Revision of the Mid-term Risk Reduction Target
for TEPCO’s Fukushima Daiichi Nuclear Power Station

August 6, 2018
Hiroshi YAMAGATA
Director-General for Emergency Response
The Secretariat of Nuclear Regulation Authority

Contents
 What is Mid-term Risk Reduction Target?
 Concepts of the Revision of March 2018 Version

 Revision of the Mid-term Risk Reduction Target Priority Items
 Summary1Mid-term Risk Reduction Target
 Nuclear Regulation Authority(NRA) formulated the “Mid-term Risk Reduction Target” inFebruary 2015 to set out targets for risk reduction during the decommissioning of
TEPCO’s Fukushima Daiichi Nuclear Power Station. It is reviewed regularly and theachievement statuses of the targets are evaluated.

2Concepts of the Revision ofMarch 2018 Version
 Characters of the risk reduction target:
Focusing on presenting the residual risks, in addition thathas the characters of the risk reduction work processes.
 Targets to be noted:
In principle, targets with high risks concerning radioactive
substances are noted, as well as targets of high interestfor the completion of decommissioning.
 Target period:
Approximately three years.
 Targets’ position on the timeline:
To be placed at the expected time of completion.

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Revision of
Mid-term Risk Reduction Target Based on concepts of the revision, the contents of the documents
are as follows:• Mid-term Risk Reduction Target for
TEPCO’s Fukushima Daiichi Nuclear Power Station(March 2018 version)• Conceptual diagram of main risks, etc. for the beginning of
FY2018 and the end of FY2020 [p. 6, 7]• Specific processes for mid-term risk reduction of
TEPCO’s Fukushima Daiichi Nuclear Power Station [p. 8, 9]

4Mid-term Risk Reduction Target for TEPCO’s Fukushima Daiichi Nuclear Power Station
March 7, 2018
Nuclear Regulation Authority(March 2018 version)
Issue

Liquid radioactive waste

Solid radioactive waste

Objective

Reducing the risk of leakage that
occurs due to the accumulation ofliquid radioactive waste

Restraining the risk of scattering andleakage of solid radioactive wastethat is produced along with theprogress of decommissioning work

〇 Install the 9th Solid
Waste Storage
Facility(February 2018)〇 Restrain the inflow ofgroundwater into
buildings

2018〇 Treat accumulated
contaminated waterin buildings• Reduce the amountof radioactive
substances to halfor less• Increase pumpcapacity of the
sub-drain

Spent fuel pool

Earthquake/tsunamiReduction ofenvironmental impact

Decommissioning/
Facility
investigation (*2)

Removing risks of spent fuel pools

Removing risks regarding thebuildings, etc.,
which contain contaminated waterand spent fuels

Reducing background radiation doses
and scattering of radioactive dustthat occurs during thedecommissioning process

Steady progressindecommissioningwork〇 Install Unit 3 Building
Cover and equipment
removing spent fuels,
etc.
(February 2018)〇 Install the large
equipment
decontamination
facility• Increase treatment
capacity of the
sub-drain〇Treat contaminatedwater with Sr in theflange-type tanks● Reduce the total
amount of storedliquid radioactive
waste〇 Prevent the outflow
of accumulated
contaminated waterin buildings withconsideration of the2011 Tsunami(max. 15.5 m)〇 Install temporarystorage facilities forcontaminated soil

• Discharge water
treated in the
ALPS to the sea,etc.
in accordance withthe regulatory
standards,• Block the
openings(Unit 3 Turbine
Building, process
main building)2019〇 Restrain the inflow
of rainwater into
buildings• Facings of groundlevel 2.5, 6, 8.5m,
etc.

