Provisional Translation

The Status Report of Plutonium Management in Japan - 2023 July, 16, 2024
Office of Atomic Energy Policy
Cabinet Office1.

Preface
Japan has been limiting its research, development and use of nuclear energy
exclusively for peaceful purposes under the Atomic Energy Basic Act.
From the viewpoint of peaceful use under the Act on the Regulation of Nuclear
Source Material, Nuclear Fuel Material and Reactors, and under the Treaty on the
Non-Proliferation of Nuclear Weapons (NPT), all nuclear materials and activities inJapan are subject to the stringent safeguards implemented by the International
Atomic Energy Agency (IAEA), thus guaranteeing the peaceful use of nuclear energy
in Japan*.
In addition, Japan upholds the principles of not possessing plutonium without
specific purposes guided by the policy of peaceful use. Japan Atomic Energy
Commission has also declared the policy to reduce the amount of Japan’s plutonium
stockpile in "The Basic Principles on Japan’s Utilization of Plutonium＊１" published inJuly 2018. Given the importance of enhancing transparency and gaining public
understanding on use of plutonium at home and abroad, Japan has published thestatus report of management of unirradiated separated plutonium (hereinafterreferred to as "separated plutonium") including usage and stockpile both within andoutside of Japan since 1994. Moreover, Japan has also reported the status annuallyto the IAEA in conformity with "the Guidelines for the Management of Plutonium＊２".
In this report, Japan voluntarily publishes the use, storage status and other items ina more detailed manner than required by "the Guidelines for the Management of
Plutonium" to further improve its transparency.

2.

The Current Status of Separated Plutonium Management in Japan(1) Overview
As of the end of 2023, the total amount of separated plutonium both managed
within and outside of Japan was approximately 44.5 tons, approximately 8.6 tons ofwhich was held domestically and the rest of approximately 35.8 tons was held abroad.
In 2023, no additional separated plutonium was recovered in Japan, but
approximately 0.6 tons of separated plutonium was consumed at Kansai ElectricPower Company Takahama Unit 3.
As a result, the amount of separated plutonium held domestically at the end of 2023
was approximately 8.6 tons.

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Provisional Translation

The Status of Separated Plutonium Management<Unit: t Pu>

Total
Held in Japan(Total)U.K.
Held abroad
Breakdown
FranceAs of the end of
2022
45.1
9.3
35.9
21.8
14.1

As of the end of
2023
44.5
8.6
35.8
21.7
14.1

(Note) All figure are approximate numbers.
The total figures may not agree completely due to rounding.
(2) The Data in the Attachment
The status of separated plutonium management in Japan as of the end of 2023 isgiven below. In this document, the amounts of separated plutonium in the tables are
given in kilograms unless otherwise mentioned, and each figure of fissile plutonium
is the total of plutonium 239 and plutonium 241. Figures in brackets are the data
published last year.
"Separated plutonium held in Japan" in Section 1-(1) of the Attachment is separated
plutonium in the process between separation from spent fuel, fabrication into MOX
powder at reprocessing facilities, fabrication into MOX fuel assemblies from MOX
powder at fuel fabrication facilities, and loaded into a reactor core but yet to be
irradiated. Such plutonium is held in the following facilities:
1) Reprocessing facilities: in the form of plutonium nitrate in the separation andpurification processes, or of MOX powder, etc. both in the co-conversion
process and in containers.
2) Fuel fabrication facilities: MOX powder held as raw materials, in the stage oftesting or fabrication, or contained in newly fabricated fuels.
3) Nuclear reactors and other facilities: separated plutonium contained inunirradiated fuels held at fast reactor sites and commercial reactor sites (thisincludes unirradiated MOX fuels loaded into the reactor core but yet to be
irradiated, and such fuels unloaded from the reactor core without having been
irradiated), and those held for research at R & D facilities of universities or
institutes, and those in fuels for critical assemblies.
"Separated plutonium held abroad" in Section 1-(2) of the Attachment is plutonium thathas been separated by reprocessors in the U.K. and France under contracts withJapanese electric utilities, but not yet returned to Japan. Basically, such plutonium is
to be fabricated into MOX fuels overseas and be utilized at commercial reactors inJapan.
2

Provisional Translation"Utilization of separated plutonium from Jan. to Dec., 2023" in Sections 2-(1), (2), and(3) of the Attachment is to provide further clarity of the plutonium management. It
shows the amount of separated plutonium form recovered at reprocessing facilities,
the net amount of separated plutonium transferred to fabrication process of the fuelfabrication facilities and the amount of separated plutonium in unirradiated MOX fuelsloaded into the reactors and irradiated.

