June 1-6, 2014
ARIS2014
Transmutation of
Long-lived Nuclear Wastes
Hiroyuki Oigawa
Office of Strategic Planning
(Nuclear Science and Engineering Directorate, and J-PARC Center)
Japan Atomic Energy Agency
1
Background
 Concern to radioactive waste management has been increasing in Japan.
 Transmutation technology for long-lived nuclides is drawing the attention
from public, media and politicians.
 JAEA (former JAERI and PNC/JNC) has been studying this technology for
more than 20 years.
 The Ministry of Education, Culture, Sports Science and Technology (MEXT) in
Japan has launched a Working Party to review Partitioning and
Transmutation Technology in August, 2013, and issued an interim report in
November, 2013.
2
Major Long-lived Nuclides in Spent Nuclear Fuel
0.7B
47
10kg
U-238
4.5B
45
930kg
Minor actinides (MA)
Trans-uranic elements (TRU)
Dose
Actinides
(per 1tHM)
U-235
Half-life
coefficient
Nuclide
(year) (μSv/kBq)
Mass
(per 1tHM)
Pu-238
87.7
230
0.3kg
Pu-239
24k
250
6kg
Pu-240
6.6k
250
3kg
Pu-241
14.3
4.8
1kg
Dose
Half-life
coefficient
Nuclide
(year) (μSv/kBq)
Dose
Mass
Fission products (FP)
Dose
Half-life
coefficient
Nuclide
(year) (μSv/kBq)
Half-life
coefficient
Nuclide
(year) (μSv/kBq)
Mass
(per 1tHM)
Se-79
0.3M
2.9
6g
Sr-90
28.8
28
0.6kg
Zr-93
1.53M
1.1
1kg
Tc-99
0.21M
0.64
1kg
Pd-107
6.5M
0.037
0.3kg
Sn-126
0.23M
4.7
30g
I-129
15.7M
110
0.2kg
Cs-135
2.3M
2.0
0.5kg
Cs-137
30.1
13
1.5kg
Mass
(per 1tHM)
Np-237
2.14M
110
0.6kg
Am-241
432
200
0.4kg
Am-243
7.4k
200
0.2kg
Cm-244
18.1
120
60g
Dose Coefficient:
Committed dose (Sv) per unit intake
(Bq), indicating the magnitude of
influence of radioactivity to human
body. α-activity is more influential
than β,γ-activity.
3
Partitioning and Transmutation (P&T)
Spent fuel
Reprocessing
FP、MA
Partitioning
Recycle
U、Pu
Geological disposal
(Glass waste form)
Conventional scheme
MA (Np, Am, Cm)
P&T technology
Transmutation by ADS and/or FR
PGM (Ru, Rh, Pd)
Utilization and/or disposal
(Example)
Heat generator (Sr, Cs)
Remaining elements
MA:
FP:
PGM:
FR:
ADS:
Minor Actinides
Fission Products
Platinum Group Metal
Fast Reactor
Accelerator Driven System
Geological disposal after cooling and/or
utilization (Calcined waste form)
Geological disposal
(high-density glass waste form)
4
Reduction of Radiological Toxicity by P&T
Radiological Toxicity:
Amount of radioactivity weighted by dose coefficient of each nuclide.
1.E+09
使用済燃料
Spent fuel (1t)
高レベル廃棄物
High-level waste
分離変換導入
MA transmutation
天然ウラン9トン
Natural uranium (9t)
toxicity (Sv)
Radiological
潜在的有害度（Sv）
1.E+08
1.E+07
1.E+06
• 9t of natural uranium
(NU) is raw material of
1t of low-enriched
uranium including
daughter nuclides.
Time period to decay
below the NU level:
1.E+05
• Spent fuel
1.E+04
100,000y
↓
• High-level waste 5,000y
↓
• MA transmutation 300y
Reduction
1.E+03
1.E+02
1.E+01
• Normalized by 1t of
spent fuel.
