DISTRIBUTION OF FISSION PRODUCT CONTAMINATION IN THE SRE

Technical Report · Thu Mar 01 04:00:00 EST 1962

OSTI ID:4797424

Hart, R S

BS>In the safety analysis of sodium-cooled reactors, a remaining area of significant uncertainty was the fate of various fission products that may be released to the coolant in the event of a fuel element failure; that is, the degree of their retainment in the sodium, movement to the reactor cover gas system or deposition in other portions ot the primary system. During the recovery procedures following the fuel element damage that occurred at the Sodium Reactor Experiment (SRE) in July 1959, the opportunity was provided for obtaining such data on a full-scale basis. The collection and-analysis of pentinent information from this incident was undertsken. AIthough significant fuel melting did not occur, some degree of preferential fission products volatility was involved in the relative release of the various fission products into the primary coolant. Only Xe and Kr isotopes were found in the reactor cover gas (helium). The carbonaceous particulate material, resulting from the decomposition of tetralin which leaked into the primary sodium, proved to be an effective fission product scavenger. A generally non-selective concentration of activity by this material of 10/sup 3/ to 10/sup 4/ times that of the filtered sodium was measured. The cold trap located in the primary system was effective in removing fission product contamination. Appreciable deposition of fission product contamination oc curred throughout the primary piping system. A marked selectivity was evident in this process, with Sr, Ce, and Zr-Nb deposition being much greater than that of Cs or I. Although 5,000 to 10,000 curies of fission product activity were unexpectedly released to the primary sodium system, no radiological emergency of any nature occurred. Recovery operations were completed at a reasonable speed well within accepted personnel exposure limits. The same sodium is still in use during current operation of the SRE, with only Cs/sup 137/ and possibly Sb/sup 125/ remaining as significant, dissolved, long-lived contamination. Even these are now reduced to the same order as the Na/sup 22/ activity (~ 10/sup -2/ mu c/ gram), and their presence should not appreciably affect future operations of the reactor. (auth)

• Research Organization: Atomics International. Div. of North American Aviation, Inc., Canoga Park, Calif.
• DOE Contract Number: AT(11-1)-GEN-8
• NSA Number: NSA-16-012740
• OSTI ID: 4797424
• Report Number(s): NAA-SR-6890
• Country of Publication: United States
• Language: English

Related Subjects

ACCIDENTS
ADSORPTION
ANTIMONY 125
CERIUM
CESIUM
CESIUM 137
CLEANING
CONTAMINATION
COOLANT LOOPS
DECOMPOSITION
DECONTAMINATION
DISTRIBUTION
FAILURES
FILTERS
FISSION PRODUCTS
FUEL ELEMENTS
HELIUM
IMPURITIES
INERT GASES
IODINE
KRYPTON
LEAKS
LIQUID METAL COOLANT
MELTING
NAPHTHALENE
NIOBIUM
PERSONNEL
PIPES
POISONING
POWER PLANTS
RADIATION DOSES
RADIATION PROTECTION
RADIOACTIVITY
RADIOISOTOPES
REACTOR CORE
REACTOR SAFETY
REACTOR TECHNOLOGY
SODIUM
SODIUM 22
SRE
STRONTIUM
TETRALIN
VOLATILITY
XENON
ZIRCONIUM