Transmutation

Robert HillArgonne National LaboratoryNational Technical Director – Advanced RConceptsNRC Seminar SeriesDecember 8, 2010
Outline

 Current Fuel Cycle Perspective

– Technical Overview of Options– Role of Transmutation

 Transmutation Options

 A ti id T t ti Actinide Transmutation

– Previous Fuel Cycle Studies– Current R&D Program

 Fission Product Transmutation
Potential Fuel Cycle Options

Ore recovery, refining and 

enrichment Fuel

Reactor Geologic disposal of used fue

Electricity, process heat

Once-Through (Open) 

Modified Open * Electricity, process heat

Geologic disposal o

f l ( ft t l 

Full Recycle (Fully Closed) *

Separation

Ore recovery, refining and 

enrichment Fuel

Reactor

Electricity, process heat

Geologic 

waste

Fuel treatment

Geologic d

waste

Ore recovery, refining and 

enrichment

Fuel

Reactor fuel (after at le

reburn)

*A specific fuel cycle strategy may include more than one fuel design, reactor design, or fuel treatmen

Transmutation technology needed for latter two fuel cycle opti
Modified Open Cycle Example

 Breed and burn concepts 

– Enhanced uranium utilization using 

natural uranium feed material

– Fuel conditioning option to extend life

 Deep burn of transuranics in nonuranium inert matrix fuels uranium inert matrix fuels

– Initial fuel processing required, but 

direct disposal after deep burn

– High-temperature gas reactor fuel, or– Driven systems to extend burnup

 DUPIC process for recycle of LWR 

fuel into CANDU reactors

 Neutron-source driven options:

– Fusion-fission systems– Accelerator driven systems

Starter

(Initial active core)

Depleting zone

(Depleted uranium)

8.0 m

1.2 m
Fast Spectrum Breed and Burn Principles

 Enriched U-235 (or Pu-239) starter core would be 

surrounded by a blanket of fertile fuel

 Enriched fuel would produce neutrons that generate 

power and convert fertile fuel to fissionable fuel

 Irradiated fertile fuel would replace enriched fuel 

after original U-235 (or Pu-239) is burned and new Pu239 is formed

 Use of “Standard Breeders” exploit this physics in 

conjunction with reprocessing

 Complete U-238 conversion and fission, with the 

uranium utilization limited only by losses

 Breed and Burn concepts promote conversion, but 

minimize reprocessing (modified open)

 Once fertile zone dominates, once-through 

uranium utilization at the fuel burnup limit

Tra
Traveling Wave Approach

for Breed-Burn Concept

U8

Natural Uranium

U8

99.3% DU

F lBlanket

Enriched Uranium 

(15-20%)

Mass Blanket

Mass Fuel ~ 25

• High utili

possible with adv

• Cleanup 

allows fo

U5 0.7% U5

U8

Fuel

Startup 

Fuel

l

1

l

2

l

2

l

1

~ 25

• The physics works• Difficult design 

issues for control 

1D Core Model (Candle)

d1

d2

d2d1 

2D Core Model

• Radia

unlike

• Look

shuff

• High • Toug
Alternative “Traveling Fuel” Approach

 Thermal power = 300 Core configuration

– Number of assem– Active core 

• Height=1.6 m

3.3 m

– Blanket thicknes

• Radial = 0.5 

Fuel volume frac

Active core zone

Blanket zone

Reflector

Fuel Cycle Boundaries and Limits

– Fuel volume frac– Initial core enrich

 Fuel management sc

– 34-batch and 1.5– DU is fed to radia

resides for 21 yeshuffled to active 

– Fuel resides in ac

years and discha

 Overall breeding rati Equilibrium core stat

DU

Burnt 

Fuel
Comparison of Once-Through 

Cycle Performance

 Thermal reactor systems

– PWRs with burnups of 50 GWd/t and 100 GWd/t

 Fast reactor systems – breed and burn concepts

– CANDLE Constant 

Axial shape of 

Neutron flux, nuclide density a

shape 

During 

Life of 

Energy production by Tokyo Institu

Technology (TIT), Japan

– SSFR Sustainable Sodium-Cooled Fast Reactor by ANL– FMSR Fast mixed spectrum reactor by BNL– ULFR Ultra Long Life Fast Reactor by ANL– TWR Traveling Wave Reactor concept by TerraPower LLC– EM2 Energy Multiplier Module by General Atomics

 PWRs, CANDLE, SSFR/FMSR, and ULFR results are pr
CANDLE

Power Density Evolut

 Burn-zone (power) propagates from starter region to dep

– Reactor operation time is dependent on height of depletion regio
Reactor Performance Paramet

Parameter PWR-50/100 CANDLE SSFR Reactor power, MWt 3000 3000 3000 Thermal efficiency, % 33.3 40.0 40.0 Fuel Form UO2 U-Zr U-Zr 

Uranium enrichment, % 4.2 / 8.5 1.2 a) 6.2 / 0.25 

Number of batches 3 1 34 

Burnup GWd/t Burnup, GWd/t 50 / 100 50

/ 100 258 277 

Specific power density, MW/t 33.7 3.7 16.9 Cycle length per batch, yr 1.5 / 3.0 b) 200 1.5 

HM inventory, t 89 824 178 HM fission, t/yr 1.03 1.03 1.02 

 Compared to PWR systems, once-through fast reactor syst

have significantly derated power densities

 Due to long fuel residence time, however, average burnups 

than that of PWRs

a) First core and subsequent cores b) Reactor operation time with 8 m active core height
Deep-Burn Example in Gas Re

