Fukumoni
We will tell you about the current state ofradiation in Fukushima Prefecture

Fukushima
PrefectureIntroduction radiation/radioactivity?

Introduction

What is

The Great East Japan Earthquake, which occurred on March 11, 2011 severely
damaged the TEPCO Fukushima Daiichi Nuclear Power Station due to onslaught of alarge tsunami that accompanied the earthquake. As a result, the fuel could not becooled, and hydrogen, a flammable gas, which was generated, produced an explosion
releasing radioactive substances, such as cesium and iodine, into the atmosphere.
Fukushima Prefecture monitored environmental radiation before the Great East
Japan Earthquake. After the earthquake, we have additionally installed measurement
equipment, such as monitoring posts, added measurement points, and expanded themeasurement area to enhance and strengthen our monitoring system.

What is radiation/radioactivity?
Heat/light = Radiation (Particles andelectromagnetic waves emitted fromradioactive substances)
Fire = Radioactivity (Ability
to emit radiation)

What are radiation,
radioactivity, andradioactive substances?
Let's imagine them as a“campfire.”

Firewood = Radioactive
substance(Substance with theability to emit radiation(radioactivity))

Unit

If you compare these units of radiation to boxing .…
● Becquerel = The number of punches● Gray = The power of punch● Sievert = Body damage caused by punch

1＝0.001Sv
1mSv＝

Becquerel (Bq)
→A unit that expresses the level of the ability of radioactive
substances to emit radiation (radioactivity)
Gray (Gy)→A unit that expresses how much radiation energy isabsorbed by a substance
Sievert (Sv)
→A unit that expresses the impact on human body when
exposed to radiation

1,000μ S v

1mSv is 1,000 times more than 1μSv

What is the half-life of a radioactive substance?
What isradiation/radioactivity?

Radioactive materials emit radiation, which
gradually weakens and becomes weaker
until it finally emits no radiation.
The period it takes for the radioactivity
to halve (reduce by 50%) is called the“half-life.”
Half-life varies depending on the type ofradioactive substance. It can be about
eight days for iodine-131, two years for“BOOKLET to Provide Basic Information Regarding Health Effects
cesium-134, and 30 years for cesium-137. Source:of Radiation (2021 Edition) ” (The Ministry of the Environment)

Can radiation pass through things?
Radiation has the power to pass through objects;
this is known as penetrating power. There arevarious kinds of radiation, such as α (alpha)particles , β (beta) particles, γ (gamma) rays, X
rays, and neutron beams, and each one has adifferent level of penetrating power.
Alpha particles, the one with the weakest
penetrating power, won’t even pass through a sheetof paper, while it takes something like water orconcrete to weaken neutron beams, the one with thestrongest penetrating power.
Source: “BOOKLET to Provide Basic Information Regarding Health
Tritium emits β (beta) particles, but their energy is Effects of Radiation (2021 Edition)” (The Ministry of the Environment)
small, and won’t even pass through a sheet of paper.

How are we exposed to radiation?
Radiation originally exists in nature and is notunique to nuclear power plants or hospitals.
There are two types of radiation that we receivefrom our surroundings: “natural radiation” and“artificial radiation.”
Natural radiation refers to radiation received
from space, air, the ground, food, and so on. In
Japan,people are exposed to 2.1mSv ofradiation on average annually (World average:
2.4mSv per year).
The higher levels of radiation contained inJapanese food compared to the world averageis related to high consumption of fish, whichcontain a lot of natural radionuclides.
Artificial radiation refers to the radiation received from abdominal (stomach, intestines,etc.) X-ray examinations, CT scans, and cancer treatments. The figure shows that, inJapan’s population, the main contributor to radiation exposure comes from medical
examinations and treatments, and this is related to Japan’s long life expectancy andextensive medical care.
※ Radiation exposure refers to being exposed to radiation.

2

Monitoring of radiation in the environment
in Fukushima Prefecture
Fukushima Prefecture measures the air dose rate ※, analyzes radioactive substances
contained in environmental samples (air, water, soil, etc.) and publishes the measurement
results to ensure the safety and security of everyone concerned.

Monitoring of radiation in theenvironment in Fukushima Prefecture

Monitoring the areas around thepower plants

Prefecture-wide monitoring

Fukushima Prefecture monitors
the types, locations and levels ofradioactive substances in theenvironment that came from
nuclear power plants in the area.

Fukushima Prefecture monitors
various parts of the prefecture tokeep track of the trends incontamination caused by the
nuclear accident.

