Jun 26, 2026 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPS

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

Updated on 26 Jun 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	March-2026			April-2026			May-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	9	9	0	0	0
5<E≤10	0	32	32	0	29	29	0	14	14
1<E≤5	19	547	566	9	300	309	9	343	352
E≤1	1026	6704	7730	1028	6737	7765	962	6527	7489
Total	1045	7283	8328	1037	7075	8112	971	6884	7855
Maximum(mSv)	4.30	9.20	9.20	2.80	12.80	12.80	2.28	7.26	7.26
Average(mSv)	0.08	0.28	0.26	0.06	0.20	0.18	0.05	0.19	0.17

(*) 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 2026 (Internal and External)
Effective dose (E) mSv	April-2026			April 2026 - May 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	9	9	0	11	11	0	2	2
5<E≤10	0	29	29	1	71	72	1	42	43
1<E≤5	9	300	309	19	656	675	10	356	366
E≤1	1028	6737	7765	1113	6968	8081	85	231	316
Total	1037	7075	8112	1133	7706	8839	96	631	727
Maximum(mSv)	2.80	12.80	12.80	5.08	13.34	13.34	-	-	-
Average(mSv)	0.06	0.20	0.18	0.09	0.35	0.32	-	-	-

Same as the table in (2).

(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 Regulation 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.