Fixed Particulate, Iodine and Gas Monitor

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Fixed Particulate, Iodine and Gas Monitor

MODEL RS-60D
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The Model RS-60D Particulate, Iodine and Gas Monitor is an offline continuous air monitor consisting of sampling equipment, a detector subassembly, and a signal processor, mounted on a skid frame. The sampling equipment includes a continuously

operating electric pump, flow control valves, and piping connected to the plant sample lines. The detector subassembly provides three channels for (1) radioactive particulates, (2) iodine ¹³¹, and (3) noble gases. An RM-80 Signal Processor processes measured activity data and transmits them to an RM-23 Control/Display Module. Remotely controlled, solenoid-actuated checksources for each detector can be remotely inserted and retracted to verify detector operation (see RD-60 Detector data sheet).

SPECIFICATIONS

DETECTOR: Model RD-60 offline radiation detector assembly consisting of fixed-filter particulate, iodine and gas (P.I.G.) scintillation detectors. Refer to Model RD-60 data sheet for more detail

SIGNAL PROCESSOR: Model RM-80 Signal Processor

ALARMS: Each of the three channels has two-level radiation alarms (alert and high) continuously and independently adjustable over full range; one failure alarm (operate status, where green = normally on, actuated by low-line voltage trip, loss of counts from detector, tolerance not within 85% of preset checksource count rate, or loss of sample flow). Operation condition alarms: out-of-tolerance flow rate alarm and over-temperature alarm. One dpdt relay contact per alarm (not per channel) rated

7.5 A at 120 V ac; relays RM-80

CONTROL/DISPLAY MODULE: Model RM-23 Control/Display Module mounted in control room for monitor information/controls

SELF TEST: Self-diagnostics of RM-80 and RM-23 electronics; remote controlled, solenoid-operated checksources; automatic and manual purge

TEMPERATURE: 41° to 120°F (5° to 49°C) ambient

POWER: Input 120 V ac, 50/60 Hz, 25 A, 1ø

WEIGHT: 1700 lb (771 kg) approximate

ELECTRICAL CONNECTIONS: One shielded, twisted-pair communication cable from RM-80 to RM-23 and alarm contact wiring through top plate of customer junction-box assembly. Input power for the entire assembly through top of power and control junction box

MECHANICAL CONNECTIONS: Condensate drain valves are provided and should be connected to a radioactive waste line. Separate installation instructions are available for monitors using isokinetic nozzles

PLUMBING: Type 304 or 316 stainless steel (except gaskets); maximum use of mechanical fittings to facilitate maintenance, removal, and/or component replacement

CUSTOMER PIPING INTERFACES: 1/2-in. (127-cm), 150 lb (68 kg), raised-face, stainless steel pipe flanges at sample inlet, purge inlet, and sample outlet

THEORY OF OPERATION

In the particulate and iodine channels, the sample enters the detector chamber between the scintillation detector and the filter cartridge assembly. A beta-sensitive plastic phosphor detects radioactive particulates deposited on the filter face. In the next chamber, an NaI scintillation crystal and a photomultiplier tube detect gamma rays emitted by radioactive iodines adsorbed into an activated charcoal or silver zeolite cartridge. After passing through the other filters, the sample in the noble-gas channel enters the detector chamber in front of the scintillation detector. A beta scintillator detects particles emitted by gases. The RM-80 Signal Processor reads current pulses and shows a corresponding count rate or activity level for each of the three channels.

THE MODEL RM-80 Signal Processor performs signal processing and control functions for the monitor. The RM-80 database contains calibration constants for the RD-60 detector assembly, alarm setpoints, history (24 10-min averages, 24 1-hr averages, and 28 1-day averages), and other constants and control functions, including flow. It provides alarm relays and analog outputs. The RM-80 enclosure, rated NEMA 12, can operate at integrated radiation doses up to 10³ rad. The RM-80 is interrogated and controlled using an RM-23 Control/display Module (described below) It communicates with the RM-23 and with an RM-11 Console over shielded, twisted-pair cable.

THE MODEL RM-23 Control/Display Module provides the normal operator interface with the monitor. It allows the operator to display and alter the calibration constants, alarm setpoints, and all history contained in the RM-80 data base. The radiation exposure rate seen by the RD-60 detector assembly is continuously displayed as cpm or _Ci/cm³ in the IEEE standard format X.XXE±XX. Calling up other information form the data base requires five keystrokes maximum. Alarm status is displayed on red (HIGH), amber (ALERT), and green (OPERATE) LEDs. The RM-23 mounts in a SE NIM bin (optional) that fits in a standard 19-in.-(48.3-cm-) wide instrument rack.