1 Monitoring of radiationin the environment
Measurement ofenvironmental samples

We analyze radioactive substances contained in environmental samples,such as air, water and soil collected in the prefecture.

Measurement of air
dose rate● Station-type monitoringpost
To monitor the radioactive substances newly released
into the environment from the nuclear power plants, wehave installed 42 monitoring posts in the areas withinapproximately 30 km from the nuclear power plants.

2 Monitoring, analysis, evaluationand confirmation of data

● Monitoring and analysis
Fukushima Prefectural Centre for Environment
Creation (FPCEC) constantly monitors the air dose rate,
and analyzes the collected and accumulated
environmental radiation data.

● Evaluation and confirmation
Fukushima Prefecture has set up an “Environment
Monitoring Evaluation Subcommittee” to evaluate themonitoring data collected from around the nuclear
power plants. The subcommittee is composed ofexperts in radiation management, environmental
radioactivity and water resources studies, and themembers from national, prefectural, and municipal
governments who meet on a quarterly basis.

Measurement of air
dose rate● Real-time dosimetry system
In order to monitor air radiation
dosage rates in areas wherechildren gather, 2,900 units
have been installed in schools,
nurseries and other locations
across the prefecture.

● Portable monitoring post
We installed approximately 570
units in public facilities in theprefecture to grasp changes in theradiation level in the air.

● Mobile monitoring
We use survey meters to measure the air radiationdose rate in places where many people gather, such as
tourist spots and meeting places.

● Car-borne survey
We installed radiation measuring devices in cars tomeasure the dose of radiation in the air along the driving
route. We also installed the radiation measuring devices
in some fixed-route buses for ease of radiation
measurements.

3 Publication of data

● Fukushima Prefecture website

See page 11● Fukushima Prefecture Radioactivity Measurement Map, etc.

3

※ Air radiation dosage rate: Air radiation dosage is the amount (strength) of radiation in the air.
This includes gamma radiation from the ground, cosmic radiation, etc.
The air radiation dosage per unit of time (years, months, weeks, days,etc.) measured in a certain airspace is called the air radiation dosage rate.

Changes in air radiation dosage rate in
Fukushima Prefecture
The air radiation dosage rate in Fukushima Prefecture has decreased
significantly from that as of April 2011.
April, 2011

Changes in air radiation dosage rate
in Fukushima Prefecture

Created based on “Basic Map Information (Digital Elevation Model)”,(The Geographical Survey Institute) and “National Land Numerical Information (Administrative
Areas, Roads)” (The Ministry of Land, Infrastructure, Transport and Tourism National Land
Policy Bureau)

April ~ May,2023

Created based on the “Basic Map Information (Digital Elevation Model)”,(The Geographical Survey Institute) and “National Land Numerical Information (Administrative
Areas, Roads)” (The Ministry of Land, Infrastructure, Transport and Tourism National Land
Policy Bureau)※The results of the car-borne survey conducted in ”Difficult-to-Return zone” from
September to October , 2023 were added.

In the Nakadori and Hamadori regions, the effects of natural attenuation and decontaminationof radioactive substances are definitely appearing. The Aizu region has been restored to the airradiation dosage level which existed before the nuclear accident.

4

Let's look at the numbers
Measurement
point※2

Measurement
date※1
Before the accident(2009)※3

Air dose rate in Fukushima Prefecture
Fukushima
City

Koriyama
City

0.04
1.91
1.00
0.69
0.33
0.24
0.20
0.18
0.15
0.14
0.13
0.13
0.12
0.12
0.11

0.04
1.83
0.88
0.51
0.17
0.14
0.12
0.10
0.09
0.09
0.08
0.07
0.07
0.07
0.07

Changes in air radiation dosage rate
in Fukushima Prefecture

Aplil 2011
September 2011
September 2012
September 2013
September 2014
September 2015
September 2016
September 2017
September 2018
September 2019
September 2020
September 2021
September 2022
September 2023

※4

※4

unit: μSv/hShirakawa Aizu-wakamatsu Minamiaizu Minamisoma
City
City
Town
City

※4

0.04
0.67
0.42
0.21
0.12
0.10
0.09
0.08
0.07
0.07
0.06
0.06
0.06
0.06
0.06

0.05
0.19
0.13
0.09
0.07
0.07
0.06
0.06
0.05
0.05
0.05
0.05
0.05
0.05
0.05

0.04
0.08
0.08
0.06
0.05
0.05
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04

