IRRADIATION OF U-Mo BASE ALLOYS

Technical Report · Thu Jan 30 04:00:00 EST 1964

DOI:https://doi.org/10.2172/4126051· OSTI ID:4126051

Johnson, M P; Holland, W A

A series of experiments was designed to assess the suitability of uranium-molybdenum alloys as high-temperature, high-burnup fuels for advanced sodium cooled reactors. Specimens with molybdenum contents between 3 and 10% were subjected to capsule irradiation tests in the Materials Testing Reactor, to burnups up to 10,000 Mwd/MTU at temperatures between 800 and 1500 deg F. The results indicated that molybdenum has a considerable effect in reducing the swelling due to irradiation. For example. 3% molybdemum reduces the swelling from 25%, for pure uranium. to 7% at approximates 3,000 Mwd/MTU at 1270 deg F. Further swelling resistance can be gained by increasing the molybdenum content, but the amount gained becomes successively smaller. At higher irradiation levels, the amount of swelling rapidly becomes greater, and larger amounts of molybdenum are required to provide similar resistance. A limit of 7% swelling, at 900 deg F and an irradiation of 7,230 Mwd/ MTU, requires the use of 10% Nonemolybdenum in the alloy. The burnup rates were in the range of 2.0 to 4.0 x 10/sup 13/ fissiom/cc-sec. Small ternary additions of silicon and aluminum were shown to have a noticeable effect in reducing swelling when added to a U-3% Mo alloy base. Under the conditions of the present experiment, 0.26% silicon or 0.38% aluminum were equivalent to 1 to 1 1/2% molybdenum. The Advanced Sodium Cooled Reactor requires a fuel capable of being irradiated to 20,000 Mwd/MTU at temperatures up to 1500 deg C in metal fuel, or equivalent in ceramic fuel. It is concluded that even the highest molybdenum contents considered did not produce a fuel capable of operating satisfactorily under these conditions. The alloys would be useful, however, for less exacting conditions. The U-3% Mo alloy is capable of use up to 3,000 Mwd/MTU at temperatures of 1300 deg F before swelling becomes excessive. The addition of silicon and aluminum would increase this limit to at least 3,000 Mwd/MTU, and possibly more if the alloy were heat treated to provide a fine dispersion of second phase. (auth)

• Research Organization: Atomics International. Div. of North American Aviation, Inc., Canoga Park, Calif.
• Sponsoring Organization: USDOE
• DOE Contract Number: AT(11-1)-GEN-8
• NSA Number: NSA-18-008870
• OSTI ID: 4126051
• Report Number(s): NAA-SR-6262
• Country of Publication: United States
• Language: English

Related Subjects

ALUMINUM
BURNUP
CERAMICS
DISTRIBUTION
EXPANSION
HEAT TREATMENTS
HIGH TEMPERATURE
IRRADIATION
LIQUID METAL COOLANT
MATERIALS TESTING
METALS, CERAMICS, AND OTHER MATERIALS
MOLYBDENUM
MOLYBDENUM ALLOYS
NESDPS Office of Nuclear Energy Space and Defense Power Systems
PHASE DIAGRAMS
QUANTITY RATIO
RADIATION DOSES
REACTORS
SILICON
SODIUM
STABILITY
TEMPERATURE
TRACE AMOUNTS
URANIUM ALLOYS