A new system for in-core wide range neutron monitoring

Abstract

For in-core reactor application, we have developed a new system in order to measure the thermal neutron flux from 107 n.cm-2.s-1 up to 1014 n.cm-2.s-1 at a temperature of 310°C. For this purpose, a new fission chamber with an external diameter of 3 mm has been developed. To obtain the wide range, the single detector operates continuously in the three modes, pulse counting, Campbelling or mean-square-voltage measurement and current. The new electronics system is built to work with this 3 modes simultaneously. Its design is based on massive use of digital technology and advanced digital signal processing. To transmit the signal from the fission chamber to the electronic cabinet, we have used a mineral coaxial cable with typical characteristics specially designed in order to operate in pulse mode and an external diameter of 1.4 mm to be introduced into the core of the reactor. Experiments were carried out in the ISIS and OSIRIS reactors, both experimental facilities available on the CEA Saclay site. These experiments have shown the capability of the system to obtain a linear measurement of the neutron flux from 106 n.cm-2.s -1 up to 2.1014 n.cm-2.s-1 at a temperature of 37°C. The next step, planed at the end of the year 2004, is to operate at the temperature of 310°C during 1000 hours.

Neutron Flux Monitoring Based on Blind Source Separation Algorithms in Moroccan TRIGA MARK II Reactor

“…The detector's sensitivity depends directly on the mean charge deposited by fission products in the gas [5]. Figure 2 illustrates the electronic system used for the IRINA project [19,20] to analyze the output signal of the FC according to the three possible modes (pulse, Campbelling, and current).…”

Development of a data acquisition and control system for the International Thermonuclear Experimental Reactor neutron flux monitor

“…Since the 1960s, Campbell's method has been studied and used for high neutron flux measurement and nuclear reactor control [1,9]. In recent years a wide-range method [10][11][12] has been developed by the combination of the counting and Campbelling mode. By the application of the wide-range method as well as two fission chambers (FCs) of different sensitivities, the measurement range is expected to reach 10 10 cps.…”

Final qualification of an industrial wide range neutron instrumentation in the OSIRIS MTR reactor

“…MARINE is the acronym of 'Mesure Automatisée Rapide des Informations NEutroniques'. As an extension for in-core reactor applications [3] [4], the IRINA project (Instrumentation RES Interne Neutronique Automatisée) has been initiated in 2002. Since then, a built-in system comprising the neutron detector [5], its signal transmitting coaxial cable and a fast fully digitalized wide range neutron monitor system has been developed to meet the in-core reactor conditions requirements: a thermal neutron flux from 10 7 n.cm -2 .s -1 up to 10 14 n.cm -2 .s -1 and a temperature of 300°C.…”