Adequacy of radioiodine control and monitoring at nuclear fuels reprocessing plants
The present backlog of irradiated reactor fuel leads to projections that no fuel out of the reactor less than 10 years need be reprocessed prior to the year 2000. The only radioiodine present in such aged fuel is /sup 129/I (half-life 1.6 x 10/sup 7/ y). The /sup 131/I initially present in the fuel decays to insignificance in the first few hundred days post-reactor. The /sup 129/I content of irradiated fuel is about 1 Ci per gigawatt-year of electricity generated (Ci/GW(e)-y). The US EPA has specified, in 40 CFR 190, a release limit for /sup 129/I of 5 mCi/GW(e)-y. Thus a retention factor (RF) of 200 for /sup 129/I at the fuel reprocessing plant (FRP) is required. Experience indicates that RF values obtained under actual FRP operating conditions can average as little as 10% of experimentally determined RF values. Therefore processes theoretically capable of achieving RF values of up to 10/sup 4/ have been investigated. The US EPA has also specified in 40 CFR 90 a thyroid dose limit of 75 mrem/y for a member of the general public. This dose limit could be readily met at a typical FRP site with an RF value of about 10 or less. Therefore, the limit of 5 mCi/GW(e)-y is more restrictive than the thyroid dose limit for /sup 129/I. The absence of /sup 131/I in effluents from processing of aged fuels makes analysis of /sup 129/I somewhat easier. However, in-line, real-time monitoring for /sup 129/I in FRP gas streams is currently not feasible. Moisture, chemicals, and other radioactive fission products interfere with in-plant measurements. Samples collected over several days must be taken to a laboratory for /sup 129/I analysis. Measurement techniques currently in use or under investigation include neutron activation analysis, scintillation counting, mass spectroscopy, and gas chromatography coupled with electron capture detection. 26 references, 3 figures, 7 tables.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6993477
- Report Number(s):
- PNL-5108; ON: DE84013311
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
FUEL REPROCESSING PLANTS
OFF-GAS SYSTEMS
IODINE 129
MONITORING
IODINE 131
RADIOACTIVE WASTE PROCESSING
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODINE ISOTOPES
ISOTOPES
MANAGEMENT
NUCLEAR FACILITIES
NUCLEI
ODD-EVEN NUCLEI
PROCESSING
RADIOISOTOPES
WASTE MANAGEMENT
WASTE PROCESSING
YEARS LIVING RADIOISOTOPES
052001* - Nuclear Fuels- Waste Processing
050800 - Nuclear Fuels- Spent Fuels Reprocessing