UNCERTAINTIES IN THE RISKS OF EXPOSURE TO GAMMA RADIATION AND POSSIBLE APPLICATION OF FUZZY LOGIC(Fuzzy Logics in Biomedical Systems)

スポンサーリンク

概要

• 論文の詳細を見る

• The safety policy of the European Space Agency (ESA) gives precedence to the protection of human life and is applicable to all ESA space flight projects. The ESA safety program is based on the performance of safety analysis comprising hazard analysis and risk assessment. One of the hazardous conditions to be studied for future manned space missions is the exposure of astronauts to gamma radiation. The space radiation environment consists of mainly galactic cosmic rays, trapped particles and solar cosmic rays. The interaction of radiation with the space Vehicle and the astronaut space suit produces direct effects such as ionization and secondary effects i.e. mainly bremsstrahlung. Such a generated photon flux can constitute a significant radiological hazard and can be more penetraing than the electrons that produce it. In hazard analysis all radiation exposure scenarios leading to sever detrimental health effects of the astronauts are identified. In risk assessment the scenarios are evaluated on a probabilistic basis, by taking into consideration all possible uncertainties. There are uncertainties in the radiation environment, the bremsstrahlung generation, the exposure situations of astronauts to radiation and the dose response relationship. In particular in the low dose region there is large uncertainty. Effects of the microgravity environment on orbit increase this uncertainty even further as e.g. biomedical effects can be synergetic and non additive. As there are no relevant statistical data systematic use of subjective expert judgement has to be made. The elicitation and use of expert judgement data as well as the representation of non-statistical uncertainty involves "fuzzy logic". Fuzzy logic is an extension of binary logic and allows the use of qualitative formulations. For example the "degree of information dependence" that determines the coupling of uncertainties in the risk calculations ranges between "no dependence" and "complete dependence". Several radiation hazard and risk reduction alternatives exist. These are passive protection by shielding, in orbit radiation monitoring and warning, mission profile planning and chemotherapeutical protection. Risk reuslts with a proper representation of uncertainties are finally used to determine the optimum radiation hazard and risk reduction approach.

• バイオメディカル・ファジィ・システム学会の論文

著者

• Nishiwaki Y.

  International Atomic Energy Agency

• Preyssl C.

  European Space Agency, Product Assurance and Safety Department

• Preyssl C.

  European Space Agency

関連論文

• OPTIMISATION OF RADIATION PROTECTION BASED ON FUZZY RISK ANALYSIS
• UNCERTAINTIES IN THE RISKS OF EXPOSURE TO GAMMA RADIATION AND POSSIBLE APPLICATION OF FUZZY LOGIC(Fuzzy Logics in Biomedical Systems)

スポンサーリンク