Thoria target element failures

Technical Report · Fri Apr 15 04:00:00 EST 1966

DOI:https://doi.org/10.2172/10146078· OSTI ID:10146078

Bowles, K C; Schmidt, J P

The thoria program at Hanford was initiated in response to an order placed by the Atomic Energy Commission for the production of uranium-233 from the irradiation of thorium or thorium oxide (thoria). The initial orders called for approximately 130 kg U-233 and subsequent orders have since increased this figure. This report provides a brief history of the thoria program, an analysis of the thoria target element failures which occurred during the irradiation phase, and the significant changes in the fabrication methods and inspection criteria and techniques which were made in response to the large number of failures that occurred in the early stages of the program. The thoria program has sustained 25 thoria target element failures. Eighteen of these failures are believed to have been caused as a result of water entry through fabrication defects in the closure weld. Two of the failures were attributable to water entry through the cladding as a result of charging machine damage, and the remaining five failures were caused by water entry in some undetermined manner. The majority of thoria element failures occurred in the early stages of the program. Upon determining the cause of failure, Production Fuels Section initiated programs to upgrade the quality of the closure weld on thoria elements. Process improvements resulted in the thoria element failure rate being reduced by about a factor of ten from 0.035 percent (approximately twice the failure rate for uranium fuel elements) to 0.0041 percent. The current performance of thoria target elements is very satisfactory. No future problems are foreseen that in any way should prevent the fulfillment of thoria program goals, In the event of further requests for high purity U-233, the equipment and knowledge exist with which these orders may be filled with a minimum of effort.

• Research Organization: Douglas United Nuclear, Inc., Richland, WA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 10146078
• Report Number(s): DUN--1010; ON: DE93012154
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220600
FAILURES
FUEL ELEMENTS
HANFORD PRODUCTION REACTORS
IRRADIATION
ISOTOPE PRODUCTION
RESEARCH
TEST
TRAINING
PRODUCTION
IRRADIATION
MATERIALS TESTING REACTORS
TARGETS
THORIUM
THORIUM OXIDES
TRANSMUTATION
URANIUM 233
WATER
WELDED JOINTS