※4

Iwaki City

0.05
0.63
0.42
0.37
0.15
0.12
0.09
0.08
0.08
0.07
0.07
0.06
0.06
0.06
0.06

0.06
0.37
0.18
0.10
0.09
0.08
0.07
0.07
0.06
0.06
0.06
0.06
0.06
0.06
0.06

※1 Monthly averages are listed (except for 2009).
※2 Fukushima City is measured at Ken-poku Public Health and Welfare Office, and others are measured at the prefectural joint
government building. (except for 2009)※3 2009 figures are the results of the radiation level survey.
Fukushima City : August 18, 2009 (Prefectural East Branch Office)Shirakawa City: August 11, 2009 (Shirakawa Joint Government Building)Minamiaizu Town: August 11, 2009 (Maruyama Park)

Minamisoma City: August 19, 2009 (Nishiki Park)

Iwaki City: August 18, 2009 (Iwaki Joint Government Building)※4 Decontamination was conducted in Fukushima City andKoriyama City from April to May 2013, Shirakawa City inJune 2016, and Minamisoma City in December 2016.

※Difficult-to-return Zones are not included in the above measuring points.

Let‘s look at the graph

Currently, the entire
prefecture is stable at a
low value!

Air radiation dosage rate in Fukushima Prefecture（μSv/h）

2

Koriyama City: August 11, 2009 (Hayama Park)
Aizuwakamatsu City: August 19, 2009 (Aizu Tsurugajo Castle Park)

Fukushima City
Koriyama City
1.5

Shirakawa City
Aizuwakamatsu City
Minamiaizu Town

1

Minamisoma City
Iwaki City

0.5

23
p.
20
Se

p.
20
22
Se

20
21
Se
p.

20
20
Se
p.

20
19
Se
p.

20
18
p.
Se

Se

p.
2

01
7

20
16
Se
p.

4

Se
p.
20
15

20
1
Se
p.

20
13
Se
p.

Se

p.
2

01
2

01
1
p.
2
Se

Ap
r.2

01
1

0

※Monthly averages are listed.
※For measurement locations, prefectural north health and welfare office for Fukushima City, and prefectural joint government buildings for other cities.
※Decontamination was conducted in Fukushima City and Koriyama City from April to May 2013, Shirakawa City in June 2016, and Minamisoma City in December 2016.

Trivia● Changes in radiation dose due to weather

Air radiation dosage rate at Kaibama Bureau,
Minamisoma City (September 3, 2023 to October 3, 2023)

The radiation dose varies depending on theweather.
For example, when it rains, naturally occurring
radioactive substances in the atmosphere can fallto the ground, increasing the radiation dose. Whensnow accumulates, the radiation dose may fall
↑The light blue lines indicate the time when it rained.
because the radiation from the ground is blocked.

It can be seen that the rain increases the air radiation dosage rate (red line).

5Comparison of Air Radiation Dosage rates inFukushima Prefecture to major cities in the world
The air radiation dosage rate in Fukushima Prefecture (excluding the areas where
evacuation was ordered) is now about the same level as that of major cities in the world.
Unit: μSv/h

World

Berlin0.08

Beijing

0.07

New York
0.05

London

0.11

Seoul
0.12

Paris

0.04
0.10

Sapporo City

0.04

0.14

Various partsof Japan

Fukushima
Prefecture

Osaka City

Comparison of Air Radiation Dosage rates inFukushima Prefecture to major cities in the world

Singapore

Hong Kong

0.06

0.11

Minamisoma

Fukushima

0.06

0.05

Shinjuku Ward

0.04

Aizuwakamatsu

0.04
Minamiaizu

0.07

Koriyama

0.06

Fukushima Daiichi
Nuclear Power
StationShirakawa

0.06
Iwaki

Fukuoka City

0.06

Averages in September 2023
[Source] "Radiation Monitoring Information Sharing andPublication System”(The Nuclear Regulation Authority)（https://www.erms.nsr.go.jp/nra-ramis-webg/）

Averages in September 2023
Fukushima Prefecture Disaster
Countermeasures Headquarters(provisional value)

Environmental radiation monitoring work was
carried out all over Japan even before the nuclear
accident.
Monitoring posts are also installed all over thecountry.
6

Environmental samples in Fukushima
In Fukushima Prefecture, the concentration of radioactive materials is
measured in environmental samples, including the air, water, and soil,
around the power plant.
●Sampling points for environmental samples
Wide areas around the power plants

Immediate areas around the power plants
N

Iitate Vil.
Odaka District,Minamisoma City
Kawamata
Town

Minamisoma
City

Namie Town

Katsurao
Vil.
Namie Town
Futaba Town
Tamura City

Okuma Town
Tomioka Town

Environmental samples
in Fukushima

Kawauchi Vil.
Naraha Town

Futaba Town

Fukushima
Daiichi
NPP

Fukushima
Daini
NPP

Fukushima
Daiichi
NPP
Okuma Town

Tomioka Town

Hirono Town
Iwaki City

Fukushima
Daini
NPP

30㎞

30㎞

Naraha Town

Hirono Town

Dust

Drinking water

Fallout

Seawater※

Measured after the accident

Soil

Marine soil※※Refer to page 10 for the sampling

Measured before the accident

locations of seawater and marine soil
around the Fukushima Daiichi NPP.