〇 Install large storage〇 Restrain the inflow
of rainwater into
buildings

2020◎ Treat accumulated
contaminated waterin buildings• Treat accumulated
contaminated waterin buildings
excluding those in
Units 1 to 3
Reactor Buildings◎ Dismantle the upper
part of the exhauststack forUnits 1 and 2• Restrain the inflow
of rainwater into
Waste Treatment
Buildings of Unit 1
and 2〇 Install additional
incineration facilities(felled trees,
flammables inrubble, etc.)〇 Restrain the inflow
of rainwater into
buildings• Restrain the
inflow of rainwater
into Unit 3 Turbine
Building〇 Install a stabilizationequipment for
ALPS slurry (HIC)〇 Take measures for
Mega-Float

andonwards〇 Treat accumulated
contaminated waterin buildings• Treat accumulated
contaminated waterin the reactor
buildings〇 Remove rubble fromaround the buildings◎ Remove spent
fuels, etc. from
Unit 3 SFP◎ Transfer sludge fromdecontamination
instrument (AREVA)• Implement andmonitorcountermeasuresagainst scattering of
dust during rubble
removal on Unit 1
Operating Floor〇 Removecontaminated waterin trenches, etc.
〇 Removeundergroundcisterns〇 Restrain the inflow
of rainwater into
buildings• Facings aroundbuildings, etc.

〇 Improve theenvironment ofground level 2.5 m〇 Implement andmonitor enhanced
countermeasuresagainst scattering ofdust〇 Install volume
reduction facility(metal, concrete)

2021(Fiscalyear)● Install Radioactive
Substance Analysis
Facility(building No. 1)〇 Decrease theconcentration ofradioactive substancesin the water ofdischarge channels● Survey thecontamination
status inside thereactor buildings,
etc. (nuclide
analysis, etc.)● Grasp the properties
and characteristicsof the cooling water
after the reactors
have cooled down
(nuclide analysis, etc.)● Analyze the flow ofcontaminated water,etc. inside thereactor buildings● Directly observe
inside thecontainment vessel
and pressure vessel

LegendMain risk reduction target:〇 Install stabilizationequipment forsludge of thedecontamination
facility (AREVA)● Install Radioactive
Substance Analysis
Facility(building No. 2)◎ Remove spent
fuels, etc. from
Unit 1 SFP◎ Remove spent
fuels, etc. from
Unit 2 SFP〇Take measuresagainst deteriorationof building structures

Target which corresponds to main risks:〇 Maintain dose level of less than 1 m Sv/year at
the site boundary

Measures significant for decommissioning:〇 Continuously improve the work environment

Measures underway as planned:

Completed measures:
Measures behind schedule:〇 Remove used
control rods

*1: Sr treated water: Water that has been reduced in concentration of cesium and strontium to some extent
before purification treatment with the multi-nuclide removal system (ALPS).
*2: Targets of decommissioning/facility investigation are noted regardless of the implementation period.
(Note) Not all targets are listed, only the main ones.
The targets’ position on the timeline indicates the expected time for completion.

Measures (timing to be determined):
Measures requiring evaluation,
including decisions on whether to implement:◎〇●

Conceptual Diagram of Main Risks, etc. for the Beginning of FY2018 and the End of FY2020
TEPCO’s Fukushima Daiichi Nuclear Power Station

Beginning of FY2018
Multi-nuclide removal
system (ALPS)
FacingTreatment of contaminatedwater (treated water with Sr)
from the flange-type tank

Tank forSr treated water

Treated water tank
for ALPS

Dismantling of the upper
part of the exhaust stack for
Units 1 and 2▽ T.P. + 33.5 m

Removal of spent fuels from
Unit 3 SFP

Spent fuels(Units 1 to 3)

Desalination system (RO)(3)

Reactorbuilding

Restraining the inflow ofrainwater into buildings

Groundwater level

Ground waterTransfer of sludge from Treatment
the decontamination
device(Kurion/SARRY)
instrument (AREVA)(1) (2) (3) (4)Spent fuel pool

