What is the vision for nuclear energy thatsupports carbon neutrality in 2050?
Reiko Fujita
Former President of Atomic Energy Society of Japan
Former Program Manager of ImPACT* Program*ImPACT : Impulsing Paradigm Change through Disruptive Technologies Program

Present situation in Japan

Japanese government has no vision for nuclear energy in 2050.
In Japan, where resources are scarce, the land is small, the population
density is high, the large amount of spent nuclear fuel will begenerated from many nuclear power plants built in the future.
One of most important issue in Japan is radioactive waste such as
Minor Actinides (MA*) reduction.
Japan has no role model for nuclear fuel cycle all over the world.
Because Russia and France have no MA recycle but only Uranium (U)and Plutonium (Pu) recycle.
Japan's original nuclear fuel cycle with reactor safety should beclarified as nuclear energy that supports carbon neutrality in 2050.
MA*: More heavier nuclides than U such as Neptunium, Americium, Curium and so on in next page

Minor Actinides (MA) in Spent Nuclear Fuel MA are contained in high level radioactive wastes(HLW) and should be reduced.
 The radioactivety of HLW decreases less than that ofnatural Uranium within 300 years with MA
transmutation .
 MA Transmutation research has already started in theNuclear Fuel Cycle by JAEA’s ADS-PJ and FBR.

Radioactivity (Bq)

1E+9

Spent fuel
HLW
MA Trans.

1E+8
1E+7

Natural Uranium

1E+6

NuclidesHalf life(Billionyear)

Radiation
conversion
coefficient(μ Sｖ/ kBq)

Content(Spentfuel /ton)

U-235

0.7

4710 kg

U-238

4.5

45930 kg

NuclidesHalf life(year)

Radiation
conversion
coefficient(μ Sｖ/ kBq)

Content(Spentfuel/ ton)

Pu-23887.7

230

0.3 kgPu-239

24000

250

6 kg

Pu-240

6564

250

3 kg

TRU Pu-241

14.3

4.8

1 kg

NuclidesHalf life(year)

Radiation
conversion
coefficient(μ Sｖ/ kBq)

Content(Spentfuel/ ton)Np-237

2.14Million110

0.6 kgAm-241432

200

0.4 kgAm-2437370

200

0.2 kgCm-244

18.1

120

Ac

1E+51E+4MA

1E+31E+21E+1

1E+21E+31E+4

1E+51E+61E+7

Time after Spent Fuel reprocessing (Years)

360 g

Why is Purex process not suitable for FBR multi recycle with MA?
Spent Oxide fuel with MA recycle is difficult to be dissolved by only boiling HNO3 solution
such as Purex process.
The complex oxides such as the fuel debris from Three Mile Island Reactor-2 (TMI-2)
accident in the U.S. has been found to be dissolved by not only boiling HNO3 but added HF*.
 The organic solvent such as Tributyl Phosphate (TBP) is easy to be attacked by strongly
radiation with MA and be produced degradative TBP such as Dibutyl Phosphate (DBP) or
Mono-butyl Phosphate (MBP).
 MA is not accompanied with Pu, therefore MA should be recovered from High Level Liquid
Wastes by additional process.
Fuel cycle cost increases than without MA recycle.
Russia and France gave up MA recycle in Purex process of oxide fuel FBR.

Clean fuel but dirty waste
High nuclear proliferation risk

*Reference :R.K.Mccardell et al., Nucl.Eng. Design, 118, 441 (1990)
D.W.Akers et al., EGG-OECD-9168 (1992).
Washiya et al., the next generation reprocessing technology
committee, 2012 Annual meeting (2012) [In Japanese]

Dissolution/Clarification/Separation/Purification in One Unit

Integrated FBR with fuel cycle (IFR)*
As core temperature increases, reactor power
decreases: Self- shutdown passive safety

MA is accompanied with Pu in liquid Cd cathode.
Product U,Pu
contain MA, FP

Low proliferation risk

*Reference: Y. I. Chang, “Integral fast reactor - a next-generation reactor
concept,” in Panel on future of Great Lakes symposium on smart grid
Low Decontamination and the new energy economy, Sept. 24-26, 2012.

process

Dirty fuel but clean waste

The principle of the pyrochemical process for metallic fuel cycle
Reference : The Sasakawa Peace Foundation’s Project “Research on Sustainability of Nuclear”, Technical Feasibility report of an Integral Fast Reactor(IFR) as a Future Option for Fast Reactor Cycles -Integrate a Small Metal-Fueled Fast Reactor and Pyroprocessing Facilities-

