ASTM C1430-00

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Designation:C1430–00
Standard Test Method for
Determination of Uranium, Oxygen to Uranium (O/U), and
Oxygen to Metal (O/M) in Sintered Uranium Dioxide and
Gadolinia-Uranium Dioxide Pellets by Atmospheric
Equilibration
This standard is issued under the fixed designation C 1430; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope loaded into a sample boat. The boat is placed in a tube furnace
capable of holding a temperature of 800 6 10°C. The furnace
1.1 This test method applies to the determination of ura-
is purged with a moist gas flow of 4 % hydrogen and 96 %
nium, the oxygen to uranium (O/U) ratio in sintered uranium
argon or nitrogen to remove all air. The temperature of the
dioxide pellets, and the oxygen to metal (O/M) ratio in sintered
furnace is raised to 800°C and held at this temperature with
gadolinium oxide-uranium dioxide pellets with a Gd O con-
2 3
constant gas flow for 4 h. The furnace then is turned off and
centration of up to 12 weight %. The O/M calculations assume
allowed to cool, with gas purge on, to room temperature. The
that the gadolinium and uranium oxides are present in a metal
samples are removed from the furnace and reweighed.
dioxide solid solution.
3.2 The weight change, gadolinia content, and chemical
1.2 This standard does not purport to address all of the
impurity content are used to calculate % uranium and the O/U
safety concerns, if any, associated with its use. It is the
or O/M.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Significance and Use
bilityofregulatorylimitationspriortouse.Forspecifichazards
4.1 Uranium dioxide is used as a nuclear-reactor fuel. This
statements, see Section 8.
test method is designed to determine whether the percent
2. Referenced Documents uranium and O/U or O/M content meet Specifications C 776
and C 922.
2.1 ASTM Standards:
C 696 Test Methods for Chemical, Mass Spectrometric, and
5. Interferences
Spectrochemical Analysis of Nuclear-Grade Uranium Di-
2 5.1 Parameters for temperature, gas composition, gas flow,
oxide Powders and Pellets
2 and moist air purge must be monitored and maintained care-
C 776 Specification for Sintered Uranium Dioxide Pellets
fully within the limits set in the procedure.
C 922 Specification for Sintered Gadolinium Oxide-
2 5.2 This test method assumes that chemical impurities meet
Uranium Dioxide Pellets
Specifications C 776 and C 922 limits. Potential method inter-
C 968 Test Method for Analysis of Sintered Gadolinium
2 ferences from higher impurity concentrations will require
Oxide-Uranium Dioxide Pellets
evaluation.
C 1287 Test Method for Determination of Impurities in
5.3 Furnace tubes or boats made from metals that oxidize
Uranium Dioxide by Inductively Coupled Plasma Mass
under the test conditions may prevent proper equilibration by
Spectrometry
consuming available oxygen.
3. Summary of Test Method 5.4 Preciseweighingofsamplesiscriticaltotheaccuracyof
this test method.
3.1 The uranium, and either O/U or O/M, are determined by
5.5 Loss of weight due to pellet chipping would invalidate
measuring the weight change of a sintered pellet after it has
the analysis. Handle pellets with care.
been exposed to an equilibrating atmosphere to bring it to the
5.6 This test method assumes that pellets are sintered. It
stoichiometric condition. Sintered pellets are weighed and
does not correct for moisture or volatile additives.
5.7 This test method assumes that UO -Gd O pellets have
2 2 3
This test method is under the jurisdiction ofASTM Committee C26 on Nuclear formed a solid solution; however, the error from incomplete
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
dissolution of Gd O would be very small (see the calculation
2 3
Test.
in 10.2).
Current edition approved Jan. 10, 2000. Published March 2000.
Annual Book of ASTM Standards, Vol 12.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C1430–00
6. Apparatus 9. Procedure
6.1 Analytical Balance, capable of weighing to 6 0.0001 g.
9.1 Analyze samples as whole pellets. No preparation is
6.2 Tube Furnace, capable of controlling temperatures at
required. The nominal sample size is 5–10-g pellet. Smaller
800 6 10°C, that has been fitted with a fused quartz furnace
pellets may need to be composited (two pellets/test) to main-
tube.
tain minimum weight.Avoid using chipped or cracked pellets.
