MCNP SIMULATION FOR THE CALCULATION OF NEUTRON DOSE RATE OF AmBe AT CUBOID WATER PHANTOM

The neutron dose rate can be determined by a measurement using Radiation Measuring Instrument and by calculation using statistical methods, one of them by MCNP MCNP can simulate the trip of neutron, electron and photon particles in a three-dimensional material. This paper presents a simple MCNP simulation for calculating the neutron dose rate from a point source of AmBe, 1 MBq activity, the distance 10 cm from the surface of 1 cm cuboid water phantom, with dead areas at a distance of 15 cm from the source. The neutron dose rate calculation is performed with a number of 1,000,000 and 10,000,000 neutrons, to see the difference in yield and error. The second exercise, the input of water volume is enlarged to 8 cm, 27 and 125 cm, and the third exercise, the input of neutron sources varies in activity 1, 3 and 5 MBq and the input distance is varied to 5; 10; and 13 cm from the phantom. From the simulation, it was obtained that the greater the number of neutrons, the longer the running process but the smaller the error. The neutron dose rate will be smaller if the distance of the neutron source and the volume of water phantom were greater, on the contrary the neutron dose rate will be greater if the neutron source activity is greater and the distance of the neutron source to the phantom and water volume is getting smaller