Main stages of a nuclear fuel cycle (NFC) are considered in the paper. A short list of radioactive and toxic compounds is presented as possible components of an emergency emission at each stage of the NFC. The vibrational spectra of the uranium fluorides and oxifluorides and the elements from chromium subgroup in various aggregate states have been studied. The main chemical processes in the atmosphere with the uranium fluorides and oxifluorides participation have been analyzed as well as their influence on the vibrational spectra of the pointed compounds. It is shown that a structurally nonrigid molecular complex with general formula (HF)nЧ(H2O)m, (n, m >= 2) is formed as the result of the HF and H2O molecules interaction, characterized by several types of motions of large amplitude, the spectrum of which may significantly differ both from the pure HF and H2O spectra and from spectra of the well-known complex HFЧH2O.