Patent GB-952022-A (GB)
Title: Method and apparatus for monitoring the operation of a system
IPC: G21D3/04
Filed: 1962-08-10
Abstract: 952,022. Nuclear reactors. NORTH AMERICAN AVIATION Inc. Aug. 10, 1962 [Aug. 31, 1961], No. 30808/62. Heading G6C. A monitoring system comprises first means adapted to provide input signals representing the values of a plurality of parameters of the system to be monitored, second means adapted to determine whether the input signals are individually within predetermined limits, third means adapted to determine from the input signals whether at least one function of the parameters is within predetermined limits, and fourth means responsive to the second and third means to indicate whether the monitored system is operating within an acceptable region of operation whose boundary is defined by the aforesaid limits. The system may be applied to monitoring the primary coolant flow rate through a nuclear reactor and heat exchanger and the secondary coolant flow rate through the heat exchanger, and is used to determine whether the system is operating in the safe area 70 of Fig. 5, or in the alarm area 71, or in the scram area 72. Flow meters in the two coolant circuits produce analogue electrical outputs which are amplified and passed through a ratio computer to produce outputs P (primary flow) S (secondary flow) and R (ratio) on lines 73, 75 and 77 in Fig. 7. Each of these signals is fed to two trigger circuits 79; the two trigger circuits to which the S output is fed change state respectively when S crosses the 10% line in Fig. 5 and when S is above or below the point corresponding to the junction of the vertical and inclined boundaries of safe area 70, and the P triggers are similarly arranged; the R triggers respond at the upper and lower safe limits of R. Some of the outputs of triggers 79 are reversed in further triggers 89. The outputs of the triggers pass through isolating stages 92 to four "OR" circuits 95-98 and two "AND" circuits 99 and 100. It is explained that with the connections shown in Fig. 7, the outputs of circuits 99 and 100 are both "0" if operation is within the safe region of Fig. 5 and one of them will be "1" if operation is outside the safe region. A second circuit similar to Fig. 7 but with different thresholds for the triggers 79 determines whether operation is within the scram area 72 of Fig. 5 or not. The outputs of these two circuits are arranged to operate lamps indicating which of the three operating conditions obtain and to initiate corrective action when necessary, Fig. 3 (not shown). Another system, Figs. 8 and 11 (not shown), monitors the temperature and coolant flows of three coolant loops of a nuclear reactor. There are seven inputs, corresponding to the three coolant rates and inlet temperatures and the neutron flux. The three coolant rates are averaged in a summing circuit to give a mean output W T , and computer circuits calculate a quantity where W 1 -W 3  and T 1 -T 3  are measured flows and temperatures, n is the neutron flux, k 1 -k 2  are constants, and C is a constant. The quantities W T  To and n are fed to triggers and logic circuits which indicate which of four conditions (safe, alarm, setback, or scram) obtain.