Reduction
1.E+02
1.E+03
1.E+04
1.E+05
Time after
reprocessing (Year)
処理後経過時間（年）
1.E+06
1.E+07
5
How to Transmute MA and LLFP
Example of fission reaction of MA
Np-237
Neutron
Mo-102
Tc-102
(T1/2=11min.)
β-ray
(T1/2=5s)
Ru-102
β -ray
(stable)
(T1/2=2.14M yr.) Fission reaction
(n, f)
Note: 10% or less of FPs
are Long-lived ones.
Fast neutrons (> 1MeV)
Neutron
β -ray
I-133
(T1/2=21hr.)
Xe-133
β -ray
(T1/2=5d)
Cs-133
(stable)
Example of capture reaction of LLFP
Xe-130
I-130
Capture
reaction
(T1/2=12hr.)
(T1/2=15.7M yr.)
(n, γ)
I-129
Neutron
(stable)
T1/2: Half life
Β-ray
Thermal neutrons
Example of (n, 2n) reaction of LLFP
Sn-126
Neutron
(T1/2=230k yr.)
High energy neutrons (> 10MeV)
(n, 2n) reaction
Sn-125
Sb-125
Te-125
(T1/2=9.6d)
(T1/2=2.8yr.)
(stable)
Β-ray
Β-ray
6
Cross Sections of Neutron-induced Reaction :
Am-241
Total
Scattering
Capture
Fission
inelastic
Chain reactions of fission by fast neutrons are advantageous for
transmutation of MA.
7
Examples of “Reduced Half-life”
“Reduced Half-life” can be written as
T1/2 ＝ ln2 / (φ·σ )
, if there is no competitive
reaction nor production reaction, where φ is neutron flux and σ is reaction cross section.
Nuclide
Half-life
Reaction
(year)
Am-241
432
Tc-99
211k
Sn-126
230k
I-129
15.7M
Cs-135
2.3M
Cs-137
30.1
n,f
n,γ
n,2n
n,γ
n,2n
n,γ
n,2n
n,γ
n,2n
n,γ
n,2n
Neutron
energy
Cross section
σ (JENDL-4.0)
(barn=10-24cm2)
Fiss. Spec.
Maxwell
14MeV
Maxwell
14MeV
Maxwell
14MeV
Maxwell
14MeV
Maxwell
14MeV
1.378
23.68
1.233
0.09
1.686
30.33
1.464
8.304
1.61
0.27
1.549
Neutron flux φ （/cm2/s）
1013
1014
1015
Reduced half-life (year)
1,600
160
16
93
9.3
0.93
1,800
180
18
24,000 2,400
240
1300
130
13
72
7.2
0.72
1,500
150
15
260
26
2.6
1,400
140
14
8,100
810
81
1,400
140
14
Condition of realistic transmutation: φ·σ >1015 (barn/cm2/s)
8
Accelerator Driven System (ADS)
for MA Transmutation
Proton beam Max.30MW
Super-conducting LINAC
100MW
To accelerator
800MW
170MW
Fission energy
To grid
MA: Minor Actinides
LBE: Lead-Bismuth Eutectic
Spallation target
(LBE)
270MWPower generation
Transmutation by ADS
Utilizing chain reactions in
subcritical state
Fission neutrons
Short-lived or stable
nuclides
MA-fueled LBEcooled subcritical
core
Proton
Spallation target
Fast neutrons Characteristics of ADS:
Long-lived
nuclides (MA)
• Chain reactions stop when the accelerator is
turned off.
• LBE is chemically stable.
 High safety can be expected.
• High MA-bearing fuel can be used.
 MA from 10 LWRs can be transmuted.
