Wide-Range Gas Monitor

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Wide-Range Gas Monitor

MAJOR ASSEMBLIES
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Sample Conditioning Skid
Sample Detection Skid
RM-80 Microprocessor/Customer Interface Junction Box
Control Room Display Assembly

SYSTEM FEATURES

More than 70 systems operating in domestic and foreign nuclear power plants.
Gas monitor range from 10^-7 to 10⁵ _Ci/cm³ (Xe¹³³) with 1 mr/hr background
Skids designed for 10⁵ Rad integrated dose
Two sample paths with automatic switchover: high-flow rate for low concentrations; low-flow rate for mid/high concentrations
Automatic isokinetic process flow tracing

ASSEMBLY FEATURES

Sample Conditioning Skid
- Separate particulate and iodine filter sets for each flow path
- Two prefilters and one sample filter in each set
- 4π lead shielding enclosures for the high concentration filters
- Manual filter selection controls located in side enclosure
Sample Detection Skid
- RD-52 Gas Detector with a thin plastic scintillation detector for low concentrations
- RD-72 Dual-Range Gas Detector with two CdTe solid state detectors for mid and high range concentrations
- 12-decade range
- 4π lead shielding for detectors and electronics
- Long half-life integral checksources for each detector
- Automatic purge and isolation of RD-52 Gas Detector or RD-72 Dual-Range Gas Detector when concentration is out of range
- Separate flow sensors, flow control valves, and pumps for each sample path
RM-80 Microprocessor/Customer Interface Junction Box
- RM-80 Microprocessor
  - Data acquisition and control
  - Application-specific data base
  - Local status indication

DOCUMENTATION

Equipment Manual
- Operation and maintenance instructions
- Engineering drawings
- Parts lists

OPTIONS

Equipment
- Isokinetic Sample Probe Assembly with vent
- flow rate measurement system
- Multipoint Sample Selector
- Special sample conditioning systems for high
- temperature/high humidity samples
Qualifications
- Seismic oe IEEE 344-1975
- Environmental oe IEEE 323-1974
  - Analog outputs
  - External digital communications
  - Multiple history files
  - Continuous self-test
  - Online diagnostics
  - Internal 120 V ac power filter
  - Outlet for test instruments
- Customer Interface Junction Box
  - Terminal blocks for field cable termination
  - Cable entry from above through removable cover plate
  - Wire trough for Customer Interface Junction Box to RM-80 Microprocessor cables
Control Room Display Assembly
- RM-23A Control/Display Module
- Display and analog outputs of three gas concentration channels and one effluent release rate channel
- Display and alteration of RM-80 Microprocessor data base
- Status indication
- Purge, checksource, and pump control
- Alarm relay drivers
- NIM bin or rack-mounted Grab Sample Timers
- Two strip-chart recorders

SAMPLE CONDITIONING SKID

The Sample Conditioning Skid is located down-stream from the Isokinetic Sample Probe Assembly. Each of the two sample flow paths is provided with two prefilters and one sample filter. The selectable prefilters prevent contamination of the detectors on the Sample Detection Skid by filtering particulates and iodine. The sample filter provides particulates and iodine sample for laboratory analysis. Solenoid valves control the sample flow path by operator request. This configuration allows filters to be changed quickly without affecting monitor operation (all filters have quick-disconnect fittings). Filters on the mid/high-range flow path have 4π solid cast-lead shielding enclosure to minimize exposure to personnel (see Flow Diagram). A sample can be collected or a prefilter path selected locally with switches in the electrical enclosure or remotely with switches in the Control room Display Assembly. The Sample Conditioning Skid should be floor-mounted as closely as possible to the sample point to minimize plate-out and provide easy access for sample retrieval.