*：The broader conclusion for Japan（2023）＊３
Under the Treaty on the NPT, based on the Comprehensive Safeguards
Agreement concluded with the IAEA and its Additional Protocol, Japan accepts
safeguards by the IAEA on all nuclear materials including plutonium in Japan.
The IAEA’s Board of Governors held in June 2024 affirmatively concluded that thesafeguards implemented by the IAEA in 2023 found that all nuclear material remainedin peaceful activities (the broader conclusion) on the basis that there are no indicationof the diversion of declared nuclear material from peaceful nuclear activities and no
indication of undeclared nuclear material or activities in Japan.

＊１

https://www.aec.go.jp/kettei/kettei/20180731_2.pdf＊２https://www.iaea.org/sites/default/files/infcirc549.pdf＊３

https://www.nra.go.jp/data/000473292.pdf[References]
Reference 1

The amount of separated plutonium held in nuclear reactors and otherfacilities in Japan as of the end of the year 2023.

Reference 2

The balance of separated plutonium held in Japan as of the end of theyear 2023.

Reference 3

The Status of Separated Plutonium in Japan (2023) (illustration)

Reference 4

The amount of plutonium held in Japan as of the end of the year 2023
published by the IAEA under the Guidelines for the Management of
Plutonium.

Reference 5

The amount of plutonium held in each country as of the end of the year
2022 published by the IAEA under the Guidelines for the Management of
Plutonium.

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Provisional Translation

Attachment
The Status of Separated Plutonium Management in Japan as of the end of the year 2023
1. Separated plutonium in storage(Previous year’s figures in brackets)(1) Separated plutonium held in Japan<Unit: kg Pu>

Reprocessing Facilities (Note 1)
MOX powder, etc. (Note 2)

3,790 (3,793)

Fissile Plutonium

2,463 (2,465)(Note 1) "Reprocessing Facilities" refers to the reprocessing plants in Japan Atomic Energy Agency (JAEA) andJapan Nuclear Fuel Limited (JNFL).
(Note 2) The changes of the figures may occur from the movements of sampling materials for analysis andinspection.

Fuel Fabrication Facilities (Note 3)
Breakdown(Note 4)

MOX powder, etc. (held as raw materials, inthe stage of testing or fabrication)

3,358 (3,428)

Unirradiated fuel, etc. (held as finished fuelassemblies, etc.)

550 (484)
3,908 (3,912)

Total（＊）
Fissile Plutonium

2,692 (2,695)(Note 3) "Fuel Fabrication Facilities" refers to JAEA plutonium fuel fabrication facility.
(Note 4) The changes of the figures may occur from the movements of materials between material balance areas
in a facility caused by samplings for analysis and inspection, safety check of storage materials, andconsolidation of nuclear materials.

Reactors and Other Facilities

Fast Reactors(Note 5)

Commercial
Reactors

R&D Facilities,
etc. (Note 6)

Unirradiated fuel held at nuclear reactor sites,etc.

411 (411)

418 (1,048)

113 (113)941 (1,572)

Total（＊）
Fissile Plutonium

659 (1,063)(Note 5) "Fast Reactors" refers to Joyo and Monju.
(Note 6) "R&D Facilities, etc." includes critical assemblies and other R&D facilities.

8,640 (9,277)

Total（＊）
Fissile Plutonium

5,814 (6,222)(2) Separated plutonium held abroad (Note 7)
This is the plutonium that was separated by reprocessors in the U.K. and France under the
reprocessing contracts with Japanese electric utilities. Basically, this plutonium is to be fabricated into
MOX fuels overseas, and transferred to Japan for use in light water reactors (LWRs). Thus,"Separated plutonium held abroad" should not be a concern from the peaceful use point of view.

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Provisional Translation

However, for the sake of better transparency, the current status of separated plutonium held abroadfor the fabrication of fuel is also shown below.

<Unit: kg Pu>
Separated plutonium
Fissile Plutonium
U.K.

21,735 (21,757)

14,458 (14,480)

France14,097 (14,113)

9,105 (9,122)

Total（＊）

35,831 (35,870)

23,563 (23,602)(Note 7) Nuclear losses (refer to Note 2 of Reference 2) are taken into account in the assessment of the amountof plutonium held in reprocessing facilities.

2.

