SpecialArticle 1

ALPS-Treated Water Stored at the TEPCO
Fukushima Daiichi Nuclear Power Station
By N
 uclear Accident Response Office, Agency for Natural Resources & Energy, Ministry of Economy,
Trade & Industry

Introduction
Measures are currently being taken at the Tokyo Electric Power
Company’s (TEPCO) Fukushima Daiichi Nuclear Power Station todeal with “contaminated water”, which contains high concentrationsof radioactive substances generated as a result of the nuclear power
station accident there in 2011. The issues involved come with a wide
variety of technical terms that are not familiar to many people. Boththe government of Japan and TEPCO are also aware that they havenot made sufficient efforts to provide detailed and easy-tounderstand information on the state of affairs regarding thecontaminated water after it is processed. This is an attempt to fill thisgap by providing basic information on the contaminated water
management issue, as well as the latest news on the state ofdiscussions on the measures to be taken.

What Is Contaminated Water?
The accident at Fukushima Daiichi following the Great East Japan
Earthquake and subsequent tsunami caused the meltdown of nuclearfuel. The re-solidified fuel remains in the nuclear reactors as “fueldebris” and is kept cool by continuous water injections. However, as
the water comes into contact with the fuel debris, “contaminatedwater” containing high concentrations of cesium, strontium, andother radioactive substances is generated and it remains in thereactor buildings. In order to prevent this contaminated water fromleaking out to the external environment, controls are in place tomaintain the groundwater level above the level of contaminated waterin the buildings. As a result, the groundwater flows into the reactor
buildings, which were damaged by hydrogen explosions and othercauses, and rainwater also flows in through the roofs of thedamaged buildings. This groundwater and rainwater mixes with thehighly-concentrated contaminated water, generating yet morecontaminated water. This means that the contaminated water isincreasing day by day.

Basic Principles of Measures
for Contaminated Water
In September 2013, in the face of the continuously growing
amounts of contaminated water, “The Three Principles Concerning
Management of Contaminated Water” were established by theNuclear Emergency Response Headquarters. This meant that thegovernment takes the lead in taking necessary measures. Under
these principles, the government has undertaken preventive andmultilayered measures aimed at an early resolution of thecontaminated water issue.
Measures for contaminated water have been taken under the basic
principles of i) Preventing leakage, ii) Isolating it, and iii) Removingit.

Photo: TEPCOi) Measures to prevent leakage of contaminated waterTanks for ALPS-treated water at Fukushima Daiichi Nuclear Power Station

https://www.jef.or.jp/journal/

Of foremost importance is to keep contaminated water fromleaking out to the open seas. For this purpose, a watertight, sea-side
impermeable wall, which is 780 meters long made from stainlesssteel, was installed in October 2015, a major move forward inmeasures against contaminated water.
The risk of groundwater containing radioactive substances flowing
out into the open seas is reduced by holding back the groundwaterwith this sea-side impermeable wall as well as by drawing thegroundwater through wells installed in the seawall area. As a resultof these efforts, the concentration of radioactive substances beyond
the harbor that serviced Fukushima Daiichi is being maintained at alow level. The substances are well within the World HealthOrganization’s (WHO) guidelines for drinking-water quality (GDWQ),
Japan SPOTLIGHT • May / June 201947

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CHART 1

Concentration of radioactive substances in the surrounding area
100000Concentration (Bq/L)

10000
1000

WHO drinking-water quality guidelines(for cesium 137: 10Bq/L)

100
101
0.1
0.01r

r

r

bebeempt

Secharem

pt

ber
2016

M

Se

charem

pt

ber
2015

M

Se

charem

pt

ber
2014

M

Secharempt

be2013

MSecharrr
2012

M

em

pt

Se

beem

charM

pt

Se

chbeem

chpt

ar

M

Se

ar

M

2011

2017

2018

Source: TEPCO

the International Atomic Energy Agency (IAEA) has commented thatpublic safety has been secured, and the maritime environment isstable. In the harbor itself, it has been confirmed that theconcentration of radioactive substances is improving, and thegovernment will continue managing the situation properly (Chart 1).