TRISO

Barrier Fuel

48

42

36

30

24

LWR

 Transuranics are separated from LWR used fuel Non-uranium TRISO fuel burned in gas-cooled thermal react

– Optimum packing fraction and kernel size were determined– Four batch scheme to maximize single pass deep burnup (~5– Spent TRISO could be direct disposed or stored for recycle 

Higher Temperature

Improved FP Retention

1

2

3

LWR

Transuranics

Repository (or Interim Storage)

Pu, Np, Am
Full Recycle Options

with Actinide Management

 A wide variety of full recycle 

strategies have been explored

Energy Production 

Reactor

Recycle Used 

U i

Extend Uranium 

Resources

strategies have been explored

 Transmutation options ranging from 

conventional reactors to sourcedriven minor actinide fuels

 In closed cycle, used fuel separated 

into re-useable and waste materials

 Residual waste will go to a 

geological repository 

 Recycled material converted in 

transmutation system

 Fuel cycle closure with repeated 

recycle (e.g., in a recycle reactor)

Transmutation 

System

Recycle Fu

Fabricatio

Uranium
Transmutation Technology

 The recycle material is transmuted for either waste ma

or resource extension purposes

– Fission of selected actinides, termed “actinide burning”– Conversion of problematic waste isotopes (e.g., to shorter de– Conversion of natural uranium into usable fuel materials 

 For actinide transmutation the recycled fuels produce

actinide transmutation, the recycled fuels produce

significant energy in the transmutation process

– Transmutation systems are expensive (often dominate fuel c

– Potential for revenue production with energy conversion– Handling of radioisotopes and heat is a key safety considera

 Therefore, performance goals include:

– Efficient transmutation of targeted waste materials– Efficient utilization of uranium resources

– Efficient and safe energy utilization
Transmutation R&D Objectiv

The mission is to research and develop advanced techno

significantly improve the efficiency and safety perform

transmutation systems

Three grand challenges are identified:

 Develop transmutation options that meet a broad rang

Develop transmutation options that meet

a broad rang

cycle strategies ranging from deep burn actinide cons

to extended uranium utilization

 Develop high performance transmutation options with 

energy products – comparable to LWR generation cos

 Demonstrate prevention of radiation release to public 

events – normal operation, accidents, or malevolent ac
Outline

 Current Fuel Cycle Perspective

– Technical Overview of Options– Role of Transmutation

 Transmutation Options

 A ti id T t ti Actinide Transmutation

– Previous Fuel Cycle Studies– Current R&D Program

 Fission Product Transmutation
Resource Utilization

 Natural uranium is 

significantly under-utilizedby current and innovative advanced once-through

nuclear systems

– LWR utilization less than 1%

10.0

100.0

l Utilization (%)

10.0

100.0

l Utilization (%)

Theoretical Uraniu

(assuming complete 

– LWR utilization less than 1%– Utilization in advanced oncethrough systems less than 2%– Theoretical limit of fuel burnup

for breed-burn concepts

 Any system that requires enriched will have limited ura

utilization, <1% to fuel burnup limit (~20% for fast react

 Full recycle options can approach full utilization, >90% 

on recycle losses

0.11.0

0 20 40 

Uranium Enrich

Theoretical

0.11.0

0 20 40 

Uranium Enrich

Theoretical
 Radiotoxicity reflects the hazard of the source materials

– TRU dominate after about a 100 years; FPs contribution to radiotoxic

small after 100 years

 Radiotoxicity alone does not provide any indication of how a 

repository may perform

– Engineered and natural barriers serve to isolate wastes or control 

release of radionuclides 

Waste Hazard and Risk Measu

0.001

0.01

0.1

1

10

100

1000

10000

10 100 1000 10000 100000 1000000 10000000

Time after Discharge (year)

Normalized Radiotoxicity

UOX SNF - TotalUOX SNF - FP w/o Tc & IUOX SNF - Tc & IUOX SNF - NpUOX SNF - Actinide w/o Np

242 

Pu 237Np

99Tc 129I 239Pu 242 

Pu 237Np 99Tc 129I 239Pu
 Cs/Sr (and decay products), Cm, and Pu dominate “early” de

 Am dominates “later” decay heat Removal of decay heat producers would allow for increased 

of repository space

Advanced Nuclear Fuel Cycle Potential Benefits
Neutron-based Transmutation

Most transmutation strategies utilize neutrons to convert  High cross sections and flux are attractive for nuclide c Achievable neutron flux level limited in practice

– Limits transmutation rate achievable for most radionuclides, pa

fission products

 Once-through near through near-complete consumption is prohibited 

complete consumption is prohibited 

limits (e.g., irradiation damage) in most situations 

 Reactors have operated for over 60 years and are matu

– Low cost fast reactors being developed

 Continuous recycle of fuel material in advanced reactor

allow ~99% uranium utilization and eliminate need for uenrichment, and drastically improve repository utilizatio

– Conversion ratio must be greater than 1– Fast reactors ideal for this purpose
Non-Neutron-based Transmut

