Nov 28, 2025 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPP

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

Updated on 28 Nov 2025

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	August-2025			September-2025			October-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	0	0	0	0	0	0	2	2
5<E≤10	0	43	43	0	46	46	0	47	47
1<E≤5	1	318	319	8	353	361	16	504	520
E≤1	1038	6347	7385	1009	6443	7452	999	6595	7594
Total	1039	6708	7747	1017	6842	7859	1015	7148	8163
Maximum(mSv)	1.30	8.40	8.40	1.60	9.90	9.90	4.49	10.50	10.50
Average(mSv)	0.03	0.22	0.20	0.06	0.25	0.22	0.08	0.29	0.27

(*)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 - September 2025			April 2021 - October 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	1	1	0	0	0
50<E≤75	0	165	165	0	177	177	0	12	12
20<E≤50	39	1530	1569	39	1544	1583	0	14	14
10<E≤20	79	1999	2078	82	2034	2116	3	35	38
5<E≤10	150	1829	1979	151	1845	1996	1	16	17
1<E≤5	382	2974	3356	384	3010	3394	2	36	38
E≤1	1417	9687	11104	1417	9785	11202	0	98	98
Total	2067	18185	20252	2073	18396	20469	6	211	217
Maximum(mSv)	39.52	75.32	75.32	40.96	75.78	75.78	-	-	-
Average(mSv)	2.12	5.85	5.47	2.15	5.89	5.51	-	-	-

(*) 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 - September 2025			April 2025 - October 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	169	169	0	256	256	0	87	87
5<E≤10	2	436	438	7	525	532	5	89	94
1<E≤5	94	1396	1490	108	1595	1703	14	199	213
E≤1	1266	6726	7992	1260	6732	7992	-6	6	0
Total	1362	8727	10089	1375	9108	10483	13	381	394
Maximum(mSv)	5.90	19.60	19.60	7.99	19.77	19.77	-	-	-
Average(mSv)	0.23	1.11	0.99	0.28	1.30	1.16	-	-	-

(*): 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.