Japan's nuclear plants face renewed safety checks in the wake of the Fukushima No. 1 nuclear plant meltdowns, experts have called on TEPCO to conduct a detailed age assessment of the faults.

TEPCO decided to excavate the Kashiwazaki-Kariwa faults and date them by studying fossilized pollen deposits, among other telltale factors. The survey results will be released in February 2013.

In a 2006 government revision to anti-earthquake design inspection standards, it was decided that faults that had shifted in the past 120,000-130,000 years should be considered active. Before the change, only faults that had moved in the past 50,000 years were considered active.

TEPCO had until recently maintained that the alpha and beta faults under the Kashiwazaki-Kariwa plant hadn't moved for between 120,000 and 240,000 years, and were therefor inactive. Geological experts had, however, pointed out that the age estimation did not have a clear foundation, and called for a new survey. Source