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Applying the pulsed ion chamber methodology to full range reactor ...

Applying the pulsed ion chamber methodology to full range reactor ...

X = B.I 6! + i.4986y

X = B.I 6! + i.4986y .4590y 2 - .2C15y 3 - .4586y 4 + ,2038y 5 * .366:;/ + .0S162y 7 - .009803y 8 , X = 5.6355 + 1 .532: z + .'I500z 2 - .3241z 3 + .048842 4 + .41387° + .251 9z 6 + .05276:: 7 + .0025762", where; x " 1 on R/hr, y = log v f (t c ), z -" log v (t c ), Vjr(t ) - the PiC voltage signal from the fission chamber, v (t ) - the PIC voltage signal from the gamma chamber. (4-1) (4-2) A code was then written for the HP9821 which caused it to record the v(t ) c signals from the chambers, at given exposure rates, compute the measured R/hr from equation 4-1 or 4-2 for the corresponding chamber, subtract the results, compute the compensation error and finally output all results. The code is listed in the Appendix under the title of Compensation Code. Table 4-1 contains a set of typical results of this application. The sixth column in the table plotted in figure 4-6 indicates the com- pensation results. The first siy values are as large as they are for two reasons. The first is that the curve fit did not fit the low data points well and, second, the system's electronic stability was +2mV, which, as one can see, has a large effect on the computed R/hr values at the low ex- posure rates. The remainder of the values in that column, nevertheless, indicate that, at least for fixed temperatures, reasonable compensation can be obtained. The fluxuations that do exist are due to curve fitting, chamber positioning, and the precision of the measuring system. The last of these was measured at +1%. The other two were difficult to accurately determine, but combined, are on the order of +5%.

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