Figure 1: Top-angled 3-D View of the Gamma Cave Facility (top removed for clarity).
The Gamma Cave facility (Figure 1) is a dry ventilated irradiation room located on the experimental level of the University of Massachusetts Lowell Research Reactor (UMLRR) containment building. The gamma cave has a 15 cubic meter volume to accommodate experimental apparatus of various sizes. The cobalt-60 sources used for gamma irradiations are located inside the water-filled bulk-irradiation pool at the UMLRR. Inside the Gamma Cave, a 2.7 square meter opening in the pool wall tapers inward to the 0.356 square meter source window. Several small ports penetrate one shielding wall to provide access for instrumentation cables.
The Co-60 sources are configured into 25 centimeter (cm) x 36 cm frames to produce a planar source geometry. When an irradiation is performed, the source frame is positioned onto a wall mounted rack inside the pool. For the Gamma Cave, the rack is located in front of a 19 millimeter thick aluminum source window through which the Cobalt-60 gamma photons enter the Gamma Cave. A wide range of dose rates are achievable by varying the source activity and the centerline distance of the sample from the source window. The highest dose is obtained up against the window and decreases exponentially with distance from the window.
Dose Rates:
- 1 Megarad/hour (10 kiloGray/hour) to 1 rad/hour (0.01 Gray/hour)
Sample Size:
- Various
Uses:
- Bulk medical product sterilization
- Hardness testing and characterization of electronics, optical components, mirrors, lenses, and windows for space applications
- Material Evaluation