 Non-neutron elementary particles have been consider Charged particle systems – protons, electrons, ions, e

also been considered

 Photon-based (high-energy) systems to induce photo-

reactions

– New sources of mono-energetic photons may enable transm

select isotopes that are difficult to treat with other processes

 Electromagnetic radiation (EM)-based systems 

– Directly transmute individual isotopes by exciting nuclei with 

narrow-band EM radiation to pre-defined energy levels promenhanced 

β-decay to more stable, less hazardous or stable e

– Source of EM radiation can be lasers and rf-fields
Gamma Transmutation 

 Conceptually possible to use gammas for transmutation of T

stable or shorter-lived nuclides by inducing fission, or raisinto an energy level that then decays via neutron or beta emis

 High photon energies (several MeV) required to initiate these 

 Currently, photons generally produced with an electron acce

Brehmstraulung on a heavy metal target resulting in a contiBrehmstraulung on a heavy metal target, resulting in a conti

photon energy spectrum

– Most of photons are produced below desired MeV range, wh

coupled with relatively low interaction probability results in a transmutation rate 

 Thus, technologies capable of producing high flux, mono-en

photons required for efficient transmutation
Proton Transmutation 

 Likely not cost-effective, as it requires high-energy/high-cur

accelerator (1-2GeV, 100s of mA) to overcome Coulomb barrneeds sufficiently high proton flux for effective transmutatio

 Energy required to produce high-power proton beams would 

these systems net user rather than generators of power

 High gas production in any actinide-containing targets and a

embrittlement of cladding/structural materials introduces adcomplexities that need to be addressed

 High-power proton beam could also generate neutrons in irr

material via spallation

– Bulk of transmutation may derive from the neutrons (e.g., AD

 Thus, transmutation based on direct nuclide interaction with 

does not appear to offer any advantages relative to neutron-systems
Summary on Non-Neutron-bas

Transmutation Options

 Significant research and development required before 

approaches can be practically used for transmutation 

 Non-neutron systems for nuclear power production ar

ineffective due to fundamental physics limitations

– Low intensity and production-efficiency of particles– High system cost

 Advanced materials required for significant nuclide co Energy balance is important

– Electric power required for transmutation very likely more tha

generated while transmuting nuclides 

– Systems would be impractical for power production, and cou

relegated to use as scientific instruments where efficiency is 
Outline

 Current Fuel Cycle Perspective

– Technical Overview of Options– Role of Transmutation

 Transmutation Options

 A ti id T t ti Actinide Transmutation

– Previous Fuel Cycle Studies– Current R&D Program

 Fission Product Transmutation
 Reduce the long-term environment burden of nuclear e

through more efficient disposal of waste materials

– Remove transuranics (TRU) from waste– More efficient utilization of permanent disposal space

– Significantly reduce released dose and radiotoxicity

 Enhance overall nuclear fuel cycle proliferation resistan

Objectives of Advanced Fuel C

Enhance overall nuclear fuel cycle proliferation resistan

improved technologies for spent fuel management

– Avoid disposal of weapons usable materials– Improve inherent barriers and safeguards

 Enhance energy security by extracting energy recovera

fuel, avoiding uranium resource limitations

– Extend nuclear fuel supply

 Continue competitive fuel cycle economics and excelle

performance of the entire nuclear fuel cycle system
Extensive Previous Studies 

Full Recycle Fuel Cycle Opti

 Systematic evaluations of transmutation in reactor systems and Ac

Driven Systems (ADS) were conducted under the ATW/AAA/AFCI Pr

 Assessment of recycle in LWRs

– Conventional mixed oxide (MOX) and inert matrix fuels

– Recycle of all transuranics and/or limited elements (e.g., Pu+Np)

– Limited recycle (1-5 passes) in a tiered fuel cycle strategy

 Fast reactor transmutation options

Fast reactor transmutation options

– Comparison to fast spectrum ADS options– Variable conversion ratio for actinide management

– Application as second tier transmuter after LWR recycle

 Transmutation impacts of all six Generation-IV reactor options

 Other specific transmutation issues or systems

– Deep-burn in gas-cooled thermal systems– Plutonium transmutation in CANDU reactors– Long-lived fission product transmutation– Reduced moderation water reactors– Heterogeneous recycle strategies (i.e., targets) in thermal and fast r
Density of Use of Evaluation 

Criteria in Past Advanced FueCycle Studies

Evaluation Criteria Density of Use in Past SNuclear waste management HighResources HighProliferation risk MediumSafety Low/mediumSecurity LowEconomics LowTechnical maturity Low/medium

Basis: Table generated from pure observation• First three criteria used in the past as indicators of system effectiven

• R&D is to ensure that systems are feasible, safe, secure, and econom
 Radiotoxicity quantifies the effect of exposure (hazard)

– Effectively assumes complete release and uptake

 Repository environment will impact radiological risk

– Regulatory limit is based on released dose

– All material is contained for ~10,000 years

Waste Management Criteria and Benefits

– Plutonium moves slowly, fission products quickly– Maximum dose results from Np-237 in long-term

 Repository design is typically constrained by thermal limits 

– For Yucca Mountain license application based on high-tempe

operating mode (HTOM) of the cold repository, criteria were:

• peak temperature below the local boiling point (96 oC) at a

midway between adjacent drifts

• peak temperature of the drift wall below 200 oC at all time
Radiotoxicity of LWR Spent 

1 E+011.E+021.E+031.E+04

Hazard Total 

Total 

1.E-031.E-021.E-01

1.E+00

1.E+01

1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

Time, years

Relative CD H Np-23

Pu-23Pu-24Am-2
Systems Studies Scenarios 

Considered in Multi-Tier Study 

Approach Tier I Thermal System Tier II Fast System 

 Type Power 

(GWt) 

