August 31, 2022 | Status of Radiation Exposure | TEPCO Fukushima Daiichi NPP

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

Updated on 31 Aug 2022

1. 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	May-2022			June-2022			July-2022
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	0	0	0	14	14	0	18	18
1<E≤5	10	340	350	29	612	641	15	505	520
E≤1	980	5347	6327	1045	5431	6476	992	5583	6575
Total	990	5687	6677	1074	6057	7131	1007	6106	7113
Maximum(mSv)	2.78	4.90	4.90	2.27	7.40	7.40	4.37	9.44	9.44
Average(mSv)	0.08	0.24	0.22	0.10	0.36	0.33	0.09	0.30	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 - June 2022			April 2021 - July 2022			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	57	57	0	106	106	0	49	49
10<E≤20	23	1008	1031	28	1058	1086	5	50	55
5<E≤10	71	999	1070	71	1012	1083	0	13	13
1<E≤5	244	2298	2542	250	2348	2598	6	50	56
E≤1	1110	5272	6382	1131	5398	6529	21	126	147
Total	1448	9634	11082	1480	9922	11402	32	288	320
Maximum(mSv)	16.84	24.22	24.22	17.13	25.93	25.93	-	-	-
Average(mSv)	1.04	3.06	2.79	1.07	3.16	2.89	-	-	-

(*) 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 2022
Effective dose (E) mSv	April 2022 - June 2022			April 2022 - July 2022			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	0	0	0	9	9	0	9	9
5<E≤10	2	162	164	3	329	332	1	167	168
1<E≤5	102	1249	1351	128	1494	1622	26	245	271
E≤1	1112	5473	6585	1134	5530	6664	22	57	79
Total	1216	6884	8100	1265	7362	8627	49	478	527
Maximum(mSv)	7.06	9.40	9.40	7.31	12.21	12.21	-	-	-
Average(mSv)	0.28	0.75	0.68	0.34	0.95	0.86	-	-	-

(*): Exposure doses and the number of workers are subject to change due to the replacement of accumulated dosesmeasured 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*
(Specified high-dose work has not been performed since October 2015.)
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.
(*): Workers engaged in specified high-dose work in each month is the number of workers registered as workers engaged in specified high-dose work in that month.
However, the total of March 2011 to September 2015 includes workers released from specified high-dose work.
(*): 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.