DEVELOPMENT OF A CONTAINER FOR THE TRANSPORTATION AND STORAGE OF PLUTONIUM BEARING MATERIAlS

There is a large backlog of plutonium contaminated materials at the Rocky Flats Environmental Technology Site near Denver, Colorado, USA. The clean-up of this site requires this material to be packaged in such a way as to allow for efficient transportation to other sites or to a permanent geologic repository. Prior to off-site shipment of the material, it may be stored on- site for a period of time. For this reason, it is desirable to have a container capable of meeting the requirements for storage as well as the requirements for transportation. Most of the off-site transportation is envisioned to take place using the TRUPACT-ll Type B package, with the Waste Isolation Pilot Plant (WIPP) as the destination. Prior to the development of this new container,theTRUPACT-llbadalimitof325 FGE(fissilegramequivalents)ofplutoniumdue to criticality control concerns. Because of the relatively high plutonium content in the material to be transported, transporting 325 FGE per TRUPACT-ll is uneconomical. Thus, the purpose of the new containers is to provide criticality control to increase the allowed TRUPACT-ll payload and to provide a safe method for on-site storage prior to transport. The Pipe Overpack Container was developed to meet these needs. It consists of an outer 55 gallon steel drum with polyethylene drum liner, a layer ofcane fiberboard to provide insulation and energy absorption, and an inner stainless steel pipe container. The pipe container contains a welded-on pipe flange with an integral elastomeric 0-ring and a bolted on lid. The pipe containers are currently built in two sizes: (15.2 em) diameter and 12-inch (30.5 em) diameter. The lid of the pipe container contains a filter to allow venting of gases created by thermal or radiolytic decomposition of the materials to be stored and transported. The outer drum contains a similar ftlter. This paper will describe the analysis and testing used to demonstrate that the Pipe Overpack Container provides safe on-site storage o f plutonium bearing materials in unhardened buildings and provides criticality control during transportation ·within the TRUP ACT-ll. Analyses included worst-case criticality analyses, analyses of fork-lift tine impacts, and analyses of roof structure collapse onto the container. Testing included dynamic crush tests, bare pipe impact tests, a 30-minute totally engulfmg pool-fire test. and multiple package impact tests in end-on and side-on orientations.