Operations to decontaminate highly radioactive water at the crisis-stricken Fukushima No. 1 Nuclear Power Plant came to a screeching 13-hour halt when workers discovered a section of pipe emitting 3 sieverts of radiation per hour in one decontamination system, said plant operator Tokyo Electric Power Co. (TEPCO).
Workers found the high radiation emissions from the pipe section at just after 7 a.m. on Aug. 22 while doing the first ever change-out of a decontamination system part for absorbing radioactive cesium, TEPCO said. Work on the part change stopped immediately.
After washing radioactive mud away from the area, radiation levels dropped, and decontamination operations resumed at about 8:15 p.m., though the delay pushed replacement of the cesium absorption component back to Aug. 23. TEPCO officials still do not know what caused the radiation leak.
Electronics and heavy machinery giant Toshiba Corp. built the water decontamination system, called “Sally.” There are high expectations for Sally’s performance after two other decontamination systems at the site — one made in the United States and the other in France — continued to have problems and delays.
This is the third time workers found high radiation emissions at the plant in August. On Aug. 1, emissions of 10 sieverts per hour came from the substructure of exhaust pipes in the No. 1 and 2 reactor housings, while on Aug. 2 emissions of more than 5 sieverts per hour were in the air conditioning room in the No. 1 reactor building.