Turbinebuilding

Accumulated
contaminated waterin the buildings

Facings of groundlevel 2.5, 6, 8.5m,
etc

FacingGroundwater bypass▽ T.P. + 8.5 m
Discharging the treatedwater of ALPS to the sea,etc.
in accordance with theregulatory standards,(1): Unit 1(2): Unit 2(3): Unit 3(4): Unit 4

SludgeFuel debris

Groundwater
level

FacingSeasideimpermeable
wall▽ T.P. + 2.5 m

Ground waterSea water piping trench (1)Sub-drain

Increasing pumpcapacity of the
sub-drain

Landsideimpermeable wall

Treatment of accumulated
contaminated water excluding
those in Units 1 to 3 Reactor
Buildings

Conceptual Diagram of Main Risks, etc. for the Beginning of FY2018 and the End of FY2020
TEPCO’s Fukushima Daiichi Nuclear Power Station

The End of FY2020
Multi-nuclide removal
system (ALPS)
FacingTreated water tank
for ALPS

Tank fortreated waterwith Srtreated water with Sr:137Cs: 10-2 to 0 Bq/cm3,
90Sr: 101 to 3 Bq/cm3
Spent fuels(Units 1 and 2)

Desalination system (RO)

▽ T.P. + 33.5 m
Groundwater
Sludgelevel

Treatment
device(Kurion/SARRY)

Reactorbuilding(1): Unit 1(2): Unit 2(1) (2)Spent fuel pool

Ground water

Turbinebuilding

FacingGroundwater bypass▽ T.P. + 8.5 m
FueldebrisFacingMulti-nuclide removal systemtreated water:
137Cs: 10-4 to -1 Bq/cm3,
90Sr: 10-4 to 0 Bq/cm3,
3H: 103 Bq/cm3

Groundwaterlevel

Seasideimpermeable
wall▽ T.P. + 2.5 m

Ground water

Sub-drain
Landsideimpermeable wall

Accumulated contaminatedwater in buildings:
137Cs: 105 Bq/cm3,
90Sr: 104 Bq/cm3

Regulatory standards (liquid):
137Cs : 9×10-2 Bq/cm3
90Sr : 3×10-2 Bq/cm3
3H : 6×101 Bq/cm3

Specific Processes for Mid-term Risk Reduction for TEPCO’s Fukushima Daiichi Nuclear Power Station (excerpt)
Unit 3Main category

Sub-category Completed measure

Treatment ofaccumulated
contaminatedwater

Liquid radioactive
waste

Spent fuel pool

2019

• Treatment
accumulated
contaminated waterof inside thecondenser(December 2017)

Removal of
spent fuels

Train staff, remove
small rubble, etc.
[until around the
middle of FY2018]

Restrain the inflow ofground water into theturbine building[until the first halfof FY2020]

Remove spent fuels[from the middle of FY2018 to the end of FY2020]

2021
Treat
accumulated
contaminatedwater of inside
the reactor
building (R/B)

2022

Repair the roof of
the waste
treatment building
Restrain the inflow ofgroundwater after
completing the treatmentof accumulated
contaminated water,
excluding Units 1 to 3
Reactor Buildings

Removeused
control
rods

Drain
water

Decide upon the strategy on
the seismic motion for review(observing the status ofcontainment vessels, such as
suppression chambers)

Earthquake/tsunamiBlock theopenings of Unit 3
Turbine Building

TsunamiFacility
investigation

Adopt air coolingfor fuel debris

Treat accumulated
contaminated water inside
the turbine building (T/B)
and waste treatment building(Rw/B)[until the first half of FY2020]

Adopt fullcirculation of fueldebris coolingwater• Installation of cover(February 2018)2020
Decide on thestrategy of fueldebris cooling

No additional
accumulated
contaminatedwater(restraining the
inflow ofgroundwater,
rainwater, coolingwater, and workuse water)

