ML18309A060
| ML18309A060 | |
| Person / Time | |
|---|---|
| Issue date: | 11/19/2018 |
| From: | Richard Chang Division of Decommissioning, Uranium Recovery and Waste Programs |
| To: | |
| R CHANG DUWP | |
| Shared Package | |
| ML18309A059 | List: |
| References | |
| Download: ML18309A060 (3) | |
Text
Enclosure REVIEW COMMENTS AND REQUEST FOR ADDITIONAL INFORMATION (RAI) ON THE DRAFT TECHNICAL MEMORANDUM: REQUEST FOR UNRESTRICTED RADIOLOGICAL RELEASE OF SELECT OPEN SPACES INSTALLATION RESTORATION SITE 12, FORMER NAVAL STATION TREASURE ISLAND, SAN FRANCISCO, CALIFORNIA U.S. Nuclear Regulatory Commission (NRC) staff and its contractor, Oak Ridge Associated Universities, reviewed the Draft Technical Memorandum: Request for Unrestricted Radiological Release of Select Open Spaces Installation Restoration Site 12, Former Naval Station Treasure Island, San Francisco, California, dated September 2018 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML18277A072).
Although not titled as such, the NRC staff considers this Technical Memorandum (TM) to be analogous to a final status survey report (FSSR) based on the TM providing the statement:
lines of evidence supporting the U.S. Department of the Navys request for unrestricted radiological release of select open spaces, also referred to as housing areas, within Installation Restoration Site 12...
The NRCs role at this site is consistent with the monitoring approach defined within the NRC and U.S. Department of Defenses Memorandum of Understanding (ADAMS Accession Number ML16092A294). Under a monitoring approach, NRC staff will review selected documents and provide comments to ensure that NRCs dose criterion of 25 millirem per year will be met at a site.
The NRC staff understands that the previous site investigation results that are summarized within the TM were not designed or specifically referred to as final surveys, but rather would be considered as scoping and/or characterization surveys as defined for the radiological survey and site investigation process. Both of these survey types may serve as the Final Status Survey (FSS), or provide supplementary data to the FSS, if the data are of sufficient quantity and quality and the surveys satisfied the applicable FSS design and assessment objectives that support unrestricted release.
NRC staff has the following comments for the U.S. Navys consideration:
- 1.
Provide additional discussion associated with your previous site characterization efforts on survey design, decision points, decision confidence levels, information on the process used to classify the site, information used to determine survey coverage, and the sample population used to support release of the site; or provide an alternative method for demonstrating compliance with NRCs 25 millirem per year dose criterion.
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Description:==
A FSS demonstrates that a facility meets NRC criteria for release (i.e., the 25 millirem per year dose criterion). Attributes of a FSS for this purpose have been described in Section 15.4.3 of NUREG-1757, Vol. 1. In the TM, the U.S. Navy treats these previous characterization surveys like a FSS.
Consistent with a FSS, please provide the following information: 1) a discussion of systematic planning methods that are designed for site-specific conditions, and FSS decision points and confidence levels; 2) additional detail on the data quality inputs that were used to generate the sample population size and locations; 3) additional information as to how these sample results and the resulting average concentrations demonstrate that release criteria are satisfied; 4) additional information on the systematic process that was used to plan and collect data, the statistical or other appropriate methods applied to data assessments, and whether the site
satisfies the requirements for release without radiological restrictions; and 5) additional information and illustrations of Site 12 classification and decision unit boundaries and methods used to demonstrate either a non-impacted determination, or that each decision unit demonstrates compliance with the unrestricted release criteria at a specified level of confidence.
As described in Section 15.4.3 of NUREG-1757, there are four methods, including Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) methodology or an alternative methodology, acceptable to NRC as the basis for facility radiation surveys associated with a FSS. One such alternative would be dose assessments that would bound reasonable foreseeable future uses.
Basis: 10 Code of Federal Regulations (CFR) 20.1402 dose criterion of 25 millirem per year RAI: As discussed above, in order to be consistent with a FSS, please provide additional discussion associated with your previous site characterization efforts on survey design, decision points, decision confidence levels, information on the process used to classify the site, determine survey coverage, and the sample population to support release of the site.