7

Look at the measurement results from 2022
Tips on how to read the graphRadioactive materials
detected

Measurement results

Unit (mBq/m3)

Dust

RainfallMaximum value
after the accident

Cs-137

Radioactivity of environmental samples
Types

Range of measurement
values before the accident

Range of measurement
values in 2022
Results for 2022

Measurement
valuesTrends

Cs-134

Decreased

Cs-137

Decreased

Maximum
value
after theMeasurement accident(Apr., 2011values from2019 to 2022 Mar.,2022)

Range ofmeasurement
values before
the accident(since 2001)

Unit(mBq/m2 month)Cs-134

Decreased

Cs-137

Decreased

Unit (Bq/kg dry)Soil

Cs-134

Decreased

Cs-137

Decreased

Unit (Bq/kg dry)

Remained at
the same level

Sr-90
Unit (Bq/kg dry)Same level as
before theaccident
Same level as
before theaccident

Pu-238
Pu-239+240
Unit (Bq/L)

Decreased

Cs-134

Decreased

Tap water Tritium

Same level as
before theaccident

Unit (Bq/L)

Same level as
before theaccident

Sr-90
Pu-238
Pu-239+240

Radioactivity ofenvironmental samples

Cs-137

Pu-238 was not detected.
Pu-239+240 was not detected.

Unit (Bq/L)

Cs-134

Decreased

Cs-137

Decreased

Seawater Tritium

Same level as
before theaccident

Sr-90

Decreased

Unit (mBq/L)

Pu-238
Pu-239+240
Unit (Bq/kg dry)Marine soilSame level as
before theaccident

Cs-134

Decreased

Cs-137

Decreased

Unit (Bq/kg dry)

Sr-90

Decreased

Pu-238

Remained at
the same level
Same level as
before theaccident

Pu-239+240※ND: less than limit of detection

8

Discharging ALPS treated water into the sea
What is ALPS treated water?
At the Fukushima Daiichi NPP (Units 1-3),
water is injected into the reactors to cool thefuel debris that melted and solidified during
the accident. This cooling water becomes
contaminatedwithradioactive

Contaminated water purification treatment
Reuse the desalinated water for cooling

Rainfallmore“contaminated

water

★1

is

produced when it mixes with groundwater or
rainwater flowing into the reactor building.

ALPS
treatedwater

Contaminatedmaterials
water”（ A L P S ）Reactor building

when it comes in contact with the fuel debris.
Even

Advanced Liquid
Processing System

Tank storage★2
Water desalination equipment (salt removal)

Groundwater

Cesium adsorption device
Strontium removal device★1 Most of cesium and strontium are removed.
★2 T he water has been purified and treated to the extent that radioactive
materials other than tritium are below the minimum safety standard.

The contaminated water in the buildings is treated to remove cesium and strontium, and some of it is reused to cool the fueldebris in the reactor after the salt is filtered out (desalination). The remaining water is purified using the 'Advanced Liquid
Processing System' (ALPS). This 'ALPS treated water,' which has been treated and purified to radiation levels below theminimum safety standards for radioactive materials (other than tritium), is stored in on-site tanks.

Why do we need to dispose of ALPS treated water?
There are over 1,000 giant tanks storing ALPS treated water at the Fukushima Daiichi NPP.
Disposing of the treated water and reducing the number of tanks is essential for decommissioning (shutting down) the plant.
It is necessary in order to make room to construct facilities required for the future decommissioning processes.
In April 2021, the government decided to discharge ALPS treated water into the sea under a policy created after repeateddiscussions by experts on the handling of the treated water. The ocean discharge began on August 24, 2023.
It was carried out in compliance with safety standards, and is not expected to have any adverse effects on the environmentor human health. However, it is very important to take measures to ensure safety by checking the operation status of thedischarge facilities and tritium concentrations in ALPS treated water. Careful monitoring of the ocean area must also bedone, due to the long period of time involved.

