[en] For guiding the environmental assessment and radiation protection, radioactive source terms in the decommissioning should be analyzed. According to the mechanism of source terms in the 3 steps in decommissioning, the neutron activated production surrounding core and activated corrosion product deposited on the primary and auxiliary systems are the major part of source terms in the decommissioning. The typical nuclides including ⁶⁰Co, ⁶³Ni, ^110mAg, etc. The calculation method is proposed based on the history of neutron irradiation, which can used for quantitative estimation of source terms in the decommissioning. (authors)

[en] Highlights: • In this work, we have reported a convenient method to modify molybdenum disulfide (MoS₂) nanosheets. • The organic modified MoS₂ nanosheets dispersed well in organic solvents and aqueous solution simultaneously. • This well dispersion can be used to prepare polymer/MoS₂ nanocomposites with an exfoliation structure by a simple solvent mixing method. • The organic modified MoS₂ nanosheets show promising reinforcing efficiency in the thermal stability, fire resistance and thermomechanical properties of the polymer/MoS₂ nanocomposites. - Abstract: In the evolution of high performance layered inorganic compounds/polymer nanocomposites, homogeneous dispersion of inorganic nanoplatelets in the polymer matrix and exact interface control are difficult to achieve due to the potent interlayer cohesive energy and surface inactiveness of the nanocomposites. Pristine MoS₂ exhibits poor solubility in both water and organic solvents. Herein, it is necessary to modify the surface of molybdenum disulfide (MoS₂) nanosheets with functional groups, in order to enhance its dispersity and compatibility in various solvents and polymer matrices. In this paper, we have reported a convenient method to modify MoS₂ nanosheets with common cationic surfactant and polymer, these organic modified MoS₂ nanosheets dispersed well in organic solvents and aqueous solution simultaneously. This well dispersion can be used to prepare polymer/MoS₂ nanocomposites by a simple solvent mixing method which was found to display an exfoliation structure of MoS₂ nanosheets and improve the performances of the polymer nanocomposites. With the addition of 3 wt% CTAB-MoS₂, T_10% and T_50% of the samples are increased by 60 °C, respectively. Moreover, the storage modulus of sample PS/3% CTAB-MoS₂ had 84% increment compared with that of pure PS at 30 °C

[en] Highlights: • Co_3O_4 crystals had been synthesized by one step template-free hydrothermal method. • The H_2O_2 plays a crucial role in morphological control of Co_3O_4 nanostructures. • The morphology has significant effect on the optical property of Co_3O_4. - Abstract: We had developed a facile synthetic route of Co_3O_4 crystals with different morphologies via one step template-free hydrothermal method. The phase and composition of the Co_3O_4 were investigated by X-ray powder diffraction and Raman spectrum. The morphology and structure of the synthesized samples were characterized by scanning electron microscopy and transmission electron microscopy. The H_2O_2 played a crucial role in morphological control of Co_3O_4 nanostructures. It only obtained Co-based precursor in the absence of H_2O_2. On the contrary, the Co_3O_4 with different morphologies including nanoparticles, nano-discs and well-defined octahedral nanostructures were synthesized in the presence of H_2O_2. In addition, the optical property of the obtained Co_3O_4 samples was investigated by UV–vis spectra

[en] Highlights: • Absorption capacity and absorption mechanism of NO_x by ILs with different cations and anions is compared. • NO_x absorption capacity is as follows: NO₂>NO>N₂O, which is in good agreement with bind energy between NO_x and ILs. • Functionalized ILs with active N or O sites can effectively improve NO capacity by chemical interaction. • ILs with [NO₃]⁻ anion can efficiently catalyze conversion of NO into HNO₃ in the presence of O₂ and H₂O. Ionic liquids (ILs) can be used as absorbents and catalysts for NO_x absorption and conversion due to their low toxicity, low energy consumption and excellent reusability. The capacity and absorption mechanism of NO_x absorption by ILs are presented in this paper. Generally, NO_x are physically absorbed by conventional ILs such as imidazolium-based ILs. The absorption capacity is as follows: NO₂>NO>N₂O, which is in good agreement with the binding energy between NO_x and ILs. Furthermore, low temperature, high pressure and large cation volume are favorable for NO_x absorption. The strategies of enhancing NO_x capacity through functionalized ILs with metal-containing anions (e.g. [FeCl₄]²⁻), amine groups, sulfonate and carboxylate anions are also concluded. Active N or O sites in functionalized ILs can react with the dimer of NO (N₂O₂), resulting in high capacity. Moreover, introducing electron-withdrawing substituents such as chlorine and bromine into carboxylate or sulfonate anions reduces desorption residue. Besides NO_x absorption, ILs with [NO₃]⁻ can activate NO and efficiently catalyze its conversion into HNO₃ in the presence of O₂ and H₂O, and have better performance than ILs with [Cl]⁻, [Ac]⁻ and [CF₃SO₃]^−, which is attributed to the strong oxidization capability of [NO₃]⁻. In addition, low temperature and high O₂ content can further improve NO conversion.

