Transmutation of long lived nuclear wastes
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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. Background. Concern to radioactive waste management has been increasing in Japan.

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Transmutation of long lived nuclear wastes

June 1-6, 2014

ARIS2014

Transmutation of Long-lived Nuclear Wastes

Hiroyuki Oigawa

Officeof Strategic Planning (Nuclear Science and Engineering Directorate, and J-PARC Center)

Japan Atomic Energy Agency


Background

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.


Transmutation of long lived nuclear wastes

Major Long-lived Nuclides in Spent Nuclear Fuel

Fission products (FP)

Trans-uranic elements (TRU)

Actinides

Minor actinides (MA)

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.


Partitioning and transmutation p t

Partitioning and Transmutation (P&T)

Spent fuel

Reprocessing

Recycle

U、Pu

Geological disposal (Glass waste form)

FP、MA

Conventional scheme

P&T 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


Reduction of radiological toxicity by p t

Reduction of Radiological Toxicity by P&T

Radiological Toxicity: Amountof 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 fuel100,000y  ↓

  • High-level waste 5,000y  ↓

  • MA transmutation 300y

Reduction

Reduction

Time after reprocessing (Year)


Transmutation of long lived nuclear wastes

Howto Transmute MA and LLFP

Mo-102

(T1/2=11min.)

Tc-102

(T1/2=5s)

Ru-102

(stable)

Example of fission reaction of MA

β-ray

β -ray

Np-237

(T1/2=2.14M yr.)

Fission reaction

(n, f)

Neutron

Note: 10% or less of FPs are Long-lived ones.

Fast neutrons (> 1MeV)

High energy neutrons (> 10MeV)

Neutron

β -ray

β -ray

I-133

(T1/2=21hr.)

Xe-133

(T1/2=5d)

Cs-133

(stable)

Thermal neutrons

T1/2:Half life

Example of (n, 2n) reaction of LLFP

Example of capture reaction of LLFP

Te-125

(stable)

Sb-125

(T1/2=2.8yr.)

Sn-125

(T1/2=9.6d)

Sn-126

(T1/2=230k yr.)

Xe-130

(stable)

I-130

(T1/2=12hr.)

I-129

(T1/2=15.7M yr.)

Capture reaction

(n, γ)

(n, 2n) reaction

Neutron

Neutron

Β-ray

Β-ray

Β-ray


Transmutation of long lived nuclear wastes

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.


Transmutation of long lived nuclear wastes

Examples of “Reduced Half-life”

“Reduced Half-life” can be written as T1/2 = ln2 / (φ·σ ), if there isno competitive reaction nor production reaction, where φ is neutron flux and σ is reaction cross section.

Condition of realistic transmutation: φ·σ >1015(barn/cm2/s)


Transmutation of long lived nuclear wastes

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

MA: Minor Actinides

LBE: Lead-Bismuth Eutectic

Power generation

Transmutation by ADS

MA-fueled LBE-cooled subcritical core

Utilizing chain reactions in subcritical state

Proton

Spallation target

Fission neutrons

Fast 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.

Short-lived or stable nuclides

Long-lived nuclides (MA)


Transmutation of long lived nuclear wastes

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 :

    • 10%MA / Year

  • 600EFPD, 1 batch

Conceptual view of 800 MWth LBE-cooled ADS


Components of double strata fuel cycle concept

Components of Double-strata Fuel Cycle Concept

U [752t/y]

Pu [8t/y]

Scope of P&T

Partitioningprocess

Fission Products (FP) [39t/y]Minor Actinides (MA) [1t/y]

Reprocessing

Spent fuel

[800t/y]

Dedicated

transmutation fuel

Fuel fabricationprocess

Minor actinides (MA)

Remaining

elements

PGM

Sr-Cs

[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


Transmutation of long lived nuclear wastes

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

  • R&D of SC-LINAC

  • Reliability Assessment

  • Construction and operation of J-PARC accelerator

  • R&D 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


Transmutation of long lived nuclear wastes

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 (<10s) 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. >5min.

Beam trip duration


Transmutation of long lived nuclear wastes

Design of Beam Window

Temperature

Outer surface

Temperature

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.


Transmutation of long lived nuclear wastes

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


Transmutation of long lived nuclear wastes

Japan Proton Accelerator Research Complex:J-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


Transmutation of long lived nuclear wastes

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 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


Transmutation of long lived nuclear wastes

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, 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

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


Transmutation of long lived nuclear wastes

Working Party to Review Partitioning and Transmutation Technology

  • The Ministry ofEducation, 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.


Transmutation of long lived nuclear wastes

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 collaborationis of great importance.


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