A 11 IQS 140^1 NBS

PUBLICATIONS

N8SIR 82-2496

Determination of Water in

PSutonium Dioxide

AlllOt. 4Q7SS1

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, DC 20234

April 1932

Finai Report

red for: e of Safeguards & Security

Department of Energy

lincton, DC 20545

J4ATTONAI. BUREAU

G>F STANDARDS UBhARY

HOV 4 19$2

NBSIR 82-2496

DETERMINATION OF WATER IN

PLUTONIUM DIOXIDE

Frank E. Jones

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington, DC 20234

April 1982

Final Report

Prepared for: Office of Safeguards & Security

U.S. Department of Energy

Washington, DC 20545

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler. Director

Determination of Water in Plutonium Dioxide

Frank E. Jones

Fluid Engineering Division

Center for Chemical Engineering

National Bureau of Standards

Washington, DC 20234

Techniques developed to very effectively apply automatic Karl Fischer

reagent titration to the determination of H^O in solids were used to determine

the moisture content of samples of plutonium dioxide powder under the con- straints imposed by the necessity of working in a glove box. The moisture

contents of three samples were found to be 0.2934%, 0.7298%, and 0.4640%. The

estimate of the relative standard deviation of the mean for three determinations on the 0.2934% H^O sample was 0.0091. The method apparently has potential as the basic reference method for determination of H^O in plutonium

dioxide, as a means of standardizing other methods, and as a diagnostic tool.

Key Words: Automatic titration; Karl Fischer reagent titration; moisture;

nuclear safeguards; plutonium dioxide; water determination.

1. Introduction

The interaction between water and plutonium dioxide has been studied by

Stakebake [1,2,3]-*- and others. The exchange of water vapor between plutonium

dioxide (PuO^) and its environment is considered to be one of the sources of

differences in the plutonium content of the oxide as determined by shippers and

receivers. In a program on the determination of the moisture content of PuO ?

, techniques were developed to very precisely apply automatic Karl. Fischer reagent

titration to the determination of H^O in solid materials. Measurements have been

made on uranium oxides, titanium dioxide, and other metal oxides. This note reports

the determinations of H^O in PuO^ using an automatic Karl Fischer reagent titrator

and modified techniques under the constraints imposed by the necessity of working in

a glove box. The work was performed at the Hanford Energy Development Laboratories

at Richland, WA.

2. Experimental Part

The apparatus and reagents are described in a previous paper [4], Since the

titrations were to be made in a glove box, it was necessary to slightly modify the

apparatus. The reaction vessel of the titrator was placed inside the glove box on

the base of a magnetic stirrer; the generator leads and the sensing electrode leads

Numbers in brackets indicate the literature references at the end of the paper.

1
were extended and attached to a "bulkhead" connector mounted on the face of the

glove box. Leads connected the connector outside the glove box to the binding p on the base which enclosed the electronics of the titrator. The mixer /mill used to

mill the oxide in methanol to extract the H.,0) , without the cover, was installed

inside the glove box.

Three samples (ca. 15 g each) of PuO powder from three different suppliers

(Los Alamos Scientific Laboratories, Los ilamos, NM; Rockwell Hanford Operations,

Richland”

0

WA

; ° and Savannah River Plant, Aiken, SC) were used in the determination of

HO It was not practical to run replicate samples. Each sample was weighed on an

analytical balance. The sample and three tungsten carbide pellets were put into the

milling vessel of the mixer/mill and 25 mL of methanol was pipeted into the vessel

from a class A pipet. The lid was sealed and the sample was milled in the methanol

for 15 min The vessel was then set aside for ca. 42 h during which time the soli

residue settled to the bottom. The milling and succeeding procedures were repeate

for 25 mL of methanol without sample, to prepare a blank.

Calibrated syringes [5] of 1-mL capacity were used to withdraw 0.5-mL Tuan“

Cities of methanol-extracted H O mixture from the milling vessels

th”nol blLk

into the reaction vessel of thl titrator; 2.5-mL quantities of the methanol blank

were introduced from a 5-mL capacity uncalibrated syringe A specimen

£°^

r the end- was introduced into the titration vessel, titration was started, and af ter the end

point was reached the mass of HjO titrated as indicated by the counter on the

titrator was noted.

The titrator was standardized using a mixture of methanol and water,

mixture was prepared at the National Bureau of Standards by mixing 2 mL of distill

water with 250 mL of methanol. Ten milliliters of the mixture was injected into

each of seven evacuated test tubes through rubber stoppers using a 10-mL capacity

"gastight" syringe which had been rinsed with methanol and heated in an oven at

about 84°C . 'After filling, molten paraffin was poured into the concavity “ *

stopper and then the stoppered end of the test tube was dipped into the paraffin as

a precautionary measure to further seal the hole made by the syringe needle and to

immobilize the stopper. The titer of the mixture was determined using

which was standardized [4] with distilled water.

3. Results and Discussions

The moisture content, % H

2 0, of the samples of Pu0

2 was calculated [4] using

the equation

% H 9 0 = (VC/l0

6 m

a

) x {[Z(A

s /v

s

) - (A^v^l/tl - (ZC/10 p)(A

s /v

g )]}

O

100 ( 1 )

where V is the volume (25 mL) of methanol used for extraction C is the standardization factor for the titrator (pg/pg), m is the mass (g) of the Pu0

2 sample, Z (dimensionless) is a factor which takesgaccount of the fact that the vol

methanol-H,0 mixture is less than the sum of the volumes the components would occupy

separately

2 A is the titration value (pg of HO) for the specimen. of methanol

extracted' H O

s mixture, is the volume (mOolth^specimen. ^o^he'denfitv

value for the

water (g/ cm )

.

methanol blank, v

K is the volume of the blank, and p is the density of

Z is calculated [6] using the equation

Z - 1 - 1.985 x 10

; x C x t(A

s /v

s

) - (A^v^l

where the units on the numerical coefficient in the second term are mL/pg. The

results are listed in Table 1.