Otherwise, please provide the alternative method for demonstrating compliance with 10 CFR Part 20.1402. Section 15.4.3 of NUREG-1757, Vol. 1 provides four methods, including alternative methodology, acceptable to NRC as the basis for facility radiation surveys associated with a FSS. One such alternative would be dose assessments that would bound reasonable foreseeable future uses. If the dose assessment methodology approach is chosen, please conservatively define the source terms used and the scenarios chosen.
- 2. Provide additional information that clarifies that survey coverage satisfies the potential for contamination (e.g., percent coverage).
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Description:==
Section 2.5.1 describes the 2013/2014 radiological scoping survey, the intent of which was to determine if residual radioactivity requiring remediation was present and, as noted in the introductory review summary, was to provide design input for either characterization or final status surveys. Section 2.5.2 of the TM presents the results of the 2017 Scoping Survey Follow-up Investigation, where 196 potential anomalies that were judgmentally selected for further survey following review and assessment of the 2013/2014 radiological scoping gamma survey files. Section 2.5.3 summarizes the 2017 Open Space Surveys. These surveys were not described as final status surveys.
Basis: Scoping and characterization surveys performed during the radiological survey and site investigation process may also support FSS decisions, provided the methods, field and laboratory instrumentation type and sensitivity, and the resulting data quality also can be demonstrated to have satisfied FSS requirements.
The Section 3 descriptions and discussions for the gamma radiation scanning equipment sensitivities and applicability to MARSSIM-based requirements achieve the desired FSS objective for use and detection sensitivity. However, the adequacy of the survey coverage when using the described detectors cannot be assessed. MARSSIM and NUREG-1757 FSS planning and FSSR content includes scanning requirements as a function of contamination potential by applying a graded approach based on area classification. As noted previously, area classification is not clearly defined. Furthermore, the TM does not specify scanning coverage.
Figures 2 through 5 of the TM Appendix A give the appearance of high-density coverage during
the 2013/2014 scoping survey of the four housing series areas. However, the coverage or plotting methods are not specifically described in the text.
The 2017 follow-up scoping survey was limited to gamma scanning and measurements within 3 meter x 3 meter blocks and soil sampling. The scanning data were not mapped, graphically plotted or otherwise statistically summarized for review and assessment. Instead, the data were simply included by housing series in over 1000 pages of individual count rates without the coordinate reference data.
RAI: Provide additional information on survey scan coverage and area classification for review to determine if FSS requirements for these data were satisfied.
Should an alternative method, such as conservative dose assessments, serve as the response basis to Comment 1 and is provided for NRC staffs review, please incorporate information that addresses how scanning coverage and the measurement system sensitivity were integrated into the final status site investigation and decision process. If the scanning data and coverage serve as inputs to conservative scenarios or are otherwise used to demonstrate confidence in LLRO discovery, provide information that demonstrates that coverage and sensitivity were adequate and provide information that bounds decision error probabilities. Most notably, false negative decision errors and dose consequence to a future site receptor encountering undiscovered LLROs is of interest.
- 3. Provide confirmation of historical site grading to ensure the depth of contamination would not exceed historic grading records and remain within the detectability depth of instruments.
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Description:==
The lines of evidence summary is discussed in Section 2.8 of the TM. The statements are made that the Site 12 open areas have been characterized and in some cases fully investigatedthe Navy has taken reasonable efforts to investigate the majority of open spaces and discover LLROs. As part of the argument for release of Site 12, the NRC staff understands that the records of historical site grading (for areas where fill is less than a depth of 3 feet) is used in conjunction with survey instruments that are likely able to detect radium at similar depths.
NRC staff also understands that there has been a lot of subsurface investigations at Site 12 dating back many years. NRC staff is seeking information on what efforts have been made to validate historical records on site grading with previous subsurface investigations at Site 12.
Basis: Section 15.4.3 of NUREG-1757, Vol. 1 provides four methods, including MARSSIM methodology, acceptable to NRC as the basis for facility radiation surveys associated with FSS.
Requirements for the FSS and information to be included in the FSSR are stated in NUREG-1757, Vol. 2 Sections 4.4 and 4.5, and special circumstances and alternative methods are addressed in the appendices.
RAI: Please provide additional information on the systematic radiological survey process that was used for subsurface investigations, and how that information has confirmed historical site grading records.