Nuclear power plant tritium monitor model 321 NPPM

Produced by Overhoff Technology Corporation

This tritium monitor is a version of the OTC standard 321/421 series, configured for the special environmental conditions associated with nuclear power plants, especially those of the CANDU type. This monitor can be used for other applications where tritium specific measurements in the presence of other radionuclides are required.

Nuclear power plant tritium monitor model 321 NPPM (.pdf)

Technical specifications

RANGE

5 – 19999 kBq/m3(.005 – 19.999 MBq/m3)

DISPLAY

4½ digit DPM, digits are LED’s

ACCURACY

±2 % of reading, ± L.S.D., whichever is greater

STABILITY AND DRIFT

±0.005 MBq/m3
long term (at least 30 days) ambient temperature

NOISE

± 0.005 MBq/m3, 1 sigma with alpha suppression in use

OFFSET COMPENSATION

manual zero control provided to offset the effects of gamma radiation and/or tritium build-up

RESPONSE RATE

Two linear time constants

ELECTRONIC

approximately 15 seconds for signals up to about 1 MBq/m3
approximately 3 seconds for signals from 1 to 20 MBq/m3

WARM UP TIME

less than 30 minutes

SIGNAL ALARMS

Very High and High Concentration alarms set point adjustable from 0.001 – 1.000 MBq/m3.
Visual indicators with latching or non-latching (toggle) modes, rear panel relay interface.
10-turn potentiometer with turns counting dial

VOLUME

measuring: 6,500 cm3
total wetted: 11,240 cm3
port to port compensation: 8,000 cm3

ELECTRODES

Phantom wall wire grid on measurement chamber
Solid wall stainless steel on compensation chamber

GASKETS

Silicone

IN/OUT

3/16” I.D. vinyl tubing hose barb fittings installed in 1/8 NPT ports

CONNECTIONS MATERIALS OF CONSTRUCTION

Chambers, stainless steel; electrometer housing, aluminum

TEMPERATURE

storage: -20°C to +70°C
operating: +5°C to +40°C

HUMIDITY

0 to 95 % R.H. (non-condensing)

VOLTAGE

230 VAC +10 %, 50 Hz, 20 W max

FUSE

 ½ A, slow blow .25” diameter x 1.25” long