Outline of Offshore Marin Survey
Offshore Marin Survey○SampleCoastal Marin Survey

・Seawater・Fish・Plankton○Nuclides to measure○Sample・Radioactive Cesium ・Strontium90 ・Tritium

・Seawater○Nuclides to measure○Sampling Site

Soma Port

・4 sites in 1.5 km offshore of the Fukushima Daiichi NPP(Point A, B, C and D)
・If no fish can be caught above the sites, the skipper
may change locations to fish.
Fukushima
Daiichi Nuclear
Power Plant

Point D

Point B

Point A

○Sampling Site

Rockfish, Chubmackerel, Green
ling

Point C
Greenling, Fox jacopever,White-edged rockfish,
Saddled brown rockfish

・Radioactive Cesium ・Strontium90 ・Tritium

Fukushima Daiichi
Nuclear Power Plant

・From Soma Port to Onahama Port, Twice a year
・Soma Port
Kaibama Beach・Kaibama, Murakami Beach
・Ukedo Port・Futaba Beach
Ukedo Port・Kumagawa CoastMarin House Futaba
・Tomioka Port
Kumagawa Coast・Iwasawa BeachTomioka Port・Onahama Port
Hirono Thermal Power Station〇Sampling Seawater
Seawater and fish sampling sites for the marine survey in May 2022

〇 Sampling Seawater・Seawater is collected from 2 depths (from the surface and the lower layer)
・The surface layer is collected using a bucket, and the lower layer is collectedwith a van dornwater sampler. (For cesium = 20 L, for strontium = 20 L, for tritium = 2 L)

〇Sampling Fish・Obtain fish by fishing.
・Ichthyology researcher collects blood from the fish on board.

〇 Sampling Plankton
・Pump seawater by the ship's large-capacity pump and pass it through aplankton net to collect.

Onahama Port・Sample seawater from the surface.
・Collect it with a bucket.
For Cesium = 20L, for Strontium = 20L,
for Tritium = 2L

Offshore Marine Survey

Measurement Results: Radioactive Cesium-137 in Seawater and Fish・Measurement data of radioactive cesium-137 in seawater and fish sampled from 1.5km offshore of Fukushima Daiichi Nuclear Power
Plant in November 2022, May/August 2023 and May 2024.
・Radioactive cesium is removed from 20L of seawater by adsorption on ammonium molybdophosphate before measurement.
・Cs-137 is detected in most of the fish sample collected.
Cs-137 Measurement Results in Seawater (Bq/L)
Point A
Surface

Point A
Lower

Point B
Surface

Point B
Lower

Point C
Surface

Point C
Lower

Point D
Surface

Point D
Lower

Tomioka Port
Surface2022/11/9

0.004±0.0005

0.004±0.0006

0.003±0.0005

0.003±0.0005

0.002±0.0005

0.003±0.0005

0.005±0.0006

0.003±0.0005

0.012±0.0007

2023/5/31

0.003±0.0005

0.003±0.0005

0.004±0.0005

0.005±0.0005

0.004±0.0006

0.003±0.0005

0.004±0.0005

0.003±0.0006

0.01±0.0007

2023/8/2

0.002±0.0005

0.008±0.001

0.003±0.0005

0.003±0.0006

0.003±0.0005

0.003±0.0005

0.003±0.0005

0.004±0.0006

0.008±0.0006

2024/3/5

0.004±0.0005

0.005±0.0005

0.004±0.0005

0.004±0.0005

0.003±0.0005

0.004±0.0005

0.024±0.0008

0.020±0.0007

0.063±0.001

Cs-137 Measurement Results in Fish (Bq/kg raw)
2022/11/9

2023/8/2

2023/5/31

2024/3/5

Red sea bream

1.0±0.1

Goldeye rockfish

1.3±0.1

Shark

1.7±0.1

Crimsonseabream

0.4±0.1

Flounder0.9±0.04

Blowfish0.7±0.1

Flounder0.9±0.1

Roundnoseflounder0.3±0.1

Blowfish1.3±0.1

White rockfish

1.0±0.1

Black sebastes

0.3±0.1

Goldeye rockfish

1.2±0.1

White rockfish

1.8±0.1

White rockfish

1.4±0.1

White rockfish

0.7±0.05

White rockfish

1.0±0.07

Greenling

0.9±0.1

Fox jacopever

0.3±0.1

Fox jacopever

0.4±0.05

Greenling

1.1±0.06

Offshore Marine Survey

Measurement Results: Strontium-90 in Seawater and Fish・Measurement data of Strontium-90 in seawater and fish sampled from 1.5km offshore of Fukushima Daiichi Nuclear Power Plant inNovember 2022 and May/August 2023.
・Strontium-90 was detected in the different points depending on the sampling date.
・For fish, analysis was performed mainly on the head and bones.
Sr-90 Measurement Results in Seawater (Bq/L)
Point A
Surface

