Measurement and Survey ProtocolsMeasurement and Survey Protocols

Defining and Identifying Radioactive Materials

2

OverviewOverview

• 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

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Materials from Inside Accelerator HousingMaterials from Inside Accelerator Housing

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Expected Materials and IsotopesExpected Materials and Isotopes

• 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

5Path Forward for Suspension Relief: 1. EvaluationPath 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

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MeasurementsMeasurements

• 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

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Field Surveys – Gross beta-gammaField 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 contactCERN used comparable detector:

CERN used a NaI (1.3”x1.3”) that could detect down to 3.5 µrem/hr

Ludlum Model 18 with 44-2 NaI detector used at SLAC

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Field Surveys – Gross beta-gammaField 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-55Pantex 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

TBM P15 used at SLAC

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Field Surveys: Minimum Detectable Activity (MDA)Field Surveys: Minimum Detectable Activity (MDA)

• 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

2m

2cmt x 10

NaI detector (1” x 1” ) with Pb wrapFe

MCNP geometry used for volumetric model

   Expected count rate per

unit specific activity, cpm/(pCi/g)

=0 2902

=0 =10 1177

=0 =20 433

 uniform

214

=∞ =0.1 277

=∞ =0.2 340

=∞ =0.7 556

Eff

BKGMDA

10Path Forward for Suspension Relief: 2. Release CriteriaPath 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

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Gamma Spectroscopy SurveysGamma 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

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Portal Monitor SurveysPortal Monitor Surveys

• Every truck that leaves with a non-regulated load would be surveyed by a portal monitor

Portal Monitor system at CERN

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Preliminary Field Surveys: PEP ActivationPreliminary Field Surveys: PEP Activation

• Gross survey map• Yellow shading

represents some items in the area read above background on the Ludlum Model-18

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Preliminary Field Surveys: BaBar ActivationPreliminary Field Surveys: BaBar Activation

• Past surveys suggest little activation will be found inside of detector

• Preliminary survey of Muon Shield indicated no detectable activity