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Measurement and Survey Protocols

Measurement and Survey Protocols. Defining and Identifying Radioactive Materials. Overview. Materials disposition overview Expected materials and isotopes Field surveys Protocols and procedures Minimum Detectable Activity (MDA) determination Gamma spectroscopy Portal monitor surveys

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Measurement and Survey Protocols

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  1. Measurement and Survey Protocols Defining and Identifying Radioactive Materials

  2. Overview • Materials disposition overview • Expected materials and isotopes • Field surveys • Protocols and procedures • Minimum Detectable Activity (MDA) determination • Gamma spectroscopy • Portal monitor surveys • Initial field surveys • PEP-II Ring and BaBar

  3. Materials from Inside Accelerator Housing

  4. Materials: Concrete blocks Electronic copper cables of various diameters and lengths Iron and steel plates Electronic components and crates including PMTs Rubber and plastic hoses Aluminum piping, cable plant, and components Special items including the Be DHC Isotopes: In Copper: Co-60, Fe-55, Mn-54 In Plastic: Na-22, Si-32, H-3 In Lead: Bi-207, Tl-204, Hg-194, Pt-193, Ta-179 In Stainless Steel: Co-60, Fe-55, Mn-54, Co-57, V-49, Ni-63, Nb-91, Ar-39, Ti-44 Expected Materials and Isotopes

  5. Path Forward for Suspension Relief: 1. Evaluation • Process knowledge • Identify areas and activities that can potentially activate materials • FLUKA calculations • BaBar detector model • Other geometries model • Confirmatory measurements • Measurement and survey protocols that follow MARSSIM guidance • Gross beta-gamma field surveys • Gamma spectroscopy surveys • Portal monitor surveys

  6. Measurements • Gross beta-gamma field survey on all surfaces using an appropriate survey instrument • Detailed procedures for surveying and defining radioactive material • Technical Basis Document • Optimized survey instrument performance • Point-source geometry measurement efficiency as reference • MCNP calculations of measurement efficiency for an unknown volumetric source distribution based on the point-source geometry • Source distribution for BaBar components can be estimated by FLUKA • MDA calculated for most conservative case of source distributions • Gamma spectroscopy survey using portable or fixed HPGe system on critical items • Portal Monitor survey of outgoing shipments

  7. Field Surveys – Gross beta-gamma • SLAC uses the Ludlum Model 18 with 44-2 1”x1” NaI detector • Sensitive from <100 keV to several MeV • Protocols per Procedure • All surfaces of every item surveyed • CERN protocols are similar: • All surfaces of every item surveyed in low background area – slow scanning on contact Ludlum Model 18 with 44-2 NaI detector used at SLAC CERN used comparable detector: CERN used a NaI (1.3”x1.3”) that could detect down to 3.5 µrem/hr

  8. Field Surveys – Gross beta-gamma • Surface contamination surveys performed using a GM pancake detector (Eberline HP360, Ludlum 44-9, TBM P15) • Protocols per Procedure • All surfaces of every item surveyed • Swipes taken on Fe/steel for LSC measurement for Fe-55 TBM P15 used at SLAC Pantex used comparable detectors: Pantex used a Ludlum Model 12 with a GM frisker for surface contamination. Pantex estimated their MDAs for contamination to be about 8 dpm for alpha, 13 dpm for beta, and 60 dpm for tritium

  9. MCNP then used to model volumetric activation Activation profile for BaBar/PEP components estimated by FLUKA Conversion factor used to determine MDA in field setting Field Surveys: Minimum Detectable Activity (MDA) NaI detector (1” x 1” f) with Pb wrap Fe 2cmt x 10 2mf MCNP geometry used for volumetric model

  10. Path Forward for Suspension Relief: 2. Release Criteria • Screening levels for clearance • DOE Order 5400.5 • Guidance for surface contamination (based on 25 mrem/yr) • Case-by-case approval for volumetrically contaminated materials • ALARA principle be observed • ANSI N13.12-1999 • Guidance for volumetrically activated materials (based on 1 mrem/yr) • 30 pCi/g for most beta-gamma isotopes at SLAC such as Co-60, Na-22, etc. Only items without radioactivity, i.e., below MDA, would be released for recycling

  11. Gamma Spectroscopy Surveys • Surface and/or sampling measurements with portable or fixed HPGe systems on critical items • Very sensitive instruments • Long count time required • Critical items pre-selected • Measurement results compared with FLUKA results to confirm FLUKA results and establish efficiencies and MDAs of measurement methods SLAC Radioanalysis Laboratory’s fixed HPGe system

  12. Portal Monitor Surveys • Every truck that leaves with a non-regulated load would be surveyed by a portal monitor Portal Monitor system at CERN

  13. Preliminary Field Surveys: PEP Activation • Gross survey map • Yellow shading represents some items in the area read above background on the Ludlum Model-18

  14. Preliminary Field Surveys: BaBar Activation • Past surveys suggest little activation will be found inside of detector • Preliminary survey of Muon Shield indicated no detectable activity

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