Announcements

Asahi Shimbun wrote in its article of July 19, 2013 (morning edition page 1) that "estimated radiation doses in thyroid glands exceeded safe levels in nearly 2,000 people who worked at the stricken Fukushima nuclear plant, more than 10 times the number previously announced" last December. The facts are as below.

After the accident at Fukushima Daiichi Nuclear Power Station (NPS), we were requested from the World Health Organization (WHO) to report the data of the exposure doses, of the.522 workers who had received cervical checks directly through the thyroid monitor. Iodine 131 was detected and the eqquivalent dose in the thyroid glands of the 178 workers exceeded 100mSv. We reported these data to WHO at the time in March, 2012. (Previously announced on December 6, 2012)

In the meantime, we set our original standard^*1 which is more conservative than the guidance of the Ministry of Health, Labour and Welfare (MHLW). After the accident, TEPCO and the contractors have been engaged in the designated emergency works. We decided to include these workers whose equivalent dose in their thyroid glands exceeded 100mSv as those eligible for long-term health management, and since then, we had been working on the estimation of the equivalent doses they were exposed to.

On the other hand, we have been estimating the exposure dose of TEPCO workers and gathering the estimation results of the contractors who are working at Fukushima Daiichi, and have reported their data to the MHLW every month, at the same time announcing the data via our homepage. Regarding the estimation, the ministry had been reviewing the validity of the estimation method and completed the review in July. The ministry instructed us (TEPCO and the contractors) to re-estimate the dose and we reported the dose distribution that reflected the instruction. (Previously announced on July 5, 2013)

We have announced the workers eligible for long-term health management (workers eligible for the cervical ultrasonic test).
·19,592 workers have been engaged in the designated emergency works at Fukushima Daiichi until December 16, 2011 and the equivalent dose of the thyroid glands of 1,972 workers exceeded 100mSv. (Previously announced on July 12, 2013, correction made on July 22, 2013)

Workers who continue to engage in the designated emergency works whose thyroid equivalent doses exceed 100mSv are eligible of long term health management. Additionally, thyroid equivalent doses of those eligible for long-term health management are calculated by iodine correction^*2 and the "addition of external exposure dose to a figure 20 times of internal exposure dose by iodine (till March, 2016)". By these reasons, the doses will continue to increase by the works continued, and the number of the eligible workers for long-term health management is expected to increase in future by progress of time.

We have announced to the workers eligible for cervical ultrasonic test that they could take charge-free examination once a year. For 2012, we have completed the announcement.

We will continue to conduct health management of the workers for the long term.

*1 Our standard
The workers eligible for blood tests of thyroid gland are prescribed as "the effective dose by the designated emergency work applies to the workers more than 100mSv" in the guideline of the Ministry of Health, Labour and Welfare. However, we have added our original conservative standard as "the workers who were engaged in the designated emergency works, and the total of the effective dose at those designated emergency works and the accumulated effective dose at works until the next end of March, 2016 at Nuclear Power Stations in TEPCO exceeds 50mSv".are eligible for blood tests of thyroid gland. Additionally, we have set the workers eligible for cervical ultrasonic tests as "those whose equivalent dose in their thyroid glands exceeds 100mSv.

*2 Iodine correction
In case that the internal dose measurements by whole body counter (WBC) has been delayed and short half-life Iodine131 has not to been detected as time passes, we are evaluating Iodine dose on the safe side by the ratio of Iodine and Cesium in the air or the minimum detectable activity of Iodine.

Data on Radiation Exposure Doses of the Workers who Engaged in Restoration Work at Fukushima Daiichi Nuclear Power Station Provided to the World Health Organization (WHO) (PDF 26.2KB)

Revisions in "Exposure Dose Distribution" Following Reconfirmation Work on Internal Exposere Doses at Fukushima Daiichi Nuclear Power Station

Review and Follow-up of Fukushima Daiichi NPS Workers Eligible for Long-Term Health Management Following Internal Exposure Dose Correction (PDF 122KB)