ISO CD 1856. Guideline for radiation exposure of nonmetallic materials

Full text: In the framework of the International Organization for Standardization (ISO) activity we started development of international standard series for space environment simulation at onground tests of materials. The proposal was submitted to ISO Technical Committee 20 (Aircraft and Space Vehicles), Subcommittee 14 (Space Systems and Operations) and was approved as Working Draft 15856 at the Los-Angeles meeting (1997). A draft of the first international standard 'Space Environment Simulation for Radiation Tests of Materials' (1st version) was presented at the 7th International Symposium on Materials in Space Environment. The 2nd version of the standard was limited to nonmetallic materials and presented at the 20th Space Simulation Conference. It covers the testing of nonmetallic materials embracing also polymer composite materials including metal components (metal matrix composites) to simulated space radiation. The standard does not cover semiconductor materials. The types of simulated radiation include charged particles (electrons and protons), solar ultraviolet radiation, and soft X-radiation of solar flares. Synergistic interactions of the radiation environment are covered only for these natural and some induced environmental effects. This standard outlines the recommended methodology and practices for the simulation of space radiation on materials. Simulation methods are used to reproduce the effects of the space radiation environment on materials that are located on surfaces of space vehicles and behind shielding. It is very important to use the ISO regulations for radiation test and selection of nonmetallic materials for spacecrafts with onboard nuclear reactor where serious synergistic effects of space and nuclear radiation are predicted. It was discovered that the problem of radiation environment simulation is very complex and the approaches of different specialists and countries to the problem are sometimes quite opposite. To the present moment we developed seven versions of the standard. The last version is a compromise between these approaches. It was approved at the last ISO TC20/SC14/WG4 meeting in Houston, USA, October 2002. At a splinter meeting of Int. Conference on Materials in a Space Environment, Noordwijk, Netherlands, ESA, June 2003, the experts from ESA, USA, France, Russia and Japan discussed the last version of the draft and approved it with some notes. A revised version of the standard was presented this May at ISO TC20/SC14 meeting in Russia. (author)