Development and Characteristics of an ANSI/ANS-8-3-1997-Compliant Criticality Alarm
A Criticality Alarm System (CAS) was developed at the Savannah River Site (SRS) beginning in 1964, which used an ionization chamber and battery - powered tube amplifier. Three generations of improvements are described here, to improve reliability, reduce maintenance cost, and eliminate false alarms. The original configuration for the CAS instrument (called Nuclear Incident Monitor-NIM model I) was a single chassis containing all components including the batteries and the detector, and a warning bell and light. To decrease the contamination potential of NIMs, the detector can now be removed from the chassis and remotely located for some installations. In the presently used second generation model II, each unit consists of an ion chamber with electrometer amplifier, voltage comparator circuits, battery and power supplies, monitoring circuits, and relay alarm circuits. The electrometer circuit is housed with the ion chamber in an aluminum enclosure. The remaining components are located in the main chassis. An alarm point of one R per Hour is adjustable over a narrow range for calibration purposes. Evacuation zones were determined on a 25 rad dose basis, and then modified to the 12 rad level.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC09-96SR18500
- OSTI ID:
- 799457
- Report Number(s):
- WSRC-MS-2002-00539; TRN: US0300039
- Resource Relation:
- Conference: ANS 2002 Winter Meeting, Washington, DC (US), 11/17/2002--11/21/2002; Other Information: PBD: 7 Jun 2002
- Country of Publication:
- United States
- Language:
- English
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