Lower Limit of Detection (LLD) for Potentially Contaminated Oil
See the memorandum from F. J. Congel to D. M. Collins dated January 30, 1985.
For cases in which no release of radioactive material is authorized, the appropriate lower limit of detection (LLD) is the "operational state of the art" value used for laboratory measurements of environmental samples. This is the LLD value given in the standard Radiological Effluent Technical Specifications (RETS) for environmental samples.
The health physics position was written in the context of 10 CFR 20.302, but it also applies to "new" 10 CFR 20.2002. HPPOS-071 and HPPOS-072 contain related topics.
Region II requested that licensee guidance be developed for acceptable surveys of potentially contaminated oils and referred to IE Circular No. 81-07 (see HPPOS-071) as espousing the use of operational state-of-the-art measurements for release of materials. However, IE Circular No. 81-07 does not establish criteria for releasing radioactively contaminated materials from restricted areas for unrestricted use (see HPPOS-072).
The regulations applicable to nuclear power reactor licensees do not provide for the release of materials that are known to be radioactively contaminated at any level. Authorization for disposal of specific radioactively contaminated materials may be requested as specified in 10 CFR 20.302 [or 10 CFR 20.2002].
The intent of the above IE circular was to provide guidance on acceptable limits of detection of portable survey equipment, thus defining "how hard you have to look" for the case in which no release of radioactive material is authorized. When no release of radioactive material is authorized, the appropriate LLD is the "operational state-of-the-art" value used for laboratory measurements of environmental samples.
This is the LLD given in the standard RETS for environmental samples (e.g., 15 pCi/L, or 1.5 x 10-8 micro-Ci/ml for Co-58, Co-60 and Cs-134). 49 FR 36653, PRM-20-15 states that the measured radioactivity for major sources of waste oil at BWRs and PWRs are typically 1 x 10-7 to 1 x 10-6 micro-Ci/ml.
For cases in which disposal of radioactively contaminated oil has been authorized by the NRC pursuant to 10 CFR 20.302 [or 10 CFR 20.2002], the necessary LLD need only be sufficiently low to ensure that the particular limits are not exceeded.
Therefore, these LLDs may be substantially above the technical specification environmental LLD if the NRC authorized release limits correspond to radioactivity concentrations substantially above these levels. Since the release limits authorized pursuant to 10 CFR 20.302 [or 10 CFR 20.2002] are established on a case-by-case basis, the corresponding LLDs necessary to ensure that the release limits are not exceeded will vary accordingly.
Regulatory references: 10 CFR 20.302, 10 CFR 20.2002
Subject codes: 3.6, 6.8, 7.6, 12.8