[en] To control excess reactivity, natural boric acid is used in PWRs as chemical shim. As the boric acid concentration is relatively high at the beginning of life (BOL), especially with the implement of long cycle fuel management, the high boric acid concentration will lower the pH, increase the corrosion rate of materials, and result in the increase of the radiation risk and the decrease of heat transfer efficiency between fuel rod and coolant. The study abroad finds that, the water chemistry improves and the corrosion will be restrained with the application of enriched boric acid (EBA). This paper analyzes the influence of EBA on deposits of corrosion product in PWR. The study shows that EBA can reduce the mass of corrosion product deposits on the fuel rod and lower the activity of corrosion product deposits on pipes, contributing to the heat transfer between fuel rod and coolant and lower radiation field. (authors)

[en] Highlights: • In this paper, α-FeOOH/rGO hybrids had been prepared by a facile hydrothermal method. • The addition of the α-FeOOH/rGO hybrids showed a significant effect on the thermal stability and smoke suppression properties of PS composites. • Graphene can be employed to improve the smoke suppression properties of polymer and further extended the application of graphene. - Abstract: In this work, α-FeOOH/rGO hybrids were firstly prepared by a facile hydrothermal method. X-ray diffraction and transmission electron microscopy results indicated that α-FeOOH nanoparticles were dispersed uniformly on the surface of graphene nanosheets. Subsequently, the α-FeOOH/rGO hybrids were incorporated into polystyrene (PS) matrix for the improvement of the thermal stability and smoke suppression properties. It was found that the thermal stability of PS nanocomposite was obviously enhanced upon the introduction of 2.0 wt% α-FeOOH/rGO hybrids. Furthermore, the addition of α-FeOOH/rGO hybrids could improve the smoke suppression properties of PS nanocomposites, as evidenced by the dramatical reduction of carbon monoxide production rate, total smoke release and total smoke production. The total flammable gaseous products from the PS nanocomposites were decreased which further led to the inhibition of smoke. Such a significant improvement in thermal stability and smoke suppression properties was mainly attributed to the physical barrier effect of graphene nanosheets and the catalytic carbonization function of α-FeOOH nanoparticles

[en] The calculation method of ¹⁴C in PWR was studied in the paper. MCNP code was used to calculate the generation rate of ¹⁴C. Compared with the method used for ¹⁴C source term calculation of AP1000, this method is more convenient and exact. This method was used to calculate ¹⁴C source term of a 1000 MW reactor, the result show the ¹⁴C effluent of this reactor is complied with the rule in GB 6249. (authors)

[en] Severe accident release categories of a nuclear power plant of third generation were introduced. The release characteristics to the environment were calculated using MAAP code for those release categories and its severe accident sequences which can result in the large release of radioactive materials. On this base, several nuclides which contribute the most personnel dose were selected. This paper calculated the cumulative activity released to the environment and whole body and thyroid dose of 500 m site boundary with and without considering the decay of nuclides. The effect of decay on the results was analyzed. All these analysis can provide some reference for the improvement of severe accident simulation program. The effect of decay on the cumulative activity of fission products released to the environment is related to the radionuclide half-life and the release time of the fission products after the accidents. From the off-site dose analysis, the effect of decay on whole body dose is more obvious than that on the thyroid dose. (authors)

[en] Egongshan volcanic basin which is rich in the uranium-polymetallic mineral in the Gan-Hang Tectonic volcanic belt. On the basis of collecting the previous exploration results, this paper has summarized the mineralization geological characteristics of uranium, gold and silver, analyzed the metallogenic conditions of Uranium-polymetallic deposits in Volcanic Basin from Ore-forming elements gathering, structure, magmatic activity, wallrock alteration, cryptoexplosion and mantlederived material, etc. It is considered that the strong volcanic magma activity and function in Mesozoic has provided favorable basic geological conditions for the volcanic-cryptovolcanic hydrothermal Uranium-polymetallic deposits in the volcanic basin. It is suggested that study on the relationship between cryptoexplosive breccia and mineralization and whether the mantlederived material involves in the mineralization should be strengthened. (authors)

[en] The research on the division of the emergency planning zone size of small reactor was introduced. The fission product release fractions of floating nuclear power plant ACP100S and AP1000 to the environment were compared under the same accident sequence. By choosing an envelope severe accident source term, the emergency planning zone size of ACP100S was estimated. It shows that the release fraction of ACP100S is little smaller than that of AP1000 under the same accident sequence. With the smaller initial core inventory of ACP100S, the smaller source term of ACP100S releases to the environment. On the 500 m distance, two days effective dose and seven days effective dose and thyroid dose are smaller than the relative interval levels. It is appropriate to define the radius of 500 m for the ACP100S plume emergency planning zone and its off-site emergency could be eliminated. (authors)