readiness of current and new u.s. reactors for mox...

Readiness of Current and New U.S. Reactors for MOX Fuel

North Carolina and Virginia Health Physics Societies Joint 2009 Spring MeetingNew Bern, North Carolina

13 March 2009

Andrew Sowder, Ph.D., CHPProject ManagerHLW & Spent Fuel Management Program

2© 2009 Electric Power Research Institute, Inc. All rights reserved.

Motivation for this Review

• Use of mixed uranium-plutonium oxide (MOX) fuel in light water reactors is a mature technology

• Timing

– nuclear renaissance

– U.S. policy shifts

– mature technology– state of knowledge

• Pu-recycle as a bridge to other fuel cycle options

• Question: Are there knowledge gaps and technology barriers that could inhibit use of MOX in U.S. reactor fleet (current and GEN III/III+)?


Substantial Existing Knowledge Base

• U.S. Government and National Labs

• Regulatory and licensing documents

• Reactor vendors• Utilities• Academia• International organizations

(IAEA, NEA)• EPRI


Drivers, Constraints, and Concerns

• Regulatory environment • Energy security

• Nonproliferation

• Public opinion

• Resource utilization

• Waste management• Economics

• Technology

This review


Current Context for Considering MOX

• 2000 U.S. – Russia Plutonium Disposition Agreement• 2001 National Energy Policy Development Group

• 2003 Advanced Fuel Cycle Initiative

• 2005 - 2008 MOX lead-test assemblies irradiated in Catawba Unit 1

• 2006 launch of Global Nuclear Energy Partnership

• Utilities pursuing extended reactor lifetimes

• Seventeen companies/consortia pursuing licensing for > 30 new units• 2008 DOE -TVA MOU for technical exchange on advanced fuel cycles• 2008 DOE Yucca Mountain License Application, Second Repository

Report and Draft GNEP PEIS• 2009 – New U.S. administration and waste policy

• MOX as bridge between once-through and advanced fuel cycles


Open Fuel Cycle

• Once-through cycle in U.S.

• Suitable for:– secure U supply

– nonproliferation credentials

– simplicity

• Poor U resource utilization

• Less than 1% of potential energy recovered

10 – 20% Unat Savings


LWR Fuel: Waste or Resource?


Closed Fuel Cycles

• Fast reactor fleet required

• Complex – technical challenges yet to be addressed

• Much higher utilization of U resources

• Manifold increase in energy recovery

• Nonproliferation concerns

• Potential for reducing long-lived wastes for disposal

• Repository still required

15 – 25% Unat savings

35 – 95% Unat savings


What is MOX Fuel?

• Standard LWR fuel employs low enrichment 235U as primary fissile isotope in bulk 238U matrix (as sintered/ceramic UO2) = UOX

• Mixed oxide (MOX) fuel incorporates 239Pu as primary fissile isotope in bulk 238UO2 matrix

• All LWRs operating on UO2–based fuel eventually derive a substantial fraction of energy from 239Pu fission


Plutonium Grades

• Weapons grade (WG) – derived from low burnup uranium fuel to optimize 239Pu content

• Reactor grade (RG) – recycled Pu from spent UOX fuel irradiated in an LWR at high burnup

Isotope Weapons Grade (wt%) Reactor Grade (wt%) 238Pu 0 1 4 239Pu 92 – 95 50 – 60 240Pu 5 – 7 24 27 241Pu 0 – 0.5 6 11 242Pu 0 – 0.05 5 10


MOX vs. UOX Fuel

• Physically very similar – predominately UO2

• Neutronics are different; Pu has:– harder neutron spectrum– shorter neutron lifetimes and fewer delayed neutrons– greater σf and σtot for 239Pu– greater capture to fission ratio

• Differences greater for RG Pu than WG Pu• Use of MOX fuel results in:

– reduced effectiveness of thermal neutron absorbers (control/shutdown rods, soluble boron, poisons)

– faster core response to reactivity transients– large thermal neutron flux gradient at MOX – UOX interfaces– slower reactivity decrease with increasing burnup– potentially enhanced pressure vessel embrittlement– localized power peaking (esp. in fresh MOX)


MOX vs. UOX Fuel (cont’d)

• Radiation protection:– fresh fuel will contain significant Pu content

– irradiated fuel will have a much higher neutron dose (238Pu, 242Cm, 244Cm) but comparable gamma

• Higher heat loads in irradiated MOX – require longer cooling times (2 – 6 x)

