LEU-Foil Development/Qualification
Experiment Plan Outline
Rev. 0
Introduction
There is limited experimental data published that characterizes the physical behavior of thin uranium foils
during irradiation. Macroscopic U-swelling and fission gas generation data is needed to construct models
capable of predicting the performance of LEU-foil Mo-99 targets during irradiation. The models will be used to
demonstrate the structural integrity of U-foil targets during irradiation.
Post irradiation examination (PIE) data specific to quantifying the amount (moles) of fission that escapes a
U-foil target during irradiation will be used to validate the conclusions presented in TDR - 0112, “Production of
Fission Product Mo-99 Using the LEU-Modified Cintichem Process – Assessment of Fission Gas Release During
LEU-Foil Target Irradiation & Disassembly.”
This experiment plan outlines a strategy for acquiring U-foil irradiation behavior data using the Pitesti reactor
and its PIE facility. The PIE data will be used to support the development of a universal LEU-foil based target
that can be used by any current or future Mo-99 producer who desires to evaluate the LEU-foil targetry option.
The effectiveness of nickel, aluminum, and zinc fission-recoil barrier materials applied to LEU-foils will be
evaluated by testing. The tests will be performed under irradiation conditions that represent the maximum
irradiation parameters (i.e., thermal neutron flux and irradiation time) of dispersion type targets that are now
being irradiated to produce Mo-99.
Background
U-Foil Irradiation Behavior
The property of U-growth (no large change in volume) is a function of: 1) the temperature at which U-foil was
hot rolled, 2) the temperature of the U-foil during irradiation, and 3) the percent burnup of U-235 atoms(1). The
magnitude of macroscopic U-swelling (measurable change in volume) is directly proportional to the integrated
neutron flux (i.e., fluence; n/cm2-s x irradiation time in seconds). The magnitude of U-growth can be reduced
by β-quenching the U-foil after it is cold-rolled to its final thickness. A β-quench heat treatment of a U-foil after
the cold-rolling process produces a fine grain structure with random grain orientation. A fine grain structure with
random orientation is known to reduce the magnitude of U-growth.
For the fluence and irradiation temperature range experienced by an LEU-foil Mo-99 target, the three (3) major
mechanisms for macroscopic U-foil swelling are:
1) Irradiation growth (also referred to as U-growth or anisotropic growth) is a change in shape with no large
change in volume(2).
2) Fission gas (Kr, Xe & I) accumulation(2), and
3) Solid fission product accumulation. This can account for an atomic volume increase of ≈ 2% per %
burnup(2).
The increase in volume, resulting from gaseous and solid fission-product accumulation can be approximated
as three (3) times % burnup(3).
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LEU-Foil Development/Qualification
Experiment Plan Outline
Rev. 0
Objectives
1) Determine the change in dimensions of the LEU-foil caused by macroscopic U-swelling and evaluate the
integrity of a fission-recoil barrier material’s bond to the U-foil during irradiation.
2) Determine any change of irradiated-foil flexibility with time after its removal from the target. The purpose of
this objective is to provide assurance that the foil does not become brittle and break before it is placed in
the dissolver.
3) Determine the amount of contamination on the surface of the fission-recoil barrier after the foil’s removal
from the target. The purpose of this objective is to address the issue of potentially contaminating the hot
cell during target disassembly as discussed at the recent IAEA Consultancy Meeting.
4) Measure the amount (i.e., moles) of fission gas (Kr, Xe & I) that escapes the fission-recoil barrier of the
LEU-foil test coupons during irradiation. This will be compared to the theoretical amount of fission gas that
escapes through the fission-recoil barrier as determined by the analytical method used in TDR-0112.
Phase-1 Experiments
Prior to performing the Phase 1 experiments, special equipment, supporting procedures, and a metrology set
will be developed as outlined in Attachment 1.
Test Coupon Materials
The Phase 1 test coupon set will consist of three (3) LEU-foils. Each LEU-foil will have a thickness of
approximately 127 µm and a mass of > 4.0 grams. All foils in this first set will be wrapped in a 40 µm thick
piece of aluminum foil. This wrap (i.e., envelope) serves as a fission-recoil barrier to prevent the foil
component of the target from bonding to the irradiation sample holder.
