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Delayed Neutron Detection in Burst Can Detection Studies; ETUDE SUR LA DETECTION DES NEUTRONS DIFFERES EN VUE DE LA DETECTION DES RUPTURES DE GAINES

Technical Report ·
OSTI ID:4790944
A theoretical and experimental study on the detection of neutrons present in the primary cooling circuit of a reactor cooled by heavy or light water is described with a view to the installation of a canning burst detection unit. The concentration of background neutrons is first calculated, taking into account the neutrons from nitrogen-17 decay and the photoneutrons produced by the decay of nitrogen-l6 and sodium-24. The emission of delayed fission neutrons, originating at a given crack in the canning, is estimated. Using the D/sub 2/O circuit of the pile EL 3, three units were developed by means of which the following three types of detector may be compared: (l) BF/sub 3/ proportional counter, (2) Boron scintillator, and (3) Fission chamber. Under the presest experimenial conditions, the BF3 counter gave the best results. The influence on these detectors of the gamma flux, which in certain cases reaches 200 r/hr, is analyzed. Finally, a calibration is carried out with an experimental crack of 30 mm/sub 2/ of uranium exposed to a flux of 5.8 x l0/sup 13/ neutrons/cm/sup 2/sec. The sensitivity obtained with the BF/sub 3/ counter during this test is 2 counts/ sec per mm/sup 2/ of exposed urianium. (auth)
Research Organization:
France. Commisariat a l'Energie Atomique. Centre d'Etudes Nucleaires, Saclay
NSA Number:
NSA-16-016523
OSTI ID:
4790944
Report Number(s):
CEA-2101
Country of Publication:
France
Language:
English