TEPCO orderd to check underground trench

August 13, 2013

Nuclear watchdog orders TEPCO to check trench at Fukushima plant over leaks

http://mainichi.jp/english/english/newsselect/news/20130813p2a00m0na017000c.html

The Nuclear Regulation Authority (NRA) instructed Tokyo Electric Power Co. (TEPCO) on Aug. 12 to check an underground trench connected to the No. 1 reactor at the Fukushima No. 1 Nuclear Power Plant as highly radioactive substances were detected at the seawall on the east side of the reactor.

The instruction came on the heels of a revelation that groundwater contaminated with radioactive substances from the crippled Fukushima nuclear complex likely flowed into the Pacific Ocean over an underground wall on the east side of the No. 2 reactor. There is a possibility that highly radioactive water left inside the trench for the No. 2 reactor, which is believed to be the "source of contamination," moved into the trench for the No. 1 reactor. The NRA also decided to conduct an on-the-spot investigation on Aug. 23.

The NRA held its working group meeting on Aug. 12. At the meeting, TEPCO reported that it had detected 34,000 becquerels of tritium per liter in the groundwater sample collected from a newly built observation well on the east side of the No. 1 reactor. The radiation level is quite high as compared with 1,500 to 210 becquerels detected at the seawalls on the east side of the No. 3 and No. 4 reactors. NRA Commissioner Toyoshi Fuketa said, "We have to take seriously the fact that highly radioactive substances were detected in front of the No. 1 reactor as well."

According to TEPCO, the operator of the crippled Fukushima nuclear power station, water contaminated with low levels of radiation (89 becquerels of radioactive cesium-137) is still remaining in the trench for the No. 1 reactor, but TEPCO conducted its last survey in December last year, and therefore it has not recently checked the radiation levels. The NRA instructed the utility to re-inspect the water in the trench for the No. 1 reactor and drill wells around the trench to monitor radiation levels as it saw the possibility of highly radioactive water moving into the trench for the No. 1 reactor through the trench for the No. 2 reactor.