Dec 24, 2021 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPP

Exposure Dose Distribution of the Workers at Fukushima Daiichi Nuclear Power Plant

Updated on 24 December 2021

1. Radiation Exposure Dose Distributions

(1)The distribution of external exposure dose of the workers during the last 3 months
(Numbers of workers who entered each area every month)
Effective dose (E) mSv	September-2021			October-2021			November-2021
Effective dose (E) mSv	TEPCO	Contractors	Total	TEPCO	Contractors	Total	TEPCO	Contractors	Total
100<E	0	0	0	0	0	0	0	0	0
75<E≤100	0	0	0	0	0	0	0	0	0
50<E≤75	0	0	0	0	0	0	0	0	0
20<E≤50	0	0	0	0	0	0	0	0	0
10<E≤20	0	1	1	0	0	0	0	0	0
5<E≤10	0	66	66	0	40	40	0	25	25
1<E≤5	12	607	619	19	472	491	9	547	556
E≤1	980	4821	5801	998	5070	6068	998	5171	6169
Total	992	5495	6487	1017	5582	6599	1007	5743	6750
Maximum(mSv)	2.60	11.30	11.30	1.96	8.69	8.69	2.00	8.53	8.53
Average(mSv)	0.07	0.45	0.39	0.09	0.36	0.32	0.09	0.36	0.32

(*)Exposure doses and the number of workers are subject to change due to the replacement of accumulated doses measured using PAD with monthly doses measured using an integrating dosimeter and the reflection of values for workers wearing only an integrating dosimeter (e.g., workers working only within a seismically isolated building).

(2)Combined Cumulative Effective Dose from April 2021 (Internal and External)
Effective dose (E) mSv	April 2021 - October 2021			April 2021 - November 2021			Difference
Effective dose (E) mSv	TEPCO	Contractors	Total	TEPCO	Contractors	Total	TEPCO	Contractors	Total
100<E	0	0	0	0	0	0	0	0	0
75<E≤100	0	0	0	0	0	0	0	0	0
50<E≤75	0	0	0	0	0	0	0	0	0
20<E≤50	0	0	0	0	0	0	0	0	0
10<E≤20	0	214	214	0	285	285	0	71	71
5<E≤10	17	612	629	25	666	691	8	54	62
1<E≤5	154	1850	2004	164	2062	2226	10	212	222
E≤1	1095	4726	5821	1116	4743	5859	21	17	38
Total	1266	7402	8668	1305	7756	9061	39	354	393
Maximum(mSv)	9.39	16.90	16.90	9.78	16.94	16.94	-	-	-
Average(mSv)	0.48	1.69	1.52	0.54	1.88	1.69	-	-	-

(*) Exposure doses and the number of workers are subject to change due to the replacement of accumulated doses measured using PAD with monthly doses measured using an integrating dosimeter and the reflection of values for workers wearing only an integrating dosimeter (e.g., workers working only within a seismically isolated building).

(3) Distribution of sum of external exposure dose and internal exposure dose of workers engaged in specified high-dose work*
(Specified high-dose work has not been performed since October 2015.)
Effective dose (E) mSv	March 2011- September 2015
100<E	1
75<E≤100	191
50<E≤75	233
20<E≤50	267
10<E≤20	186
5<E≤10	129
1<E≤5	145
E≤1	51
Total	1203
Maximum(mSv)	102.69
Average(mSv)	36.49

(As specified high-dose work has not been performed since October 2015, the table shows the data up to September 2015.)

(*): Workers engaged in work to which dose limit (100 mSv) during emergency work is applied in line with Article 7 of the Ordinance on Prevention of Ionizing Radiation Hazards.
Specifically, these workers are those who are engaged in work to maintain the functions of a nuclear reactor facility or spent fuel storage pool, or in work to maintain functions to suppress or prevent the possible release of a large amount of radioactive materials due to a failure of or damage to the nuclear reactor facility at a location around the nuclear reactor facility, steam turbine, or accessory facility where hourly dose may exceed 0.1 mSv.
It should be noted that only TEPCO employees have so far been engaged in specified high-dose work.
(*): Workers engaged in specified high-dose work in each month is the number of workers registered as workers engaged in specified high-dose work in that month.
However, the total of March 2011 to September 2015 includes workers released from specified high-dose work.
(*): Exposure doses and the number of workers are subject to change due to the replacement of accumulated doses measured using PAD with monthly doses measured using an integrating dosimeter and the reflection of values for workers wearing only an integrating dosimeter (e.g., workers working only within a seismically isolated building).
(*): The results of re-evaluating committed doses in March 2011 reveal that maximum cumulative effective doses for the period between March 2011 and September 2015 exceeded 100.