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SECTION I - GENERAL INFORMATION
A.
General description and application
The QSA Global, Inc. Model 989 gamma radiography exposure device is used to perform directional beam gamma
radiography of welds and the adjacent heat affected areas on pipelines and industrial structures. The Model 989 is
designed to contain a Selenium-75 special form sealed source with a maximum activity of 20.0 Curies (740 GBq)
and is used on pipelines and other industrial structures as a beam type exposure device. The use of other
radioisotopes in the Model 989 exposure device is not authorized.
During radiographic operations, the source assembly is exposed either by a pneumatic actuator or crank-out remote
controls which push the source assembly from a shielded position into a beam port within the Model 989 (see figure
1). The standard directional beam devices are manufactured with a lead shielded beam port that is collimated to a 30
by 60, or a 40 by 40 degree emergent beam. To terminate a radiographic exposure, the source assembly is retracted
to the fully shielded position by exhausting the pneumatic actuator or by retraction using the mechanical remote
controls.
Figure 1 – Cross-Section View of 989 (Source in Stored Position)
The Model 989 is specifically designed for SCAR and requires radiographers to consider the primary beam area
created at the film plane to determine shielding requirements for the technique. The primary beam is shielded after
passing through the specimen and film cassette to effectively reduce the working distances to the controlled areas.
Proper SCAR technique allows radiography to be conducted in areas congested with personnel and significantly
reduces the distances to the “Controlled” or “Restricted” areas when compared to conventional crank-out
radiography systems. The Model 989 is designed to be used with two options to enable exposure of the radioactive
source; specifically a Sentinel
TM
authorized pneumatic actuator with a remote air pump control or a Sentinel
TM
manufactured crank-out remote control. There is no elevation in dose rates (commonly referred to as “flash dose”)
when the source is exposed from the shielded position to the beam port position, as expected in ANSI N432 Type I
crank-out type radiography systems.
The basic radiography system consists of the Model 989 exposure device, a pneumatic actuator and remote pump
control and/or the optional crank-out remote controls and shielding materials to shield the primary beam after
passing through the specimen and film cassette. An optional fixture kit is available for use with the Model 989 that
includes a handle assembly and fixture attachment plate that facilitates its handling and attachment to pipes for
performance of radiographic exposures (see Figure 2).
Summary of Contents for 989
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