Feb 27, 2026 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPP

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

Updated on 27 Feb 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	November-2025			December-2025			January-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	0	0	0	0	0	0	1	1
5<E≤10	0	24	24	0	4	4	0	20	20
1<E≤5	7	379	386	19	319	338	3	290	293
E≤1	999	6753	7752	989	6935	7924	983	6790	7773
Total	1006	7156	8162	1008	7258	8266	986	7101	8087
Maximum(mSv)	1.60	7.70	7.70	3.00	5.70	5.70	1.52	10.79	10.79
Average(mSv)	0.06	0.24	0.21	0.08	0.19	0.18	0.06	0.19	0.17

(*)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 - December 2025			April 2021 - January 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	2	2	0	3	3	0	1	1
50<E≤75	0	191	191	0	194	194	0	3	3
20<E≤50	41	1579	1620	41	1592	1633	0	13	13
10<E≤20	88	2063	2151	90	2103	2193	2	40	42
5<E≤10	146	1882	2028	144	1887	2031	-2	5	3
1<E≤5	395	3025	3420	404	3052	3456	9	27	36
E≤1	1409	10039	11448	1405	10126	11531	-4	87	83
Total	2079	18781	20860	2084	18957	21041	5	176	181
Maximum(mSv)	43.32	76.27	76.27	43.59	76.80	76.80	-	-	-
Average(mSv)	2.21	5.94	5.57	2.23	5.95	5.59	-	-	-

(*) 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 - December 2025			April 2025 - January 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	359	359	0	422	422	0	63	63
5<E≤10	18	681	699	23	734	757	5	53	58
1<E≤5	117	1763	1880	127	1921	2048	10	158	168
E≤1	1258	6941	8199	1252	6951	8203	-6	10	4
Total	1393	9744	11137	1402	10028	11430	9	284	293
Maximum(mSv)	9.10	19.80	19.80	9.28	19.80	19.80	-	-	-
Average(mSv)	0.38	1.53	1.39	0.41	1.62	1.48	-	-	-

(*): 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.