Point A
Lower

Point B
Surface

Point B
Lower

Point C
Surface

Point C
Lower

Point D
Surface

Point D
Lower

Tomioka Port
Surface2022/11/9

0.001±0.0003

0.0008±0.0003

0.0015±0.0003

0.0012±0.0003

0.0019±0.0004

0.0011±0.0004

0.001±0.0003

0.0012±0.0003

0.0008±0.0003

2023/5/31

0.0005±0.0003

0.0006±0.0003

0.0009±0.0003

0.0006±0.0003

0.0008±0.0003

0.0009±0.0003

0.0009±0.0004

ND＜0.0005

0.0005±0.0002

2023/8/2

0.0005±0.0003

ND＜0.0004

ND＜0.0004

0.0007±0.0003

ND＜0.0004

ND＜0.0004

ND＜0.0004

ND＜0.0004

0.0005±0.0003

Sr-90 Measurement Results in Fish (Bq/kg dry)
2022/11/9

2023/5/31

2023/8/2

White rockfish

ND＜0.14White rockfish

ND＜0.13

FlounderND＜0.14FlounderND＜0.1

BlowfishND＜0.60

Black sebastes

ND＜0.12Red sea bream

ND＜0.12White rockfish

0.46±0.13

White rockfish

ND＜0.25

Greenling

ND＜0.11Fox jacopever

ND＜0.12

Offshore Marine Survey

Measurement Results: Tritium in Seawater and Fish・Measurement data of Tritium in seawater and fish sampled from 1.5km offshore of Fukushima Daiichi Nuclear Power Plant in
May and August and November 2022 and May 2023.
・From August 2022 we started using liquid scintillation counters specialized to measure tritium, which allowed us to lower thedetection limit.
・Free-water Tritium and Organically Bound Tritium in fish was not detected (ND) at this stage.

Tritium Measurement Results in Seawater (Bq/L)
Point A
Surface

Point A
Lower

Point B
Surface

Point B
Lower

Point C
Surface

Point C
Lower

Point D
Surface

Point D
Lower

Tomioka Port
Surface2022/5/10

ND<0.11

ND<0.11

ND<0.11

ND<0.12

ND<0.11

ND<0.11

ND<0.11

ND<0.12

ND<0.112022/8/24

ND<0.04

ND<0.04

ND<0.04

ND<0.04

ND<0.04

ND<0.05

ND<0.05

ND<0.05

ND<0.052022/11/9

ND<0.04

ND<0.05

ND<0.05

ND<0.04

ND<0.04

ND<0.04

ND<0.04

ND<0.04

ND<0.04

2023/5/31

ND<0.04

ND<0.04

0.05±0.04

0.05±0.04

ND<0.04

ND<0.04

ND<0.04

ND<0.04

ND<0.04

Free-water Tritium Measurement Results in Fish (Bq/L )Organically Bound Tritium Measurement Results in Fish (Bq/kg raw)
2022/52023/82022/5White rockfish

ND＜0.37

FlounderND＜0.34

White rockfish

ND＜0.09

White rockfish

ND＜0.37

Black sebastes

ND＜0.35

Fox jacopever

ND＜0.09

White rockfish

ND＜0.37

Greenling

ND＜0.36

FlounderND＜0.09

Fox jacopever

ND＜0.36

Black sebastes

ND＜0.092023/8

Coastal Marine Survey Measurement Results for Seawater・Seawater measurement data of Fukushima coast.
・Concentrations of radioactive cesium tend to be higher at points closer to the nuclear power plant.
・Strontium-90 in seawater was detected at different sampling sites depending on the date of sampling.
・Tritium was also detected, but at the stage before the contaminated water was discharged, there was no significant difference
from the normal seawater concentration.
Cs-137 Measurement Results in Seawater (Bq/L) North