Each test coupon-size foil will be manufactured using a different technique, as identified in Attachment 1. Two
foils will be cold-rolled at Y-12 and the third foil will be cooling-roll cast by KAERI. One of the Y-12 foils will be
β-quenched after cold-rolling. This first set of foils will allow the properties of LEU-foil grain orientation and size
to be evaluated with respect to their impact on the U-growth component of macroscopic U-swelling as defined
in Reference 2.
Methods
Pre-irradiation dimensions of the LEU-foil test coupons (i.e., samples) manufactured by Y-12 and KAERI will
be obtained. The LEU-foil test coupons will then be irradiated in the Pitesti reactor at a thermal neutron flux of
approximately 2.0E14 n/cm2-s for an irradiation period of 300 hours. This magnitude of fluence (i.e., 2.16E20
n/cm2) equates to the fluence experienced by an LEU-foil Mo-99 target that is irradiated at a maximum neutron
flux of 3.0E14 n/cm2-s for a maximum irradiation time of 200 hours.
A special irradiation target (sample holder) will be designed to ensure that the LEU-foil is in an “unrestrained”
state during irradiation. This will allow the foil to grow freely in all directions during irradiation. The irradiation
sample holder can be made from an alloy of aluminum. Thermal analysis will need to be completed on the
target to ensure that there is sufficient cooling so as to not violate any reactor safety requirements. The target
must maintain its integrity during irradiation to prevent fission gas from escaping to the reactor pool.
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LEU-Foil Development/Qualification
Experiment Plan Outline
Rev. 0
After the test coupons have been irradiated, they will be measured again in the PIE facility to determine the
irradiation induced dimensional change that will be used to quantify macroscopic U-swelling. The postirradiated measurements will be obtained using the pre-irradiation measurement toolset to ensure that the
observed property changes and dimensional changes are not due to differences in metrology. The irradiated
test coupons will be visually inspected. They will also be flexed to qualitatively assess their post-irradiation
brittleness as a function of time after target disassembly.
Each set of experiments will be performed in triplicate, one for each of the foils in a test coupon set.
Phase-2 Experiments
Prior to performing the Phase 2 experiments, special equipment, supporting procedures, and a metrology set
will be developed as outlined in Attachment 2.
Test Coupon Fission-Recoil Barrier Materials
The composition of the Phase 2 test coupon set is described in Attachment 2. The first set of test coupons will
be electroplated with a 10 µm thick nickel fission-recoil barrier. The second set of test coupons will be
wrapped with a 15 µm thick nickel foil fission-recoil barrier. The third set of test coupons will be wrapped with a
40 µm thick aluminum foil fission-recoil barrier. The fourth set of test coupons will be electroplated with a 10
µm thick zinc fission-recoil barrier.
Methods
In this phase, the amount of any fission gas that escapes through the fission-recoil barrier material will be
measured by the method of mass spectrometry. A method for evacuating any fission gas from the test coupon
target to the mass spectrometer will be developed and validated in the laboratory. Following disassembly of
each test coupon target, a swipe of the foil will be obtained and counted to assess any loose surface
contamination on the foil. As in Phase 1, dimensions of the test coupon will be measured and its brittleness
assessed over time after its removal from the target.
Each Phase 2 test coupon will be irradiated in a “restrained” state. This means that the macroscopic Uswelling of the LEU-foil is restrained by the target’s cladding. This represents the configuration of an
assembled Mo-99 annular target.
Each set of experiments will be performed in triplicate, one for each of the foils in a test coupon set.
Phase-3 Experiment(s)
In this phase, one or more full-size (i.e., commercial scale) LEU-foil annular targets will be irradiated and
evaluated. The LEU-foil type used will be selected based on the results of Phase 2. The PIE objectives will be
the same as those for Phase 2. These experiments will be planned after completion of Phase-2 and are not
part of the current scope.
