Radiation Detectors SOURCE RANGE NUCLEAR INSTRUMENTATIONSOURCE RANGE NUCLEAR INSTRUMENTATIONThree ranges are used to monitor the power level of a reactor throughout the fullrange of reactor operation. The source range makes use of a proportionalcounter.EO 3.3 Given a block diagram of a typical source rangeinstrument, STATE the purpose of major components.a. Linear amplifierb. Discriminatorc. Pulse integratord. Log count rate amplifiere. DifferentiatorSource range instrumentation normally consists of two redundant count rate channels, eachcomposed of a high-sensitivity proportional counter and associated signal measuring equipment.These channels are typically used over a counting range of 0.1 to 106 counts per second, but varybased on reactor design. Their outputs are displayed on meters in terms of the logarithm of thecount rate.Source range instrumentation also measures the rate of change of the count rate. The rate ofchange is displayed on meters in terms of the startup rate from -1 to +10 decades per minute.Protective functions are not normally associated with source range instrumentation because ofinherent limitations in this range. However, interlocks may be incorporated.Many reactor plants have found it necessary to place source range proportional counters in leadshielding to reduce gamma flux at the detectors. This serves two functions: (a) it increases thelow end sensitivity of the detector, and (b) it adds to detector life. Another means by whichdetector life is extended is to disable the high voltage power supply to the detector and short thesignal lead when neutron flux has passed into the intermediate range. There are some reactorplants that have made provisions for moving the source range detectors from their operatingpositions to a position of reduced neutron flux level, once the flux level increases above thesource range.Rev. 0 Page 63 IC-06
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