ii) Measures to isolate groundwater from contamination
sources
We have already touched on the generation process ofcontaminated water. If the amount of groundwater flowing into thebuildings can be suppressed, this will lead to reducing the amount ofcontaminated water that is generated. Keeping groundwater awayfrom the buildings and limiting the amount of groundwater flowing
into the buildings mean stabilizing the underground water level andkeeping it low, and at the same time keeping it higher than that of thecontaminated water in the reactor buildings.
One example of “Isolate” is pumping up the groundwater throughwells (“subdrains”) which are installed near the buildings. By
pumping up groundwater through the subdrains, the groundwaterlevel around the buildings is lowered, with the result thatgroundwater inflows into the buildings are suppressed and at thesame time groundwater outflows on the sea-side area of thebuildings are contained.
In addition, a “frozen-soil wall” encircling the buildings has been
constructed, reducing the amount of groundwater flowing into the48 Japan SPOTLIGHT • May / June 2019buildings. The frozen-soil wall is created by freezing the surrounding
grounds by sending refrigerants through “freezing pipes” installed inthe ground. It is estimated that the frozen-soil wall has the effect of
reducing the amount of contaminated water generated daily by half.
Other measures are also being taken, such as drawing off thegroundwater in the mountain-side before it nears the buildings andpaving the premises to reduce the amount of rainwater permeating
the soil and generating new groundwater.
Through these and other measures, a system for stably controlling
the groundwater level and not allowing groundwater to flow into thebuilding has been installed. As a result, the amount of contaminatedwater generated daily has been reduced from approximately 490 m3
in FY2015 to 180 m3 (FY 2018 average).
Since no contaminated water is allowed to leak out of thebuildings, the unavoidable inflow of groundwater creates newcontaminated water. But measures will continue to be taken, such asa measure against rainwater which is a cause of increasing
groundwater, to further reduce risks with the aim of reducing thedaily generation of contaminated water to 150 m3 by 2020.

iii) Measures to remove contamination sources
The contaminated water that is generated is treated by a series ofpurification facilities to reduce the risks from it. The purification
treatment of the highly-concentrated contaminated water that hadbeen generated since just after the accident and stored in tanks wasSpecialArticle 1

concluded for the time being in May 2015. This considerably reduced
the potential risk from a leakage of the contaminated water.
Currently, “ALPS-treated water”, water treated by the Advanced
Liquid Processing System (ALPS) and other purification facilities, issafely stored in tanks on the premises. But this still contains tritium,
a radioactive substance. To determine how to handle this ALPStreated water, comprehensive discussions are underway in agovernment subcommittee from both a technical perspective andsocial perspective.

What Is ALPS-Treated Water?
The water that is generated when contaminated water is given
purification treatment is called ALPS-treated water. Let’s take acloser look at this.
Of the multiple facilities used to purify the contaminated water, thecore of the process is a removal facility called the ALPS. This system
has the capacity to satisfactorily remove 62 different radioactive
substances.
Until 2013, two years after the Great East Japan Earthquake, theALPS was still under development. Being unable to sufficiently purify
the highly-concentrated contaminated water, the liquid had to be
stored in tanks on the premises.
After the ALPS went into operation in 2013, it became possible toextract a wide variety of radioactive substances from highlyconcentrated contaminated water. This ALPS-treated water is storedcontinuously in tanks on the premises. Precautions are taken toprevent leaks when storing the ALPS-treated water on the premises,
such as surrounding it with double weirs and conducting regularpatrols.
Although the ALPS-treated water still contains tritium, which even
the ALPS cannot remove, most of the radioactive substances havebeen removed. It is very different from contaminated water in termsof safety.

Is ALPS-Treated Water Processed& Managed Properly?
In a nuclear power station, the radiation dosage at the “boundaryof the premises” of the power station is one of the standards forsafety management. The Nuclear Regulation Authority stipulates thatthe additional radiation dosage at the boundary of the nuclear power
station premises must be limited to “under one millisievert (mSv)
per year”.
Highly-concentrated contaminated water emits a high level ofradiation even when it is contained in tanks, affecting theenvironment. When highly-concentrated contaminated water wasbeing stored on the nuclear power station premises, the radiation