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LEU-Foil Development/Qualification
Experiment Plan Outline
Rev. 0
References:
(1) Irradiation Effects in Nuclear Fuels - An AEC Monograph (pg. 25); J.A.L. Robertson, Atomic Energy of
Canada, Ltd.; 1969
(2) Experimental Studies of U-Pu-Zr Fast Reactor Fuel Pins in EBR-II, G.L. Hofman, et al, Argonne National
Laboratory; “Submitted for publication in the proceedings of the Fall 1988 AIME Meeting, “Symposium on
Irradiation-Enhanced Materials Science”, Chicago, IL
(3) Irradiation Effects in Nuclear Fuels - An AEC Monograph (pg. 40); J.A.L. Robertson, Atomic Energy of
Canada, Ltd.; 1969
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Attachment 1
Rev. 0
LEU-Foil Experiment Plan
Phase-1 Test Matrix
Phase-1: Target, Equipment, Procedures, and Metrology Development
1) In cooperation with U.S. partners, design test coupon-size foil targets to facilitate all PIE procedures, including:
a. Visual inspection
b. Foil dimension measurement
c. Flexure test of foil to assess brittleness with time after removal from target
2) Develop procedures, equipment, and metrology for all PIE measurements of foils
3) Assemble/install all equipment and supplies necessary to perform PIE in hot cell
4) Optimize and validate all procedures, equipment, and metrology using cold simulants
5) Perform safety analysis for irradiation, sample transport, and for PIE; and obtain permission to irradiate test
coupon targets and perform all PIE procedures
6) In cooperation with U.S. partners:
a. Design container and irradiation rig for the test coupon targets
b. Develop procedures for irradiation of test coupon targets, transferring them to the PIE facility, and disposing
of all waste from the experiments
Phase-1Test Coupon Set – “Unrestrained”
Unalloyed LEU-foil (with 40 µm thick Al-foil fission-recoil barrier)
LEU-foil mass/size: To be determined;
Ave. LEU-foil thickness = 127 µm [ 5.0 mils ]
Test Coupon “A”
Test Coupon “B”
Test Coupon “C”
Y-12 Foil Manufacturing Method:
Cross Cold Rolled with no
β-Quench Heat Treatment
Y-12 Foil Manufacturing Method:
Unidirectional Cold Rolled with
β-Quench Heat Treatment
KAERI Foil Manufacturing Method:
Cooling-Roll Casting
PIE Objectives:
1) Visual inspection
2) Dimensional measurements
3) Flexure test to assess brittleness as
a function of time after target
disassembly
PIE Objectives:
1) Visual inspection
2) Dimensional measurements
3) Flexure test to assess brittleness as
a function of time after target
disassembly
PIE Objectives:
1) Visual inspection
2) Dimensional measurements
3) Flexure test to assess brittleness as
a function of time after target
disassembly
Page 1 of 1
Attachment 2
Rev. 0
LEU-Foil Experiment Plan
Phase-2 Test Matrix
Phase-2: Target, Equipment, Procedures, and Metrology Development
1) In cooperation with U.S. partners, design test coupon-size foil targets to facilitate all PIE procedures, including:
a. Fission gas evacuation for mass spectrometer analysis
b. Visual inspection
c. Foil dimension measurement
d. Loose contamination survey (swipe)
e. Flexure test of foil to assess brittleness with time after removal from target
2) Develop procedures, equipment, and metrology for all PIE measurements of foils
3) Optimize and validate all procedures, equipment, and metrology using cold simulants
4) Perform safety analysis for irradiation, sample transport, and PIE; and obtain permission to irradiate test
coupon targets and perform all PIE procedures
5) In cooperation with U.S. partners:
a. Design container and irradiation rig for the test coupon targets
b. Develop procedures for irradiation of test coupon targets, transferring them to the PIE facility, and
disposing of all waste from the experiments
Phase-2 Test Coupon Set No. 1 – “Restrained”
Unalloyed LEU-foil (with 10 µm thick electroplated nickel fission-recoil barrier)
LEU-foil mass/size: To be determined;
Test Coupon “2/1A”
Ave. Thickness = 127 µm [ 5.0 mils ]
Test Coupon “2/1B”
Y-12 Foil Manufacturing Method:
Cross Cold Rolled with no
β-Quench Heat Treatment
1)
2)
3)
4)
5)
Y-12 Foil Manufacturing Method:
Unidirectional Cold Rolled with
β-Quench Heat Treatment
KAERI Foil Manufacturing Method:
Cooling-Roll Casting Method
PIE Objectives:
Fission gas evacuation for mass spec. analysis
Visual inspection
Foil dimension measurements
1
Loose contamination assay (swipe)
Flexure test to assess brittleness as a function of time after target disassembly
______________
1
Test Coupon “2/1C”
May require constructing and installing a containment box in the PIE hot cell to keep the foil free from potential hot cell
contamination.