What is tritium?
Tritium is a common form of hydrogen (hydrogen-3), that occurs naturally every day. It can be found in rainwater, tapwater, and the human bodies. It is a radioactive material that is broadly present in the natural environment.
Discharging ALPS treatedwater into the sea

Tritium exists as a liquid that combines with oxygen and has almost the same properties as water, making it difficult toseparate from water.

How much is tritium being discharged by each country around the world?
Many nuclear facilities around the world
About 432 TBq

release tritium in compliance with safety

About 11400 TBq

standards.
About 220 TBq
About 91 TBq
Below 22 TBq

9Prepared based on ”Let’s learn and think about thedecommissioning and future of the Fukushima Daiichi
NPP!” published by the Agency for Natural Resources
and Energy

Annual ALPS treatedwater discharged into
the sea at the
Fukushima Daiichi NPP

ROK
Kori
NPP(2019)

CanadaDNGS(2018)

UK,
Sellafield Site
(2019)

FranceLa Hague site
(2018)

How high is the tritium concentration that’s discharged into the sea?
Before discharging, the concentration of tritium is reduced to 1,500 Bq/L, through a dilution of morethan 100 times with seawater.
ALPS treatment water discharging process

ALPS
treated water
Tanks formeasurements andconfirmation

Dilution withseawater ofmore than
100 times

Discharging

Concentration of tritium:
below 1,500 Bq/L

Transfer of seawater with pumps
What is the tritium concentration
when discharging ALPS treated water into the sea?

Undersea tunnel

Below 1/40 of the Regulatory Standards (60,000Bq/L)
Below 1/7 of the WHO Standards for Drinking Water (10,000 Bq/L) ※※Guidelines for drinking-water quality, 4th edition

Is discharging into the sea really safe?
Fukushima Prefecture conducts sea area monitoring at nine locations around the Fukushima Daiichi NPP toassess the impact of discharging ALPS treated water into the sea.
The monthly analysis of tritium in seawater after discharging into the sea has consistently remained below
20 Bq/L or the maximum value for seawater in Japan since 2015. Additionally, the analysis results of otherradioactive materials, such as radioactive cesium and radioactive strontium, have shown values within
the range of those measured before discharging (April 2022 to August 2023).

Results of tritium analysis
After discharging into the sea(September -November, 2023)

Before discharging into the sea(April, 2022 -August, 2023)

Below the detection limit (＜0.05)~ 1.6Bq/L

Below the detection limit (<0.04)~ 0.66Bq/L

North 2 km and West 0.5 km from
ALPS treated water discharge outlet
Along the perimeter ofFukushima Daiichi NPP
North of discharge outlet from

Fukushima Daiichi NPP (※)

2 km, off the coast of
Futaba/Maedagawa

North 1 km from ALPS
treated water discharge outlet
ALPS treated water
discharge outlet

The water intake of Fukushima
Daiichi NPP（※）

South of discharge outlet from
Fukushima Daiichi NPP（※）

South 1 km from ALPS
treated water discharge outlet

2 km, off the coast of
Ottozawa/Kumagawa（※）
1㎞（※）Measured before the accident

Seawater monitoring results map

How high is the tritium concentration
that’s discharged into the sea?

2 km, off the coast of
Fukushima Daiichi NPP（※）

10

Fukushima Prefecture website
https://www.pref.fukushima.lg.jp/sec/16025d/

POINT

You can see the results of measurementby the monitoring posts and measurementof environmental samples on the“Fukushima Prefecture website” and“Fukushima Prefecture Radioactivity
Measurement Map.”

Click the desired icon and check theresults of measurement of radioactive
substances with monitoring posts or
survey meters.
You can also see the report on themeasurement results of environmental
radioactivity around the nuclear power
plants and the materials of theEnvironmental Monitoring Evaluation
Subcommittee.

Fukushima Prefecture Radioactivity Measurement Map
http://fukushima-radioactivity.jp/pc/
POINT

foreign language

Information is also available in
English, Chinese, and Korean.

POINT

You can search formeasurement results for otherdates and times.

POINT
Displays a graph of airradiation dosage rate.

POINT
The icon colors are
displayed according to the
air radiation dosage rate.

POINT
The icons are displayed according to
the measurement method. You cancheck the measurement results byclicking a desired icon.

Edited and published by: Radiation Monitoring Unit, Risk Management Department,
Fukushima Prefecture112-16 Sugitsuma-cho, Fukushima City,
Fukushima Prefecture 960-8670
TEL 024-521-8498／FAX 024-52１-8368

Published in March 2024