Radiological characterization of spent control rod assemblies

Technical Report · Sun Oct 01 00:00:00 EDT 1995

DOI:https://doi.org/10.2172/125115· OSTI ID:125115

Lepel, E A; Robertson, D E; Thomas, C W; Pratt, S L; Haggard, D L ^[1]

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1. Pacific Northwest Lab., Richland, WA (United States)

This document represents the final report of an ongoing study to provide radiological characterizations, classifications, and assessments in support of the decommissioning of nuclear power stations. This report describes the results of non-destructive and laboratory radionuclide measurements, as well as waste classification assessments, of BWR and PWR spent control rod assemblies. The radionuclide inventories of these spent control rods were determined by three separate methodologies, including (1) direct assay techniques, (2) calculational techniques, and (3) by sampling and laboratory radiochemical analyses. For the BWR control rod blade (CRB) and PWR burnable poison rod assembly (BPRA), {sup 60}Co and {sup 63}Ni, present in the stainless steel cladding, were the most abundant neutron activation products. The most abundant radionuclide in the PWR rod cluster control assembly (RCCA) was {sup 108m}Ag (130 yr halflife) produced in the Ag-In-Cd alloy used as the neutron poison. This radionuclide will be the dominant contributor to the gamma dose rate for many hundreds of years. The results of the direct assay methods agree very well ({+-}10%) with the sampling/radiochemical measurements. The results of the calculational methods agreed fairly well with the empirical measurements for the BPRA, but often varied by a factor of 5 to 10 for the CRB and the RCCA assemblies. If concentration averaging and encapsulation, as allowed by 10CFR61.55, is performed, then each of the entire control assemblies would be classified as Class C low-level radioactive waste.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of Regulatory Applications; Pacific Northwest Lab., Richland, WA (United States)
• Sponsoring Organization: Nuclear Regulatory Commission, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 125115
• Report Number(s): NUREG/CR--6390; PNL--10806; ON: TI96001903
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
22 GENERAL STUDIES OF NUCLEAR REACTORS
BWR TYPE REACTORS
COBALT 60
CONTROL ELEMENTS
ENCAPSULATION
LOW-LEVEL RADIOACTIVE WASTES
NICKEL 63
NONDESTRUCTIVE ANALYSIS
NUCLEAR POWER PLANTS
PWR TYPE REACTORS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE MANAGEMENT
RADIOACTIVE WASTE PROCESSING
RADIOASSAY
RADIOCHEMICAL ANALYSIS
REACTOR DECOMMISSIONING
SILVER 108