25.03.2014

Dacon introduces New RT Technology

Dacon Inspection Services recently acquired Small Controlled Area Radiography (SCAR) Radiographic Testing (RT) systems, which allow low radiation RT work to be conducted alongside normal work at construction sites. With conventional Gamma Ray sources, work sites usually require evacuation of all personnel, due to the high radiation – which usually means RT operations can only be conducted at lunchtime or at night. Now, with the advent of better radiation source holders, the radioactive source never leaves it’s container and the container is what shields people from receiving high doses of radiation.

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The picture below shows an older method of exposing the source from its container to the exposure point. The source in transit indicates the danger of radioactive sources. In its container it is quite safe, and at the exposure point it can be shielded. Transit gives off high flash doses. The SCAR family (SCAR and “Baby” SCAR) has set a precedent for safer working in the industry and has enabled radiography to be carried out with radiation levels ALARP (As Low As Reasonably Practicable). The SCAR system is capable of performing radiography inside a controlled area in the workplace with limited disruption to normal operations. Reduction of unwanted radiation scattering effects around the film by effective photoelectric absorption has an additional benefit of improving radiograph quality.

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Features

  • Reduced Radiation Exposure
  • Simple Recovery Procedure with Zero Risk of Source Detachment
  • Requires Mandatory Pre-Planning of the Work
  • A Small Controlled Area Means, Positive, Direct & Easy Control
  • Minimum Interference with Emergency Escape Routes
  • Minimizes Operator Error
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Safety Zone comparison for standard radiography and the SCAR system

Engineered Safety Features – 989 “Baby” SCAR

  • Posilock safety locking mechanism
  • Only 1/3rd turn hand crank operation. Source only moves approx. 3 inches in its holder.
  • Direct physical access to the source is impossible
  • Beam limited to one direction
  • Lightweight tungsten & lead shield
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Baby SCAR gamma ray container showing lock device and beam port.

Cost Savings

  •  Minimal disruption to adjacent operations
  • Improved productivity from 24 hour radiography minimizing delays on commissioning activities
  • No risk of radiation incident therefore no risk of incident costs
  • Minimal interference with Nucleonic Level Gauges, less risk for unscheduled plant shutdown
  • HOIS recommended technique for fast screening of complex geometry small bore – piping for corrosion and erosion
  • Inspection through insulation for corrosion, no need for insulation removal
  • Proven to help reduce shutdown durations
  • Reduced downtime for any trades

Summary

  • SCAR is safe to use 24 hours a day – no need for specific radiography windows
  • Cost efficient
  • The barriered area is always very small, normally less than 10 m diameter
  • Area is easy to see & control
  • SCAR will rarely affect other work
  • Equipment fits most pipe geometries
  • SCAR can replace most conventional radiography when planned in advance
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