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

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

and gain were checked

and gain were checked over the full voltage and current range of interest by "injecting known signals. Over the entire period of operation the sys- tem's response remained both linear and at a constant gain within a +2% accuracy. On the other hand, zero drift in the PIC mode was found to be a strong function o\ the ambient temperature of the HVP. The impedance switching transistors 0-8 and 0-9 were identified as the cause. Their temperature coefficient was approximately 10 mV/°C. For the measurements taken, baseline drift was carefully monitored to ensure false readings were not obtained. Gamma Compensation Expe r jmen_ta 1 Measurements & Results After carefully ascertaining the system's linearity and verifying its calibration, measurements of exposure rate versus v(0 were begun. c . 60 The radiation source utilized was the Westinghouse Han ford 230 kCi Co irradiation facility, which is depicted in figure 4-1. A plot of the radiation intensity versus vertical position for the port used is shown in figure 4-2, The data points were obtained using an RSG-8A gamma ionization chamber. The curve represents a seven-.h order polynominal fit of the data; log(R/hr; - 6.226 .4033* - .'i939 2 x + 02524 x 3 - 2.2067xl0" 3 X 4 J - !.682>:'i0" 4 Y h - 3.3963xi0" D b A -8 7

\^"^^"rr^r-«^":tf.fV)Cf*--l^f^ k > : ': i. V 9 , 41k* •**•! i *rth'«W< n" Ct£L-# ;A, - . Vrifirtfajitfti in nan I ii i -. ^ i.-j^-^t-j 60 Figure 4-1. Westinghouse Hanford 230 kCi "Co irradiation facility. '