Page 1 of 3
Attachment 2
Rev. 0
LEU-Foil Experiment Plan
Phase-2 Test Matrix
Phase-2 Test Coupon Set No. 2 – “Restrained”
Unalloyed LEU-foil (with 15 µm thick Ni-foil fission-recoil barrier)
LEU-foil mass/size: To be determined;
Test Coupon “2/2A”
Ave. Thickness = 127 µm [ 5.0 mils ]
Test Coupon “2/2B”
Y-12 Foil Manufacturing Method:
Cross Cold Rolled with no
β-Quench Heat Treatment
1)
2)
3)
4)
5)
Y-12 Foil Manufacturing Method:
Unidirectional Cold Rolled with
β-Quench Heat Treatment
Test Coupon “2/2C”
KAERI Foil Manufacturing Method:
Cooling-Roll Casting Method
PIE Objectives:
Fission gas evacuation for mass spec. analysis
Visual inspection
Foil dimension measurements
1
Loose contamination assay (swipe)
Flexure test to assess brittleness as a function of time after target disassembly
Phase-2 Test Coupon Set No. 3 – “Restrained”
Unalloyed LEU-foil (with 40 µm thick Al-foil fission-recoil barrier)
LEU-foil mass/size: To be determined;
Test Coupon “2/3A”
Ave. Thickness = 127 µm [ 5.0 mils ]
Test Coupon “2/3B”
Y-12 Foil Manufacturing Method:
Cross Cold Rolled with no
β-Quench Heat Treatment
1)
2)
3)
4)
5)
Y-12 Foil Manufacturing Method:
Unidirectional Cold Rolled with
β-Quench Heat Treatment
KAERI Foil Manufacturing Method:
Cooling-Roll Casting Method
PIE Objectives:
Fission gas evacuation for mass spec. analysis
Visual inspection
Foil dimension measurements
1
Loose contamination assay (swipe)
Flexure test to assess brittleness as a function of time after target disassembly
______________
1
Test Coupon “2/3C”
May require constructing and installing containment box in the PIE hot cell to keep the foil free from potential hot cell
contamination.
Page 2 of 3
Attachment 2
Rev. 0
LEU-Foil Experiment Plan
Phase-2 Test Matrix
Phase-2 Test Coupon Set No. 4 – “Restrained”
Unalloyed LEU-foil (with 10 µm thick electroplated zinc fission-recoil barrier)
LEU-foil mass/size: To be determined;
Test Coupon “2/4A”
Ave. Thickness = 127 µm [ 5.0 mils ]
Test Coupon “2/4B”
Y-12 Foil Manufacturing Method:
Cross Cold Rolled with no
β-Quench Heat Treatment
1)
2)
3)
4)
5)
Y-12 Foil Manufacturing Method:
Unidirectional Cold Rolled with
β-Quench Heat Treatment
KAERI Foil Manufacturing Method:
Cooling-Roll Casting Method
PIE Objectives:
Fission gas evacuation for mass spec. analysis
Visual inspection
Foil dimension measurements
1
Loose contamination assay (swipe)
Flexure test to assess brittleness as a function of time after target disassembly
______________
1
Test Coupon “2/4C”
May require constructing and installing a containment box in the PIE hot cell to keep the foil free from potential hot cell
contamination.
Page 3 of 3
Attachment 3
LEU-Foil Experiment Plan
Phase-3 Test Matrix
Rev. 0
First Generation Full-Size Target
Phase-3 Test Coupon Set No. 1 – “Restrained”
LEU-foil mass: ≥ 20 g;
LEU-foil /size: To be determined
Ave. Thickness = 127 µm [ 5.0 mils ] to 200 µm [ 7.9 mils ]
Test Coupon “3/1”
LEU-Foil Type:
To be determined based on the results of Phase 2
1)
2)
3)
4)
5)
PIE Objectives:
Fission gas evacuation for mass spec. analysis
Visual inspection
Foil dimension measurements
1
Loose contamination assay (swipe)
Flexure test to assess brittleness
______________
1
May require constructing and installing a containment box in the PIE hot cell to keep the foil free from potential hot cell
contamination.
Page 1 of 1