SAMPLE DETECTION SKID

The Sample Detection Skid is located down-stream from the Sample conditioning Skid. It monitor radioactive gas concentrations over a 12-decade range using three radiation detectors. Each of the two flow paths has separate pumps, valves flowmeters, relays, and control switches. The flow through the monitor is automatically controlled by the RM-80 Microprocessor to maintain isokinetic sample flow rates from the Isokinetic Sample Probe Assembly. Each detector has a radio-active checksource to verify proper operation, and a 6in. lead shield to reduce background radiation effects. Each detector has a hinged, lead door to allow easy access to the sample canister or the detector. The low concentration flow path uses the RD-52 Gas Detector which contains a thin plastic scintilla-ion detector. The mid/high concentration flow path uses the RD-72 Dual-Range Gas Detector which has two beta/gamma-sensitive solid-state CdTe detectors (one each for mid-and hig-range detection). Range overlap provides continuity of measurement. A Customer interface Junction Box (CIJB) houses alarm relays and terminal blocks. detector signal and communications wiring is in another junction box to minimize electrical noise. Active electronics including power supplies and preamplifiers are located in a lead shielding enclosure to ensure their survival through high radiation doses. the Power Control Center accepts incoming 120 V ac power, distributes power to the Sample Detection Skid, and provides a main power disconnect switch. The Sample Detection Skid can be floor-mounted next to the Sample Conditioning Skid or up to 50 away.

Xe¹³³Concentration (_Ci/cm³)	Low-Range Pump Status	Mid/High-Range Pump Status	Purge	Detector Data Used by RM-80 Microprocessor
Increasing
10^-7 to 5 x 10^-2	On	Off	-	Low-range
5 x 10^-2 to 10^-1	On	On	-	Low-range
10^-1 to 10	On	On	Low-range purged at 10 _Ci/cm³	Mid-range
10 to 10²	Off	On	-	Mid-range
10² to 10⁵	Off	On	-	High-range

Decreasing
10² to 10	Off	On	-	Mid-range
10 to 10^-1	On	On	-	Mid-range
10^-1 to 5 x 10^-2	On	On	Mid/High-range purged at 5 x 10^-2 _Ci/cm³
10^-2 to 10^-7	On	Off	-	Low-range

OPTICAL ISOKINETIC SAMPLE PROBE ASSEMBLY

The optional isokinetic Sample Probe Assembly obtains representative sample from the vent. Accordingly, the WRGM has two sets of probes, one set for each of the two sample flow paths. Custom isokinetic probes are usually necessary for compatibility with different installations. Sorrento Electronics has extensive experience in custom isokinetic probe designs. Designs are based on effluent point parameters such as flow rate, cross-section, construction material, access, and temperature. The probe design balances technical refinement with reasonable cost. Typically, all probes, including a vent flow sensor for automatic isokinetic flow control, are mounted on a support structure that adapts to existing installation, such as flanges or plates.

OPTIONAL MULTIPOINT SAMPLE SELECTOR

An optional Multipoint Sample Selector (adjacent photo) allows a WRGM to monitor up to three effluent paths. The effluent path to be monitor is selected at the Control Room Display Assembly.

SERVICING

The WRGM is easy to service. Prefilters and samples can be replaced in less than 5 minutes without special tools. High activity sample can be transported to the radiochemistry laboratory for analysis inside the filter‘s 4π solid lead shielding, minimizing radiation exposure to personnel retrieving the samples. isolation valves isolate selected parts of the monitor for service.

A portable RM-23P Control/display module, included with the WRGM, is used to help maintain and calibrate digital radiation monitors (see adjacent photo). The RM-23P has the same capabilities as the RM-23A Control/Display Module in the Control Room Display Assembly. The RM-23P can be connected locally to the Sample Detection Skid or the RM-80 Microprocessor/CIJB.

RM-80 MICROPROCESSOR/CUSTOMER INTERFACE JUNCTION BOX

The RM-80 Microprocessor performs data acquisition and control functions, and provides alarm relays, analog outputs, and digital communications. The RM-80 Microprocessor data base, which can be programmed for specific applications by the user, contains the calibration constants for the RD-52 Gas Detector and RD-72 Dual-Range Gas Detector, alarm setpoints, and history files (twenty-four 10-min averages, twenty-four 1-hr averages, and twenty-eight 24-hr averages). This allows the monitor to be customized to its particular application. The RM-80 Microprocessor/CIJB can be located up to 500 ft from the Sample Detection Skid. The CIJB contains terminal blocks for all field cables, which enter through top entry conduit fittings.

