Determination of Tehran Research Reactor power by 16N gamma detection

The radioisotope 16N is produced by the interaction of fast neutrons with 16O in water reactor coolant. This radioisotope emits at the two major gamma ray energies of 6.13 MeV and 7.1 MeV. Exploiting the linear relation between the number of gamma particles versus the reactor power change, the reactor power is determined by detecting and counting the emitted gammas. In this work, for the detection of gammas to measure the reactor power, two different methods are employed. First, by NaI(Tl) scintillator detector and second, by assembly of ten GM detectors. The obtained results confirm that the number of emitted gammas is proportional to the change in reactor power as shown by different monitoring systems such as UIC, CIC, FC, Cherenkov and thermal power. Both of the applied methods are shown to give reliable results for reactor power above 20 kW. Both systems, having been calibrated, are being used as monitoring systems of power in Tehran Research Reactor. These systems are usable in other research reactors and possibly in power reactors as well.

► The 16N is produced by interaction of fast neutrons with 16O in water reactor coolant.
► The numbers of 16N gammas and reactor power change, have a linear relationship.
► The reactor power was defined by detecting the emitted gammas.
► A NaI(Tl) scintillator and assembly of ten GM tubes were employed.
► Both systems were used as reliable power monitoring system in Tehran Research Reactor.