9
ADS Proposed by JAEA
Movable support
•
•
•
•
•
•
•
Proton beam : 1.5GeV
Spallation target : Pb-Bi
Coolant : Pb-Bi
Max. keff = 0.97
Thermal output : 800MWt
MA initial inventory : 2.5t
Fuel composition :
(MA +Pu)Nitride + ZrN
• Transmutation rate :
10%MA / Year
• 600EFPD, 1 batch
Bending magnet
Proton beam
Fuel exchanger
Beam duct
Primary pump
Steam generator
Spallation target
Reactor vessel
Subcritical core
Beam window
Core support
Conceptual view of 800 MWth LBE-cooled ADS
10
Components of Double-strata Fuel Cycle Concept
U [752t/y]
Pu [8t/y]
[7t/y]
Recovered actinides
Spent fuel
Reprocessing
[8t/y]
[1t/y]
Fission products
[4t/y] [5t/y]
Remaining
elements
Accelerator
Driven System
(ADS)
Sr-Cs
Dedicated
Fuel fabrication
transmutation fuel
process
[1t/y]
[8t/y]
PGM
Reprocessing
[800t/y]
Partitioning
process
Fission Products (FP) [39t/y]
Minor Actinides (MA) [1t/y]
Minor actinides (MA)
Spent fuel
Scope of P&T
[30t/y]
Optimization by utilization /
Disposal after cooling
Final disposal
PGM: Platinum Group Metal
11
Technical Issues for ADS
•Accelerator
• R&D of SC-LINAC
• Reliability Assessment
Construction and operation
of J-PARC accelerator
•Structure
•Design study on reactor
vessel, beam duct, quakeproof structure, etc.
•Fuel
•Fabrication, irradiation and
reprocessing tests
J-PARC: Japan Proton Accelerator
Research Complex
TEF-P: Transmutation Physics
Experimental Facility
TEF-T: ADS Target Test Facility
SC-LINAC: Superconducting LINAC
•R&D of Pb-Bi technology
Construction of TEF-T in
J-PARC
•Spallation Target, Material
•Operation of Pb-Bi system
•Experiments in existing
facilities and analyses
Construction of TEF-P in
J-PARC
• Reactor Physics
• Control of Subcritical System
12
Reliability of Accelerator
Number of beam trips per year (7,200 hours)
Beam trip rate (times/year)
Acceptable trip rate
 We are comparing the trip rate estimated
from data of existing accelerators and the
maximum acceptable trips to keep the
integrity of the ADS components.
 Short beam trip (<10s) can meet the criteria.
 Longer beam trip should be decreased by:
 Reducing the frequency of trips and
 Reducing the beam trip duration
Estimation from experiences
LANSCE
＋KEKB
J-PARC
0-10s
10s – 5min.
>5min.
Beam trip duration
13
9
1
φ4610
ビーム導入管
Cylinder
r3,i
Xi(=Xo)
θt
Transient part
・Suffix
i: inner, o: outer
490oC
ビーム窓
Temperature
o
外表面温度
Of beam
window 470 C
t3
(2700)
Partition wall
Flow control nozzle
450oC
t3
r2,o
3390
Temperatur
温度分布
e
Outer
surface
6450
r3,o
1030
High temperature
Corrosion and erosion by LBE
Pressure difference between vacuum and LBE (~0.8MPa)
Irradiation by protons and neutrons
1390
1890




Beam duct support
Proton beam
Beam duct
Beam window
Core barrel
Core region
Reflector
Target region
1000
 Beam window is subjected to severe conditions:
5250
Design of Beam Window内　筒
θ
θf
t2
r1,o
t2
Coolant flow
Zi (Zo)
zoff
r2,i
Constants
θf = 60°
r1,i = 200mm
r3,i = 225mm
r3,o = 235mm
Support structure
Transient part
r1,i
z
Top part
t1
x
t1
(unit: Kelvin)
 Temperature at the outer surface of the window can be less than 500ºC.
 Buckling failure can be avoided by a factor of safety (FS)=3.
 The life time of the beam window should be evaluated from viewpoints of corrosion
and irradiation.  necessity of irradiation data base.
14
Accuracy of Neutronics Design
JAEA J3.3
1.01
JAEA J3.2
1
JAEA J4.0
241Am
0.99
k-eff, JENDL
J4.0
0.98
207Pb
206Pb
0.97
0.96
0.95
J3.2, J3.3
0.94
0.93
BOC
EOC
Benchmark calculation for 800MWt ADS for BOC and EOC.
