[en] This paper aims to clarify that the subcritical measurement at the solid moderated KUCA core is useful to reduce nuclide data-induced uncertainties of the effective neutron multiplication factors k_eff in other light water moderated systems. For this purpose, we pay attention to the prompt neutron decay constant, α, which was measured by the Feynman-α method with the moving block bootstrap method for the deep subcritical KUCA core under the shutdown state without any external neutron source. The sensitivity analyses of α for the subcritical KUCA core and of k_eff for various light water moderated critical cores were carried out based on the first-order perturbation theory. Consequently, it is demonstrated that the nuclear data-induced uncertainties of k_eff can be reduced by the bias factor method using the measurement value of α, if the target k_eff value has a strong correlation with the measured α value in the subcritical KUCA core. (author)