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Expansion of the Cold Neutron Facilities and Upgrades at the NIST Center for
Neutron Research
Robert Williams
Joint IGORR 2014 & IAEA Technical Meeting
November 17-21, 2014
Bariloche, Argentina
New Guide Hall and Support Building - 2010 ◦ Nearly doubled the size of the Guide Hall
◦ Five additional guides installed, now 12 guides
◦ Several new or upgraded instruments available to users
Second LH2 Cold Source installed in BT-9 ◦ Operational since April 2012
◦ More intense source for MACS-II
◦ Cooled by existing refrigerator
Additional Facility Upgrades (13 month Outage): ◦ Thermal Shield Cooling System
◦ Fuel Storage Pool Liner
◦ Secondary Cooling Pump Building
◦ Electric Power Switchyard
Major Expansion of Cold Neutron Facilities
2
3
Technical Support
Building
Guide Hall
Addition
Original Building 1963-1967
NCNR Expansion – Fall 2010
4
New Guide Hall
Old
“Pump
House”
Existing Instrument Layout – Nov 2014
Existing LH2 CNS, In-pile Guides as of April 2011
NG-1
NG-2
NG-3
NG-4
NG-5
NG-6
NG-7
CTW Beam Port
(now has inpile
piece for new
guides)
CTE
Side View of BT-9 Cold Source
Peewee:
11 cm ID, 0.5 liter LH2 vessel
14.6-cm OD water jacket
It has its own H2 tank.
“Piccolo” keeps vessel full
Status:
Cryostat Assembly fabricated
and installed
Operating since March 2012
MACS began operating in
December 2012
Peewee very successful! Monochromatic beam of
5 x 108 n/cm2-s on 2x4 cm
sample. IGORR - 2009
CNS Team installed Peewee in BT-9 in September 2011.
8
Five New Cold Neutron Guides
Guides were custom built for
each instrument:
• NG-A isolates the Spin-Echo
Spectrometer from stray
magnetic fields.
• NG-B splits into upper and
lower parts for 10-m and 30-m
SANS.
• NG-D has 4 instruments: PBR,
MAGIK, PGAA and NDP.
• NG-C (right) has curved sides
to maximize cold neutron
acceptance to obtain a gain of
15 for Physics Lab.
9
Penetration through the North Wall of the Confinement Building
for NG-B (2), NG-C and NG-D, Autumn 2011
(note old secondary pipes in old “Pump House”)
10
NG-C and NG-Blower during installation in the Guide Hall, Summer 2012
NG-Blower is
50x50 mm Ballistic Guide
NG-C opens to
110x300 mm
(maximum)
11
Carbon Dioxide
surrounds the
Reactor Vessel to
decrease Argon-41
formation
Thermal Shield
(lead, copper
tubes, steel) Biological Shield
Reactor Vessel
Beam Port
Thermal Shield Cooling System Upgrade
IGORR - 2013
12
Problems with the Thermal Shield…
TS Liner in BT-9
Buckled
Evidence that
some of the TS
Lead Melted
13
Thermal Shield Photos - 1964
BT-9
14
• Function: Limit heat in the
Biological Shield
• 188 Upper and 32 Lower lines
• 9.5 mm(3/8”) copper lines run
through the concrete
• Some lines have stress cracks
and leak
• Excessive leaks or too many
consecutive closed lines
requires shutdown!
TS Return and Supply Ring
Headers, Cooling Lines
The TS Cooling System was the most vulnerable
component of the NBSR.
Prior Outside Experience ◦ In the early 1960’s the Australian Atomic Energy
Commission, presently ANSTO, installed a vacuum system on their leaky HIFAR Shield Cooling lines. Ref. AAEC/TM133 and 149, ANSTO NTP/TN189
Considerations ◦ Gas drawn into the tubes has a lower impact than water
leaking out of the tubes
◦ But can produce other problems: pH control
15
Solution: Place the Thermal Shield Lines
Under Negative Pressure
CO2 in the system o Decreases the pH of the cooling water down to around pH 5.
