At around 12:42 pm on March 27, 2012, during the work to receive samples (water) for performance verification test of ALPS (Advanced Liquid Processing System) which were carried in from Fukushima Daiichi Nuclear Power Station, at Service Building of Unit 3 and 4 of Fukushima Daini Nuclear Power Station, our employee has found the spot contaminated with radioactive materials on the table next to the small monitor in the check point (uncontrolled area*) to check the contamination of the goods when leaving controlled area.
Investigation for cause is currently underway.
The table where pollution was found and the area where pollution is suspected are set as a restricted area to prevent expansion of the contamination and are under control.
(previously announced)
After the investigation, it was confirmed that the contamination on the table next to the small monitor in the check point was due to the spilled sample (water). The spilled amount was approx. 2.5 cc and the surface contamination concentration was approx. 206Bq/cm2 according to the measurement by the contamination survey meter.
During the investigation for the contamination in the entire route of sample transportation, 7 spots were confirmed to be contaminated (max above 700Bq/cm2). In order to prevent expansion of the contamination, 4 spots were decontaminated and 3 spots were temporarily put under control.
While inside of the vehicle transported such sample was also confirmed to be contaminated, outside surface of the vehicle nor the entrance area of the service building were not contaminated. Therefore, it is considered that the contamination is limited in the service building of Unit 3 and 4.
As this incident corresponds to the event that requires reporting based on the clause 19, article 17 of the Rules for the Installation and Operation, etc. of Commercial Power Reactors, we will report the result of the investigation for the cause once it is completed to NISA.
* uncontrolled area
Controlled area is an area where control is necessary to prevent unnecessary exposure to radiation and to prevent expansion of the contamination with radioactive materials. Uncontrolled area is area outside of the controlled area.
* We would like to make corrections to the press release published on March 27, 2012. We apologize for any inconvenience and would like to correct from the expression of "for analysis" to "for performance verification test of ALPS (Advanced Liquid Processing System)".(April 13, 2012)
Appendix:
Map of contaminated area under the control in Unit 3/4 Service building in Fukushima Daini NPS (PDF 42.4KB)