Pyrochemical process for an accident debris and MA

Reference : The Sasakawa Peace Foundation’s Project “Research on Sustainability of Nuclear”,
Technical Feasibility report of an Integral Fast Reactor (IFR) as a Future Option for Fast Reactor Cycles-Integrate a Small Metal-Fueled Fast Reactor and Pyroprocessing Facilities-

Summary

The vision for nuclear energy that supports carbon neutrality is desirable
Japanese nuclear fuel cycle with reactor safety.
The desirable nuclear fuel cycle required in Japan:① Utilization and reduction of Plutonium with nuclear non- proliferation risk
② Radioactive Wastes such as Minor Actinides reduction③ A reprocessing method with low decontamination factor and a treatment ofdebris from the Fukushima Daiichi Nuclear Power Plant Accident④ Economical and multi nuclear fuel cycle
One of most promising candidates for fuel cycle is a metallic one
with dirty fuel but clean waste.

We propose to start the experiments of the debris from Fukushima
Daiichi Nuclear Power Plant Accident cooperated with the U.S, in orderto make sure the feasibility of pyrochemical process for the debristreatment.

Thank you for your kind attention!

Small Metal-Fueled Reactor Safety
As core temperature increases, reactor power decreases: Self- shutdown passive safety(Reactor Shutdown using Reactor Safety)

Adopt a passive mechanism to more reliably shut down the reactor and prevent core damage GEM (GasExpansion Mechanism) produces a large negative reactivity effect for flow reduction type events.
Reference : The Sasakawa Peace Foundation’s Project “Research on Sustainability of Nuclear”, Technical Feasibility report of an Integral FastReactor (IFR) as a Future Option for Fast Reactor Cycles -Integrate a Small Metal-Fueled Fast Reactor and Pyroprocessing Facilities-

Demonstration Test of Passive Safety of Small Metal Fuel Reactors
Intrinsic safety verification test of small metal-fueled reactors at the EBR-II experimental reactor in the United States
Example of simulated test results for failed reactor emergency shutdown (ATWS) event conducted from May 1985 toApril 1986 (1) Flow rate decrease from rated power (ULOF), (2) Secondary flow rate shutdown from rated power(ULOHS) The reactor core was not damaged and the reactor was safely shut down.

EBR-II・Sodium cooling・Small metal fuel・Electrical output: 20,000 kWe
・Thermal output: 62,500 kWt
Reactor coolant outlet temperature rises sharply to about
200°C in about 30 seconds ⇒Neutron leakage increases
due to thermal expansion of core components ⇒Reactor
output drops due to negative reactivity feedback ⇒Reactor
coolant outlet temperature drops

Reactor coolant inlet temperature rises by approximately
40°C in about 10 minutes ⇒Neutron leakage increases
due to thermal expansion of core components ⇒Reactor
output drops due to negative reactivity feedback ⇒Reactor
coolant outlet temperature stabilizes

Reference：M.T. Farmer, et. al, “US Experience and Current Activities Related to Passive Shutdown Systems for SFRs, Tech. mtg on Passive Shutdown Systems
for Liquid Metal-Cooled Fast Reactors, IAEA, 21 Oct. 2015
Reference : The Sasakawa Peace Foundation’s Project “Research on Sustainability of Nuclear”, Technical Feasibility report of an Integral Fast Reactor (IFR) as a Future Option for FastReactor Cycles -Integrate a Small Metal-Fueled Fast Reactor and Pyroprocessing Facilities-

LWR running with a long life and introduction ofMetallic fuel FBR with fuel cycle in 2060
Start of introduction of Metallic fuel FBR with fuel cycle in order to replace with
old existing LWR in 2050
LWR running life extended with 80 years similar to United States in 2050
Full-scale Introduction ofMetallic fuel FBR with fuelcycle in 2060
Stop running JMOX fuelfabrication to storage Pu for
FBR in 2050

(10,000kW)

LWR spent MOX fuelfor interim storage

LWR spent MOX fuelfor reprocessing(10,000kW)

Real introduction
Current LWR plant of FBR(80 years running)

Rokkasho reprocessing plant

Second era of FBRFirstFirsteraeraof
ofFBR
FBR

Second reprocessing plant

Introduction of FBR 既設炉80年で高速炉導入
in place of existing LWR with 80 years
Reference: Agora investigation committee, com_agora_gei202206.pdf (aesj.net)

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