South

Soma Port

Murakami Beach

Ukedo Port

Futaba Beach

Kumagawa Coast

Tomioka Port

Iwasawa BeachOnahama Port

2023/5,6

0.005±0.0006

0.005±0.0005

0.01±0.0007

0.004±0.0006

0.02±0.0008

0.01±0.0007

0.008±0.0006

0.001±0.0006

2023/120.007±0.0006

0.005±0.0005

0.009±0.0006

0.012±0.0006

0.013±0.0004

0.010±0.0007

0.006±0.0006

0.003±0.0005

Sr-90 Measurement Results in Seawater (Bq/L)
Soma Port

Murakami Beach

Ukedo Port

Futaba Beach

Kumagawa Coast

Tomioka Port

Iwasawa BeachOnahama Port

2023/5,6

0.0011±0.0003

0.0005±0.0003

0.0012±0.0003

0.0009±0.0003

0.0006±0.0003

0.0005±0.0002

0.001±0.0003

0.001±0.0003

2023/12

ND<0.0003

ND<0.0008

ND<0.0008

0.0011±0.0003

0.0006±0.0003

0.0008±0.0003

ND<0.0003

ND<0.0005

Tritium Measurement Results in Seawater (Bq/L)
Soma Port

Kaibama Beach

Ukedo Port

Futaba Beach

Kumagawa Coast

Tomioka Port

Iwasawa BeachOnahama Port

2022/12

ND<0.04

ND<0.04

ND<0.04

0.07±0.04

ND<0.04

ND<0.04

0.05±0.04

Missing data

2023/50.06±0.04

0.06±0.04

0.09±0.04

ND<0.04

ND<0.04

ND<0.04

ND<0.04

Missing dataMeasuring Radiation levels in Ookuma Town
TARACHINE conducted surveys on environmental radioactivity in Ookuma Town in the fall of 2022.
NPO Mothers’ Radiation Lab Fukushima – TARACHINE

https://tarachineiwaki.org/【Reason for the Surveys】◼ The evacuation order for the designated 860-hectare reconstruction and revitalization zone was lifted, and the standard value for returning home was set 20
millisieverts (mSv) as an annual dose limit. This standard value is the upper value recommended by International Commission on Radiological Protection (ICRP)[*]. This means the standard value for the general population of Okuma including children and annual exposure limit for the nuclear industry workers are
the same.
◼ “Manabiya Yumenomori” (a comprehensive school for 0~15year-olds) will be opened in Okuma Town. It’s expected health concerns will arise in the future as
children will be studying and living under such high radiation levels permitted as 20 mSv/y. We believe it’s important to know the correct values of radiationlevels in the environment in order to protect ourselves from the radiation exposure scientifically.
[*] ICRP recommended in 2007 that in the event of large-scale radioactive contamination due to a nuclear power plant accident, the standard value should be adopted from 【 thelower values of 1 to 20 mSv/y】, to protect the people living in the contaminated area. However, 【 the uppermost value of 1-20 mSv/y】was adopted.

【 The background and reason why 20 mSv was set as the annual dose reference level for Ookuma Town】
Previously, the reference value was 1 mSv/y, or 0.23 microsieverts per hour (μSv/h). Decontamination measures were implemented accordingly. However, due tosubsequent media reports and the indifference of the town residents, 20 mSv/y , or 3.8 μSv/h seemed to be accepted as the reference value which is on par with
the nuclear power plant premises. It’s obviously abnormal that the reference value for the area where children live, learn, and play.
＊From the minutes of the Okuma Town Decontamination Investigation Committee ＊◼ “For the areas such as Oogawara and Nakayashiki where evacuation order was lifted, I think we’d been basically considering things with 0.23μSv/h as the base.
But this time around 3.8μSv/h is set as the base, there are still some areas remained with a radiation dose of 2 ~ 3 μSv/h. The decontamination work is said tobe done, even though the dose is still high this time. The standards for around here are quite different from that of the areas the evacuation order had alreadybeen lifted.”◼ " We had been discussing about 1mSv, or 0.23μSv/h for the decontamination work in Oogawara area, when I first heard that it has become 20mSv, or 3.8μSv/h,
I thought 'Huh? However, after that, the media kept reporting 3.8μSv/h was the standard, so the residents probably had that image, I think the previous
standard of 0.23μSv/h or 1mSv has been diminishing in our mind.”【 Regarding Air Dose Standards 】
Air Dose

Annual Exposure Dose(μSv/h)(mSv/y)Annual dose limit for the general public

0.23

1.00

Criteria for Terminating Evacuation Order of Okuma Town

3.80

19.76

General dose before the nuclear accident

0.04

0.00

Onahama Yokomahi Park, Iwaki City as of 2023

0.06

0.11

Fukushima Railway Station West Exit “Corasse Hiroba” as of 2023

0.12

0.42

The annual exposure dose is calculated assuming 8 hours spent outdoors and 16 hours spent indoors per day. The assumption was madethat radiation would be reduced by 60% indoor. The values do not include natural background radiation.

