Abstracts ASN Report 2019

׫٫ ڲ Oversight of nuclear safety 1. The sipping technique consists in heating water containing the assembly and monitoring the activity of this water at the outlet. א ِ׏ IɖƺǼ א ِ׏ِ׏ !ǝƏȇǕƺɀ ɎȒ ǔɖƺǼ ƏȇƳ ǔɖƺǼ ȅƏȇƏǕƺȅƺȇɎ ǣȇ Ɏǝƺ ȸƺƏƬɎȒȸ In order to increase the availability and performance of the ŅĸĴĶŇłŅņ ļŁ łŃĸŅĴŇļłŁё ĴŁķ ŇĻĸ ŁňĶĿĸĴŅ ĹňĸĿ ŀĴŁňĹĴĶŇňŅĸŅņ are developing improvements to be made to the fuels and to how they are used in the reactors. ĻĴņ ņŇĴŁķĴŅķļņĸķ ļŇņ ĹňĸĿ ŀĴŁĴĺĸŀĸŁŇ ŀĸŇĻłķņє ĸŁņňŅĸņ that each change to fuel management undergoes a specific safety demonstration in the reactors concerned. Any change in the fuel or its management must first be examined by ASN and may not be implemented without its consent. As fuel behaviour is a key element in the safety of the core in a normal or accident operating situation, its reliability is crucial. Thus, the leaktightness of the fuel rod cladding, tens of thousands of which are present in each core and which constitute the first containment barrier, receives particularly close attention. In normal operation, leaktightness is monitored ĵŌ ŇĻŅłňĺĻ ŃĸŅŀĴŁĸŁŇ ŀĸĴņňŅĸŀĸŁŇ łĹ ŇĻĸ ĴĶŇļʼnļŇŌ łĹ ŇĻĸ radionuclides contained in the primary system. Any increase in this activity beyond predetermined thresholds is a sign of a loss of ĿĸĴľŇļĺĻŇŁĸņņ ļŁ ŇĻĸ ĹňĸĿ ĴņņĸŀĵĿļĸņє ňŅļŁĺ ĸĴĶĻ ņĻňŇķłŊŁё must look for and identify the assemblies containing leaking rods, which must not then be reloaded. If the activity of the primary system becomes too high, the General Operating Rules (RGE) require shutdown of the reactor before the end of its normal cycle. ĸŁņňŅĸņ ŇĻĴŇ Ŀłłľņ ĹłŅ ĴŁķ ĴŁĴĿŌņĸņ ŇĻĸ ĶĴňņĸņ łĹ ŇĻĸ Ŀłņņ of leaktightness observed, notably by examining the leaking rods in order to determine the origin of the failures and prevent them from reoccurring. The preventive and corrective measures may concern the design of the rods and assemblies, their manufacture or the reactor operating conditions. In addition, the conditions of fuel assembly handling, of core loading and unloading, as well as preventing the presence of foreign objects in the systems and pools are also covered by operating specifications, some of which ĶłŁŇŅļĵňŇĸ Ňł ŇĻĸ ņĴĹĸŇŌ ĶĴņĸ ĴŁķ ĹłŅ ŊĻļĶĻ ѡņ ĶłŀŃĿļĴŁĶĸ is spot-checked by ASN during inspections. ASN also carries łňŇ ļŁņŃĸĶŇļłŁņ Ňł ĶĻĸĶľ ŇĻĸ ŁĴŇňŅĸ łĹ ѡņ ŀłŁļŇłŅļŁĺ łĹ ļŇņ ĹňĸĿ ņňŃŃĿļĸŅņє ļŁĴĿĿŌё ŃĸŅļłķļĶĴĿĿŌ ĶłŁņňĿŇņ ŇĻĸ ķʼnļņłŅŌ Committee for Nuclear Reactors (GPR) concerning the lessons learned from fuel operating experience feedback. א ِ׏ِ א ɀɀƺɀɀȅƺȇɎ Ȓǔ Ɏǝƺ ƬȒȇƳǣɎǣȒȇ Ȓǔ Ɏǝƺ ǔɖƺǼ ƏȇƳ ǣɎɀ ȅƏȇƏǕƺȅƺȇɎ ǣȇ Ɏǝƺ ȸƺƏƬɎȒȸ ĶłŁņļķĸŅņ ŇĻĴŇё ļŁ ӅӃӄӌё ŇĻĸ ļŁŇĸĺŅļŇŌ łĹ ŇĻĸ ĹļŅņŇ ĶłŁŇĴļŁŀĸŁŇ barrier, that is the fuel rod cladding, was on the whole satisfac- torily managed by all the NPPs. Ļĸ ŃŅłĺŅĸņņ łĵņĸŅʼnĸķ ļŁ ӅӃӄӋׇŊļŇĻ ŅĸĺĴŅķ Ňł ŇĻĸ Ņļņľ łĹ ĹłŅĸļĺŁ objects entering the primary system, which could then damage ŇĻĸ ĹļŅņŇ ĶłŁŇĴļŁŀĸŁŇ ĵĴŅŅļĸŅё ĶłŁŇļŁňĸķ ļŁ ӅӃӄӌє łŀĸ ņļŇĸņ developed good practices, for example by setting up training and awareness-raising actions intended for the personnel active łŁ ŇĻĸ ŊłŅľіņļŇĸņ ŊļŇĻ ŇĻļņ ņŃĸĶļĹļĶ Ņļņľє ĶłŁņļķĸŅņ ŇĻĴŇ must continue its efforts in this area. The number of reactors with cladding defects was similar to the previous year. ASN will remain attentive to the investigations ĶĴŅŅļĸķ łňŇ ĵŌ łŁ ŇĻĸ ĹňĸĿ ĴņņĸŀĵĿļĸņ ĶłŁĶĸŅŁĸķё ļŁ łŅķĸŅ Ňł determine the origin of these defects and identify the corrective measures in terms of manufacturing and operation. In dealing with the obsolescence of the sipping machines (1) in the fuel buildings, ASN will be attentive to the correct performance of all the maintenance operations performed on this equipment. This attention will be maintained until the deployment of new mobile sipping machines currently being designed. ņ ļŁ ӅӃӄӋё ĹĸŊ ĸʼnĸŁŇņ ĶłŁĶĸŅŁĸķ ĹňĸĿ ĻĴŁķĿļŁĺ łŃĸŅĴŇļłŁņ ļŁ ӅӃӄӌє One assembly did however snag during unloading operations in the Tricastin NPP. As this incident had already occurred on the same site in the past, ASN will pay particular attention to the effectiveness of the corrective measures taken. Ł ӅӃӄӌё ņĸʼnĸŅĴĿ ŅĸĴĶŇłŅņ ĶłŁķňĶŇĸķ Ĵ ĹļŅņŇ ŃłŊĸŅ ļŁĶŅĸĴņĸ ĴĹŇĸŅ refuelling that was long enough to require authorisation of a change to their operating baseline. The reactors concerned operated for a prolonged period of time at intermediate power, which increases the risk of rupture of the first barrier in certain accident situations. These extended power increase durations ŊĸŅĸё ļŁ ŇĻĸ ĶĴņĸņ ĸŁĶłňŁŇĸŅĸķ ļŁ ӅӃӄӌё ĶĴňņĸķ ĵŌ ļŁĶļķĸŁŇņ łŁ certain secondary system equipment not important for safety. ASN ĶłŁņļķĸŅņ ŇