Dec 26, 2025 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPP

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

Updated on 26 Dec 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	September-2025			October-2025			November-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	1	1	0	0	0
5<E≤10	0	46	46	0	52	52	0	31	31
1<E≤5	8	353	361	16	501	517	9	388	397
E≤1	1009	6443	7452	999	6594	7593	997	6737	7734
Total	1017	6842	7859	1015	7148	8163	1006	7156	8162
Maximum(mSv)	1.60	9.90	9.90	4.40	10.20	10.20	1.68	8.45	8.45
Average(mSv)	0.06	0.25	0.22	0.08	0.30	0.28	0.07	0.24	0.22

(*)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 - October 2025			April 2021 - November 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	177	177	0	185	185	0	8	8
20<E≤50	39	1548	1587	41	1563	1604	2	15	17
10<E≤20	82	2026	2108	85	2055	2140	3	29	32
5<E≤10	151	1849	2000	149	1867	2016	-2	18	16
1<E≤5	381	3000	3381	389	3020	3409	8	20	28
E≤1	1420	9795	11215	1413	9870	11283	-7	75	68
Total	2073	18396	20469	2077	18561	20638	4	165	169
Maximum(mSv)	41.12	75.82	75.82	41.67	75.91	75.91	-	-	-
Average(mSv)	2.15	5.90	5.52	2.18	5.94	5.56	-	-	-

(*) 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 - October 2025			April 2025 - November 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	254	254	0	323	323	0	69	69
5<E≤10	5	532	537	13	607	620	8	75	83
1<E≤5	107	1555	1662	118	1715	1833	11	160	171
E≤1	1263	6767	8030	1256	6770	8026	-7	3	-4
Total	1375	9108	10483	1387	9415	10802	12	307	319
Maximum(mSv)	7.90	19.80	19.80	8.32	19.80	19.80	-	-	-
Average(mSv)	0.28	1.30	1.17	0.33	1.44	1.30	-	-	-

(*): 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.