Fuel 

Form 

Type Fuel 

Scenario 1: Double-Tier Variations with Pu Separated from MA

1x-S1 ALWR 3.0 MOX 1x-S2 ALWR 3.0 MOX 

ADS NFF 

 ALWR and Adv

Cooled Reactofor Tier I

– ALWR uses 

nonfertile fuZrO

2-TRUO

1xt ALWR 3.0 MOX Burner Fertile GT MHR us1z ALWR 3.0 NFF ADS NFF 1g GT-MHR 0.6 NFF ADS NFF 

Scenario 2: Double-Tier Variations with Pu and MA Together 

2x ALWR 3.0 MOX ADS NFF 2z ALWR 3.0 NFF ADS NFF 2g GT-MHR 0.6 NFF ADS NFF 

Scenario 3: Single-Tier Variations with Pu and MA Together 

3m ADS NFF 3t 

n.a. 

Burner Fertile 

– GT-MHR us

TRISO fuel

 Tier II units are 

accelerator-drivor burner react

– Fuel form fo

TRU-40Zr, wthe burner s30TRU-10Z

– Tier II units 

rating of 0.8
Key Conclusions from FY2001 

Multi-Tier Fuel Cycle Study

 Given clean fuel processing 

(0.1% losses), typical goals for transmutation can be achieved

– TRU and plutonium losses to waste 

less than 0.6%

– Radiotoxicity below level of natural 

ore in < 1,000 years

 First-tier thermal spectrum irradiation 1 00E-01

1.00E+001.00E+011.00E+021.00E+031.00E+04

First tier thermal spectrum irradiation

does not significantly reduce the radiotoxicity

– Confirms need for a final tier fast 

spectrum system 

 Utilization of first-tier thermal 

spectrum system can increase the Tier 2 support ratio

– Fewer specialized transmutation 

systems required

 Better benefit measures (heat load, 

dose) in recent studies

1.00E-01

10 100 

Time (years)

0.1

1

10

100

1000

10000

10 100 1000 10000 

Time (years)
Importance of Processing Los

Fraction

Impact of Loss Fraction - Single Tier ATW Case

1 00E+021.00E+031.00E+04

xicity 0

Toxicity goal cannot be achieved if loss fraction increases beyon

0.2%, and extends to 10,000 years at 1% losses

1.00E-01

1.00E+001.00E+01

1.00E+02

10 100 1000 10000

Time (years)

Relative Tox 0

01
 Radiotoxicity alone does not provide any indication of how a g

repository may perform

– Different species are more mobile, depending on environment a

242 237 226Ra

99Tc 129I 239Pu 242 237 226Ra 99Tc 129I 239Pu

Repository Released Dose (Yucca Mountain Example)

242Pu 237Np 226Ra Pu I 242Pu 237Np 226Ra Pu I
Repository Thermal Response (YM Example)

Heating in Drift 

→

120160200

ature, C

 51 GWd/MTIHM Spent PWR Fuel,  Emplaced 25 Years After Discharge

Drift Loading = 58.6 GWd/m

(1.15 MTIHM/m)

Waste Package

Surface (average)

Drift Wall

Between Drifts

Water Boiling, 96 C 

0

4080

1 10 100 1000 

Time after Disposal, years

Tempera

Airflow 

Turned Off
Potential for Repository Drift Loading Increa

 Separation of Pu 

for denser loading repository

– up to a factor 

99.9% remov

 Subsequent sepa

Sr provides for mbenefit

– up to a factor 

up to

a factor 

99.9% remov

 Removal of Cm fu

increases the pot(with Pu & Am)

– greater than a 

with 99.9% re

 Appropriate wast

needed to take adthis potential
Comparison of Repository Be

for Fast Reactor Limited Recy

2.53.03.54.04.55.0

e in Repository Drift Loading 

Inert Matrix Fuel (IMF)CORAIL-PNAMOXFast Reactor CR=0.25Fast Reactor CR=1.00 

 Fast reactor recycle yields ~1.5 benefit in first recycle

– Sustained for subsequent recycles – isotopic denaturing not severe

– Small impact for extended cooling time – less sensitive to TRU isoto

 Remote processing allows quicker turnaround time for each recycl

0.00.51.01.52.0

01234567

Total Number of Recycles

Relative Change

All LWR fuel processed at 5 

years after reactor discharge - maximize loading benefitFuel fabricated and loaded after an additional 2 years

Spent fuel sent to the repository after the last recycle, along with all prior 

t
Evaluation of Multi-Recycle 

 Significant research on multi-recycle in conventional LWRs has bee

both in U.S. programs and international collaboration with CEA

Consensus is that continuous recycle can be achieved within two imp

constraints:

1. An external fissile “support” feed is required

– Neutron balance of recycled TRU not sufficient to sustain criticality

– Standard 5% enriched uranium or other fissile feed can be utilized

Standard 5% enriched uranium or other fissile feed can be utilized

2. A technique to manage higher actinide buildup is required

– Initial recycle may be possible, but neutron source from very high ac

becomes fuel handling problem (see backup #20)

– Long cooling time approach can mitigate

– Separation of curium can prevent higher actinide generation

 Safety impact of high TRU content fuels must also be considered

– May limit fraction of core loading, particularly for current LWRs

 In practice (e.g., France), thermal recycle limited by constraints rela

handling that get progressively worse each recycle
 From physics perspective, repeated 

recycle can be achieved

 TRU content gradually increases with 

recycle stage

 Power peaking may be a problem at high 

TRU enrichment 

2

4

6

8

0369

12

2345

Cycle

Normalized decay heat 

205

370

693

1000

10000

on source source Normalized decay heat

Evaluation Multi-Recycling of in LWR Transmutation Reacto

 High minor actinide content complicates 

fuel handling and usage, therefore, number of recycles may be limited in practice

