The 875 High Range Containment Monitor consists of a detector, readout, and cable (in metallic tubing) connected through a sealed penetration in the containment wall. The detector walls are thick enough to withstand loss of coolant accident (LOCA) pressures, but thin enough to provide full response to 133Xe (80 keV).
Key Features
Unattenuated, in-containment detector location. Responds fully to 133Xe (80 keV) and other fission products with photon energies as low as 60 keV
Monitor designed and tested to meet NRC Reg. Guide 1.89 (class 1E qualifications) and NRC Reg. Guides 1.29/1.100 (seismic qualification)
Permits continuing in-containment post-LOCA radiation assessment
Detector and cable designed and tested to meet IEEE 323 (1974) for operation in containment. Readout meets IEEE 323 (1974)
Applications
The system operates with detector/readout spacing up to 500 feet and greater distances are possible. Normally, redundant detector/readout combinations are utilized. To assure the integrity of the detector/cable/readout system, an electronic check source is automatically initiated every 17 minutes. A successful check keeps the green front panel Fail indicator illuminated. An unsuccessful check initiates a relay closure (failsafe), and turns the green Fail indicator off. The channel TEST button on the readout injects a signal to test operation of the alarm lights and relays. If a battery is connected to the readout, the system automatically switches to this supply in the event of failure of the AC input.