  The abundances of n-capture elements in the CEMP-r/s stars agree with
predictions of intermediate n-density nucleosynthesis, at $N_\mathrm{n}\sim
10^{13}$-$10^{15} \mathrm{cm}^{-3}$, in rapidly-accreting white dwarfs (RAWDs).
We have performed Monte-Carlo simulations of this i-process nucleosynthesis to
determine the impact of (n,$\gamma$) reaction rate uncertainties of 164
unstable isotopes, from $^{131}$I to $^{189}$Hf, on the predicted abundances of
18 elements from Ba to W. The impact study is based on two representative
one-zone models with constant values of $N_\mathrm{n} = 3.16\times 10^{14}\
\mathrm{cm}^{-3}$ and $N_\mathrm{n} = 3.16\times 10^{13}\ \mathrm{cm}^{-3}$ and
on a multi-zone model based on a realistic stellar evolution simulation of
He-shell convection entraining H in a RAWD model with [Fe/H]=-2.6. For each of
the selected elements, we have identified up to two (n,$\gamma$) reactions
having the strongest correlations between their rate variations constrained by
Hauser-Feshbach computations and the predicted abundances, with the Pearson
product-moment correlation coefficients $|r_\mathrm{P}| > 0.15$. We find that
the discrepancies between the predicted and observed abundances of Ba and Pr in
the CEMP-i star CS31062-050 are significantly diminished if the rate of
$^{137}$Cs(n,$\gamma)^{138}$Cs is reduced and the rates of
$^{141}$Ba(n,$\gamma)^{142}$Ba or $^{141}$La(n,$\gamma)^{142}$La increased. The
uncertainties of temperature-dependent $\beta$-decay rates of the same unstable
isotopes have a negligible effect on the predicted abundances. One-zone
Monte-Carlo simulations can be used instead of computationally time-consuming
multi-zone Monte-Carlo simulations in reaction rate uncertainty studies if they
use comparable values of $N_\mathrm{n}$ (abridged).
