ON THE REMOVAL OF VOLATILE FISSION PRODUCTS FROM URANIUM-BISMUTH REACTOR FUELS
In the Liquid Metal Fuel Reactor (LMFR) the fuel is a dilute solution of U, Mg, and Zr in bismuth. At the operating fuel temperatures (400 to 550 deg C), the volatile fission products (FPV's), which represent about 25% of the total by weight, are mostly the noble gases Kr and Xe with small amounts of the halogen fission products Br and I. Owing to the facts that the LMFR is a thermal breeder reactor and that the 9.13-hr Xe/sup 135/) isotope has a 2.7 x 10/sup 6/-barn thermal cross section, the concentration of FPV's in the fuel and in the core must be kept very low for good neutron economy. For a 1% reactor poisoning level, and assuming no Xe adsorbed on or absorbed in the graphite, the concentrations of 9.13-hr Xe/sup 135) and total Xe in the fuel are estimated to be about 1.5 and 13 parts per billion, respectively, for a typical commercial plant. Complete isotopic compositions of the volatile fission products and poison levels for different removal rates are presented. The effect of various degrees of volatilization of the iodine and bromine on these factors are also shown. Xe represents over 80% by weight of the FPV's. Both Xe and its precursor, iodine, have strong tendencies to adsorb on unwetted surfaces and to penetrate graphite, the moderator material in the reactor core. Immobilization of Xe in the core would present a problem from the standpoint of reactor poisoning. Experimental results are presented to show the extents to which both iodine and Xe adsorb on steel and graphite and penetrate graphite. It appears that the Xe problem is not so much one of removing it from the fuel in a desorber as it is in preventing it from collecting on graphite surfaces in the core. (auth)
- Research Organization:
- Brookhaven National Lab., Upton, N.Y.
- NSA Number:
- NSA-14-004396
- OSTI ID:
- 4222591
- Journal Information:
- Nuclear Sci. and Eng., Journal Name: Nuclear Sci. and Eng. Vol. Vol: 6
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
BISMUTH
BREEDING
BROMINE
CHEMISTRY
CROSS SECTIONS
EVAPORATION
FISSION PRODUCTS
FUELS
GASES
GRAPHITE
HALOGENS
IODINE
KRYPTON
LEVELS
LIQUID METAL FUEL
LIQUID METALS
LMFR
MAGNESIUM
MODERATORS
POISONING
RARE GASES
REACTOR CORE
REACTORS
SOLUTIONS
STEELS
SURFACES
TEMPERATURE
URANIUM
XENON
XENON 135
ZIRCONIUM