【 Regarding Dose standards in Soil 】
Clearance criteria

Designated Waste (after the nuclear accident)

Values that were considered unnecessary to Values that must be handled in an appropriate Values that need to be disposed of at a disposal site with atreat as radioactive wastemanner under the governmental responsibility

stricter shielding structure

Unit: Radioactive Cesium Concentration (Bq/kg)

Less than 100

More than 8,000

More than 100,000

【 Survey Method 】◼ Using Nippon Shahei Giken's "GPS-linked air dose rate automatic recording system, Hot Spot Finder", we carried out measuring at a point 1 m above theground.
◼ Detail measurement of the soil. Collecting 5 cm of top soil from the ground surface and dried it, and the concentration of radioactive cesium was measured.
Strontium-90 was measured in the half of the 12 locations. In addition, the air dose rate of the ground surface at those locations were also measured.

◼ The survey points were not special hotspots such as under rain gutters or deep in the forests where people wouldn’t usually go in, but the
points were roadside and shrubbery where there is a good possibility that children would walk or stay in their daily lives.
【 Consideration on TARACHINE’s Measuring Survey Results 】
We detected over 8,000 Bq/kg radioactive cesium in the soil at 19 out of 24 locations, and 6 locations out of them exceeded 50,000 Bq/kg.
Furthermore, over 100,000 Bq/kg was detected in 3 locations.
The highest radiation dose was 200,818 Bq/kg in the hill behind the planned construction site for the school “Manabiya Yume no mori" in the
Oogawara area.
As for cesium levels in the soil, the result shows there are observation points with highly contaminated soil and also with less contaminated soil inboth Oogawara area and the designated reconstruction and revitalization zone. We collected samples from several locations that were thought tohave been decontaminated by stripping or adding soil, however, all but one location exceeded thousands of Bq/kg.

On the other hand, the air dose rate on the ground surface exceeded 3.8 μSv/h at 5 out of 24 locations.
We were unable to find such spots by the vehicle-borne survey.
We’d like to emphasis that these surveys were not aimed at particularly concentrated hotspots.
It is noteworthy that several thousands to several hundreds of thousands of contaminated soils still remains in the places such as the hills behindthe school and the rice paddies of Oogawara Minaidaira area where children pass by to go to school or play around.

Ookuma Town
Futaba District■ Sampling Points of Measuring Soil
The sampling points were not known hotspots such as under rain gutters or deep in the forests where people don’t usually go in,
but the points were along roadside and shrubbery where there was a good possibility children would walk or stay intheir daily lives.

②Shimonogami Area
①Shimonogami Area

・Drugstore Tsuruha
・Futaba Shoyo High School・Former Ohno Hospital
・Ookuma Town Elementary
School・Nexus Farm Ookuma(strawberry)・Around Ohno Station
・Ohno Junior High School・Former Ohno Hospital
・Ookuma Town Library, Futaba District

Oogawara Area
・Around Okuma Town Hall

Ookuma Town Kuma
・Around Asahidai
・Highway 6
・Highway 251

Air dose measured 1m above soil surface Measured with a hotspot finder (unit: μSv/h)① Air dose on the ground surface Measured with a survey meter (unit: μSv/h)② Soil: Total Value of Cs-137and Cs-134 Measured with a germanium semiconductor detector (unit: Bq/kg dry)
③ Soil: Strontium-90 Measured with a liquid scintillation counter (unit: Bq/kg dry)

Surveyin November and December 2022
Around Okuma Town Hall3
1

2

①1.00 μSｖ/ｈ②11,528 ㏃/㎏①0.31 μSｖ/ｈ②3,772 ㏃/㎏①0.13 μSｖ/ｈ②191 ㏃/㎏

5①1.07 μSｖ/ｈ②15,440 ㏃/㎏

7①2.55 μSｖ/ｈ②32,451 ㏃/㎏
③7.87
㏃/㎏

OokumaTown Hall

Planned construction
site for ”Manabiya
Yumenomori” school8①1.35 μSｖ/ｈ②19,644 ㏃/㎏
③6.37
㏃/㎏
①4.20 μSｖ/ｈ②200,818 ㏃/㎏③23.22 ㏃/㎏

4①6.23 μSｖ/ｈ②63,728 ㏃/㎏
③8.59
㏃/㎏

６

12

①3.04 μSｖ/ｈ②47,710 ㏃/㎏③5.41 ㏃/㎏

Surveyin November andDecember 2022

11

①4.18 μSｖ/ｈ②3,384 ㏃/㎏

Shimonogami①
Okuma Town

13

①1.04 μSｖ/ｈ②6,984 ㏃/㎏①2.75 μSｖ/ｈ②49,523 ㏃/㎏③2.66 ㏃/㎏

10
Air dose measured 1m above
soil surface
Measured with a hotspot
finder (unit: μSv/h)

JR OhnoSation① Air dose on the groundsurface Measured with asurvey meter (unit: μSv/h)

