The Simulation Of Moderation Shield Structure Of Pulsed Neutron Coal Fast Analysis Device With Computer

In the coal industry,it is often necessary to have suitable quantitative date avaitable concerning the chemical concentrations in coal.Neutron-induced prompt gamma-ray analysis(NIPGA) can be used for fast analysis of coal .Fast-thermal neutron interact with the neclie of the coal to produce inclastic scatering(n,n,γ)reaction and neutron cappture(n,γ) reaction.We can obtain the chemical concentrations in coal by means of induced prompt gamma-ray spectrum.Neutron-induced prompt gamma-ray analysis is a highly sensitive, non-destructive, multi-element analysis of nuclear technology. In practice, it is helpful to design moderation structure of pulsed neutron coal fast analy device. The device can not only effectively analysis of coal,reduce the effect of objects around but also benefit the radiation defence of the whole system.Monte Carlo Method can realistically describe the random events and simulate the experiment courses.It is very suitable for the calculation of particle transport problem which has the randomicity.The method has been widely used in the simulation of nuclear experiments include neutron detection.MCNP is a general program to simulate nuclear experiments,whicn is made by Los Alamos Station Lab in Americal based the Monte Carlo thoughts.In the article the author introduced Monte Carlo method, determined the content of a simulation,established the geometric model and the calculation model.The author also used the MCNP-4C program to simulate and calculate the moderation structure of pulsed neutron coal fast analy device.The results show that the tungsten and the paraffin with 10% B4C by weight are good moderator material of 14MeV neutrons.While the neutron source to take the lead box and the thickness of lead box is 7cm ,thermal neutron fluence rate and total neutron fluence rate are better in the coal,the outsideγare effective shielded.When the thickness of moderator more than 47cm,the total dose equivalent rate around the pulsed fast neutron analysis device is below the safe value.Based on the simulation of moderation structure of pulsed neutron coal fast analy device,it is helpful to design a more rational device.It also helpful to design the other moderation stucture of element analysis device which use neutron generators as neutron sources.