Impact failure of MHW fuel sphere MHFT 65: report on interagency task force investigation and SRL evaluation of failure, November 1979-February 1980

Technical Report · Mon Jun 01 00:00:00 EDT 1981

DOI:https://doi.org/10.2172/6153202· OSTI ID:6153202

Taylor, D H

Following a safety verification impact test failure of a Multi-Hundred Watt (MHW) fuel sphere made at Savannah River Plant, from which 2.1 g of /sup 238/PuO/sub 2/ escaped containment, the Department of Energy organized a task force to investigate the cause of the test failure and to assess the failure probability of MHW fuel made at SRP. The task force described a two-part failure mechanism: embrittlement of the iridium containment shell by phosphorus which may have been picked up from the fuel; and large shear strains in the iridium caused by shearing or push-through of large chunks of fuel. Because the likelihood of push-through in this failure model depends on preexisting cracks in the fuel and their orientation to the impact face, the probability of further impact failures could not be easily assessed. From independent analysis of the available data at the Savannah River Laboratory, we concluded that the impact failure was caused by phosphorus embrittlement of the iridium, and breaching during impact of the graphite impact shell surrounding and cushioning the iridium-clad fuel. Excessive strain in the iridium is caused by extrusion of the iridium into the breach. This model predicts that impact failure is essentially independent of pre-existing cracks in the fuel and that SRP fuel, upon impact, should have no more failures than previously used fuel made at Mound Facility. Impact data to date indicate that SRP fuel clad in DOP-26 iridium cladding actually has fewer impact failures than earlier fuel clad in undoped iridium at MF.

• Research Organization: Du Pont de Nemours (E.I.) and Co., Gibbstown, NJ (USA). Eastern Lab.
• DOE Contract Number: AC09-76SR00001
• OSTI ID: 6153202
• Report Number(s): DP-1588; ON: DE81028938; TRN: 81-013844
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPES AND RADIATION SOURCES
RADIOISOTOPE HEAT SOURCES
FAILURES
IMPACT TESTS
SAFETY
CAPSULES
CONTAINMENT
EMBRITTLEMENT
EXPERIMENTAL DATA
FAILURE MODE ANALYSIS
FUEL SPHERES
IMPACT SHOCK
IRIDIUM
PHOSPHORUS
PLUTONIUM 238
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
CONTAINERS
DATA
ELEMENTS
EVEN-EVEN NUCLEI
FUEL ELEMENTS
HEAT SOURCES
HEAVY NUCLEI
INFORMATION
ISOTOPES
MATERIALS TESTING
MECHANICAL TESTS
METALS
NONMETALS
NUCLEI
NUMERICAL DATA
PLATINUM METALS
PLUTONIUM ISOTOPES
RADIOISOTOPES
REACTOR COMPONENTS
REFRACTORY METALS
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
TESTING
TRANSITION ELEMENTS
YEARS LIVING RADIOISOTOPES
NESDPS Office of Nuclear Energy Space and Defense Power Systems
070300* - Isotopic Power Supplies