Mass Evolution with TRU Recycling

82

205

1

10

100

2345

Cycle

Normalized neutro

3

5

7

8

0369

12

2345

Cycle

Normalized gamma energy 

emission rate 

Fuel Handling Indices at FaCompared to CORAIL Compared to CORAIL-Pu C

Pu C

Norm. gamma source Norm. neutron s

05

10152025

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

CYCLE

U enrichment

or TRU content,%

303540455055

c Fissile in TRU, %TRU-content Fissile in TRU

Uranium Enrichment
 A wide variety of recycle reactor options have been considere

– In short-term, LWRs are and will be the dominant reactor type– Early replacement plants will likely be advanced LWRs (ALWR

– Generation-IV advanced reactors

Comparison of Generation-ITransmutation Reactor Opti

0.400.450.50

SFR, metalSFR, oxideLFR, nitrideVHTR

 Neutrons are moderated by water 

in LWRs and by graphite in most 

gas cooled reactors

Actinide transmutation behavior is very different between fast/

0.000.050.100.150.200.250.300.35

1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+0

Energy (eV)

Flux/Lethargy 

VHTRPWR gas-cooled reactors

– Fission reactions occur in the 

“thermal” peak 

 In fast reactors, light materials 

are avoided and moderation is significantly reduced

– Fission reactions occur in the 

“fast” energy range
0.30

0.400.500.600.700.800.901.00

Fission/Absorpt 

Impact of Neutron Energy SpeTransmutation Behavior 

 Fissile isotopes are likely to fission in both thermal/fast spec

– Fission fraction is higher in fast spectrum

 Significant (up to 50% in Pu-240) fission of fertile isotopes in 

Net result is more excess neutrons and less higher actinide ge

0.000.100.20

U235U238Np237Pu238Pu239Pu240Pu241Pu242Am241Am243Cm244

F
Fast reactors with full recycle can effectively manage transura

 Can be configured as 

modest breeders (CR 

≥ 1) 

to moderate burners (CR 

≥ 0.5) 

with conventional technology

High Leakage PRISM Mod 

Actinide Management Flexibiliin Fast Spectrum Systems

 Low conversion ratio designs 

(CR<0.5) were investigated for transmutation applications

– Use High enrichment fuels 

 Safety performance will change at low uranium content 

(e.g., reactivity losses, reduced Doppler coefficient) 

– Detailed safety analysis conducted for (CR 

≥ 0.25) (<50% e

– Passive safety behavior is not compromised

Low Enrichment Fuel High Enrichment Fuel C

Reflector Shield Gas 
Comparison of Fast Spectru

Reactor (FR) and ADS Syste

 Electricity generation costs of ADS will be higher than FR op

– Differences of 10-25% in total fuel cycle cost-of-electricity

 Fast reactors ideal in protracted full recycle options

– Significant electricity generation and plutonium consumption

– Possible transition to uranium resource extension mode

 ADS best suited to limited transmutation inventory

ADS best suited to limited transmutation inventory

– Target deep burnup in LWRs before recycle, or 

– Apply to only the minor actinide inventory

 Different level of maturity and technical risk

– ADS requires additional technology development– Fuel cycle R&D requirements similar for both options

 Future nuclear energy scenario is a key consideration

– Growth – favors FR with flexible conversion ratio– Contraction – ADS system (using non-uranium fuel) provides 

rapid transmutation rates
FRs

FR SNF 

Separations Process Waste

Driver Assemblies Target Assemblies

FR SNF

Heterogeneous Recycle

Figure shows TRU path only

FRs

FR SNF 

Separations 

Fuel Assemblies

FR SNF

Homogeneous Rec

Figure shows TRU path 

Homogeneous and HeterogenRecycle Approaches

LWRs

LWR SNF 

Separations

Driver Fuel 

Assembly 

Fabrication

Target Fuel 

Assembly 

Fabrication

UOX SNF

Process Waste

MA Product Stream Pu Product Stream 

(or with Np)

LWRs

LWR SNF 

Separations

FR Fuel 

Assembly 

Fabrication

UOX SN

GroupProdu

SNF = Spent Nuclear FuelFR = Fast ReactorLWR = Light-Water ReactorMA = Minor Actinides
Advantages

 Allows use of technology similar to existing 

recycle fuel fabrication and co-extraction processes for early deployment of advanced fuel cycle technology 

– Conventional recycle fuel form for driver 

assemblies easier to fabricate (at least the first recycle of Pu or Pu-Np will not need to 

be remote)

Disadvantages Number of assemblies con

reduced, but still significan

– Target-containing reacto

fraction of nuclear park

 Target assemblies difficult 

manufacture and transport 

– High radiation dose and 

 He production in target ass

Advantages and DisadvantageHeterogeneous Recycle

be remote)

– Potential to permit time for additional R&D 

to find manageable solutions to handling of high dose/heat minor actinides (MA)

 Reduces number of MA-containing 

assemblies to be fabricated and handled prior to core loading

 Potential to confine remote fabrication of 

MA-containing fuels with lower throughput to dedicated sub-facility for fabrication

 Flexible management of MA loading in the 

core

 He production in target ass

significant and must be ma

– Development of advanc

stable under irradiation 

– R&D to investigate fabri

to investigate behavior u

 Core fuel management diff

“ex-core

” targets are expos

neutron flux gradient

– Difficult to achieve high 

within irradiation damagstructural material

– Accommodate with core 
General Directions of U.S.