– greater cooling capacity in spent fuel pool

• Greater fission gas/helium release in irradiated MOX

• Higher fissile content in irradiated MOX

• Transportation of fresh MOX fuel – Cat I special nuclear material

• Additional security per recently revised 10 CFR 73


MOX Impacts on Reactivity Control

Effect Remedy

control/shutdown rods and soluble boron exhibit less worth (as do gadolinium and xenon)

• increase soluble boron concentration or use enriched boron (PWR)

• use higher worth control/shutdown rods • use burnable absorbers • isolate MOX fuel relative to control rod

locations decreased reactivity safety margins (notably shutdown margin) with respect to transients, ΔT

• add control/shutdown rods (PWR) • use higher worth control/shutdown rods • increase soluble boron concentration or use

enriched boron (PWR) • increase soluble boron injection rate and/or

boron enrichment for standby liquid control systems


Global MOX experience

• MOX use in thermal reactors considered a mature technology

• Early programs (ca. 50’s and 60’s) in the U.S., Italy, Germany, and Belgium

• Routine loading of MOX in reactors in France, Germany, Switzerland, Belgium, and India (with Japan to follow)

• MOX fuel loaded in 20 of 28 French 900 MWe PWRs• MOX fuel performance comparable to that of UOX• Partial MOX cores feasible in wide range of LWR designs

– both PWR and BWR designs as suitable hosts– to date, MOX experience limited to partial cores

• MOX issues can be overcome while also satisfying safety and design margins


MOX in French 900 MW PWR Fleet

IAEA. 2007. Current Trends in Nuclear Fuel for Power Reactors. IAEA General Conference 51. Nuclear Technology Review Supplement GC(51)inf-3-att5

Num

ber

of M

OX

Fue

l Ass

embl

ies

Load

ed


MOX Irradiation in U.S. Reactors

Reactor PWR/ BWR MOX LTA Start

Total Number of Assemblies

Total Number of Fuel Rods

Vallecitos BWR 1960s -- ≥ 16 Big Rock Point BWR 1969 16 1248

Dresden-1 BWR 1969 11 103 San Onofre-1 PWR 1970 4 720 Quad Cities-1 BWR 1974 10 48

Ginna PWR 1980 4 716 Catawba-1 PWR 2005 4 full 17 x 17

assemblies


U.S. DOE Surplus Pu Disposition Program

• U.S. and Russia to meet obligations for disposition of 34 MT weapons grade Pu via irradiation in reactors

• 2005 – 2008: Duke Energy irradiates 4 lead test assemblies (LTAs) in Catawba Unit 1– LTAs manufactured in France from U.S.-origin Pu– irradiation for two 18-month cycles

– assembly growth issues NOT related to MOX

– MOX fuel performance testing considered successful

• MOX Fuel Fabrication Facility under construction at Savannah River Site, Aiken, SC

• Total estimated 1700 PWR MOX fuel assemblies over 15-years


U.S. Fleet by Vendor/Model, Size, and Lifetime

Reactor Vendor Type Units in

operation Units >750

MWe

Units in operation

beyond 2039*

Units >750 MWe in

operation beyond 2039*

Westinghouse PWR 48 39 28 28 Combustion Engineering

PWR 14 13 7

7

Babcock and Wilcox

PWR 7 7 0 0

Total PWRs 69 59 35 35

GE BWR2 BWR 2 0 0 0 GE BWR3 BWR 6 4 0 0 GE BWR4 BWR 19 17 6 6 GE BWR5 BWR 4 4 4 4 GE BWR6 BWR 4 4 4 4

Total BWRs 35 29 14 14

Total 104 88 49 49 *Assumes 60 year operating lifetime.


Existing U.S. Reactors as Candidates for MOX

• Assumptions:– commercial MOX use

in U.S. no earlier than 2020

– 20 year minimum remaining lifetime

– greater flexibility in late GEN II reactors (ca. 1980)

• Result: ~ 50% of current fleet as potential candidates

0

10

20

30

40

50

60

70

80

90

100

110

1965

1970

197

5

198

0

198

5

199

0

199

5

200

0

2005

2010

2015

2020

2025

2030

2035

2040

2045

205

0

205

5

206

0

Year

Nu

mb

er

of

Op

era

tion

al R

eac

tors

60 yr reactor lifespan

0

10

20

30

40

50

60

70

80

90

100

110

1965

1970

197

5

198

0

198

5

199

0

199

5

200

0

2005

2010

2015

2020

2025

2030

2035

2040

2045

205

0

205

5

206

0

Year

Nu

mb

er

of

Op

era

tion

al R

eac

tors

60 yr reactor lifespan

NOTE: Similar estimate from DOE: 3 Palo Verde CE System 80 PWRs + 48 other late model (ca. 1980) designs (34 PWRs + 14 BWRs) = 51 total [M. Todosow (BNL) email to P. Fink (INL), 15 October 2007]


