1.

2.

3.

Contrast of "between bottle" and "within
bottle" agreement, as shown by NBS individual
assay results, for six bottles of two INX
lots sealed 2-6-57

Interlaboratory disagreement of assay results
for 12 INX lots bottled between September
1956 and March 1957

Comparison of NBS individual assay values for
thirty lots of three types of Colorado Plateau
uranium concentrates (July-August 1963) .

(Appendix B)

1. NBS initial results for standard concentrate "D", Bottles I and II (sampled in helium on 7-21; titrated on 7-30-58)

2.

NBS initial results for standard concentrate
"D", Bottles III and IV (sampled in dry air on
9-5; titrated on 9-12-58)

3. NBS initial results for standard concentrate "E" (sampled in dry air on 8-8; titrated on 8-15-58).

4.

NBS initial results for standard concentrate

"F" (sampled in dry air on 8-20; titrated on
8-28-58)

69

5.

NBS recheck and initial average results

70

(Appendix B; Youden)

1.

2.

CONTENTS (Con't)

Statistical analysis of ranges for 45 sets
of four determinations (for three samples,
by three methods of base line establishment,
in five laboratories)..

Averages of the 45 sets of four determina-
tions; deviations from interlaboratory
averages; and laboratory average discrepancy

(Appendix D)

Changes in weight of Blockson samples during
heating at 110 °C in varied atmospheres, and
during storage

FIGURE NO.

LIST OF FIGURES

PAGE

75

77

91

1.

Change in weight of INX samples and/or caps
during storage in a humid atmosphere (about
0.012 g H20/g dry air)

14

2.

Change in weight of INX samples and/or caps
during storage in a dry atmosphere (over
Anhydrone)

15

3.

Change in weight of separate components of
INX bottle caps during storage in a dry
atmosphere (over Anhydrone)

Relative laboratory positions and average
differences from overall averages for three

1. NBS results for drying IMCC material in room air

FIGURE NO.

CONTENTS (Con't)

PAGE

(Appendix C)

2. NBS results for drying pre-treated IMCC material in "dry" air

3. NBS results for heating pre-treated IMCC material in humid air (about 0.013 g H20/g

83

85

STANDARD REFERENCE MATERIALS:

ANALYSIS OF URANIUM CONCENTRATES AT THE
NATIONAL BUREAU OF STANDARDS

M. S. Richmond

Institute for Materials Research
National Bureau of Standards

ABSTRACT

NBS experiences with the problems of assaying uranium concentrates are described. Umpire determinations of

Also,

uranium were performed on several thousands of ore concen-
trates from world-wide sources. Contributions were made
to the resolution of the sampling base line problem.
it was demonstrated that the standard Uz0g, NBS No. 950a,
provides the over-all standard necessary for precise assay
of uranium materials. A comprehensive analytical procedure
applicable to all types of uranium concentrates is pre-

sented.

Key words:

analytical procedure, assay,
assay, ore concentrates,

sampling base line, standard Uz0g, umpire determinations,

uranium concentrates.