NORM: Radiation Surveys

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NORM Radiation Surveys (an Attempt for Source
Inventory) Gert Jonkers Engineering Analytical
- GSEA/4 Problem Solving (Shell EP 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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MODES OF (NATURAL) DECAY
222Rn 218Po a
emission of mono-energetic, fast (MeV) He nuclei
214Pb 214Bi b
emission of poly-energetic, fast (keVlt gtMeV)
electrons
hn
234mPa 234Pa g
emission of mono-energetic, penetrative (keVlt
gtMeV) photons
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RADIATION PENETRATION CHARACTERISTICS
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NOR g-yields
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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.

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MEASUREMENTPROTOCOL
Equipment dose rate monitor Victoreen 190 /
RP1 (gt 10 nSv/h, Eg gt 15 keV) calibrated August
2003 Measurement Procedure Surface Dose Rate
taken as close as possible to surface (2 ltgt 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)

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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
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EXPLOIT a priori EP 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
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Reported External Radiation Levels at the
Circumference (internally) of Oil/Gas Production
Facilities
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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.

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NORM SURVEY- maintenance

• Inside External Radiation Monitoring
• External g(b)-Radiation Monitor (ex-proof,
  surface/assesment)
• g/b Contamination Monitor (sensitive gt
  maintenance)
• Sampling Suspect Deposits
• Where appropriate (recording of selected, grab,
  representative sample and sampling data
  characteristics)

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Grab Sampling Infield Measurements
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SYSTEMATIC APPROACH TO PROTECTION AGAINST NORM
OPERATIONS NORM (external/contamination)
radiation survey dose readings gt 0.5
mSv/h NORM contaminated or contamination readings
gt 50 c/s above bg signpost areas 0.1
mSv/h lt dose readings lt 0.5 mSv/h NORM suspect Or
5 c/s above bg lt contamination readings lt
50 c/s above bg dose readings lt 0.1 mSv/h no
NORM restrictions and contamination readings lt 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
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NORM RADIATION SURVEYS

• OPERATIONS
• surface dose rates (mSv/h) gt 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) gt g-dose component
  (records)
•  
• MAINTENANCE
• ambient dose rates (mSv/h) gt g-dose component gt
  record
• sample dose rate (mSv/h) and sample contamination
  (c/s) gt record
• send in NORM-suspect samples for measurement and
  analysis (record, evaluate, corrective actions) gt
  final classifcation against legislation