System for measuring the period of a nuclear reactor using frequency conversion or period conversion

摘要

1,020,756. Reactors. NIHON GENSHIRYOKU KENKYU SHO. Sept. 14, 1962 [Nov. 7, 1961], No. 35216/62. Heading G6C. The period of a nuclear reactor in which the power level changes slowly, is derived from the measurement of the neutron flux at spaced intervals. Electrical signals having frequencies proportional to the natural logarithm of the neutron flux are derived and applied in the expression:- where n is the neutron flux. The denominator may be written, Hence, using the signals:- frequency f 1 = K 1 ln n 1 frequency f 2 = K 1 ln n 2 the period of the reactor may be written, Alternatively the difference of the electrical signal period may be employed in place of the frequency change, #f. The frequencies of two oscillators are controlled by reactor flux signals and the instants at which the frequencies are selected are predetermined by a separate control circuit. The latter controls a gate circuit which passes on to a digital display circuit the value #f and the corresponding time interval.