Abstract: A Control Neutron Absorber (CNA) assembly for a microreactor that produces nuclear energy is disclosed. The CNA assembly includes a housing, a CNA rod, and a burnable absorber. The housing includes an inner housing and an outer housing. The inner housing is configured to receive a CNA rod. The outer housing extends coaxially with the inner housing and is positioned radially outward and offset from the inner housing defining a cavity therebetween. The CNA rod includes a neutron absorbing rod including a first neutron absorbing material. The neutron absorbing rod is positioned within the inner housing and is configured to move axially relative to the inner housing. The burnable absorber includes a second neutron absorbing material, exhibits a neutron absorbing strength that is less than that of the neutron absorbing rod, is positioned within the inner housing, and is configured to receive the neutron absorbing rod therein.