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NORM: Radiation Surveys (an Attempt for Source Inventory) Gert Jonkers

NORM: Radiation Surveys (an Attempt for Source Inventory) Gert Jonkers Engineering & Analytical - GSEA/4 “ Problem Solving ” (Shell E&P Ionising Radiation/NORM HSE Expert CHP) location Shell Research & Technology Centre, Amsterdam P.O. 38000 NL-1030 BN Amsterdam the Netherlands.

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NORM: Radiation Surveys (an Attempt for Source Inventory) Gert Jonkers

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  1. NORM: Radiation Surveys (an Attempt for Source Inventory) Gert Jonkers Engineering & Analytical - GSEA/4 “Problem Solving” (Shell E&P Ionising Radiation/NORM HSE Expert CHP) location Shell Research & Technology Centre, Amsterdam P.O. 38000 NL-1030 BN Amsterdam the Netherlands

  2. MODES OF (NATURAL) DECAY 222Rn 218Po +a emission of mono-energetic, fast (MeV) He nuclei 214Pb 214Bi + b emission of poly-energetic, fast (keV< >MeV) electrons hn 234mPa 234Pa + g emission of mono-energetic, penetrative (keV< >MeV) photons

  3. RADIATION PENETRATION CHARACTERISTICS

  4. NOR g-yields

  5. g-RADIATION SURVEY OF OPERATING INSTALLATIONS (objective: potential presence of NORM [maintenance], workforce dose assessment) • External detection of NORM present on the inside of installations using  dose-rate monitors (mSv/h) • activity concentration (Bq/g) , • 228Ra, 228Ra and/or 228Th equilibrium with their progeny, • total amount and NORM spatial distribution, • elemental composition and specific density of NORM deposit, • elemental composition and wall thickness of the installation part, • presence of other radiation attenuating material, • total distance of NORM-source to monitor, • detector sensitivity & field of view, • ‘natural radiation’ background readings.

  6. MEASUREMENTPROTOCOL Equipment dose rate monitor: Victoreen 190 / RP#1 (> 10 nSv/h, Eg > 15 keV) calibrated August 2003 Measurement Procedure Surface Dose Rate: taken as close as possible to surface (2 <> 5 cm) ‘Ambient’ Dose Rate: taken at ~ 1 m height (used for HS assessment) • Protocol • take 12 readings • remove maximum and minimum value of this series • compute average and standard deviation (s) of the 10 remnant readings • check if maximum and minimum values are outliers with respect to the 95% (2s) confidence interval – one occasional outlier is acceptable • quote averaged dose rate (if series of readings is acceptable)

  7. MEASUREMENT STRATEGY • Identify product/waste streams in the flow diagrams of the installations (records with time?); • Identify all spots where, under normal plant operating conditions, deposits might have been formed c.q. Accumulated (DT, DP, changes mixing/flow/phasetreatment); • Check wall thickness of the spots under review (interprete); • Check for the presence of other attenuating materials at these spots (insulation material); • Estimate the distance of the (potential) NORM deposit to the monitoring device (take surface and ambient dose rate readings); • Select suitable radiation monitor (other hazards, confounders); • Take background readings of this monitor at the location of the installation (not at concrete strcutures); • Measure, both at the surface and at 1 m away/height to the installation parts, the external radiation level. Take notes of the monitor readings and mark, for future reference, the monitoring spots on the isometrics of the installation; • Decide on the presence of enhanced radiation levels; • Report on the findings from the current survey. OUTPUT Maintenance attention Workforce dose

  8. EXPLOIT a priori E&P NORM KNOWLEDGE FLARE FUEL GAS FLARE K.O. DRUM GAS SCRUBBER GAS SCRUBBER METERING PACKAGE EXPORT LINE PRODUCTION MANIFOLD 2ND STAGE SEPARATOR 1ST STAGE SEPARATOR DEHYDRATOR OIL SHIPPING PUMP SKIMMED OIL PUMP FLOTATION CELL WELLHEADS DE- AERATOR S.W.SERVICES COOLERS ETC. OVERBOARD PUMP SEA WATER PUMP PRODUCTION TUBING WATER FLOOD INJECTION SEA WATER BOOSTER PUMP

  9. Reported External Radiation Levels at the Circumference (internally) of Oil/Gas Production Facilities

  10. b/g-CONTAMINATION MONITORING (objective: potential presence of NORM [maintenance], pre-classifaction) • Detection of NORM present on the inside of installation parts using b/-monitoring devices (c/s) • activity surface contamination (Bq/cm2), • 228Ra, 210Pb, 228Ra and/or 228Th equilibrium with their • progeny, • remnant oily films, roughness of the surface, • (grab) sampling • ‘natural radiation’ background readings.

  11. NORM SURVEY- maintenance • Inside External Radiation Monitoring • External g(b)-Radiation Monitor (ex-proof, surface/assesment) • g/b Contamination Monitor (sensitive > maintenance) • Sampling – Suspect Deposits • Where appropriate (recording of [selected, grab, representative] sample and sampling data & characteristics)

  12. Grab Sampling & Infield Measurements

  13. SYSTEMATIC APPROACH TO PROTECTION AGAINST “NORM” “OPERATIONS”NORM (external/contamination) radiation survey dose readings > 0.5mSv/h NORM contaminated or contamination readings > 50c/s abovebg signpost areas 0.1mSv/h < dose readings < 0.5mSv/hNORM suspect Or5c/s above bg < contamination readings < 50c/s above bg dose readings < 0.1mSv/h no NORM restrictions andcontamination readings < 5 c/s above bg “MAINTENANCE” NORM (external/contamination) readings ad hoc NORM contaminated: take external and contamination readings for open tanks/vessels, working hours, asses dose, Waste Storage NORM suspect: take external and contamination readings for open tanks/vessels, record working times, take ‘representative’ sample Analyse for final classification of waste: normal / NORM

  14. NORM RADIATION SURVEYS OPERATIONS • surface dose rates (mSv/h) > enhanced with respect to natural background than 226Ra and/or 228Ra-containing NORM (or enhanced 222Rn-concentrations in tank gascap) (contamination monitor [c/s] may show enhanced readings more sensitively) • ambient dose rates (mSv/h) > g-dose component (records) MAINTENANCE • ambient dose rates (mSv/h) > g-dose component > record • sample dose rate (mSv/h) and sample contamination (c/s) > record • send in NORM-suspect samples for measurement and analysis (record, evaluate, corrective actions) > final classifcation against legislation

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