[en] In the CEA Project 'Cementation of LLW/ILW Slurry' EIRICH and CEA developed together a high performance mixing process matching the French security regulations for nuclear facilities. Since 2010 mixing tests had been carried out by CEA to develop and verify a new cementation process. In 2012 EIRICH started the development of the mixing equipment for the cementation plant together with CEA. This new cementation plant will be put into operation in 2016 at the CEA site in Marcoule. (authors)

[en] The biphasic product CoS₂ + Co(OH)₂ obtained by oxidation of cobalt sulfide is known to trap hydrogen at room temperature and low pressure according to a balanced reduction equation. Adding various inorganic compounds to this original absorber induces their reduction by hydrogen in the same conditions at a significant rate: (i) excess cobalt hydroxide is reduced to metallic cobalt; (ii) nitrate ions are reduced to ammonia; (iii) sulfur and sodium thiosulfate are reduced to H₂S or NaHS and Na₂S, respectively. Without a hydrogen absorber these inorganic compounds are not reduced by H₂, suggesting synergetic effects involving H₂ and the hydrogen absorber. Amorphous cobalt polysulfide, CoS₅, is also reduced by hydrogen at room temperature and releases H₂S gas. In the presence of a base to neutralize H₂S gas, the reaction rate is initially slower than with the CoS₂ + Co(OH)₂ mixture due to the higher stability of polysulfide chains but the H₂ trapping yield is improved, making CoS₅ a good candidate for H₂ trapping. (authors)

[en] The alterations induced in polyvinyl chloride (PVC) for irradiation doses in the range of a few kGy to 10 MGy have been studied; the PVC (pure or industrial) electron spin resonance (ESR) spectra have been recorded for different irradiation conditions (dose, dose rate) and conservation time after treatment. According to the irradiation and storage conditions, it has been observed characteristic ESR spectra of polyenyl or peroxyl radicals. The results obtained by thermal analysis and steric exclusion chromatography from pure PVC irradiated in different conditions are presented too. The propagation and ending reactions from radicals lead to the formation of different damage products, and in particular to reticulation phenomena for radiolysis in anaerobic condition, and chains cleavages reactions for radiolysis in aerobic conditions. (O.M.)

[en] Very early in its history, nuclear industry has taken care of the future of its wastes. Cementation processes for medium-level activity wastes, vitrification processes for minor actinide solutions and fission products are now proven technologies. The conditioning of wastes is just one ink in the full chain of the waste management process. However, this link is of prime importance because the future of the waste depends on the way it is conditioned. Reciprocally, the storage and disposal largely rely on the confidence given to the behaviour of waste packages with time. The leading role of France in the domain of radioactive wastes conditioning is a strong and valorizable asset at the international industrial plan, but also in terms of social acceptance by showing to the public that technical solutions exist. This monograph takes stock of the conditioning of nuclear wastes and describes the researches in progress, the stakes and the recent results obtained by the CEA (French atomic energy commission). Content: 1 - introduction: waste volumes and fluxes, management strategy, conditioning; 2 - Decontamination and treatment processes for effluent and technological waste; 3 - Glass, a waste conditioning matrix for the long term: Glass packages and manufacturing processes; Nuclear glass formulation, structure and properties; Long-term behavior of glasses; Cold crucible vitrification; 4 - Current conditioning systems for low and intermediate level waste: Cements as confining materials; Bitumens; Metallic structure waste conditioning; 5 - Researching alternative matrices and processes for waste treatment and conditioning: Plasma benefits for incineration / vitrification waste treatment; The Shiva process; Alternative confining matrices; Confinement of waste from pyrochemical processes: status of research; 6 - Spent fuel: a possible confining matrix?: Spent fuel initial characteristics; Spent fuel evolution in a dry storage facility; Modelling the long-term spent fuel behavior; Spent fuel containers in long-term storage and direct disposal concepts; Spent fuel storage and direct disposal: results and outlooks; 7 - general conclusion: Conditioning: a major asset for nuclear waste management; Glossary; Index

[en] Anaerobic and aerobic radiolysis mechanisms of poly(vinyl chloride) were investigated using electron spin resonance (ESR), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and size exclusion chromatography (SEC). PVC samples have been irradiated by γ rays (⁶⁰Co) at high doses (up to 4 MGy) and at room temperature. High dose anaerobic radiolysis of PVC induced several modifications in polymer. Alkyl radicals are formed, and then these radicals induced the formation of polyenic radicals. ¹³C NMR spectra have also shown the formation of polyenic sequences and crosslinking reactions. The modifications induced in PVC irradiated under aerobic condition are different. ESR spectra have shown that peroxyl radicals are formed. Propagating reactions from peroxyl radicals are mainly composed by β-scission reactions. These β-scission reactions involved the decrease of average molecular weight and the formation of aldehydes, acids chloride and/or carboxylic acids. From all these results, anaerobic and aerobic mechanisms of degradation by PVC radiolysis are proposed