Transmutation of Long-lived Nuclear Wastes

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Transmutation of Long-lived Nuclear Wastes
June 1-6, 2014 ARIS2014
Hiroyuki Oigawa Office of Strategic Planning
(Nuclear Science and Engineering Directorate,
and J-PARC Center) Japan Atomic Energy Agency
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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.

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Major Long-lived Nuclides in Spent Nuclear Fuel
Nuclide Half-life (year) Dose coefficient(µSv/kBq) Mass (per 1tHM)
U-235 0.7B 47 10kg
U-238 4.5B 45 930kg
Nuclide Half-life (year) Dose coefficient(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
Fission products (FP)
Nuclide Half-life (year) Dose coefficient(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
Trans-uranic elements (TRU)
Actinides
Minor actinides (MA)
Nuclide Half-life (year) Dose coefficient(µSv/kBq) 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.
a-activity is more influential than ß,?-activity.
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Partitioning and Transmutation (PT)
Spent fuel
Reprocessing
Recycle
U?Pu
Geological disposal (Glass waste form)
FP?MA
Conventional scheme
PT technology
MA (Np, Am, Cm)
Transmutation by ADS and/or FR
PGM (Ru, Rh, Pd)
Utilization and/or disposal
Partitioning(Example)
Geological disposal after cooling and/or
utilization (Calcined waste form)
Heat generator (Sr, Cs)
Geological disposal (high-density glass waste
form)
Remaining elements
MA Minor Actinides FP Fission Products PGM
Platinum Group Metal FR Fast Reactor ADS
Accelerator Driven System
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Reduction of Radiological Toxicity by PT
Radiological Toxicity Amount of radioactivity
weighted by dose coefficient of each nuclide.

• Normalized by 1t of spent fuel.
• 9t of natural uranium (NU) is raw material of 1t
  of low-enriched uranium including daughter
  nuclides.

Spent fuel (1t) High-level waste MA
transmutation Natural uranium (9t)
Radiological toxicity (Sv)

• Time period to decay below the NU level
• Spent fuel 100,000y ?
• High-level waste 5,000y ?
• MA transmutation 300y

Time after reprocessing (Year)
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How to Transmute MA and LLFP
Example of fission reaction of MA
Np-237 (T1/22.14M yr.)
T1/2 Half life
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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.

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Examples of Reduced Half-life
Reduced Half-life can be written as T1/2
ln2 / (fs ) , if there is no competitive
reaction nor production reaction, where f is
neutron flux and s is reaction cross section.
Nuclide Half-life (year) Reaction Neutron energy Cross sections (JENDL-4.0)(barn10-24cm2) Neutron flux f (/cm2/s) Neutron flux f (/cm2/s) Neutron flux f (/cm2/s)
Nuclide Half-life (year) Reaction Neutron energy Cross sections (JENDL-4.0)(barn10-24cm2) 1013 1014 1015
Nuclide Half-life (year) Reaction Neutron energy Cross sections (JENDL-4.0)(barn10-24cm2) Reduced half-life (year) Reduced half-life (year) Reduced half-life (year)
Am-241 432 n,f Fiss. Spec. 1.378 1,600 160 16
Tc-99 211k n,? Maxwell 23.68 93 9.3 0.93
Tc-99 211k n,2n 14MeV 1.233 1,800 180 18
Sn-126 230k n,? Maxwell 0.09 24,000 2,400 240
Sn-126 230k n,2n 14MeV 1.686 1300 130 13
I-129 15.7M n,? Maxwell 30.33 72 7.2 0.72
I-129 15.7M n,2n 14MeV 1.464 1,500 150 15
Cs-135 2.3M n,? Maxwell 8.304 260 26 2.6
Cs-135 2.3M n,2n 14MeV 1.61 1,400 140 14
Cs-137 30.1 n,? Maxwell 0.27 8,100 810 81
Cs-137 30.1 n,2n 14MeV 1.549 1,400 140 14
Condition of realistic transmutation fs gt1015
(barn/cm2/s)
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Accelerator Driven System (ADS) for MA
Transmutation
Proton beam
Max.30MW
Super-conducting LINAC
100MW
To accelerator
800MW
170MW
Fission energy
To grid
Spallation target (LBE)
270MW
Power generation
MA Minor Actinides LBE Lead-Bismuth Eutectic
Transmutation by ADS
MA-fueled LBE-cooled subcritical core
Utilizing chain reactions in subcritical state
Proton
Spallation target
Fission neutrons

• Characteristics of ADS
• 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.

