Mar 31, 2026 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPP

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

Updated on 31 Mar 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	December-2025			January-2026			February-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	9	9
5<E≤10	0	4	4	0	16	16	0	45	45
1<E≤5	19	319	338	3	277	280	16	434	450
E≤1	989	6935	7924	1001	6808	7809	974	6794	7768
Total	1008	7258	8266	1004	7101	8105	990	7282	8272
Maximum(mSv)	3.00	5.70	5.70	1.40	9.30	9.30	3.64	14.28	14.28
Average(mSv)	0.08	0.19	0.18	0.05	0.18	0.16	0.08	0.28	0.25

(*)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 - January 2026			April 2021 - February 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	195	195	0	208	208	0	13	13
20<E≤50	41	1591	1632	42	1613	1655	1	22	23
10<E≤20	90	2102	2192	93	2142	2235	3	40	43
5<E≤10	144	1881	2025	141	1882	2023	-3	1	-2
1<E≤5	403	3041	3444	413	3065	3478	10	24	34
E≤1	1406	10145	11551	1403	10255	11658	-3	110	107
Total	2084	18957	21041	2092	19168	21260	8	211	219
Maximum(mSv)	43.62	76.67	76.67	44.45	76.85	76.85	-	-	-
Average(mSv)	2.23	5.95	5.58	2.26	5.99	5.62	-	-	-

(*) 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 - January 2026			April 2025 - February 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	415	415	0	537	537	0	122	122
5<E≤10	20	725	745	30	775	805	10	50	60
1<E≤5	125	1871	1996	133	2017	2150	8	146	154
E≤1	1257	7017	8274	1250	7032	8282	-7	15	8
Total	1402	10028	11430	1413	10361	11774	11	333	344
Maximum(mSv)	9.30	19.80	19.80	9.52	19.80	19.80	-	-	-
Average(mSv)	0.41	1.62	1.47	0.46	1.76	1.61	-	-	-

(*): 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.