Design studies on small fast reactor cores, 5; Research results in JFY2005

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

A design study on "Long-life Type Concept" of a 50MWe sodium-cooled metal-fueled reactor core was performed with more emphasis on irradiation results regarding fuel smear density. The concept aims at no refueling in a core life time, and achieving higher core outlet temperature such as 550C which is advantageous to hydrogen production. The restriction of upper fuel smear density limit to 75% along with adjustments of fuel specifications showed feasibility of attaining core life time of 30 years and core outlet temperature of 550C. No indication of occurrence of absorber-cladding mechanical interaction (ACMI) was found in the evaluation of ACMI for a control rod element. A shielding with Zr-H was selected in view of enhancement of shielding performance, and the feasibility was shown to satisfy the target allowance level of the ratio of hydrogen to zirconium, more than 1.53, with PNC316 used as the cladding material.