( 2 )

2
Table 1. Results for Karl Fischer titration H

2 0 determinations on PuC>

2

sample

no

.

1

2

3

% h

2 o mean % H

2 0

0.2979 0.2934

0.2887

0.2935

0.7355 0.7298

0.7240

0.4777 0. 4640

0.4502

The results indicate that the techniques described m a previous paper [4] for t application of automatic Karl Fischer titration to the determination of H

2 0 in sol

materials, modified in the present case, produced very satisfactory results despi e

the constraints imposed by the necessity of working m a glove box. The estimate

the relative standard deviation of the mean is about 1% relative in the range 0.3

0 7% H 0 which can be compared with a value of 0.37% relative at 0.2758 % H

2 0 in

iitanISn dioxide achieved under nearly Ideal laboratory conditions [4] by an analyst

experienced in the method.

For comparison of the Karl Fischer titration results with those obtained

routinely on PuO

? at the Hanford Energy Development Laboratories, samples (ca 200

mg) were analyzed on a DuPont Model 902H Moisture Evolution Analyzer (MEA at 400 C

"to equalization." The results corresponding to samples no. 1, 2, and 3 m a are 857 ppm, 7044 ppm, and 4997 ppm, respectively. Since the MEA result was much

lower than the titration result for sample no. 1 and since it was not practical

make a titration determination on another 15 g sample two more samples taken

different places in the can were subsequently analyzed on the MEA. The results,

ppm and 750 ppm, were also much lower than the titration result in i able 1. .he

ratio of the MEA result to the titration result for samples no 2 and 3 are 0.9652

and 1.077; the ratio for the largest MEA value for sample no. 1 is 0.- . reason for this discrepancy has not been established.

The work reported here has demonstrated that the techniques developed for the

optimum application of automatic Karl Fischer reagent titration to the determination

of H 0 in solid materials, modified for the present case, can be used successfully

under the constraints imposed by a glove box by an operator with no prior experience

with the method.

The author is grateful to R. L. Moore, and G. J. Alkire of the Hanford Energy

Development Laboratories who made it possible for the experimental wor ' to e one

there- to M. C. Burt who contributed in many ways to the success of the effort;

W. B. *Larson who did the actual titration work in the glove box and the Moisture

Certain commercial equipment and materials are identified in order to ade9^ely

specify the experimental procedure; such identification does not imp y reuo

tion or endorsement by the National Bureau of Standards.

3
, fn P

C Schaus for consultation and for making "

tason ;ho

' typed the manuscript -

4. References

,

, the Storage Behavior of Plutonium Metal, Alloys, and

U1

“

A kview, a! «ucl. *«r. 38: 241-259; 1971.

[2] Stakebake, J. L. A Thermal Desorption Study of the Surf -Interactions

Between Water and Plutonium Dioxide, J. Thys. them.

[3] Stakebake, 1. L. Water Vapor Adsorption on Plutonium Dioxide, J. Colloid

Interface Sci. , 42: 328 333, 1973.

[41 Jones F. E. Determination of Water in Solids by Automatic Karl Fischer

11

Titration, Anal. Chem. 53: 1955-1957; 1981.

[51 Jones, F. E. Telescopic Viewer in Syringe Calibration, Anal. Chem. 52:

364; 1980.

.

, r c Calculation of Solvent-Water Mixture

[6] Jones, F. E. ; Brickenkamp, C S. Calculatio

Volumes, Anal. Chem. 53: 362-363,

4
N BS«1 1 4A ( REV. 2-80

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

4. TITLE AND SUBTITLE

PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No. 3. NBSIR 82-2496

Publ ication Dace April 1982

Determination of Water in Plutonium Dioxide

5. AUTHOR(S)

Frank E. Jones

6. PERFORMING ORGANIZATION (If joint or other than NBS. see in struction s) 7. Contract/ Grant No. national bureau of standards

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234 . F mal

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, State. ZIP

)

Office of Safeguards & Security

U.S. Department of Energy

Washington, DC 20545

10. SUPPLEMENTARY NOTES

__ Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a si gn i fi cant

bi bliography or literature survey, mention it here)

Techniques developed to very effectively apply automatic Karl Fischer reagent

titration to the determination of H^O in solids were used to determine the moisture

content of samples of plutonium dioxide powder under the constraints imposed by the

necessity of working in a glove box. The moisture contents of three samples were

found to be 0.2934%, 0.7298%, and 0.4640%. The estimate of the relative standard

deviation of the mean for three determinations on the 0.2934% H ? 0 sample was 0.0091.

The method apparently has potential as the basic reference method for determination

of t^O in plutonium dioxide, as a means of standardizing other methods, and as a diagnostic tool.

12. KEY WORDS (Six to twelve entries ; alphabetical order; capitalize only proper names; and separate key words by semicolon si Automatic titration, Karl Fischer reagent titration; moisture;

plutonium dioxide, water determination.

13. AVAILABILITY

_X Uni imi ted For Official Distribution. Do Not Release to NTIS

nuclear safeguards,

14. NO. OF

PRINTED PAGES

Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 15. Price

Order From National Technical Information Service (NTIS), Springfield, VA. 22161 S6 .00

jscomm-oc 6043-p;: