Jan 30, 2026 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPP

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

Updated on 30 Jan 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	October-2025			November-2025			December-2025
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	52	52	0	24	24	0	10	10
1<E≤5	16	501	517	7	379	386	21	339	360
E≤1	999	6594	7593	999	6753	7752	987	6909	7896
Total	1015	7148	8163	1006	7156	8162	1008	7258	8266
Maximum(mSv)	4.40	10.20	10.20	1.60	7.70	7.70	2.83	6.34	6.34
Average(mSv)	0.08	0.30	0.28	0.06	0.24	0.21	0.08	0.19	0.18

(*)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 - November 2025			April 2021 - December 2025			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	1	1	0	2	2	0	1	1
50<E≤75	0	185	185	0	192	192	0	7	7
20<E≤50	41	1561	1602	41	1577	1618	0	16	16
10<E≤20	84	2052	2136	88	2068	2156	4	16	20
5<E≤10	149	1867	2016	146	1881	2027	-3	14	11
1<E≤5	385	3007	3392	399	3036	3435	14	29	43
E≤1	1418	9888	11306	1405	10025	11430	-13	137	124
Total	2077	18561	20638	2079	18781	20860	2	220	222
Maximum(mSv)	41.72	75.92	75.92	43.18	76.43	76.43	-	-	-
Average(mSv)	2.17	5.94	5.56	2.21	5.94	5.57	-	-	-

(*) 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) Combined Cumulative Effective Dose from April 2025
Effective dose (E) mSv	April 2025 - November 2025			April 2025 - December 2025			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	312	312	0	368	368	0	56	56
5<E≤10	11	614	625	19	684	703	8	70	78
1<E≤5	115	1659	1774	121	1790	1911	6	131	137
E≤1	1261	6830	8091	1253	6902	8155	-8	72	64
Total	1387	9415	10802	1393	9744	11137	6	329	335
Maximum(mSv)	8.30	19.80	19.80	9.05	19.80	19.80	-	-	-
Average(mSv)	0.32	1.44	1.30	0.38	1.53	1.39	-	-	-

(*): 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).

(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 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.
(*): 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.