Patent Number: 061817619
Section: claims

1. An apparatus for monitoring reactor power of a reactor at least at the time of startup thereof, comprising: a radiation sensor for detecting radiation doses associated with the reactor power as electrical signals having pulse components according to the radiation doses;  analog filter means for filtering electrical signals having frequency components in a certain frequency band from the electrical signals detected by the radiation sensor;  digital conversion means for converting the electrical signals having the frequency components filtered by the analog filter means to first digital data with an accuracy of certain bits on sampling intervals shorter than a pulse width of the pulse components;  pulse measurement means for counting the number of pulses of the pulse components in a predetermined frequency band based on the first digital data converted by the digital conversion means;  sum operating means for adding a plurality of sampling values forming the first digital data based on preset sum operation conditions so as to obtain second digital data having accuracy having more bits than those of the plurality of sampling values forming the first digital data converted by the digital conversion means;  Campbell measurement means for calculating mean square values corresponding to power of fluctuation components caused by overlap of the pulse components in a predetermined frequency band based on the second digital data obtained by the sum operating means; and  reactor power monitoring means for continuously monitoring the reactor power based on the number of pulses counted by the pulse measurement means and the mean square values calculated by the Campbell measurement means.  wherein the digital conversion means is means for converting the electrical signals having the frequency components from the analog filter means to the first digital data at sampling intervals corresponding to 1/n of the pulse width of the pulse components, where n is a positive number; and  wherein the pulse measurement means includes  means for obtaining an operation value Out(k) at the sampling intervals, selecting the pulse components based on the Out(k), and counting the number of pulses of the pulse components selected, the Out(k) being operated based on the following formula; EQU Out(k)=C(0).times.S(k)+C(1).times.S(k-1)+C(2).times.S(k-2)+ . . . +C(k-n+1).times.S(k-n+1),  where S(k) is a k-th sampling value among a plurality of sampling values forming the first digital data from the digital conversion means, S(k-1), S(k-2), . . . , S(k-n+1) are sequential sampling values before the S(k), the number of the sampling values is determined by said positive number n, and C(0), C(1), C(2), . . . , C(k-n+1) are constants individually allotted to the sampling values S(k), S(k-1), S(k-2), . . . , S(k-n+1).  wherein the digital conversion means is means for converting the electrical signals having the frequency components from the analog filter means to the first digital data at sampling intervals, the sampling intervals being not less than one fourth and not more than one third of the pulse width of the pulse components, and  wherein the pulse measuring means includes  means for obtaining an operation value Out(k) at the sampling intervals, selecting the pulse components based on the Out(k), and counting the number of pulses of the pulse components selected, the Out(k) being operated based on the following formula; EQU Out(k)=-a.times.S(k-3)+b.times.S(k-2)+c.times.S(k-1)-d.times.S(k),  where S(k) is a k-th sampling value among a plurality of sampling values forming the first digital data from the digital conversion means, S(k-1), S(k-2) and S(k-3) are sequential three sampling values before the S(k), and a, b, c and d are constants individually allotted to the four sampling values S(k), S(k-1), S(k-2) and S(k-3).  wherein the digital conversion means is means for converting the electrical signals having the frequency components from the analog filter means to the first digital data at sampling intervals, the sampling intervals being not less than one third of and not more than a half of the pulse width of the pulse components and  wherein the pulse measuring means includes  means for obtaining an operation of value Out(k) at the sampling intervals, selecting the pulse components based on the Out(k), and counting the number of pulses of the pulse components selected, the Out(k) being operated based on the following formula; EQU Out(k)=-a.times.S(k-2)+2.times.b.times.S(k-1)-c.times.S(k),  where S(k) is a k-th sampling value among a plurality of sampling values forming the first digital data from the digital conversion means, S(k-1) and S(k-2) are sequentially two sampling values before the S(k), and a, b and c:are constants individually allotted to the three sampling values S(k), S(k-1) and S(k-2).  wherein the pulse measurement means comprises:  analog type pulse comparison means used if a wave height value is not less than or not more than a predetermined value; and  digital type pulse determination means for counting the number of pulses of the pulse components detected by the radiation sensor based on the first digital data converted by the digital conversion means; and  means for counting only the number of pulses removed noise components from the pulse components detected by the radiation sensor based on both the analog type pulse comparison means and the digital type pulse determination means.  