Original Date: 11/03/1996
Revision Date: 01/18/2007

Special nuclear [radioactive] material (SNM) must periodically be inventoried to meet Department of Energy (DOE) accountability program requirements. Oak Ridge has developed a continuous automated vault inspection system (CAVIS) to minimize the labor, time, and radiation-exposure aspects associated with SNM inventories.

Traditionally, SNM inventories require a (minimum) four-person inspection team to enter the storage area in accordance with safety regulations. Any automated security systems that need to be temporarily disabled during the inventory have to be replaced with armed guards. With the high cost of performing such a task ($200 per item), inventories typically are done only on a sampling basis. However, accidental or actual triggering of an alarm requires emergency inventories to be performed which results in shutting down all plant operations.

The CAVIS works as a virtually-passive sensor system that can continuously monitor physical attributes from stored nuclear material. By using fiber optic and solid state sensors, the CAVIS can verify item weight, temperature, gamma flux, relative enrichment, neutron flux (plutonium), location, and motion. Any changes in these attributes provoke an immediate response to the appropriate alarm system(s).

Currently, Oak Ridge has been field-testing two CAVIS systems. The CAVIS offers a quick (100%) inventory method; shows potential for adapting to various storage configurations; and meets or exceeds all current DOE requirements for inventoried SNM. Oak Ridge estimates that the CAVIS will reduce monitoring costs by $180,000 to $7.2 million for its three SNM vaults located at the Y-12 Plant.

For more information see the Point of Contact for this survey.