Question 8.12: Suppose that the designers of the pressurized water reactor ......
Suppose that the designers of the pressurized water reactor treated in Section 8.3 conclude that the thermal-hydraulic design must have larger safety margins by reducing flow velocity by 10% and the maximum coolant temperature by 5 °C. The reactor physicists are asked to accommodate these changes by reducing the radial peaking factor. What percentage reduction would be required?
Rewrite Eq. (8.42) as
F_{r} = Wc_p(T_{o}|_{\mathrm{max}}-T_{i})\,/\,P=\overline{{{{\bf v}}}}\rho A_{flow}c_{p}(T_{o}|_{\mathrm{max}}-T_{i})\,/\,P
designating the modified values with primes:
{\frac{F_{r}^{\prime}}{F_{r}}}={\frac{\overline{{{\bf v}^{\prime}}}}{\overline{{{\bf v}}}}}{\frac{(T_{o}^{\prime}|_{\mathrm{max}}-T_{i})}{(T_{o}|_{\mathrm{max}}-T_{i})}}=0.9\cdot{\frac{325-290}{330-290}}=0.787
From the inlet and outlet temperatures are from section 8.3 , and \overline{{{\bf v}}}^{\prime}/\overline{{\bf v}}=0.90\;. Thus the radial peaking factor must be reduced by 21.3%