6.3 Fused Quartz Sample Boats.
9.2 Place a small weighing tray or watch glass on the
6.4 Assorted Connectors, Tubing, Flasks, Stoppers, and
balance pan. Tare the balance and check to ensure that the
Delivery Tubes—The purge gas is passed through a humidifier,
balance is stable. If the balance will not stabilize, do not
into the tube furnace.Abubbler flask is attached to the furnace
proceed.
outlet to monitor gas flow (see Fig. 1).
NOTE 1—The extremely small weight changes that are being measured
6.5 Gas Pressure Gage and Regulator.
in this test method make it critical that the balance is working properly.
6.6 Purge Gas (4 % hydrogen, 96 % argon or 4 % hydro-
gen and 96 % nitrogen. Gas purity of 99.995 % has been found 9.3 Weigh a check weight at least daily to confirm that the
analytical balance is operating correctly.
to perform satisfactorily.
6.7 Purge Gas Humidifier, with heater and controller ca-
9.4 Create a boat map to maintain sample identity.
pable of maintaining water temperature at 35 6 10°C.
9.5 Use a pair of tweezers and carefully weigh the pellet.
Rezero the balance and repeat the pellet weighing until a
7. Standard Materials
consistent weight is obtained. Carefully place the pellet in the
7.1 NBL , NBL-traceable, or equivalent, uranium dioxide
quartz sample boat. Repeat for each pellet.
pellets. Analyze at least one standard pellet per batch.
9.6 Include one or two equilibrated standard control pellets
with each sample batch.
8. Hazards and Precautions
9.7 Carefully place the loaded boat into the sample tube.
8.1 Take proper safety precautions for handling uranium.
Position the boat as close to center of the furnace tube as
8.2 Thefurnace,sampletubeandsampleboatsareheatedto
possible.
800°C. Care must be taken to avoid burns.
9.8 Fit the purge gas connection to end of tube and clamp.
8.3 Exercise appropriate caution when working with com-
Make certain that the water in the humidifying flask is at 35 6
pressed gasses.
10°C (6 5°C is optimal) and check the gas cylinder pressure to
verify there is sufficient gas to complete the cycle.
3 9.9 Turn on the gas flow and allow the chamber to purge for
Available from the New Brunswick Laboratory, 9800 S. Cass Ave., Argonne,
IL. approximately five minutes.
FIG. 1
C1430–00
NOTE 2—The flow rate of the purge gas and the length of the purge
(% Gd O )(0.00026) = Correction factor for weight gain
2 3
cycle will vary with the size of the furnace tube. A purge of greater than
due to formation of oxygen-rich
or equal to three furnace volumes/minute is the recommended minimum.
UO -Gd O solid solution during
2 3
The flow rate must be adequate to maintain a positive pressure inside the
sintering. For processes that do not
sample chamber.
produce a 100 % solid solution,
9.10 Attach a Pyrext delivery tube with ground glass fitting
this factor should be evaluated to
to the exit end of the furnace, and place the end in a container
determine if modification is neces-
of water to verify and monitor the gas flow.
sary (see Appendix X1).
10.3 Percent Uranium:
9.11 Turn on the furnace and bring the temperature to
10.3.1 Percent Uranium, Based on Sample Weight:
800°C.
~100 – G–%I! O/M 3 G
9.12 After temperature is reached, allow the pellets to
–
F G F G
15.9994 157.25
equilibrate for a minimum of 4 h. Monitor the system occa-
%U 5 (3)
O/M 1
sionally during the run to ensure constant temperature and gas
F G F G
AW 15.9994
u
flow.
9.13 At the end of the 4-h cycle, turn the furnace down to
where:
50°C and allow the samples to cool. The purge gas flow must G = Weight % Gd = weight % Gd O 3 0.86759
2 3
%I = Total nonvolatile impurities, expressed as weight %
be maintained until the samples reach 50°C. Then, turn off the
impurity oxides in UO . Add the weight % of each
carrier gas and allow the pellets to cool to room temperature. 2
detected impurity oxide plus a correction factor to
NOTE 3—If the samples are allowed to cool to room temperature while
account for less than threshold of detection impu-
the purge gas is flowing, the water in the purge gas will begin to condense
rities. This correction factor will need to be deter-
inside the tube and on the pellets. A temperature of 50°C is high enough
mined for each facility.Afactor of 0.01 % has been
to prevent condensation but low enough to prevent oxidation by room air.
found to provide satisfactory results. See Table 1 to
9.14 Remove the sample boat and reweigh the pellets obtain conversion factors to convert common im-
purity elements to oxides.
immediately. Use multiple weighings as necessary to obtain a
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