Abstracts ASN Report 2019

א ِ ב Áǝƺ ǔȸȒȇɎ ٮ ƺȇƳ ȇɖƬǼƺƏȸ ǔɖƺǼ ƬɵƬǼƺ ǔƏƬǣǼǣɎǣƺɀ Two front-end nuclear fuel cycle facilities are in shutdown status. They are situated on the Tricastin site, one specialising ļŁ ňŅĴŁļňŀ ĸŁŅļĶĻŀĸŁŇ ĵŌ ĺĴņĸłňņ ķļĹĹňņļłŁ Ҏ ׇӌӆҏё ŇĻĸ łŇĻĸŅ ļŁ ňŅĴŁļňŀ ĶłŁʼnĸŅņļłŁ Ҏ ׇӄӃӈҏ ĴŁķ ĴŅĸ ļŁ ŇĻĸ ķĸĶłŀŀļņņļłŁļŁĺ ŃŅĸŃĴŅĴŇļłŁ ŃĻĴņĸє Ł ĴķķļŇļłŁё ŇŊł ĹĴĶļĿļŇļĸņ ҎĹłŅŀĸŅ ׇӉӈׇĴŁķ ׇӌӃҏ ŊĻļĶĻ ĶłŁņŇļŇňŇĸķ ŇĻĸ ĹłŅŀĸŅ ŁňĶĿĸĴŅ ĹňĸĿ ĹĴĵŅļĶĴŇļłŁ ŃĿĴŁŇ łĹ ĸňŅĸŌі łŅłļōĸё łŃĸŅĴŇĸķ ĵŌ ŇĻĸ Société industrielle du combustible nucléaire (SICN) belonging to the Orano group, were ķĸĿļĶĸŁņĸķ ļŁ ӅӃӄӌё ĴĹŇĸŅ ĶłŀŃĿĸŇļłŁ łĹ ŇĻĸ ķĸĶłŀŀļņņļłŁļŁĺ operations and clean-out of the structures, accompanied by almost complete demolition of the buildings. The only radioactive materials used in these plants were uranium- bearing substances. One of the particularities of these facilities lies in the presence of radioactive contamination associated with the presence of “alpha” particle-emitting uranium isotopes. The radiation exposure risks are therefore largely linked to the risk of internal exposure. ňŅŇĻĸŅŀłŅĸё ŇĻĸņĸ ĴŅĸ łĿķĸŅ ĹĴĶļĿļŇļĸņ ŊĻłņĸ łŃĸŅĴŇļŁĺ ĻļņŇłŅŌ is poorly known. Determining the initial state, particularly the pollution present in the soils beneath the structures, therefore ŅĸŀĴļŁņ ĴŁ ļŀŃłŅŇĴŁŇ ļņņňĸє ňŅŇĻĸŅŀłŅĸё ŇĻĸ ļŁķňņŇŅļĴĿ ŃŅłĶĸņņĸņ used at the time involved large quantities of toxic chemical substances (uranium, chlorine trifluoride and hydrogen fluoride, for example): the containment of these chemical substances is thus also an issue in these facilities. א ِ ג Áǝƺ ƫƏƬǸ ٮ ƺȇƳ ȇɖƬǼƺƏȸ ǔɖƺǼ ƬɵƬǼƺ ǔƏƬǣǼǣɎǣƺɀ The back-end facilities of the nuclear fuel cycle are the spent fuel storage pools, the spent fuel reprocessing plants and the facilities for storing waste from the treatment process. These facilities ĴŅĸ łŃĸŅĴŇĸķ ĵŌ ŅĴŁł ŌĶĿĸ ĴŁķ ņļŇňĴŇĸķ łŁ ŇĻĸ Ĵׇ Ĵĺňĸ ņļŇĸє Ļĸ ĹļŅņŇ ŃŅłĶĸņņļŁĺ ĹĴĶļĿļŇŌ ĴŇ Ĵׇ Ĵĺňĸ ŊĴņ ĶłŀŀļņņļłŁĸķ ļŁ ӄӌӉӉё ļŁļŇļĴĿĿŌ ĹłŅ ŅĸŃŅłĶĸņņļŁĺ ŇĻĸ ĹňĸĿ ĹŅłŀ ŇĻĸ ĹļŅņŇіĺĸŁĸŅĴŇļłŁ Ĵņі łłĿĸķ ĸĴĶŇłŅņє Ļļņ ĹĴĶļĿļŇŌё ׇӆӆё ĶĴĿĿĸķ ӅіӇӃӃё ņŇĴŁķļŁĺ ĹłŅ Ѣ ŅłķňĶŇļłŁ ŁļŇ łє Ӆ҂ӇӃӃׇŇłŁŁĸņѣ ҎŇĻĸ ĹļŅņŇ ŅĸŃŅłĶĸņņļŁĺ ŃĿĴŁŇ ŊĴņ ӄׇņļŇňĴŇĸķ ļŁ ŇĻĸ ׇłĹ ĴŅĶłňĿĸ ĴŁķ is currently being decommissioned), was definitively shut down łŁ ӄׇ ĴŁňĴŅŌ ӅӃӃӇׇĴĿłŁĺ ŊļŇĻ ļŇņ ņňŃŃłŅŇ ĹĴĶļĿļŇļĸņё ŁĴŀĸĿŌ ŇĻĸ ĸĹĹĿňĸŁŇ ŇŅĸĴŇŀĸŁŇ ņŇĴŇļłŁ ӅׇĴŁķ ŇĻĸ ņŃĸŁŇ ĹňĸĿ ŅĸŃŅłĶĸņņļŁĺ ĹĴĶļĿļŇŌ ӄׇҎ ׇӆӋҏё ŇĻĸ ŅĴķļłĴĶŇļʼnĸ ņłňŅĶĸ ĹĴĵŅļĶĴŇļłŁ ĹĴĶļĿļŇŌ Ҏ ׇӇӊҏ ĴŁķ ŇĻĸ Ѣ ŋļķĸ ļĺĻ ĶŇļʼnļŇŌѣ ĹĴĶļĿļŇŌ Ҏ ҏё built for reprocessing the fuels from the “light water” reactors Ҏ ׇӋӃҏє Unlike the direct on-line packaging of the waste generated by ŇĻĸ ӅіӋӃӃׇĴŁķ ӆі ŃĿĴŁŇņ ļŁ łŃĸŅĴŇļłŁё ŀłņŇ łĹ ŇĻĸ ŊĴņŇĸ generated by the first reprocessing plant was stored without treatment or packaging. Decommissioning is therefore carried out concomitantly with the legacy Waste Retrieval and Packaging (WRP) operations. This waste is highly irradiating and comprises structural elements from fuel reprocessing, technological waste, rubble, soils and sludge. Some of the waste has been stored in bulk with no prior sorting. The retrieval operations therefore require remotely operated pick-up means, conveyor systems, sorting systems, sludge pumping and waste packaging systems. The development of these means and carrying out the operations under conditions ensuring a