A procedure to evaluate the potential for microbially influenced degradation of cement-solidified low-level radioactive waste forms
- Idaho National Engineering Lab., Idaho Falls, ID (United States)
Because of its apparent structural integrity, cement has been widely used in the US as a binder to solidify Class B and C low-level radioactive waste (LLW). However, the resulting cement preparations are susceptible to failure due to the actions of stress and environment. An environmentally mediated process that could affect cement stability is the action of naturally occurring microorganisms. The US Nuclear Regulatory Commission (NRC), recognizing this eventuality, stated in their Technical Position on Waste Form, Revision 1, that the effects of microbial action on waste form integrity must be addressed. This paper provides recent results from a program that examined the effects of microbially influenced degradation (MID) on cement-solidified LLW. Data are provided which were obtained during the development of an evaluation method using acid-producing bacteria. Results presented here are from work with one type of these bacteria, the sulfur-oxidizing thiobacillus. Commercially prepared, cement-solidified, low-level radioactive waste form samples made from power reactor wastes were evaluated using a new biodegradation test developed for the NRC. Testing demonstrated that MID has the potential to severely compromise the structural integrity and nuclide retentiveness of ion-exchange resin and evaporator-bottoms wastes that have been solidified with cement. It was found that the waste form specimens physically deteriorated after 60 days of exposure to the thiobacilli. Also, the data show that significant amounts of Cs-137, Cs-134, Co-60, C-14, Tc-99, and Sr-90 contained in the waste forms were leached in the presence of Thiobacillus.
- DOE Contract Number:
- AC07-94ID13223
- OSTI ID:
- 264453
- Report Number(s):
- CONF-951155--; ISBN 1-55899-315-0
- Country of Publication:
- United States
- Language:
- English
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Microbially influenced degradation of cement-solidified low-level radioactive waste forms
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Related Subjects
36 MATERIALS SCIENCE
55 BIOLOGY AND MEDICINE
BASIC STUDIES
BIOLOGICAL FOULING
CARBON 14
CEMENTING
CEMENTS
CESIUM 134
CESIUM 137
COBALT 60
CORROSION
EXPERIMENTAL DATA
LEACHING
LOW-LEVEL RADIOACTIVE WASTES
MEASURING METHODS
RADIOACTIVE WASTE DISPOSAL
SOLIDIFICATION
STRONTIUM 90
SULFUR-OXIDIZING BACTERIA
TECHNETIUM 99
WASTE FORMS