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