Sep 30, 2025 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPP

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

Updated on 30 Sep 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	June-2025			July-2025			August-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	0	0
5<E≤10	0	11	11	0	16	16	0	44	44
1<E≤5	1	391	392	9	424	433	2	329	331
E≤1	1042	6375	7417	927	6381	7308	987	6335	7322
Total	1043	6777	7820	936	6821	7757	989	6708	7697
Maximum(mSv)	1.10	7.10	7.10	2.10	7.50	7.50	1.33	8.22	8.22
Average(mSv)	0.05	0.22	0.20	0.06	0.24	0.22	0.03	0.22	0.20

(*)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 - July 2025			April 2021 - August 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	152	152	0	158	158	0	6	6
20<E≤50	39	1463	1502	39	1499	1538	0	36	36
10<E≤20	77	1992	2069	77	1986	2063	0	-6	-6
5<E≤10	139	1808	1947	143	1829	1972	4	21	25
1<E≤5	391	2956	3347	389	2972	3361	-2	16	14
E≤1	1389	9490	10879	1409	9575	10984	20	85	105
Total	2035	17861	19896	2057	18019	20076	22	158	180
Maximum(mSv)	39.32	73.72	73.72	39.49	74.71	74.71	-	-	-
Average(mSv)	2.11	5.77	5.40	2.10	5.81	5.43	-	-	-

(*) 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 - July 2025			April 2025 - August 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	53	53	0	95	95	0	42	42
5<E≤10	1	288	289	1	380	381	0	92	92
1<E≤5	61	1178	1239	76	1321	1397	15	143	158
E≤1	1225	6620	7845	1260	6634	7894	35	14	49
Total	1287	8139	9426	1337	8430	9767	50	291	341
Maximum(mSv)	5.80	13.60	13.60	5.83	14.44	14.44	-	-	-
Average(mSv)	0.17	0.80	0.72	0.19	0.95	0.85	-	-	-

(*): 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.