Fast Reactor R&D

 For most closed fuel cycle options, must develop and 

demonstrate recycle reactor transmutation technology

– Limited recycle in thermal systems can be used for partial tra– Fast spectrum needed for final transmutation system

 For future fast reactor technology, research is focused 

performance improvements (i.e., result in major commperformance improvements (i.e., result in major comm

reductions or efficient electricity generation)

– Improved design approach (e.g., compact configuration)

– Advanced technologies (e.g., materials, energy conversion)– Advanced simulation for optimized design

 A second research focus is assurance of safety to pro

design simplification and licensing

 A third, related focus is high system reliability
Technical R&D Areas

Fast System R&D is focused on several technical discipli Nuclear Data

– Improved measurements and uncertainty evaluations

 Advanced Energy Conversion Systems

– Improved efficiency and reliability

 Advanced Materials

Advanced Materials

– High strength, robust alloys

 System Integration

– Utilization of technology innovations and estimation of benefi

 Safety Research

– Inherent safety approach and regulatory issues

Other DOE-NE R&D initiatives include fast reactor applica Modeling and Simulation Transmutation Fuels Separations (recovery of the nuclides for transmutatio
Nuclear Data:

Time Projection Chamber (T

 Sub-percent fission measurements will 

significantly reduce uncertainties that impact reactor and fuel cycle integral quantities

 TPC will provide 3D “pictures” of the 

charged particle trajectories

– Alpha backgrounds removed– Sample auto-radiograph (α particles)– Beam non-uniformities

Multi actinide targets

– -actinide targets

 TPC will use thin backing foils (<50μg/cm2)

– Minimize beam interaction backgrounds– Maximize efficiency– Minimize multiple scattering of fragments– H2 drift gas will also minimize scattering

 TPC will provide data on both fission 

fragments simultaneously

– Random backgrounds removed (vertex 

requirement)

– Fission vertex with <100 μm resolution (fission radiograph)

Fission fragments
 Multiple goals to improve 

performance

– Better thermal efficiency– Compact economic benefits

 Demonstration of key features of 

supercritical CO2 Brayton cycle

Advanced Energy Conversion

p 2 y y

 Development and testing of 

control strategies

 Confirmation of materials and 

performance durability

Recent Accomplishments• Now testing MWt turbomachinery test loop with recuperators• Produced electric power at low temperature and efficiency
Environmental testing of 

Advanced Materials

 Environmental (thermal, radiation and/or coolant) can have 

a significant impact on mechanical performance and alloy stability

 Thermal Aging 

– Time at temperature may degrade material properties.

 Irradiation Testing 

– Initial irradiation and PIE on candidate alloys will start in 

FY09

– Initial Testing will help prioritize PIE from MATRI

X-II

– Some HT-UPS samples from FFTF/MOTA experiments 

have also been identified

– Data interpretation and semi-empirical modeling will guide 

future tests and needs

 Corrosion in Sodium 

– Corrosion in liquid metals must be evaluated and 

understood for the candidate alloys

– The pumped-Na loop at ANL will be utilized in addition to 

convection-driven loops at ORNL

– Initial burden-modeling activities will also provide insight into 

transfer of C, O, and/or N around the reactor loop
System Integration Example:

Impact of Advanced Materials

 Four benefits considered: 

improved safety margins, longer lifetime, thinner 

components, higher operating 

temperature

 Calculated the equivalent 

thickness of the component given the material properties of 

the advanced materialsthe advanced materials

 Did not perform detailed 

calculations to determine the feasibility of fabrication

 Did not estimate differences in 

cost for alloys nor fabrication costs – used material mass as a surrogate measure

 Estimated reduction of about 

45% in considered structures

 The trend is important not

absolute value
Modeling and Simulation:

Performance Improvements

 Higher fidelity modeling allows improved performance 

existing technology

– Conservative assumptions employed for current designs– Provides assurance of performance and safety behavior– E.g., lower peak temperature (similar average) with advanced 

 Integrated physics modeling in future design tools allo

optimization of configuration and performance

– Can tailor system based on more detailed understanding– Streamlines iterations to investigate design refinements– For example, can directly examine impact of geometric tolera

 Facilitates the exploration and assessment of innovati

configurations and features outside the existing datab

– Predictive capability allows wide range of performance compa– Useful to guide and tailor validation experiments for new featu
Modeling/Simulation Example

 Axially-independent cross 

flow terms used in the subchannel model are not able to resolve the axial periodicity in the temperature due to the wire wraps (see arrows)

 Temperature distribution is 

symmetric in the subchannel results, but skewed in the RANS (advanced model) results

 Cross flow terms from higherfidelity modeling would result 

in better agreement between subchannel and RANS

Differences Between Steady-State Subchannel Coolant Temperature Distributions in a 217-Pin 
Outline