CONTROL ROOM DISPLAY ASSEMBLY

The Control Room Display Assembly provides remote control and display for the system. It is contained in a 19-in. wide modified NIM bin that fits in a standard control room rack. The Control Room Display Assembly consists of a micro-processor-based, RM-23A Control/Display Module and an operator control panel. The RM-23A Control/Display Module continuously polls the RM-80 Microprocessor for the radiation level and operation status. All relevant monitor parameters, such as gas concentration (_Ci/ cm³), effluent release rate (_Ci/sec), alarm status, flow status, purge actuation, calibration constants, and historical averages, can be displayed on the RM-23A Control/Display Module. Only one of four channels can be displayed on the RM-23A Control/Display Module at one time. Channels one through three are the gas concentration of the low-, mid-, and high-range detectors in _Ci/cm³. Channel four is the effluent release rate of the active detector channel display in _Ci/sec. The operator control panel is next to the RM-23A Control/Display Module allowing the operator to control the prefilters and samplers on the Sample Conditioning Skid. Control switches allow the operator to change a flow path through the prefilters as necessary. Sample timers allow the operator to select sampling times during routine or accident conditions. To obtain a sample, the operator sets the sample timer and presses the actuation push-button; the timed sample is then taken automatically. A key switch is provided for supervisory control of the RM-23A control/Display Module. Customer cable connections are made through terminal blocks on the rear of the bin. One strip-chard recorder gives a hard copy of the three radioactive gas concentration levels. A second strip-chard recorder gives a hard copy of the effluent release rate.

SPECIFICATIONS SYSTEM Operational Range: Pressure - Atmospheric; Temperature

-35° to 122°F (1.7° to 55°C); Humidity - to 100% (noncondensing)

Range: 10^-7 to 10⁵ _Ci/cm³ (Xe¹³³) with 1 mr/hr background

Sample Temperature: 120°F (49°C) maximum at 90% RH; 130°F (54°C) maximum at 70% RH

Sample Pressure: 15psig (1.05 kgcm²) maximum

Sample Flow: Low-range - 1.7 ft³/min (800 cm³/sec) nominal; mid/high-range - 0.06 ft³/min (28 cm³/sec) nominal

Sample Connections: Low-range - .5-in. tube fitting; mid/high-range - .25-in. tube fitting; common return line - .5in. tube fitting; connecting lines between Isokinetic Sample Probe Assembly manifold and Sample conditioning Skid by customer per ANSI N13,1-1969.

Power: 120 V ac, 50 to 60 Hz, 15 A nominal at the main power disconnect switch on the Sample Detection Skid which provides power to the Sample Detection Skid and Sample conditioning Skid; RM-80 Microprocessor/CIJB, 1 A nominal; Control room Display Assembly, 3 A nominal

Overall System Accuracy: Meets or exceed U.S. Regulatory Guide 1.97 (Rev. 3)

Quality Assurance: Meets 10 CFR 50, Appendix B; ANSI N45.2; Canadian Standard Z299.3

SAMPLE CONDITIONING SKID

Filter Assemblies: Low-range - 5-in. inline quick-disconnect; mid/high-range - .25-in. inline quick-disconnect

Filters: 1.9-in. diameter HV LB 5211 fiberglass (Particulate);

silver zeolite cartridge (Iodine); replacement time - less than 5 min

Dimensions: 43.5 in. high x 48 in. wide x 30 in. deep

Weight: 1600 lb (730 kg) approximate

Plumbing: Type 304 stainless steel for all wetted parts except gaskets

Shielding: 2 in. lead shielding with mid/high-range filters to minimize personnel exposure

Integrated Dose: 10⁵ Rad

SAMPLE DETECTION SKID

Detectors: 2-in.-diameter x 0.01-in.-thick beta phosphor; 2in.-diameter photomultiplier tube (low range); two CdTe solid-state, beta-gamma detectors with integral preamplifiers (mid and high range)