Basis for extending limits in ansi standard for mixed oxides to heterogeneous systems

Journal Article · Sat Nov 01 00:00:00 EST 1986 · Nucl. Technol.; (United States)

OSTI ID:5093942

Clayton, E D; Clarck, H K; Walker, G; Libby, R A

Subcommittee 8 of the Standards Committee of the American Nuclear society is revising the Standard for Nuclear Criticality Control and Safety of Homogeneous Plutonium-Uranium Fuel Mixtures Outside Reactors to include limits on heterogeneous systems. In connection with this effort, a number of criticality calculations were completed for mixed-oxide (PuO/sub 2/+UO/sub 2/) fuel pins in water. The concentration of PuO/sub 2/ in the UO/sub 2/ (natural uranium) covered the range from 3.0 to 34 wt%. The isotopic makeup of the plutonium was also varied, up to 25 wt% /sup 240/Pu and 15 wt% /sup 24l/Pu. A search was made on fuel pin diameters and water-to-fuel volume ratios to obtain minimum critical dimensions and masses for a given fuel composition. Calculations made independently by several different members of the Work Group are compiled and compared, together with the proposed subcritical control limits for the Standard. Some difficulties were encountered with calculations pertaining to 30% PuO/sub 2/ at /sup 240/ Pu concentrations at water-to-fuel volume ratios and fuel pin diameters outside the area covered by any critical experiment. For this reason, dimensional limits on heterogeneous systems are not being proposed at this time for the Standard with 30% PuO/sub 2/ at a /sup 240/Pu content of 25%. In general, for a given fuel composition of mixed oxides, a heterogeneous arrangement of fuel pins of optimum diameter in water results in substantially smaller minimum critical dimensions than are obtainable for and aqueous homogeneous plutonium-uranium fuel mixture.

• Research Organization: Energy Systems Dept., P.O. Box 999, Richland, Washington 99352
• OSTI ID: 5093942
• Journal Information: Nucl. Technol.; (United States), Vol. 75:2
• Country of Publication: United States
• Language: English

Related Subjects

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION
22 GENERAL STUDIES OF NUCLEAR REACTORS
FUEL PINS
CRITICALITY
STANDARDS
MIXED OXIDE FUELS
AQUEOUS SOLUTIONS
NATURAL URANIUM
PLUTONIUM 240
PLUTONIUM 241
PLUTONIUM DIOXIDE
QUANTITY RATIO
SAFETY
URANIUM DIOXIDE
WATER
ACTINIDE COMPOUNDS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ACTINIDES
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHALCOGENIDES
DISPERSIONS
ELEMENTS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FUEL ELEMENTS
FUELS
HEAVY NUCLEI
HYDROGEN COMPOUNDS
ISOTOPES
METALS
MIXTURES
NUCLEI
OXIDES
OXYGEN COMPOUNDS
PLUTONIUM COMPOUNDS
PLUTONIUM ISOTOPES
PLUTONIUM OXIDES
RADIOISOTOPES
REACTOR COMPONENTS
SOLID FUELS
SOLUTIONS
TRANSURANIUM COMPOUNDS
URANIUM
URANIUM COMPOUNDS
URANIUM OXIDES
YEARS LIVING RADIOISOTOPES
055001* - Nuclear Fuels- Safeguards
Inspection
& Accountability- Technical Aspects
220200 - Nuclear Reactor Technology- Components & Accessories
220100 - Nuclear Reactor Technology- Theory & Calculation