FUEL ELEMENT DEVELOPMENT PROGRAM FOR THE PEBBLE BED REACTOR. Quarterly Progress Report, November 1, 1960 to January 31, 1961

Technical Report · Tue Oct 31 00:00:00 EST 1961

OSTI ID:4041990

Pyroltic Carbon Coated UC/sub 2/ Particles. Two types of commercially prepared pyrolytic carbon coated UC/sub 2/ particles were evaluated. They are identified as Batch PyC-7 and Batch PaC-6. The Batch PyC-6 particles were seen to have bumpy surfaces. Metallographic examination under polarized light showed a conical carbon growth structure typical of coatings deposited at about 3600 deg F. The Batch PyC-7 particles were seen to be smooth and the conical growth structure was not evident under polarized light indicating a coating deposited below 2900 deg F. Alpha assays of ths particles showed surface uranium contaminations of 10/sup -5/ to 10/sup -4/ of ths uranium contained in each particle. The values are somewhat higher than the typical values found for Al/ sub 2/O/sub 3/ coated UO/sub 2/. Acid leaching indicated that in some cases the uranium contamination was within the coating surface and could not be reduced by leaching. In other cases, the leach test indicated that a number of faulty particles were present since a large increase was noted in uranium contamination after leaching because of uranium in solution being deposited back on the coating surfaces. Fueled Spberes. A graphite sphere fueled with PyC/UC/sub 2/ particles (Type FA-25) was examined. The coated particles were uniformly dispersed throughout the FA-25 spheres. There was no evidence of coated particle damage in the region where the molding flash was removed. The FA-25 spheres were designed to have a subsequent protective coating of siliconized silicon carbide. A neutron activation test of one specimen showsd a Xe-133 release fraction of 1.1 x 10/sup -3/ on heating for 3 hr at 1650, 2100, and 2400 deg F. Similar data on spheres fueled with AliO/sub 3/ coated UO/sub 2/ showed Xe-133 release fractions of about 10/sup -6/ in a 4 hr heating peridod. Subsequent evaluation of the FA- 25 specimens produced no clear evidence that the PyC/UC/sub 2/ particles were damaged in fabrication and appeared to indicate that there were faulty particle coatings prior to sphere fabrication. Al/sub 2/O/sub 3/ coated UO/sub 2/. A commercially prepared Al/sub 2/O/sub 3/ coated UO/sub 2/ was exmanied. The coating was applied by the vapor deposition technique at 1830DEF. A rotating kiln was used in coating ths particles rather than a fluidized bed as in previous Al/sub 2/O/sub 3//UO/sub 2/ work. The 105- to 149-Mcron UO/sub 2/ shot was coated with 40 microns of Al/sub 2/O/sub 3/ in eight steps. A 5-gin sample experienced only a 0.0024-gm weight gain after a 5-hr exposure to l2O0 deg air. There was no detectable surface uranium contamination on the as-received particles using the alpha assay technique. The total exposed uranium, i.s. residual surface contamination plus uranium in solution, after leaching in hot nitric acid was 10/sup -5/ of the contained uranium. In-Pile Loop. The installation of an In-Pile Loop in the Brookhaven Graphite Reactor was completed. The Loop was designed to study the behavior of fission products released from a PBR fuel element into a recycled helium stream. Irradiation was started using an unfueled electricallly heated, graphite sphere in place of a fueled specimen to complete shakedown testing prior to fueled-sphere operation. Operations were curtailed when it was discovered that a leak had developed in the vacuum insulation annulus of the in-pile section which appeared to have occurred during the exceptionally difficult insertion prior to startup. The effect of the leak was to limit operating temperatures to about 500 deg F gas outlet and 800 deg F in the specimen, instead of the design values of 1250 deg F and 1800 deg F. The leak could not be repaired because the in-pile section was too highly activated. Consequently, a new in-pile section was fabricated and, concurrently, a graphite sphere fueled with Al/sub 2/)/sub 3/ coated UO/sub 2/ was irradiated in the defective in-pile section.

• Research Organization: Sanderson and Porter, New York
• DOE Contract Number: AT(30-1)-2378
• NSA Number: NSA-15-015216
• OSTI ID: 4041990
• Report Number(s): NYO-9063
• Resource Relation: Other Information: Orig. Receipt Date: 31-DEC-61
• Country of Publication: United States
• Language: English

Related Subjects

REACTOR TECHNOLOGY
ACTIVATION
ALUMINUM OXIDES
CARBON
COATING
CONTAMINATION
FLUIDIZATION
FUEL ELEMENTS
GRAPHITE
HEATING
HIGH TEMPERATURE
INSPECTION
LIGHT
METALLOGRAPHY
PARTICLES
PEBBLE BED
POLARIZATION
REACTORS
SILICON CARBIDES
SPHERES
SURFACES
TESTING
URANIUM
URANIUM CARBIDES
URANIUM DIOXIDE
XENON
XENON 133