wherein the digital conversion means is means for converting the electrical signals having the frequency components from the analog filter means to the first digital data at sampling intervals, the sampling intervals being 1/n of the pulse width of the pulse components, where n is a positive number; and  wherein the pulse measuring means includes  means for obtaining a first and second operation values Out 1(k) and Out 2(k) at the sampling intervals, selecting the pulse components based on the Out 1(k) and Out 2(k), and counting the number of pulses of the pulse components selected, the Out 1(k) and Out 2(k) being operated based on the following formula; EQU Out 1(k)=C(0).times.S(k)+C(1).times.S(k-1)+C(2).times.S(k-2)+ . . . +C(k-n+1).times.S(k-n+1) EQU Out 2(k)=D(0).times.S(k)+D(1).times.S(k-1)+D(2).times.S(k-2)+ . . . +D(k-n+1).times.S(k-n+1),  where S(k) is a k-th sampling value among a plurality of sampling values forming the first digital data from the digital conversion means, S(k-1), S(k-2), . . . , S(k-n+1) are sequential sampling values before the sampling value S(k), the number of the sampling values is determined by said positive number n, C(0), C(1), C(2), . . . , C(k-n+1) are first constants individually allotted to the sampling values S(k), S(k-1), S(k-2), . . . ,S(k-n+1), and D(0), D(1), D(2), D(3), . . . , D(k-n+1) are second constants individually allotted to the sampling values S(k), S(k-1), S(k-2), . . . , S(k-n+1).  wherein the Campbell measurement means comprises:  cycle data removal means for removing data of a predetermined time interval from the second digital data acquired by the sum operating means; and  Campbell evaluating means for operating the mean square value from residue data not removed by the cycle data removal means in a frequency band higher than a frequency band of the data removal cycle and correcting and outputting the mean square value operated in accordance with a ratio of data removed from the second digital data.  wherein the cycle data removal means comprises:  noise data addition means for discriminating data of not less than or not more than a predetermined value by the digital conversion means, determining the data as noise data and adding noise information on the noise data; and  Campbell evaluating means for removing the data if the noise information is included in the second digital data and correcting and outputting a mean square value of the noise data in accordance with the ratio of the removed data to the second digital data.  wherein the cycle data removal means comprises:  noise monitoring means for evaluating the presence or absence of noise induced by an earth or the like and a cycle of the noise; and  Campbell evaluating means for removing the noise data from the second digital data if the noise information is included in the second digital data in accordance with the noise cycle evaluated by the noise monitoring means and noise recognition timing, and correcting and outputting a mean square value of the removed data in accordance with the ratio of the removed data to the second digital data. 2. The apparatus of claim 1, wherein the sum operating means includes means for outputting the second digital data to the Campbell measurement means with output accuracy of more bits than those of the first digital data. 3. The apparatus of claim 1, wherein the sum operating means includes means for outputting the second digital data to the Campbell measurement means at longer output time intervals than sampling intervals for the digital conversion means. 4. The apparatus of claim 1, wherein the sum operating means is means for adding a plurality of sampling values forming the first digital data under a plurality of sum operating conditions having different numbers of added values as the sum operation conditions. 5. The apparatus of claim 1, wherein the sum operating means is means for adding a plurality of sampling values forming the first digital data under a plurality of sum operating conditions within a certain time as the sum operation conditions. 6. The apparatus of claim 1, wherein the Campbell measurement means includes Campbell output evaluating means for evaluating the mean square values in a plurality of frequency bands based on the second digital data from the sum operating means, and Campbell signal discriminating means for selecting normal values from the mean square values in the plurality of frequency bands by the Campbell output evaluating means and supplying the normal values to the reactor power monitoring means as information on the reactor power. 7. The apparatus of claim 1, 8. The apparatus of claim 1, 9. The apparatus of claim 1, 10. The apparatus of claim 1, 11. The apparatus of claim 1, 12. The apparatus of claim 11, wherein the obtaining means is means for obtaining a plurality of operation values including third or following operation values in addition to the first and the second operation values, based on the same formula as in the case of obtaining the first and second operation values at the sampling intervals while changing the constants. 13. The apparatus of claim 1, 14. The apparatus of claim 13, 15. The apparatus of claim 13,