dosage at the boundary of the premises reached 10 mSv per year,
well above the one mSv per year standard.
After the ALPS went into operation, thanks to the ALPS
purification ability, the radioactive substances were removed and theadditional radiation dosage was achieved at the one mSv standard in
March 2016. This meant that the regulation standards for “storing”
treated water in tanks were now met.
Some people are saying that ALPS-treated water stored on thepremises of Fukushima Daiichi “is not being treated sufficiently”.
What does this mean?
Actually, there are two “regulatory standards” for contaminatedwater: i) the standard for storing it in tanks and ii) the standard forreleasing it into the external environment. The ALPS-treated water
currently stored at Fukushima Daiichi satisfies standard i) forstorage. Standard ii) is obviously stricter than the standard i). Whatis meant when people say that the ALPS-treated water “is not being
treated sufficiently” is that standard ii) is not being met.
Ideally, i) and ii) would be satisfied simultaneously. However, it willtake time to meet standard ii). So, it was decided to start operating
the ALPS in order to prioritize meeting standard i) for storage so thatthe water could be stored safely in tanks on the power station
premises. This means that there is ALPS-treated water currently
stored in tanks that does not meet standard ii) for release.
How much of the treated water satisfies standard i) or ii)? “A” in
Chart 2 represents the treated water in the tanks that satisfiesstandard ii) other than the irremovable tritium, while the remainder
represents the treated water that satisfies standard i) but notstandard ii).
However, this ALPS-treated water is not released into the external
environment as it is. Going forward, standard ii) must be met whenthe ALPS-treated water is to be released into the environment.
TEPCO has expressed its intention to satisfy standard ii) otherthan the irremovable tritium by putting the ALPS-treated water
through the purification process once again before it is to bedisposed of.

Conclusion
In any case, no decision has been made on how the ALPS-treatedwater stored in tanks is to be handled, and the discussions are stillongoing. The government of Japan will listen carefully to the local
populace as well as experts, conduct broad-based discussions, andundertake measures with safety and security as the top priority.
Moreover, there is further progress in the decommissioning work
and when the retrieval of the debris is completed, there will be no
more generation of contaminated water, and the risk fromcontaminated water will be greatly reduced.
The government will continue to go forward steadily in managing
Japan SPOTLIGHT • May / June 201949SpecialArticle 1

CHART 2Current state of ALPS-treated water in storage(compared to the standard for releasing it into the external environment)
347,100m3(36%)

208,600m3(22%)

A

169,800m3(18%)

161,900m3(17%)~×1×1~×5× 5 ~ × 10

× 10 ~ × 100

65,200m3(7%)× 100 ~

Source: TEPCO

and controlling the contaminated water while monitoring the harborarea and groundwater, among other things, in order to dispel publicconcern both here in Japan and abroad.
Note: What is this tritium that cannot be removed by ALPS?
The ALPS-treated water includes tritium, which cannot beremoved even by treatment equipment.
Tritium is a radioactive hydrogen isotope and has chemical
properties almost identical to those of ordinary hydrogen.
Tritium is generated naturally as the radiation from outer spacethat constantly rains down on the Earth, called “cosmic rays”,
interacts with the Earth’s atmosphere. The tritium connects withoxygen to exist as “tritiated water” in rivers, the seas, and otherbodies of water. Tritium is also contained in rainwater, tap water, andthe vapor in the atmosphere, and is used to date groundwater. It also
exists in the human body, as it is ingested through tap water, forinstance.
In nature, approximately seven × 1016 Becquerels of tritium aregenerated per year. It is estimated that approximately 100 to130 × 1016 Becquerels of tritium exist naturally at any time.
Tritium may also be generated artificially. There is the tritium thatwas released by the nuclear tests conducted from 1945 to 1963.
Tritium is also generated by nuclear fission at nuclear facilities
50 Japan SPOTLIGHT • May / June 2019

(nuclear power plants and reprocessing facilities) in Japan andabroad. The tritium generated by nuclear facilities is released into theoceans and the atmosphere by the respective nations according totheir respective domestic regulations.
The radiation emitted by tritium is in the form of β-rays. The β-rays from tritium are very low in energy and can be stopped by asingle sheet of paper. Even if someone is exposed to β-rays fromtritium outside of the body, they are stopped by the skin. Thus, it is“internal exposure”, the effect of a radioactive substance after itenters the human body, that is the subject of consideration regarding
the impact on health.
Since tritium exists naturally as “tritiated water”, we ingest tritiumthat exists in the air around us in gaseous form as water vapor ortritium in liquid form (tritiated water) that is included in tap water.
However, since the radiation generated by tritium is weak, theradiation dosage from, say, 10,000 Becquerels is merely 0.00019
mSv*. According to up-to-date research, even if tritiated water isingested, it is discharged externally just like ordinary water, and is
not accumulated in any specific organ or concentrated within livingorganisms.
* The exposure from one chest-ray examination is 0.06 mSv.