Sean O’KellyChief, Reactor Operations and Engineering

November 29, 2010

NIST Center for Neutron Research (NCNR)

NCNR Research Reactor (NBSR)

Conversion Strategy

Performance Penalty for NCNR Reactor

Barriers to Conversion

Applications Precluded by Performance Penalty

NIST Center for Neutron Research (NCNR)

NCNR Research Reactor (NBSR)

Conversion Strategy

Performance Penalty for NCNR Reactor

Barriers to Conversion

Impact on Current Program and Lost Opportunities

NCNR Performance Penalty Mitigation Strategy

www.ncnr.nist.gov

The NCNR Has 25 Operating Beam Instruments Tailored to Specific Needs …

NG6 NeutronPhysics

NG7 Prompt

NG7 Interferometer

BT2 Neutron Imaging Facil.

Thermal Column

Diffraction Instruments

Spectrometers

Other Neutron Methods

NG3 30 m SANS

NG7 30 m SANS

NG1 Vert. Refl.

NG1 AND/R

NG7 Hor. Refl.

BT8 Resid. Stress Diff.

BT1 Powd. Diff. BT5 USANS

NG0 MACS

NG2 Backscattering Spec.

NG5 Spin-Echo Spec.NG-5 SPINS

NG4 Disk Chopper TOF Spec.

BT7 3-Axis Spec.

BT9 3-Axis Spec.

BT4 FANS

NG2 Backscattering Spec.

NG5 Spin-Echo Spec.NG-5 SPINS

NG4 Disk Chopper TOF Spec.

NG3 30 m SANS

BT5 USANS

NG1 Depth Profiling

RESEARCH PARTICIPANTSRESEARCH PARTICIPANTS

500

1000

1500

2000

US States = 42 + DC & PRUS Universities = 146US Govt Org + Nat Lab = 32US Corporations = 45

RESEARCH PARTICIPANTSRESEARCH PARTICIPANTS

500

1000

1500

2000

US States = 42 + DC & PRUS Universities = 146US Govt Org + Nat Lab = 32US Corporations = 45

20112011--Another Upgrade ShutdownAnother Upgrade Shutdown

Major areas of activity:• Construction• Cold source• Guide systems• Shield systems• Instruments• Control room upgrade

Many sub-projects:• 5 new capabilities• MACS relocation• instrument moves• software• guides/shields• cold source

existing guide hall

guide hall addition

confinement building

•Blue Instruments relocated 2011-2012•Red Instruments are planned for fabrication and installation 2012-2015

The NCNR Research Reactor

20 MW heavy water cooled and moderated reactor

30 split-core fuel elements containing HEU

Operates on a 7 week cycle (39 days up and 11 days shutdown)

Averages >98% reliability with over 260 experimental days a year

NCNR will convert to LEU gradually by changing 4 elements per fuel cycle and transition fully in just over one year (8 cycles)

Fuel external dimensions will not change but current dispersion fuel will be replaced with monolithic (U10Mo) fuel plates

Fuel element loading will increase from 350 grams 235U to 386 grams

to maintain cycle

length

Power level will remain 20 MW but neutron availability will decrease by 10%

Qualified fuel is not yet available◦

Fuel testing not complete◦

NRC review and approval process not clear

Chapter 18 of NUREG-1537 is expected to be revised

Who will be the independent NRC fuel qualification reviewers?◦

Difficult to prepare NBSR conversion analysis without knowing final details required

Fuel has not been “manufactured”◦

Scale up to production level in progress but years away◦

Production appears to be throughput limited and not cost-

effective

◦

Experience and high quality production has not been developed

Fuel costs◦

GTRI estimates ~30% increase in fuel costs based on INEG “ROM”

analysis but final costs are unknown and could be higher

◦

NCNR needs to maintain at least a 3 year supply of fuel to support high reliability operations

◦

In the long range planning, higher fuel costs prohibit or reduce

neutron instrument development without an increase in NCNR budget

Back end of fuel cycle has not been defined◦

Reactors have not seen any confirmation that SRS will accept new fuel◦

Long-term disposal or reprocessing methods have not been established for monolithic fuels◦

GTRI says that disposal is not a conversion related issue but NIST considers it to be a barrier

Unacceptable loss of performance◦

NIST considers a 10% loss of performance to be unacceptable to user program and requires other improvements to offset conversion penalty

NCNR Expansion will increase cold neutron measurement capacity by 30% but loss of intensity will likely prevent some experiments

New Guide Hall

Old Guide Hall

10% intensity loss is equivalent to losing 3 instruments

NCNR averages a 2 to 3 oversubscription rate

Increase cold neutron intensity by replacing liquid hydrogen source with liquid deuterium source◦

Requires larger helium refrigerator and source chamber◦

Shift in neutron spectrum will require replacement of neutron guides to exploit cold source gains

Recover some intensity loss on thermal neutron instruments by improvements in detection technology

2011 2012 2013 2014 2015 2016

NBSR Fuel Spec and SAR

Design and Fabricate LD2

CNS

Outage

Design and Fabricate N-Guides

NRC Reviews

Design and Fabricate LH2

CNSInstall upgraded instruments

Fuel Fabricate (88) LEU Conversion

Install CNS

Preliminary design of LD2

Cold Source indicates intensity gain of approximately 1.5 on average

Shift in neutron spectrum would impact one high usage neutron spectrometer so additional LH2

Cold Source could be installed in single beam tube to maintain spectrometer function

Over half of NCNR research is performed using cold neutrons but thermal instruments would also require improvement in detection efficiency to compensate for 10% flux reduction

Conversion of the NCNR Reactor is feasible assuming all barriers are addressed

Loss of facility performance by conversion is considered significant and unacceptable to the NCNR user program

A mitigation strategy exists but it must be implemented in the near-term to remain off the conversion critical path

Thank you