This paper describes the origins of natural neutron flux on the air-ground interface.

The typical workplace geometric model used in neutron radiation field simulation was established, neutron migration and transport in the radiation field was then simulated by MCNP 4C with data of plutonium isotope composition and neutron energy spectrum.

The main moderating performances of above 3 kinds of materials used in constructing epithermal neutron radiation field are obtained,and the optimized moderating material,an Al-AlF_3 mixture with a mass fraction ratio w(Al)/(w(AlF_3)) of 2/3, is recommended for Tsinghua University experimental reactor.

In order to get an Epithermal neutron radiation field for the using of Boron neutron capture therapy(BNCT),based on the Tsinghua University experimental reactor neutron source,the research pro- posed two engineering schemes through MC simulating method.

An fast neutron radiation field was gained.

A strongly impulsive SOR for solving discrete ordinate equations of 1-D atmospheric radiation;

Based on the field observation data,the atmospheric radiation flux parameterization schemes in the thermo-dynamic model of the ground surface and embankment surface along the Qinghai-Tibet railway are made and used to process the solar direct radiation flux,atmospheric diffuse radiation flux and downward long-wave radiation flux,and the results are good.

A discrete ordinate algorithm was developed which was a ble to simultaneously compute multi-dimensional atmospheric radiation and remot e sensing image-formation.

Microdosimetry is a effective method to description of the spatial distribution of energy deposition, and play an important role in research of the neutron radiation protection and treatment.

In this paper, the neutron hardening ability of hardened X7805RH is studied and the neutron radiation damage threshold of hardened X7805RH with different loads is estimated.