technical challenges for conversion of the nist reactor
TRANSCRIPT
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