Contained Materials - std3028

DOE-STD-3028-2000

A.6.3 Contained Materials

A.6.3.1

Container Fill Gas

1. The stored material condition should not change significantly because of reactions

with the container atmosphere. If material stabilization has to be repeated, there

would be additional handling and worker radiation exposure. For example, the

container atmosphere for the repackaging system at ORNL will be inert.

2. The container atmosphere must not act to mask leak testing and must support leak

testing. For example, the inert backfill in the ORNL repackaging system will be used

to detect leaks.

A.6.3.2

Mass of Contained Materials

1. The mass limit for fissile materials is based on criticality safety limits for 233U. The

single parameter subcritical limits for 233U are 6.0 kg (13.2 lbm) for metal and 10.1 kg

(22.3 lbm) for oxide (the most limiting oxide is UO2) [ANSI/ANS 1983]. The limits in

this Standard are 90% of these single parameter limits to provide a margin of safety.

It should be noted that these limits are the most restrictive limits for the prevalent

fissile nuclides (i.e., 233U, 235U, 237Np, and 241Am) except for plutonium. If plutonium

is present, further restrictions on the mass limit should be considered on a case-by-

case basis. Criticality safety analyses also may impose more restrictive limits.

It is also recommended that the mass of material in single containers be kept below

the Safeguards Category II limits (< 400 g [0.882 lbm] total U for metals and < 2 kg

[4.4 lbm] total U for oxides [DOE M 474.1-1]). This requirement will ensure that single

cans of material will not require expensive Safeguards Category II security measures

during the surveillance phase or during future transportation.

Storage and handling of 233U-bearing materials shall conform to the criticality safety

requirements of DOE O 420.1. Criticality safety evaluations shall document that

storage and handling activities shall remain subcritical during all normal and credible

abnormal events. Criticality safety evaluations shall be performed for operations

(under normal conditions) within any facility containing 233U in excess of the limits

specified in DOE O 420.1 or as specified in site-specific nuclear criticality safety

program policies and procedures.