Adding Magnesium Carbonate o Onetime dose of Magnesium Carbonate (MgCO3).
o MgCO3 brings the pH back up to 6.8 to 7.2
o 27Mg has short half life: 9.45 minutes
Compared to 64Cu: 0.529 days = 762 minutes
Air in the system o Is drawn through the holes in the lines along with the CO2
Slightly increases water pH
Increases Argon-41 out the stack
Conservative calculations show that in the worst case condition the concentration of Argon-41 exhausted would only increase from 2% to 2.6% of the allowable limit.
16
Vacuum System Design Considerations
17 17
Process Room (basement)
Second Floor
Reactor
Core First Floor
To Irradiated Air Line
High Pressure Pumps Low Pressure
Supply Pump
Supply
Header
Return Header
Water Storage Tank
Aerating Fan
Negative Pressure
Negative Pressure Eductor
Eductor
Heat Exchanger
New Thermal Shield Cooling System
Success Story ◦ Curtailment of leaks – Dry Biological Shield
◦ Lowering Header Activation – ALARA gain
◦ No need for sealant, less maintenance – ALARA gain
◦ Retrieving and using more data to confirm proper operation
Thermal Shield Today
18
Fuel Storage Pool Liner
Pool is nearly 50 years old
Filled with about 33,000 gallons of water (ASTM Type II demineralized water)
Water contains tritium, radiological contamination and activated small fuel head pieces
Made of cast-in-place concrete and is coated with a neoprene primer (20 mils thick) and finished with hypalon paint (5 mils thick).
Existing coating is deteriorating
Higher Fuel Storage Capacity
Easier to load and unload fuel
Less cluttered
Easier to clean pool
Protect pool floor from being damaged
WHY THE UPGRADE?
Removed all fuel and fuel racks from the pool.
Fuel transfer system removed, refurbished, and then reinstalled at the end of the project.
Cleaned the pool, removed the existing coating and applied a water tight epoxy coating.
Placed stainless steel plates on the floor and installed new, high capacity, fuel containers with Al-B alloy dividers.
Fuel Storage Pool Upgrade during Long Outage
NBSR SPENT FUEL POOL
PLAN VIEW OF POOL AFTER UPGRADE
HOW TO COAT POOL???
Drain and dispose of water ($$$)?
Store water in tanker truck or free standing bladder?
How to get rid of “Hot” stuff in pool?
Airborne contamination control?
Hydraulic pressure from ground water?
STORAGE POOL BEFORE & AFTER
Instruments in Operation:
MAGIK* Multiple Angle Grazing Incidence k (vector) NG-D
PBR* Polarized Beam Reflectometer ND-D
nSoft* 10m Small Angle Neutron Scattering NG-Blower
SANS 30m Small Angle Neutron Scattering NG-Bupper
NSE* Neutron Spin Echo Spectrometer NG-A
MACS-II* Multi Analyzer Crystal Spectrometer BT-9
PGAA Prompt Gamma Activation Analysis NG-D
CNDP Cold Neutron Depth Profiling NG-D
Instruments in Development:
aCORN* a CORrelation in Neutron decay NG-C
CANDOR* Chromatic Analysis Neutron Diffractometer Or Reflectometer NG-1
vSANS* 40 m very Small Angle Neutron Scattering NG-3
MAD* Materials Diffractometer NG-5
NPIF* Neutron Phase Imaging Facility NG-C
* New or Upgraded
Instruments Moved, Improved or under Development
27
Further Information at: http://www.ncnr.nist.gov/instruments/
28
Future Cold Source Layout
LD2 Source
(2019?)
BT-9 LH2 Source
(installed 2012)
IGORR - 2013
The Expansion Project is nearing its completion. NCNR will have several new or upgraded instruments.
70-75% of experiments will be using cold neutrons.
Reactor upgrades are keeping the plant in good condition to relicense – 2029.
A LD2 cold source would allow us to further enhance our strength by providing a more intense source of long-wavelength neutrons.
Conclusions 29
30
The new guide hall is very busy these days…
Cut-away View of the NBSR Core
Top Grid Plate
Fuel Elements (30)
Fuel Plates
Liquid Hydrogen
Cold Neutron
Source
Bottom Grid Plate
D2O Primary
Inlet Plenums
Cd Shim Safety
Arms (4)
Reactor Vessel
Radial Beam
Tubes (9)
18-cm Unfueled
Gap – Flux Trap
Primary Outlet (2)
Thermal Shield