[RESEARCH NOTE]
Philippine Journal of Science
153 (S1): 87-92, Nuclear Science and Technology
ISSN 0031 – 7683
Date Received: 06 Jul 2023
Repurposing Steel Containers as Disused Sealed Radioactive Source Capsule Overpacks
Ray Matthew A. Bunquin1,2* and Ronald E. Piquero1
1Philippine Nuclear Research Institute, Department of Science and Technology, Commonwealth Avenue, Diliman, Quezon City 1107 Philippines 2Science Education Institute, Department of Science and Technology, Bicutan, Taguig City 1631 Philippines
*Corresponding author: rmabunquin@pnri.dost.gov.ph
Bunquin RM, Piquero R. 2024. Repurposing Steel Containers as Disused Sealed Radioactive Source Capsule Overpacks. Philipp J Sci 153(S1): 103–108.
ABSTRACT
Radioactive wastes are stored to provide for their containment prior to disposal. It is crucial that the package intended for storage have an appropriate design since it is one of the most significant barriers that prevent the release of radioactivity and, consequently, protect human health and the environment. In the Philippines, radioactive wastes are managed at the Radioactive Waste Management Facility of the Philippine Nuclear Research Institute. One of the current practices in the facility involves placing encapsulated disused sealed radioactive sources in a concrete-lined 200-L drum overpack. As the facility continuously accepts radioactive wastes and recovers sources from their devices, there is an increasing need for additional storage packaging. In this paper, two steel containers were repurposed as disused sealed radioactive source capsule overpacks. The capsule overpacks were designed to store capsules containing Category 4 and 5 sources and to allow for their easy retrieval and monitoring. All activities and dose rate calculations were done using a cesium-137 source. Surface-specific activities were calculated by setting a basis of 2 mSv/h for the dose rate with shielding. These values were used to identify the maximum allowable activity inside each capsule by comparing the dose rates they would yield for all surfaces. The designed and constructed capsule overpacks can store six stainless-steel capsules. The maximum allowable activity inside each capsule compartment is 14.12 GBq for the small overpack and 16.49 GBq for the large overpack. These values are sufficiently large to store enough Category 4 and 5 sources that the facility owns which makes the repurposed steel containers as usable capsule overpacks.
Keywords: disused sealed radioactive source, overpack, radioactive waste, storage