They are all TEPCO employees. One of them worked in the central control rooms for the Reactors 3 and 4, five others worked outside the control rooms, maintaining electrical and measuring equipments.
NISA's Nishiyama says it is regrettable.
Mainichi Shinbun Japanese (6/13/2011):
東京電力福島第１原発で緊急作業に従事する東京電力社員２人の被ばく線量が限度（２５０ミリシーベルト）の倍以上の６００ミリシーベルト超だった 問題で、厚生労働省は１３日、東電の簡易検査で新たに６人が限度を超えた可能性があると発表した。いずれも東電の男性社員で、最高値は内部被ばくと外部被 ばくを合わせて４９７ミリシーベルト。現在、精密な検査を受けている。
The Ministry of Health, Labor and Welfare announced on June 13 that 6 additional workers at Fukushima I Nuclear Power Plant may have exceeded the radiation exposure limit of 250 millisieverts. It was revealed by the quick testing done by TEPCO. All of them were male TEPCO employees. The maximum radiation was 497 millisieverts, counting both the external and the internal radiation exposures. They are currently undergoing more detailed testing. Earlier, two TEPCO employees at the plant had exceeded the limit, with the total radiation exposure of over 600 millisieverts.
同省によると、東日本大震災以降、６人のうち１人が３、４号機の中央制御室におり、５人は室外で電気機器や計測機器の保守に従事していた。また、 この他に６人（東電社員４人、協力会社員２人）が２００～２５０ミリシーベルトを被ばくした疑いがあり、同省は東電にこの１２人を緊急作業から外すよう指 示した。
According to the Ministry, one of them has worked in the central control rooms for the Reactors 3 and 4 since the March 11 earthquake/tsunami, and the other 5 have worked outside the control rooms maintaining the electrical and measurement equipments. 6 additional workers (4 TEPCO employees, 2 TEPCO affiliate company employees) may also have received between 200 to 250 millisieverts radiation. The Ministry has instructed TEPCO to remove these 12 workers from the work at the plant.
TEPCO has been testing the radiation exposure levels of 3,700 workers who have worked at the plant so far, and reported the result of about 2,300 workers by June 13.
Junichi Matsumoto of TEPCO said, "Initially, we did not conduct the radionuclide analysis in the air and we didn't fully understand the work condition, and that led to the internal radiation of the workers. We will investigate the situation further, including whether the workers wore masks."経済産業省原子力安全・保安院の西山英彦審議官は「極めて遺憾。東電に対し、６人についての被ばく量が確定次第、すみやかな報告と徹底的な原因究明を指示したい」と話した。
The Nuclear and Industrial Safety Agency (NISA) spokesman Hidehiko Nishiyama said, "It is highly regrettable. As soon as the definite numbers for the radiation exposures for the 6 workers become known, we will instruct TEPCO to report immediately and to investigate the cause thoroughly."
3 months after the accident, in the NISA's mind it is still a local accident caused by a private business.