Assessment of Criticality Safety for Spent Fuel Elements in Open Pool Type Storage

Abstract

Storage of spent fuel elements needs a previous calculation to ensure verifying the criteria of storage from the nuclear criticality point of view. So, arrangement of spent fuel elements in the storage must result in a configuration that veri-fying an effective multiplication factor (k-eff) lower than 0.85. The spent fuel elements storage is an open pool con-nected with the main pool of the reactor via transfer channel to facilitate transporting the irradiated fuel elements under water surface to verify a high radiological safety. The fuel element is a plate type material testing reactor (MTR) with enrichment of 19.97%. The storage pool was designed to store around 800 spent fuel elements as a temporary stage before transporting to a permanent storage. Basket and pool models, loaded with fresh fuel elements, were applied using SCALE/KENO-VI sequence to determine the k-eff during normal storage condition as well as water-drop accident. TRITON and KENO-VI sequence was applied to determine the k-eff for the basket and pool, loaded with spent fuel elements, during the normal and the accidental conditions. All the spent fuel elements were irradiated in a core of 22 MW power to the maximum burn up of discharge. The k-eff values show a proper agreement with previous calculations developed with MCNP5 code.