Global MOX Supply

• Existing French and UK production capacity of ~235 MTHM/yr– 100 MTHM/yr of French capacity dedicated to 20 –

900 MWe PWRs using 30% cores

• U.S. DOE MOX facility under construction ~ 70 MTHM/yr max– to support 6 – 1000 MWe PWRs with 40% MOX cores

• Planned Japanese Rokkasho facility ~130 MTHM/yr– to support 16 – 18 reactors, most with partial cores

• MOX use in the U.S. is supply limited, NOT reactor limited, for the next 20 – 30 years


GEN III/III+ Reactor Designs for U.S. Market

• Full MOX core capability reported in open literature for ABWR, AP1000, US-EPR, and US-APWR

• Construction of an ABWR at Ohma, Japan, for 100% MOX

• European Utility Requirements (EUR) explicitly call for reactor designs capable of 50% MOX cores

Generation Design Vendor Output (MWe)

Under NRC Review

NRC Design Cert.

ABWR GEH 1300 GEN III USAPWR MHI 1700 AP1000 Westinghouse 1100 USEPR Areva 1600 GEN III+ ESBWR GEH 1520


Preliminary Findings – Existing Reactors

• Most if not all reactors capable of accommodating partial MOX loadings with either no or only minor modifications and operational changes

• No technical barriers identified thus far to partial MOX loading (30% or less) in at least half of existing U.S. fleet, based on review of:– DOE sponsored reviews and analysis

– International MOX experience

– LTA irradiation history in PWRs and BWRs


Preliminary Findings – Existing Reactors

• Amendment of reactor license (substantial but manageable undertaking)– demonstration of fuel performance, safety margins

– re-evaluation of plant design basis

– NRC staff has expressed favorable views on MOX licensing based on European experience

• Additional reactivity control required for MOX– due to reduced control rod worth and shutdown margins– addressed through use of higher soluble boron concentrations and/or

enriched 10B, burnable absorbers, or higher worth control rods

• Plant wide changes to address:– security

– radiation protection and shielding

– increased minimum cooling periods, increased cooling capacity for spent fuel pool, spent fuel criticality

• No negative impact on return to 100% UOX cores


Preliminary Findings – GEN III/III+ Reactors

• All GEN III/III+ designs should accommodate high MOX core loading (50% to full cores)

• 50% MOX core loading target per European Utility Requirements

• Core loadings of 50% or greater generally require MOX-specific design

• Full MOX core capacity reported for ABWR, AP1000, US-EPR, US-APWR

• Limited information on specific design capabilities with respect to MOX loading

• Limited information on differences between designs for U.S. and international markets

• MOX use in new reactors may be restricted due to plant specific design aspects (e.g., spent fuel pool capacity)


Together…Shaping the Future of Electricity


Backup Slides


Waste Management Perspective

• Actinides are primary long-term risk drivers for disposal of HLW and SNF

• Transmutation of actinides would simplify disposal– Pu– Minor actinides: Np, Am, Cm

1.00E-08

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

1.0E+03 1.0E+04 1.0E+05 1.0E+06

Time

Mean Dosemrem/y

DoseTc-99

DoseI-129

DoseNp-237

DoseU-233

DoseTh-229

DosePu-239

DoseU-235

DoseU-238

DoseU-234

DoseTh-230

DosePu-240

DoseU-236

Total


Costs: Fuel Cycle Costs a Function of Uranium and PUREX Reprocessing Unit Costs*

*EPRI, 2009. Nuclear Fuel Cycle Cost Comparison Between Once-Through and Plutonium Single-Recycling in Pressurized Water Reactors. [Report 1018575, February 2009].

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

$104 $208 $312 $416 $520

Uranium Unit Cost ($/kgU)

Fu

el C

ycle

Co

st (

mill

s/kw

he)

FC1: Once-Through FC2: Purex $500/kgHM FC2: Purex $750/kgHM

FC2: Purex $1000/kgHM FC2: Purex $1250/kgHM FC2: Purex $1500/kgHM

readiness of current and new u.s. reactors for mox...

Documents