selected for two reasons: 1) gas filters allow the entry of moist air which could
interact with salts and other impurities contained in the stored materials; and 2) if
the container were not always oriented properly, stored powder could plug the filters
and later "blow out" causing, at a minimum, a local spread of contamination.
A welded closure is preferred because it is believed to provide the best combination
of features such as design qualification test performance, ease of assembly under
production conditions in a glove box, container (package) payload capacity, and
achievement of a 50-year life.
The material container (convenience container) is a container that is used to transfer
plutonium-bearing material. A material container is not required in packaging and is
not considered an isolation barrier by this Standard. Use of a material container can
reduce the potential for contamination during loading and closure of the inner
container, facilitate packaging, and provide an additional material barrier.
2. These requirements simply provide functionality in the design.
3. Storage of plutonium-bearing material must comply with existing MC&A, safeguards
and security, and audit and surveillance directives which rely on nondestructive
assays as a technique for validation. The MC&A requirements call for routinely
assaying stored materials for process, accountability, and inventory controls.
Plutonium packaging and storage should not preclude adherence to these directives.
4. Pressure indication, such as a pressure deflectable lid or bellows observable by
radiography, will permit early detection of inner container pressurization prior to
potential failure. The pressure detection threshold [set at 790 kPa (100 psig) in this
Standard] balances the need to minimize "false positives" with the need to eliminate
"false negatives." Pressure buildup in the container is expected to yield internal
pressures less than 790 kPa (100 psig). Additionally, there are no known
mechanisms for pressure buildup in containers holding plutonium metal
[Spearing/Crooks, 2003]. An internal pressure indication of 790 kPa (100 psig) is
therefore adequately indicative of unexpected pressurization, yet far below the
design pressure for the outer container (Criterion 126.96.36.199 requires the design
pressure to be at least 4927 kPa, or 699 psig).
5. Specifying a minimum design pressure provides compatibility with the safety
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