FIELD: instrumentation.
SUBSTANCE: method includes the measurement and record of neutron flow density at various conditions of its formation by means of the fission ionization chamber. According to the invention the neutron flow density measurement channels are calibrated outside the reactor, while the neutron flow density is measured by two measuring channels in two stages: at the first stage a source of neutrons is placed opposite to the sensor of the first measuring channel intended for installation on the pipeline of the first contour of a nuclear reactor from the heat carrier output of the reactor. The distance l1 from the neutron source to this sensor is selected so that the counting rate N1 in the first measuring channel be corresponded to the density of the neutron flow of the pipeline, and this counting rate N1 is registered, at the second stage the source of neutrons is placed opposite to the sensor of the second measuring channel intended for mounting on the pipeline of the first contour of the nuclear reactor from the heat carrier return to the reactor and the distance l2 between the source of neutrons and the second sensor is selected by the formula 
, where v - heat carrier flow speed; L - distance between sensors on the pipeline; τ - a half-life period of the isotope 17N, then the sensitivity of the second measuring channel is adjusted so that its counting rate N2 be equal to 
then the sensors are mounted on the pipeline.
EFFECT: improvement of accuracy of calibration of neutron flow density measurement channels and reduction of time for its execution.