 Current Fuel Cycle Perspective

– Technical Overview of Options– Role of Transmutation

 Transmutation Options

 A ti id T t ti Actinide Transmutation

– Previous Fuel Cycle Studies– Current R&D Program

 Fission Product Transmutation
Fission Product Transmutatio

Objectives

 Long-lived fission products (LLFP) can be significant contribu

term environmental dose rate from a repository

– Due to repository environment LLFP quite mobile (e.g. at Yucca Moun

transuranic (TRU) inventory is reduced significantly by continuous tran

 ANL study conducted within ATW program to (1) devise optim

for LLFP transmutation, (2) evaluate transmutation potentials 

and fast spectrum nuclear systems (3) assess transmutation and fast spectrum nuclear systems, (3) assess transmutation 

Yucca Mountain repository

– W. S. Yang, Y. Kim, R. N. Hill, T. A. Taiwo, and H. S. Khalil, “Long-Liv

Product Transmutation Studies,” Nuc. Sci. and Eng., 146, 291–318 (2

 Impacts of Tc-99 and I-129 transmutation (leading LLFP) on Y

– Transmutation unnecessary as regulatory dose rate limit met without i– Tc-99 and I-129 transmutation can reduce peak dose rate by factors o

– Significant transmutation could allow some relaxation of stringent was

container performance criteria, with associated economic benefits

– Some development of either specialized waste forms or transmutation 

LLFP is prudent
Transmutation Half-life of LLFPs

Isotope

Capture Cross Section1) Decay

Half-Life

( )

Transmutation Half-life2)

Pure Iso

Fast Thermal Fast Thermal Transmu

• For effective transmutation, transmutation half-life 

should be much smaller than natural decay half-life

• Nb-94, Tc-99, Pd-107, I-129, Cs-135, and Sm-151 are transm

either thermal or fast system

• Other nuclides require extremely high flux level for effectiv

transmutation

T c/

tr 1/2

=

AFCI Transmutation Studies

Pioneering Science andTechnology

1) ORIGEN2 library (fast: oxide fuel LMFBR; thermal: standard PWR)2) Thermal flux = 1.0E+14, fast flux = 1.0E+15 (n/cm2⋅sec)

(year) Transmu

Neutron Neutron Neutron Neutron

Se-79

Sr-90

Zr-93

Nb-94

Tc-99

Pd-107Sn-126

I-129

Cs-135Cs-137

Sm-151

0.002

0.010.090.220.450.53

0.007

0.350.070.012.09

0.330.081.034.229.322.790.033.122.480.03

660

6.5E+4

29

1.5E+52.0E+42.1E+56.5E+61.0E+51.6E+72.3E+6

3089

1.1E+42.2E+3

244100

4942

3.1E+3

63

314

2.2E+3

11

666

2.7E+3

213

522479

7.3E+3

7089

7.3E+3

0.33

Non-transmNon-transmQuestionablTransmutabTransmutabTransmutabNon-transmTransmutabTransmutabNon-transmTransmutab
Comparison of LLFP Transmutation Pri

Isotope

Transmutation Needs Isotope 

Separation

Toxicity Half-life Requirement Repository Impact Inventory

Nb-94 High High Low Very Low Weak

Tc-99 Medium High High High No

Pd-107 Low High Low Medium Strong

I-129 Medium High High Medium Weak

Cs-135 Medium High Medium Medium Strong

S 151 Hi h

L

L

L W k

AFCI Transmutation Studies

Pioneering Science andTechnology

• Transmutation priority can be ranked in the order of I-129, Tc-99, C

Nb-94

- I-129 and Tc-99 are major contributors to biosphere release dose rates 

their high geochemical mobility

- Cs-135 strongly requires isotopic separation because of much higher we

and capture cross sections of Cs-133 and Cs-134 

- Strong gamma rays emitted by Cs-137 make handling and isoto

separation of cesium very difficult

• The most problematic isotopes, Tc-99 and I-129, can be transmuted 

lived or stable isotopes via a single neutron capture

Sm-151 Hi

g

h

Low

Low

Low

Wea

k
• Neutron capture of Tc-99 forms Tc-100, which decays quickly to 

• Ru-100 is transmuted only to stable or short-lived isotopes by fu

capture

• Tc-99 can be effectively transmuted in the epithermal energy ran

Transmutation Characteristics of Tc-99

2.1E5

β d

15.8

(n,γ)

Ru-100

Tc-99Tc-100

Ru-99

AFCI Transmutation Studies

Pioneering Science andTechnology

β decay

42sec

39.3day

sec

Ru-101Ru-102Ru103Ru-104

Rh-103Rh-104 Pd-104

StableUnstable

Transmutation Chain of Tc-99 in Neutron Field

Capture Cross Sections of Tc-99 and (ENDF-B/VI)
• I-127 and I-129 are primarily converted to Xe-128 and Xe-130, res

- Isotopic composition of iodine: ~23% I-127 and ~77% I-129

• I-129 has a much larger capture cross section than I-127 and Xe-• Resonance integral of I-129 is much smaller than Tc-99 (RI=36b)

Transmutation Characteristics of I-129

25 min

Xe-128

I-127I-128

AFCI Transmutation Studies

Pioneering Science andTechnology

5.24 day

2.3 hr8.0 day12.3 hr

1.6E7 yr

Xe-129Xe-130Xe-131Xe-132

I-131I-130I-129I-132

Xe-133 Cs-133

β decay

(n,γ)