Utilization of separated plutonium from Jan. to Dec. 2023
(Previous year’s figures in brackets)(1) The amount of separated plutonium recovered <Unit: kg Pu>
Amount of separated
plutonium recovered(Note 8)

Reprocessing Facilities
0 (0)(Note 8) "The amount of separated plutonium recovered" is defined as the amount of plutonium contained in MOX
powder recovered after separation and conversion processes.

(2) The amount of separated plutonium in fuel fabrication processes <Unit: kg Pu>
Amount of separated
plutonium in fuel fabrication
processes(Note 9)Fuel Fabrication Facilities
0 (0)(Note 9) "The amount of separated plutonium in fuel fabrication processes" is defined as the net amount of
plutonium contained in MOX powder, etc. transferred from raw materials storage areas into fabrication
process areas at fuel fabrication facilities.

(3) The amount of separated plutonium in MOX fuel loaded and irradiated in nuclear reactors<Unit: kg Pu>
Amount of separated
plutonium in MOX fuelloaded and irradiated innuclear reactors (Note 10)

Nuclear Reactors
631 (629)(Note 10) "The amount of separated plutonium in MOX fuel loaded and irradiated in nuclear reactors" is definedas the amount of plutonium contained in unirradiated MOX fuel which was loaded into the nuclear reactor
cores for use as fuel and irradiated. The MOX fuels that are loaded into the reactor cores are either
unirradiated or in the process of irradiation. For the sake of clarity, the figure here specifically refers to theloaded and irradiated amount.
(＊) The total figures may not agree completely due to rounding.

5

Provisional Translation[Reference 1]

The amount of separated plutonium held in nuclear reactors and other facilities in Japan as of the end of the year 2023.
Plutonium held(Note 1)(Unirradiated separated plutonium)
Organization

Plutonium loaded into the reactors
out of the "Plutonium held" in the left
column (Note 2)(Unirradiated separated plutonium)(Reference Data) "Total amount of
unirradiated separated plutonium
loaded into the reactor cores by theend of the year 2023" minus "Totalamount of irradiated plutonium
unloaded from the reactor cores"(Note 3)

Fast Reactors

Commercial
Reactors

Research andDevelopment
Facilities, etc.

Total (kg Pu)

Fissile plutonium
in total(kg Puf)

Total (kg Pu)

Fissile plutonium(kg Puf)

Total (kg Pu)

Fissile plutonium(kg Puf)Japan Atomic Energy Agency

411

286

－

－

261

184

Tokyo Electric
Holdings

205

138

－

－

210

143

Chubu Electric Power Company

213

145

－

－

－

－

Kansai Electric Power Company

－

－

－

－

1,440

924

Shikoku Electric Power Company

－

－

－

－

198

136

Kyushu Electric Power Company

－

－

－

－

160

103

Japan Atomic Energy Agency（Critical assemblies and other R&D
facilities）

113

91

Others

0

0

Power

Company(Note 1) Unirradiated separated plutonium held at the end of the year 2023
(Note 2) Plutonium loaded into the reactors out of the unirradiated separated plutonium held at the end of the year 2023
During the year 2023, unirradiated separated plutonium equivalent to 631kg Pu was irradiated at Takahama Unit 3.
(Note 3) It is equivalent to the weight of plutonium of the unirradiated MOX fuel staying in the reactor cores at the end of the year 2023. For commercial reactors, some irradiated fuels may be removed to spent
fuel pools temporarily for facility periodic inspection.
Additional information for reference (as of the end of the year 2023):
・Irradiated plutonium contained in spent fuel at reactor sites and elsewhere excluding reprocessing facilities: 157,842kg Pu
・Irradiated plutonium contained in spent fuel in the storage facilities at reprocessing facilities: 26,734kg Pu
・Small amount of plutonium contained in radioactive waste and recognized as irrecoverable for the time being: 136kg Pu

6

Provisional Translation[Reference 2]

The Balance of Separated Plutonium held in Japan as of the end of the year 2023.
Unit: kg Pu< Variations during the year 2023> (Note 1)
Total amount of plutonium newly loaded into reactors and irradiatedPlutonium shipped in and out at facilities
Variance in processes at facilities
Balance

△ 631
△ 0
△ 6
△ 637

[Reprocessing Facilities]
From separation and purification process to storage of raw material
at co-conversion process in the reprocessing facility(Note 1)
Inventory as of Jan. 1, 2023 (the end of the year 2022)
Plutonium shipped in (in 2023)
Plutonium shipped out (in 2023)
Variance in processes at reprocessing facility (Note 2)increase
Transfer to retained waste
andRetransfer from retained waste
decrease
Breakdown Nuclear loss
Measured discard
Material unaccounted for (MUF)
Inventory as of Dec. 31, 2023

