Alternative Design of Temporary Spent Fuel Storage of Indonesian RDNK Reactor (Amir Hamzaha), Hery Adrial, Ihda Husnayani, Pande Made Udiyani)

Abstract. The Non-Commercial Power Reactor (Reaktor Daya Non Komersial: RDNK) is a Pebble-bed type Gas-Cooled
High Temperature Reactor with 10 MW thermal power designed by the National Nuclear Energy Agency (BATAN).
RDNK reactor follows multipass fuel loading scheme with of UO2-fueled coated with TRISO layers and duration of stay
in the reactor core for 1100 days. On the working core, the scenario of fuel loading pattern is fresh fuels loading and
discharge of spent fuel pebbles as many as 25 pieces every day. Thus, if the reactor operating cycle is grouped into 5 subcycles,
then in 220 days/sub-cycle will be as many as 5500 spent fuels are produced. Therefore, a safe temporary spent
fuels storage container must be designed in the reactor building to hold the spent fuels before sending them to further
storage. This study is to design the temporary spent fuel storage to ensure radiation safety for workers. The design of
spent fuels storage containers was carried out using a monte-carlo based program and the determination of the spent fuels
source strength using the ORIGEN2.1 program. The results of the design of temporary storage containers to hold 5500
spent fuel pebbles using alternatives shielding materials of ordinary concrete shield as thick as 50 cm, iron-portland
concrete is 20 cm thick and lead as thick as 10 cm. All these containers provide radiation safety assurance for workers
after the spent fuels have decayed for 6 months. Thus, the delivery of spent fuels to further storage outside the reactor
building is recommended after 6 months decayed.
Keywords: RDNK, HTR, spent fuel, temporary storage, radiation shielding, dose rates