StableUnstable

Transmutation Chain of I-129 in Neutron Field

Capture Cross Sections of I-127, I-129 an(ENDF-B/VI)
• Metallic technetium 

- Irradiation tests High Flux Reactor at Petten showed a good 

behavior

- Technetium can be loaded homogeneously by co-mingling it 

• Metal iodides

- NaI and CaI2 have been reported to be desirable target form

- In NaI form, sodium may melt when it is liberated from the ta

iodine is transmuted to xenon gas

Tc-99 and I-129 Target Options

AFCI Transmutation Studies

Pioneering Science andTechnology

Compound I density (x1022/cm3) Melting Point, °K Thermodynamic Stability Remark

CeI3 1.97 1033 Good Instability toward oxygen and moistu

MgI2 1.94 906 Intermediate Intermediate characteristics

ZnI2 1.80 719 Bad Easy to handle, low melting point

YI3 1.76 1238 Good Instability toward oxygen and moistu

CaI2 1.60 1056 Intermediate Intermediate characteristics

PbI2 1.59 683 Bad Easy to handle, low melting point

NaI 1.47 934 Intermediate Intermediate characteristics (metalli
PWR Target Designs

(a) Tc-99 Mixed with Fuel (b) Tc-99-Coated Fuel Pellet (c) Annular Target i

(Inner clad t

Water

Tc-99+Fuel

Fuel Clad

Water Tc-99

Fuel Clad

Fuel

Water

Tc-9

Water

Water

Tc-9

Water

AFCI Transmutation Studies

Pioneering Science andTechnology

(d) Annular Target with Inner ZrH2

0.03 cm)

(e) Cylindrical Target Mixed with ZrH2

When LLFP is loaded in guide tubes, it is assumed that 40% of the locations are 

reserved for control rods

Water

Tc-99/CaI2

Guide Tube

ZrH2

Water

Tc-99/CaI2

Guide Tube

ZrH2

Water

Tc-99/CaI2 + ZrH2

Guide Tube
LLFP Stabilizer and Burner

Case

U-235 

enrichment 

(w/o)

LLFP

Initial 

Loading 

(kg)

Production 

(kg)

Net 

Consum

(kg)

UO2 Fuel Assembly, LLFP Stabilizer

Base case 4.38

Tc-99 0.0 0.532 -0.53

I-129 0.0 0.123 -0.12

Tc mixed with fuel 4.79 Tc-99 2.568 0.5402) +0.00

Tc target mixed with ZrH2 5.17 Tc-99 4.588 0.540 +0.35

Tc-coated fuel pellet 4 79 Tc-99 2 511 0 540 -0 00

AFCI Transmutation Studies

Pioneering Science andTechnology

Tc-coated fuel pellet

4.79 Tc-99

2.511

0.540 -0.00

CaI2 target mixed with ZrH2 4.58 I-129 1.714 0.121 +0.08

Tc mixed with fuel and CaI2 target mixed with ZrH2 4.99

Tc-99 2.655 0.5402) -0.00

I-129 1.777 0.120 +0.08

UO2 Fuel Assembly, LLFP Burner

Tc mixed with fuel 5.00 Tc-99 3.968 0.5402) +0.24

Tc-coated fuel pellet 5.00 Tc-99 3.882 0.544 +0.24CaI2 target mixed with ZrH2 5.00 I-129 5.515 0.120 +0.47

1) Masses are per unit assembly and the active assembly height is 365.76 cm. 2) Self-generated Tc-99 from the Tc-coated fuel case

Target recycling is required for significant transmutation
Tc-99 and I-129 Transmutation in ATW

• Fast systems are more attractive 

transmuters because of high neutron flux and surplus neutrons

- High leakage fraction provides 

more flexibility for LLFP loading

- Moderated target assemblies can 

be employed to take advantage of higher capture cross sections of 

thermal neutrons

Cladding

Tc-99

Void

Tc-99 or HT9

Cladding

Tc-99

Void

Tc-99 or HT9

AFCI Transmutation Studies

Pioneering Science andTechnology

thermal neutrons

• Support ratio of 3.2 was achieved for 

both Tc-99 and I-129

- Moderated LLFP target 

assemblies loaded in reflector

- Thermal neutron filters to 

eliminate local power peaking problems

• Power densities in LLFP target 

assemblies are less than 10% of core average power density

258249

314308

245251

255273

1717

244236

294287

230231

2221

265258

250258

266293

BOCEOC

Technetium Assembly

258249

314308

245251

255273

1717

244236

294287

230231

2221

265258

250258

266293

BOCEOC

Technetium Assembly

a) Tc-99 Target Assembly 
Impacts of LLFP Transmutation on Yuc

Mountain Repository Dose Rates (2003)

• Given a repository dose limit of 15 mrem/yr, the cur

Mountain release evaluations do not indicate a comneed to transmute Tc-99 and I-129

• Tc-99 and I-129 transmutation reduces the peak doe

factors of ~3 and ~5 for assumed loss rates of 5% arespectively 

AFCI Transmutation Studies

Pioneering Science andTechnology

- From ~3 to ~1 mrem/yr for 5% loss rate

• Significant reduction in LLFP release rate proposed 

extended nuclear power production can be achieve

- LLFP transmutation- Superior waste forms

• Some development of either specialized waste form 

transmutation target is prudent 
Summary

 Transmutation could be utilized to transform key nucl

order to improve:

– Waste management, with the key nuclides dependi

cycle and disposal strategy

– Resource utilization

 Neutron-based transmutation is the prominent techniq

based transmutation is the prominent techniq

advanced (fast) reactors, recycle fuels, and separation

 For actinides, transmutation by fission

– To shorter-lived nuclides– Energy balance is a key issue

 For fission products, transmutation by capture

– To stable or short-lived nuclides– Capture, recycle, and waste forms are a key issue