3,793
0
△ 0
△ 3
△ 5.3
3.8
△ 0.6
△ 0.0
△ 1.0
3,790

[Fuel fabrication Facilities]
From raw material of MOX to fuel assembly products (Note 1)
Inventory as of Jan. 1, 2023 (the end of the year 2022)
Plutonium shipped in (in 2023)
Plutonium shipped out (in 2023)
Variance in processes at fuel fabrication facility (Note 2)increaseandTransfer to retained waste
decrease
Retransfer from retained waste
Breakdown
Nuclear loss
Material unaccounted for (MUF)
Inventory as of Dec. 31, 2023

3,912
0
△ 0
△ 3
△ 0.1
0.1
△ 2.9
△ 0.3
3,908

[Nuclear Reactors and Other Facilities]"Fast Reactors", "Commercial Reactors", and "R&D Facilities, etc." (Note 1)
Inventory as of Jan. 1, 2023 (the end of the year 2022)

increaseanddecrease

Plutonium shipped in (in 2023)
Decrease by plutonium newly loaded into reactors and irradiated (in2023)
Plutonium shipped out (in 2023)
Variance at reactor sites(Note 2)
Breakdown

1,572
0
△ 631
△ 0
△ 0

Nuclear loss, etc.

△ 0.0

Inventory as of Dec. 31, 2023

941

7

Provisional Translation(Note 1) The total may not agree due to rounding. "△" indicates consequential decrease.
(Note 2) The variances in processes at each facility includes, in addition to receipts into and shipments from the facility,
inventory change in the material control and accounting (transfer to retained waste, retransfer from retained
waste, nuclear loss, measured discard and so on), and material unaccounted for. The definition of inventorychange and material unaccounted for are described below. These are concepts recognized internationally inthe measurement and control of nuclear fuel materials. The variance that causes the reduction of inventory is
shown with "△".
 Transfer to retained waste:
Amount of the nuclear fuel materials that are removed from the book inventory, which is deemed to be in
unrecoverable status for the time being but which is held, such as plutonium contained in high-level
radioactive liquid or low level radioactive liquid generated in the process of recovering nuclear fuelmaterials from spent fuel solution.
 Retransfer from retained waste:
Amount of the nuclear fuel materials that had been retained as waste but was re-classified as the bookinventory in order to be processed for volume reduction and other purposes.
 Nuclear loss:
Amount of the loss (decrease) of nuclear fuel materials as a result of natural decay.
 Measured discard:
Amount of the nuclear fuel materials that has been measured or estimated on the basis ofmeasurements, and disposed of in such a way (verification, etc.) that is not suitable for further nuclear
use.
 Material unaccounted for (MUF):
The difference between the book inventory and the physical inventory that is defined by actual
measurement. MUF is inevitably generated from measurement error or adhesion of plutonium toequipment in a facility where plutonium is treated in powder or liquid state.

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Provisional Translation[Reference 3]

The Status of Separated Plutonium in Japan (2023)

Unit: kg Pu(Transferred amount in a facility andvariances in processes at facilities)[Total amount irradiated]
Amount of plutonium loaded into
reactors and irradiated[Separated plutonium
held abroad]Totalamountabroad△631

Variances in Facilities

35,831△0[Amount of Holdings]
Nuclear Reactors
and Other Facilities

Unirradiated fuel, etc.

941

Spent Fuels
Total amountshipped out

0

Total amountin Japan(Transferred amount in a facility andvariation in processes at a facility)[Used amount]
Amount of plutonium in fuelfabrication processes－

Variances in processes△3[Amount of Holdings]
MOX powder, etc
Unirradiated fuel, etc.
Total

3,358
550

Fuel Fabrication
Facilities(Transferred amount in a facility andvariation in processes at a facility)

8,640[Total amount separated]
Amount of plutonium in reprocessed
spent fuel[Amount recovered]Amounts of plutonium contained in
MOX powder recovered

Reprocessing Facilities

Variances in processes－－△3[Amount of Holdings]
Total amountshipped out－

MOX powder, etc.