Fast neutrons
Long-lived nuclides (MA)
Short-lived or stable nuclides
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ADS Proposed by JAEA

• 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
• 10MA / Year
• 600EFPD, 1 batch

Conceptual view of 800 MWth LBE-cooled ADS
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Components of Double-strata Fuel Cycle Concept
U 752t/y Pu 8t/y
Scope of PT
Partitioningprocess
Fission Products (FP) 39t/yMinor Actinides
(MA) 1t/y
Reprocessing
Spent fuel
800t/y
Dedicated transmutation fuel
Fuel fabricationprocess
Remaining elements
Sr-Cs
PGM
Minor actinides (MA)
1t/y
8t/y
4t/y
5t/y
AcceleratorDriven System(ADS)
30t/y
Transmutation cycle
7t/y
Optimization by utilization / Disposal after
cooling
Recovered actinides
Spent fuel
1t/y
Reprocessing
Fission products
Final disposal
8t/y
PGM Platinum Group Metal
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Technical Issues for ADS
J-PARC Japan Proton Accelerator Research
Complex TEF-P Transmutation Physics Experimental
Facility TEF-T ADS Target Test
Facility SC-LINAC Superconducting LINAC

• Accelerator

• RD of SC-LINAC
• Reliability Assessment
• ?Construction and operation of J-PARC accelerator

• RD of Pb-Bi technology
• ?Construction of TEF-T in J-PARC

• Structure

• Spallation Target, Material
• Operation of Pb-Bi system

• Design study on reactor vessel, beam duct,
  quake-proof structure, etc.

• Experiments in existing facilities and analyses
• ?Construction of TEF-P in J-PARC

• Fuel

• Fabrication, irradiation and reprocessing tests

• Reactor Physics
• Control of Subcritical System

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Reliability of Accelerator
Number of beam trips per year (7,200 hours)

• 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 (lt10s) can meet the criteria.
• Longer beam trip should be decreased by
• Reducing the frequency of trips and
• Reducing the beam trip duration

Acceptable trip rate
Beam trip rate (times/year)
Estimation from experiences
0-10s 10s 5min. gt5min.
Beam trip duration
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Design of Beam Window

• Beam window is subjected to severe conditions
• High temperature
• Corrosion and erosion by LBE
• Pressure difference between vacuum and LBE
  (0.8MPa)
• Irradiation by protons and neutrons

• 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.

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Accuracy of Neutronics Design
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

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Japan Proton Accelerator Research ComplexJ-PARC
Hadron Experimental Facility
Jan. 28, 2008
50 GeV Synchrotron
Materials and Life Science Experimental Facility
To neutrino detector
3 GeV Synchrotron
Site for Transmutation Experimental Facility
LINAC
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Transmutation Experimental Facility (TEF) of
J-PARC
Transmutation Physics Experimental Facility TEF-P
ADS Target Test FacilityTEF-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
lt500W
Purpose To research and develop a spallation
target and related materials with high-power
proton beam. Licensing Particle
accelerator Proton beam 400MeV-250kW Target
Lead-Bismuth Eutectic (LBE, Pb-Bi)
Multi-purpose Irradiation Area
Critical Assembly
10W
Pb-Bi Target
250kW
Proton Beam
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International Collaboration with MYRRHA
ADS without MA fuel(LBE coolant, Accelerator,
Operation of ADS)
Power
ADS Transmutation plant 30MW-beam, 800MWth
Transmute 250kg of MA annually
Experimental ADS?MYRRHA 2.4MW-beam, 50100MWth
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
TEF in J-PARC MYRRHA
Purpose RD 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 50100MWth
MA Mock-up experiment of transmutation system with massive MA (kg order) Irradiation experiment with small amount of MA
TEF in J-PARC250kW-beam LBE target technology
Reactor physics of transmutation system
Basic research (LBE loop test, KUCA experiments)
year
2050
2010
2020
2030
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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 RD 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 RD of
  the facility to the next stage.
• For MYRRHA Program, it is appropriate to proceed
  with negotiation about JAEAs 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.

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Concluding Remarks

• ADS provides us a possibility to flexibly cope
  with the waste management in various situations
  of nuclear power.
• RD 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.