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Introduction
General Description
1
1-1
Section 1
Introduction
1.1 General Description
Containment Monitor 875
The 875 Containment Monitor has been qualified
for use in Nuclear Safety related applications.
Qualification Test Reports, 950.301, 950.308A, and
950.310A define the parameters that have been
verified by test and are available for purchase.
Containment Monitor 875 functions as an accident monitor for reactor containments, refer to Figure 1-1. It
consists of the 877-1 Ion Chamber Detector that is located within the reactor containment, and the 876A-1
Readout Module that is contained in a rack in the control room. The readout module contains a power
supply that provides the necessary power both for itself and the detector. The readout module is
connected to the detector by two cables, a coaxial high voltage cable and a coaxial signal cable.
Specifications for the detector and readout module are contained below.
1.2 Specifications
Detector 877-1
Radiation Detected Photons above 60 keV
Range 1 R/h to 1E7 R/h
Energy Response ± 20% from 80 keV to 2 MeV
Chamber Construction Stacked parallel plate, 316 stainless steel housing, 3
terminal, guarded ion chamber
Saturation >80% up to full scale on instrument
Collection Voltage 450 to 550 VDC
Current Output 7E-11 to 7E-4 Amp/R/Hr (nominal)
Chamber Capacitance 435 picofarads (nominal)
Voltage Withstand and Leakage 5E10-5 amperes @ 500 VDC between either ground and
connector pins
Capacitance Approximately 430 pf
NOTE