Jul 31, 2026 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPS

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

Updated on 31 Jul 2026

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	April-2026			May-2026			June-2026
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	9	9	0	0	0	0	0	0
5<E≤10	0	29	29	0	18	18	0	27	27
1<E≤5	9	300	309	9	339	348	12	408	420
E≤1	1028	6737	7765	981	6527	7508	1046	6751	7797
Total	1037	7075	8112	990	6884	7874	1058	7186	8244
Maximum(mSv)	2.80	12.80	12.80	2.40	8.40	8.40	2.78	7.22	7.22
Average(mSv)	0.06	0.20	0.18	0.04	0.19	0.18	0.07	0.23	0.21

(*) 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 2026 (Internal and External)
Effective dose (E) mSv	April 2026 - May 2026			April 2026 - June 2026			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	11	11	0	22	22	0	11	11
5<E≤10	1	77	78	1	176	177	0	99	99
1<E≤5	19	631	650	42	857	899	23	226	249
E≤1	1116	6987	8103	1215	7229	8444	99	242	341
Total	1136	7706	8842	1258	8284	9542	122	578	700
Maximum(mSv)	5.20	13.80	13.80	5.21	13.80	13.80	-	-	-
Average(mSv)	0.09	0.36	0.32	0.14	0.53	0.48	-	-	-

Same as the table in (2).

(4) Distribution of sum of external exposure dose and internal exposure dose of workers engaged in specified high-dose work (Effective Dose)
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 Regulation 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.
(*): The number of workers engaged in specified high-dose work is that of workers who were registered as such at least once during the period between March 2011 and September 2015.
(*): 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.