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 28 Apr 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	January-2026			February-2026			March-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	6	6	0	1	1
5<E≤10	0	16	16	0	43	43	0	33	33
1<E≤5	3	277	280	15	422	437	21	569	590
E≤1	1001	6808	7809	992	6811	7803	1024	6680	7704
Total	1004	7101	8105	1007	7282	8289	1045	7283	8328
Maximum(mSv)	1.40	9.30	9.30	3.30	12.80	12.80	4.14	10.31	10.31
Average(mSv)	0.05	0.18	0.16	0.07	0.27	0.24	0.08	0.29	0.26

(*)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 - February 2026			April 2021 - March 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	3	3	0	4	4	0	1	1
50<E≤75	0	207	207	0	217	217	0	10	10
20<E≤50	42	1613	1655	44	1640	1684	2	27	29
10<E≤20	92	2135	2227	93	2158	2251	1	23	24
5<E≤10	142	1889	2031	139	1900	2039	-3	11	8
1<E≤5	411	3048	3459	413	3065	3478	2	17	19
E≤1	1405	10273	11678	1411	10366	11777	6	93	99
Total	2092	19168	21260	2100	19350	21450	8	182	190
Maximum(mSv)	44.52	76.77	76.77	44.99	77.87	77.87	-	-	-
Average(mSv)	2.25	5.99	5.62	2.29	6.04	5.67	-	-	-

(*) 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 - February 2026			April 2025 - March 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	524	524	1	641	642	1	117	118
5<E≤10	29	784	813	37	837	874	8	53	61
1<E≤5	130	1980	2110	132	2045	2177	2	65	67
E≤1	1254	7073	8327	1266	7071	8337	12	-2	10
Total	1413	10361	11774	1436	10594	12030	23	233	256
Maximum(mSv)	9.40	19.80	19.80	10.22	19.80	19.80	-	-	-
Average(mSv)	0.46	1.75	1.60	0.51	1.91	1.75	-	-	-

(*): 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.