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Applying the pulsed ion chamber methodology to full range reactor ...

Applying the pulsed ion chamber methodology to full range reactor ...

282°C as predicted.

282°C as predicted. However, at this temperature the signal began to shew a slow increasing trend which continued up to the maximum temperature used, 475°C. This requires more study.

CHAPTER I INTRODUCTION The need for dependable and accurate monitoring of neutron flux (reactor power) presents the nuclear engineer with cue of his most diffi- cult design tasks.. For safety reasons, commercial reactors of all types require the flux to be monitored over st least twelve decades tfith +10% accuracy, ''ins range, even under optimum environmental conditions, requires a minimum of two detector operational modes. However, in all cases, three nodes are used to insure over! 20 (redundancy) and thus the safe operation of the reactor. In addition to the range requirements, the detectors must operate consistently and accurately 'Ddr the jig adverse environmental conditions. These, depending on the situation, include high temperatures, excessive baccgreund radiation levels, and high neutron flux levels, ever' extended periods of time (months). For the most part, adequate monitoring systems exist for those nuclear plants which are in us? at the present time However, the i;mits of these current systems are exceeded when one attempts tc ^poly them to the nee.d~- of the fast breeder reactor or the new generation of large core light water reactors. These now plants reu-^rk fast response, in-core detection systems. Unfortunately, the in-core environment is extreme in both the temperature and flux domains and, as yet, no system has func- tioned adequately under such conditions. To delineate the exact nature of the problems faced, one must care- fully examine the reactor power measurement systems preser.tlv beinq s t