Study on long-life type concept of a small sodium-cooled metal-fueled reactor core

Uto, Nariaki  ; Okano, Yasushi; Naganuma, Masayuki  ; Mizuno, Tomoyasu; Hayashi, Hideyuki

This presents design study results on Long-life Type Concept for a sodium-cooled metal-fueled reactor core with 50MWe. The concept aims at no refueling and higher reactor outlet temperature which is advantageous to hydrogen production. It was found that the core life time of 30 years and the reactor outlet temperature of 550C can be attained by adjusting core and fuel specifications on condition that the fuel smear density is restricted within 75% with more emphasis on irradiation results. The design feasibility of durable control rod and radiation shielding was studied. No possibility of occurrence of absorber-cladding mechanical interaction was obtained on the analytical evaluation for a control rod element with BC as absorber material. A shielding with Zr-H was selected in view of enhancement of shielding performance and core compactness, and the feasibility was shown to adequately restrict the amount of hydrogen permeation from the cladding to the allowable level.