The objective of radioactive-waste container is to reduce radiation emission to the environment. For that purpose, we need material with ability to shield that radiation and last for 10.000 years. Titanium is one of the materials that can be used to make containers. Unfortunately, its buildup factor, which is an importance factor in setting up radiation shielding, has not been calculated. Therefore, the calculations of titanium buildup factor as a function of other parameters is needed. Buildup factor can be determined either experimentally or by simulation. The purpose of this study is to determine titanium buildup factor using simulation program based on Monte Carlo method. Monte Carlo is a stochastic method, therefore is proper to calculate nuclear radiation which naturally has random characteristic. Simulation program also able to give result while experiments can not be performed, because of their limitations.The result of the simulation is, that by increasing titanium thickness the buildup factor number and dosage increase. In contrary If photon energy is higher, then buildup factor number and dosage are lower. The photon energy used in the simulation was ranged from 0.2 MeV to 2.0 MeV with 0.2 MeV step size, while the thickness was ranged from 0.2 cm to 3.0 cm with step size of 0.2 cm. The highest buildup factor number is b = 1.4540 ± 0.047229 at 0.2 MeV photon energy with titanium thickness of 3.0 cm. The lowest is b = 1.0123 ± 0.000650 at 2.0 MeV photon energy with 0.2 cm thickness of titanium. For the dosage buildup factor, the highest dose is bD = 1.3991 ± 0.013999 at 0.2 MeV of the photon energy with a titanium thickness of 3.0 cm and the lowest is bD = 1.0042 ± 0.000597 at 2.0 MeV with titanium thickness of 0.2 cm. For the photon energy and the thickness of titanium used in simulation, buildup factor and dosage buildup factor as a function of photon energy and titanium thickness can be formulated as follow b = 1.1264 e – 0.0855 E e 0.0584 T, and bD = 1.0961 e – 0.0722 E e 0.0336 T. Hengky Istianto Has*Balza Achmad **, Andang Widi Harto**.; * Sarjana Teknik Nuklir, Fakultas Teknik, Universitas Gadjah Mada** Dosen Jurusan Teknik Nuklir, Fakultas Teknik, Universitas Gadjah Mada