9
14①2.44 μSｖ/ｈ②101,372 ㏃/㎏③11.74 ㏃/㎏①2.96 μSｖ/ｈ②27,795 ㏃/㎏② Soil: Total Value of Cs137and Cs-134 Measured
with a germanium
semiconductor detector(unit: Bq/kg dry)
③ Soil: Strontium-90
Measured with a liquid
scintillation counter (unit:
Bq/kg dry)

Surveyin November andDecember 202218

Shimonogami②
Okuma Town

OokumaInterchange①1.83 μSｖ/ｈ②24,206 ㏃/㎏③2.73 ㏃/㎏

17

Air dose measured 1m above
soil surface
Measured with a hotspot
finder (unit: μSv/h)①2.70 μSｖ/ｈ②23,741 ㏃/㎏③ND<1.51① Air dose on the groundsurface Measured with asurvey meter (unit: μSv/h)② Soil: Total Value of Cs137and Cs-134 Measured
with a germanium
semiconductor detector(unit: Bq/kg dry)

①0.38 μSｖ/ｈ②8,792 ㏃/㎏
1916③ Soil: Strontium-90
Measured with a liquid
scintillation counter (unit:
Bq/kg dry)

①0.74 μSｖ/ｈ②10,981 ㏃/㎏

15①2.22 μSｖ/ｈ②56,620 ㏃/㎏③5.19 ㏃/㎏

Air dose measured 1m above soil surface Measured with a hotspot finder (unit: μSv/h)① Air dose on the ground surface Measured with a survey meter (unit: μSv/h)② Soil: Total Value of Cs-137and Cs-134 Measured with a germanium semiconductor detector (unit: Bq/kg dry)
③ Soil: Strontium-90 Measured with a liquid scintillation counter (unit: Bq/kg dry)

Surveyin November and December 2022
Around Kuma, Ookuma Town

21

23
①2.21 μSｖ/ｈ②8,874 ㏃/㎏①1.23 μSｖ/ｈ②19,477 ㏃/㎏

22①1.15 μSｖ/ｈ②4,354 ㏃/㎏①5.00 μSｖ/ｈ②150,490 ㏃/㎏③20.82 ㏃/㎏
2420①3.85 μSｖ/ｈ②57,460 ㏃/㎏③7.04 ㏃/㎏

Area

Oogawara
Area

Shimonogami
Area①

Shimonogami
Area②

OokumaKuma
neighborhood

CesiumStrontium-90

Air Dose Rates(uSv/h)Total of 137 and 134(Bq/kg-dry)①Wooded area in Oogawara Minamidaira

1.00

11,528②Near Ookuma Post Office

0.31

3,772

③Near Oogawara Minamidaira Garbage Dump

0.13

191

④The mountain behind Manabiya
Yumenomori school⑤North side of Oogawara Minamidaira ricefield
⑥South side of Oogawara Minamidaira rice
field

4.29

200,818

23.22

2.55

32,451

7.87

6.16

63,728

8.59⑦Behind the Ookuma Town Office

1.07

15,440⑧Forest southeast of Ookuma Town Hall

1.35

19,644⑨Across from Former Ono Junior High School

2.96

27,795⑩In front of Shotoku Taishi Hall

2.75

49,523⑪North side of former Ono Hospital

4.18

3,384

⑫West side of former Ono Hospital

3.04

47,710⑬South side of former Ono Hospital

1.04

6,984

⑭Shrubbery in front of Ookuma Library

2.44

101,372

11.74⑮In front of Tsuruha drug store

2.22

56,620

5.19⑯Near Futaba Shoyo High School

0.74

10,981⑰Near former Ono Elementary School

2.70

23,742

ND<1.51⑱Shimonogami, near the newly built garage

1.83

24,206

2.73⑲Near the strawberry factory

0.38

8,792

⑳Near the Highway 6 Central Storage Center

3.85

57,460㉑Hill behind Tokyo Power Technology

2.21

8,874

㉒Next to Asahidai Sekisui Heim

1.15

4,354

㉓West side of Joban Line, next to Asahidai
private house

1.23

19,477㉔Field next to Prefectural road 251

5.00

150,490

Sampling Site

(Bq/㎏-dry)

List of Measurement Results
Ookuma Town, Futaba District,
Fukushima Prefecture
Environmental Radioactivity
Survey

6.37
2.66
5.41

7.04

20.82

List of Measurement Results