satisfactory level of safety and radiation protection represent a major challenge for the licensee. Given that these operations can last several decades, the management of ageing is also a challenge. Taking into account the quantities, the physical and chemical forms and the radiotoxicity of the waste contained in these facilities, the licensee must develop means and skills that involve complex engineering techniques (radiation protection, chemistry, mechanics, electrochemistry, robotics, artificial intelligence, etc.). At present about ten projects of this type are underway in the former facilities. They will span several decades and are a prerequisite to the complete decommissioning of these facilities, whereas the decommissioning of the process parts of the plant is continuing with more conventional techniques. א ِ ד Áǝƺ ɀɖȵȵȒȸɎ ǔƏƬǣǼǣɎǣƺɀ ٢ɀɎȒȸƏǕƺ ƏȇƳ ȵȸȒƬƺɀɀǣȇǕ Ȓǔ ȸƏƳǣȒƏƬɎǣɮƺ ƺǔǔǼɖƺȇɎ ƏȇƳ ɯƏɀɎƺ٣ Many of these facilities, most of which were commissioned in ŇĻĸ ӄӌӉӃņ ĴŁķ ŊĻłņĸ ĿĸʼnĸĿ łĹ ņĴĹĸŇŌ ķłĸņ ŁłŇ ĶłŀŃĿŌ ŊļŇĻ ĶňŅŅĸŁŇ best practices, have been shut down. Old storage facilities were not initially designed to allow the removal of their waste, and in some cases they were seen as being the definitive waste disposal site. Examples include the ĴļŁŇі ĴňŅĸŁŇіķĸņі Ĵňŋ ņļĿłņ Ҏ ׇӊӇҏё ŇĻĸ ŅĴŁł ŌĶĿĸ ŃĿĴŁŇ ņļĿłņ ļŁ Ĵׇ Ĵĺňĸ ҎņļĿłņ ӄӄӈׇĴŁķ ӄӆӃׇļŁ ׇӆӋё ŇĻĸ ņļĿł ļŁ ׇӋӃҏё ŇĻĸ ŃļŇņ ĴŁķ ŇŅĸŁĶĻĸņ łĹ ׇӈӉׇĴŁķ ŇĻĸ ŊĸĿĿņ łĹ ׇӊӅׇĴŁķ ׇӄӉӉє ĸŇŅļĸʼnĴĿ łĹ ŇĻĸ ŊĴņŇĸ ĹŅłŀ ŇĻĸņĸ ĹĴĶļĿļŇļĸņ is complex and will span several decades. The waste must then be packaged and stored in safe conditions. New packaging and storage facilities are thus planned or under construction. With regard to the Effluent Treatment Stations (STE) which also packaged the concentrates, they were shut down owing to the ageing of these facilities or the shutdown of the effluent- producing facilities. Examples include the Radioactive Effluent ĴŁķ ĴņŇĸ ŅĸĴŇŀĸŁŇ ŇĴŇļłŁ Ҏ ҏё ׇӆӊі ĴŇ ĴķĴŅĴĶĻĸё ӅׇĴŇ ŇĻĸ Ĵׇ Ĵĺňĸ ŃĿĴŁŇ ĴŁķ ŇĻĸ ŅĸŁŁļĿļņ є Ļĸ ķļĹĹļĶňĿŇļĸņ associated with the decommissioning of the STEs are closely dependent on their shutdown conditions, particularly the emptying and rinsing of their tanks. The major difficulties associated with the decommissioning of the support facilities are as follows: Ҋ poor knowledge of the operating history and the state of the facility to be decommissioned, which necessitates prior characterisation of the old waste and the analysis of samples of the sludge or deposits in the STE tanks. This characterisation necessitates firstly the development of methods and the use of specific equipment to take the samples, and secondly the availability of analysis laboratories; Ҋ the difficulty in accessing the waste for retrieval was not taken into consideration in the design (silos, trenches, concrete- lined pits, cramped premises, etc.), necessitating the costly construction of infrastructures in conformity with current safety requirements and leading to long retrieval times and unforeseen events; Ҋ the deterioration of the containment barriers, for example corrosion of waste drums or pollution of soils resulting from the occurrence of significant events during operation. ASN Report on the state of nuclear safety and radiation protection in France in 2019 337 ׏ ٲ ב DECOMMISSIONING OF BASIC NUCLEAR INSTALLATIONS 13