General Electric Company, San Jose, California, July 1965. —193 p.GEAP-4900 Final Progress ReportThe objective of Project was to determine the feasibility of covering the complete reactor neutron flux range from 1x1e3 to 5x1e13 nv in-core by using in-core or out-of-core ion chambers.
This report describes the analytical predictions and the experimental results of a nuclear
instrumentation development program undertaken by General Electric to determine the feasibility
of this approach. The program has been concerned with the development of a full-range reactor
control system incorporating either in-core or out-of-core ion chambers, and the purpose of the
program has been satisfied by the development of a full-range instrumentation system consisting
of two electronics subsystems. Counting techniques are utilized for source and lower intermediate
range neutron fluxes, and Campbell - or mean-square voltage - techniques are utilized for intermediate and power range fluxes.
Historically, power reactors have used out-of-core neutron detectors for source and intermediate range coverage during a plant start-up. In present power reactors, an in-core neutron source producing about 3x1e4 nv is attenuated by the water annulus surrounding the core, so that the incident flux at the detector is approximately 0.5 to 3.0 nv. Larger power plants, especially those with internal steam separation, provide for much larger water annuli and neutron source
attenuations of perhaps 1e-9 have been projected. Additionally, there is considerable interest in the in-core flux as opposed to the out-of-core flux, and consequently, it has become necessary to develop suitable in-core detectors for the source and intermediate range fluxes.
The development program has investigated the problems associated with the in-core counting
detector, the in-core Campbelling detector, the in-core transmission lines, as well as those unique
problems of a two-channel, full-range instrumentation system. In addition, the effort has been
expanded to ensure a compatible system for either in-core or out-of-core applications. In this
manner, flexibility of the developed hardware for a wide range of applications has been assured.Contents
Introduction
General
Counting Statistics
Theory of Campbell System of Reactor Instrumentation
Detectors
Cable
Counting Channel Electronic Subsystem
Campbell Channel Electronic Subsystem
Developmental System Performance
Variance of Logarithmic Count-Rate Meter Driven by a Scale-of-Two
Reference