(Left: Comparison between JENDL-4.0 and JENDL-3.3, Right: Nuclide-wise contribution for differences in k-eff)
 There is 2% difference in k-eff between JENDL-4.0 and JENDL-3.2, which is too
large to design ADS.  necessity of integral validation of nuclear data
15
Japan Proton Accelerator Research Complex:
J-PARC
Jan. 28, 2008
Hadron Experimental Facility
50 GeV Synchrotron
Materials and Life Science Experimental
Facility
To neutrino
detector
3 GeV Synchrotron
Site for
Transmutation
Experimental Facility
LINAC
16
Transmutation Experimental Facility (TEF)
of J-PARC
Transmutation Physics
Experimental Facility: TEF-P
ADS Target Test Facility：TEF-T
Purpose: To investigate physics properties of
subcritical reactor with low power, and to
accumulate operation experiences of ADS.
Licensing: Nuclear reactor: (Critical assembly)
Proton beam: 400MeV-10W
Thermal power: <500W
Purpose: To research and develop a spallation
target and related materials with highpower proton beam.
Licensing: Particle accelerator
Proton beam: 400MeV-250kW
Target: Lead-Bismuth Eutectic (LBE, Pb-Bi)
Multi-purpose
Irradiation Area
Critical Assembly
Pb-Bi Target
Proton Beam
17
International Collaboration with MYRRHA
ADS without MA fuel
（LBE coolant, Accelerator,
Operation of ADS）
Power
ADS Transmutation plant
Experimental ADSMYRRHA
30MW-beam, 800MWth
・Transmute 250kg of MA annually
~2.4MW-beam, 50~100MWth
・Engineering feasibility of ADS and fuel
irradiation
Reactor physics of MA transmutation system and
material development for spallation target material
Advanced material for
beam window
KUCA Core
FFAG Accelerator
Ion Source
Proton Beam
Target
Subcritical
Reactor
KUCA
FFAG Acc.
Magnets
TEF in J-PARC
250kW-beam
・LBE target technology
・Reactor physics of
transmutation system
TEF in J-PARC
MYRRHA
Purpose
R&D for elemental
technology
(LBE target, Reactor
physics)
Fuel irradiation,
Accumulation of operation
experience of ADS
Power
250kW-beam
TEF-P : 500W (max.)
2.4MW-beam
Power : 50~100MWth
MA
Mock-up experiment of
transmutation system with
massive MA (kg order)
Irradiation experiment with
small amount of MA
Basic research (LBE loop test, KUCA experiments)
2010
2020
2030
2050
year
18
Working Party to Review Partitioning and
Transmutation Technology
 The Ministry of Education, Culture, Sports Science and Technology (MEXT) in Japan
has launched a Working Party to review Partitioning and Transmutation Technology in
August, 2013.
 An interim report was issued in November, 2013.
Key Descriptions:
To reduce the burden of HLW management, it is expected that flexibility in future political
decision is extended by showing possibilities of new concepts of back-end with high social
receptivity.
The ADS Target Test Facility (TEF-T) is being proposed under J-PARC to verify the feasibility of
the beam window. It is appropriate to shift the R&D of the facility to the next stage.
The Transmutation Physics Experimental Facility (TEF-P) is being proposed under J-PARC to
overcome difficulties in reactor physics issues such as for a subcritical core and an MA-loaded one.
Since this facility is proposed as a nuclear reactor, the safety review by the new regulation is to
be applied. With taking care of this point, it is appropriate to shift the R&D of the facility to the
next stage.
For MYRRHA Program, it is appropriate to proceed with negotiation about JAEA’s
participation at a reasonable level and mutual collaboration with Belgium and other relevant
countries.
Progress of the development should be checked according to its stage.
19
Concluding Remarks

ADS provides us a possibility to flexibly cope with the waste
management in various situations of nuclear power.

R&D on ADS and its compact fuel cycle are under way in JAEA,
and we are proposing the Transmutation Experimental
Facility as the Phase-II of J-PARC.

To overcome various technical challenges for this technology,
the international collaboration is of great importance.
20