3,790

3,908
(Note 1) "Amount of Holdings" is the figure as of the end of the year 2023.
(Note 2) "Transferred amount in a facility and variances in processes atfacility" shows the figure for one year in 2023.
(Note 3) "△" indicates decrease.
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Provisional Translation[Reference 4]

The Amount of Plutonium Held in Japan as of the end of the year 2023 publishedby the IAEA under the Guidelines for the Management of Plutonium(Previous year’s figures in brackets)
Annual figures for holdings of civil unirradiated plutonium*１（Unit：t Pu）
1. Unirradiated separated plutonium in product stores at
3.8
(3.8)
reprocessing plants
2. Unirradiated separated plutonium in the course of
3.4
(3.4)
manufacture or fabrication and plutonium contained inunirradiated semi-fabricated or unfinished products at fuel orother fabricating plants or elsewhere
3. Plutonium contained in unirradiated MOX fuel, including that
1.4
(1.9)
loaded into a reactor core prior to use, or other unirradiatedplutonium in fabricated products at reactor sites or elsewhere
4. Unirradiated separated plutonium held elsewhere
0.1
(0.1)
［Sum of lines 1-4 above］*2(ⅰ) Plutonium included in lines 1-4 above belonging to foreign
bodies.
(ⅱ) Plutonium in any of the forms in lines 1-4 above held in
locations in other countries and therefore not included above.
(ⅲ) Plutonium not included in lines 1-4 above which is ininternational shipment prior to its arrival in the recipient State.

[

8.6

(9.3)

0

(0)

35.8*3(35.9*3)

0

(0)

]

Estimated amount of plutonium contained in spent civil reactor fuel*4（Unit：t Pu）
1. Plutonium contained in spent fuel at civil reactor sites.
158
(156)
2. Plutonium contained in spent fuel at reprocessing plants.
27( 27)
3. Plutonium contained in spent fuel held elsewhere.
<0.5(<0.5)*5［Sum of lines 1-3 above］[ 185(183) ]
（Definition）
Line 1：covers estimated amounts of plutonium contained in fueldischarged from civil reactors
Line 2：covers estimated amounts of plutonium contained in fuelreceived at reprocessing plants but not yet reprocessed.
*1: Rounded to 100 kg plutonium.
*2, *5: The sum is calculated for the sake of convenience and it is out of the scope of thereport under the Guidelines.
*3: Loss of Pu-241 due to radioactive decay is taken into account in the assessment of theamount of fissile plutonium held at the overseas reprocessing plants.
*4: Rounded to 1,000 kg plutonium.

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Provisional Translation[Reference 5]

The Amount of Plutonium Held in Each Country as of the end of the year 2022 publishedby the IAEA under the Guidelines for the Management of Plutonium（Unit：t Pu）

Unirradiatedplutonium＊１

Plutonium containedin spent fuel＊２

U.S.

49.2

804

Russia

64.5

197

U.K.

140.8

28

France

106.2

303.3

China

－＊３

－＊３

Japan

9.3

183

Germany

0.0

129.8

Belgium（< 50kg）＊4

48

< 2kg

22

Switzerland

The figures in the column of Japan is corresponded to those appeared in Reference 4.
The figures of the other countries are computed by the Office of Atomic Energy Policy Cabinet
office of Japan based on the data taken from IAEA publication.
＊１：The total amount of unirradiated separated plutonium in product storage ofreprocessing plants, in the course of manufacture, plutonium contained inunirradiated MOX fuel product in reactor sites etc., and elsewhere ( Rounded to
100 kg plutonium). The items reported as less than 50 kg are not included.
＊２：The total amount of plutonium contained in spent fuel at civil reactor sites, at the
reprocessing plants and held elsewhere ( Rounded to 1,000 kg plutonium), The
items reported as less than 500 kg are not included.
＊３：Not available at the time of IAEA publication.
＊4：The items reported as less than 50 kg which are in the course manufacture,plutonium contained in unirradiated MOX fuel product in reactor sites etc. or
elsewhere.
[A short history of the Guidelines for the Management of Plutonium]
In Feb.1994, the nine countries, i.e. U.S., Russia, U.K., France, China, Japan,
Germany, Belgium and Switzerland started to deliberate on the establishment of aninternational framework aimed at enhancing the transparency of plutonium utilization.

11

Provisional Translation

In Dec.1997, these nine countries decided on the Guidelines for the Management of
Plutonium that provided the basic norms about plutonium management, transparency
through publication of the amount of plutonium held in each country and the importanceof non-proliferation.
In Mar.1998, the IAEA published for the first time the amount of plutonium held ineach country and the policy of each country about plutonium utilization reported to the
IAEA under the Guidelines.

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