Earthquake

Decommissioning/facility
investigation

Schedule (fiscal year)
2018[until the first halfof FY2018]• Investigation inside
the containment
vessel(October 2015)• Investigation inside
the pedestal(July 2017)

Investigate inside the containment vessel

8Specific Processes for Mid-term Risk Reduction for TEPCO’s Fukushima Daiichi Nuclear Power Station (excerpt)
CommonMain category

Sub-category

Completed measure

Treatment ofaccumulated
contaminatedwater• Restraint of the outflow ofaccumulated contaminatedwater inside the buildings

2019• Removal of horizontal tanks(December 2014)• Removal of accumulated
contaminated water (ROconcentrated water) fromflange-type tanks(May 2015)

Removal ofaccumulated
water

2021

Restrain the inflow
of groundwater after
completing thetreatment ofaccumulated
contaminated water,
excluding Units 1 to
3 Reactor Buildings

Facings of groundlevel 2.5, 6, 8.5m,
etc.

Increas treatment
capacity of the sub-drain(1,500 m3/day)[until September 2017]→ [until March 2018]

Liquid radioactive
waste

2020

~

Facings aroundthe buildings, etc.

[until October 2018]

Remove undergroundcisterns

Remove accumulated contaminatedwater on the premises, etc.

Earthquake

Take measuresagainst thedeterioration ofbuilding structures

Decide upon the strategy on
the seismic vibration for review(observing the status ofcontainment vessels, such as
suppression chambers)• Installation of temporary
seawalls (June 2011)• Blocking openings

Tsunami2023

Treat accumulated
contaminated water (Srtreated water) in flangetype tanks

Dismantle the upper part ofthe exhaust stack on Units 1
and 2[until the second half of FY2019]

Earthquake/tsunami2022

Reduce the amount ofradioactive
substances to half or
lessIncrease pump capacityof the sub-drain[until January 2018]→ [until June 2018]

Restraint of
water
contamination

Treatment ofaccumulated
contaminatedwater in tanks

Schedule (fiscal year)
2018

Common pool (September2013);
Units 1 and 2 Turbine Buildings,
high-temp. incinerator(October 2014)

Block openings ofthe process mainbuilding

Transfer sludge fromdecontamination
instruments (AREVA)[until the first halfof FY2018][until the second halfof FY2020]

Decide on thestrategy ofmeasures for
Mega-Float

Take measures for
Mega-Float

9

Priority Targets(Treatment of Accumulated Contaminated Water) NRA recognizes that, in order to reduce the risk of accumulated contaminated water inbuildings, which is high concentration liquid radioactive waste, flowing out, the treatment ofaccumulated contaminated water must be conducted promptly.
 Complete the treatment of accumulated contaminated water in buildings, excluding thereactor buildings, within 2020.
• In the 12th Extraordinary Meeting of NRA held in May 2018, the president of Fukushima Daiichi
Decontamination & Decommissioning Engineering Company
Mr. Ono stated that he “will achieve this goal at any cost.”• As the amount of accumulated contaminated water in buildings is treatable within approximately
one month if the currently installed multi-nuclide removal systems are operated at full capacity,
the treatment should be conducted immediately.
The amount of accumulated contaminated water as of July 2018: Approx. 50,000 m3 ÷ ALPS total capacity: 2,000
m3/day = 25 days?
(Existing: 750 m3/day, additional: 750 m3/day, high performance: 500 m3/day)• TEPCO should consider operating the currently stopped high performance multi-nuclide removal
systems and moving up the schedule so that the treatment can be completed prior to 2020.

 Complete the treatment of treated water with Sr contained in the flange-type tank by
November 2018.
• The treatment plan for treated water with Sr is approximately one month behind schedule.
To avoid further delays, TEPCO should establish backup systems to prevent unexpected eventsfrom affecting the treatment plan.
The amount of treated water with Sr stored in the flange-type tank as of June 2018: Approx. 50,000 m3

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Priority Targets(Liquid Radioactive Waste)
 NRA recognizes that, in order to avoid the risk of leakageof high concentration liquid radioactive waste caused by
Tsunami, the waste must be transferred to a higher
ground and stabilized promptly.

Maincomponent
Barium sulfate(66%)
Ferrocyanide Complete the transfer of AREVA sludge to higher ground.

1st Floor• Although the transfer is scheduled to be completed within
FY2020, TEPCO should consider completing the transfer
as early as possible from the perspective ofcountermeasures against Tsunami.

Concentration ofmajor nuclide
90Sr：

Generation
rate

Approx. 3  108 Bq/cm3

37 m3

Place for thedecontaminationequipment(AREVA)

Storage tank D
Sludge +supernatant water Install a stabilization system for AREVA sludge.

• While the research and development of stabilization
treatment has been underway, the installation plan for thestabilization system must be formulated at an early stage,
and the timing at which the operation can be started must
be clarified.
 Install a stabilization system for ALPS slurry (HIC), etc.
• Preparation, such as moving up the schedule to prevent
delay in the start of operation of the treatment system, must
be done steadily, so that the approval of changes on theimplementation plan can be requested at an early stage.

Storagecondition

HIC
Main component

Concentration ofmajor nuclide

Generation
rate

Existing
ALPS

Iron co-precipitation
slurry:FeO (OH) / H2O
(75%)

90Sr:

386 HIC units
1,008 m3

Existing
ALPS

Carbonate slurry:
CaCO3, Mg(OH)2

90Sr:

971 HIC units
2,535 m3

Additional
ALPS

Approx. 1  106 Bq/cm3

Approx. 4  107 Bq/cm3

1121 HIC units
2,926 m3

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Priority Targets(Treated Water by Multi-nuclide Removal System) NRA recognizes that a decision on discharging treated water that contains tritium to the sea,etc. in accordance with the regulatory standards must be made as soon as possible for thedecommissioning work.
 As for the long-term storage of tritium-containing treated water in several hundred tanks(approx. 900 units), the possibility of leakage to the environment due to earthquakes, etc.
cannot be ruled out. The environmental impact of it leaking into the environment is small;
however, economic damage
may be incurred as a result of
rumors.
 TEPCO should consider all thepossibilities and takecountermeasures.
TEPCO should immediately address
specific countermeasures forhandling treated water that
contains tritium.
Image: Google Map

 TEPCO should have awareness as the responsible body and proactively make the decision
to progress the decommissioning work.

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Priority Targets(Others)
 Start the removal of spent fuels from Unit 3 from the November 2018.
• Although the malfunction of the crane of the fuel handling machine
is said to have affected the schedule for removal of spent fuels,
removal must be started in November 2018 as planned.

 Complete the dismantling of the upper part of the exhaust stack for Units 1 and 2
by the second half of FY2019.
• As for the exhaust stacks to which damage due to earthquakes has been confirmed, dismantlingwork must be started in December 2018 and carried out
as planned.

 Evaluate the seismic resistance of the containment vessels (suppression chambers, etc.)
using the earthquake for review.
• The evaluation of earthquake resistance must be conducted immediately, since the suppression
chamber is currently filled with contaminated water and considering the damage caused byearthquakes and corrosion, there is a safety concern in the event of occurrence of earthquakesof the same level as the 3.11 earthquake.

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Summary TEPCO needs to implement the items indicated in the
Mid-term Risk Reduction Target in a planned andsteady manner.
 The Nuclear Regulation Authority will continue to monitor andevaluate that risk reduction is implemented without delay.
 In particular, move up the schedules for the treatment ofaccumulated contaminated water in buildings, transfer of AREVA
sludge, and removal of spent fuels in Unit 3.
Decisions on handling the treated water, such as discharging
water treated in the multi-nuclide removal systems to the sea, etc.
in accordance with the regulatory standards, should be made assoon as possible.

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