Effect of continuous refueling on decay heat $($Section $3\mathrm{.}9)$

Using Equation $3\mathrm{.}70c$ or $3\mathrm{.}70d,$ cstimate the decay heat rate in a

$3000M{W}_{th}$ reactor in which $3\mathrm{.}2\%235$U$-$enriched $U{O}_2$ assemblies are

being fed into the corc. The burned$-$up fuel stays in the core for $3$ years

before being replaced. Consider two cases:

The core is replaced in two batches every $18$ months.

The fuel replacement is so frequent that refueling can be considered

a continuous process. $($Note: The PHWR reactors and some of the

water$-$cooled graphite$-$moderated reactors in former Soviet Union

are effectively continuously refueled.$)$

Compare the two situations at $1$min,$1h,1$ month, and $1$ year.

$\frac{P}{P_0}=0\mathrm{.}066[t_s^{-0\mathrm{.}2}-(t_s+{}_s{)}^{-0\mathrm{.}2}]$