Device for estimating neutron flux distribution in BWR type reactor

Purpose: To convert the neutron flux distribution obtained by the migration of TIP (moving type neutron detector) into the power distribution and to accurately estimate the neutron flux distribution between LPRMs (neutron detectors) on the basis of the thus converted power distribution. Constitution: A computer calculates the infinite multiplication factor K sub(infinity)sup(+) (K) from a TIP indication signal and a control rod positioning signal, and converts the resulting value into a value corresponding to K sub(infinity)sup(+) (K) in a case where the control rods are not inserted, thus sending the value to a K sub(infinity)sup( b) (K) memory device, the TIP indication value computer estimates and calculates the TIP indication value from K sub(infinity)sup( b) (K) stored in the memory device when the surveilance of the neutron flux distribution is required, and the control rod positioning signal and LPRM indication value signal at that time, and sends the resulting value to an indicator and a recording device. (Nakamura, S.)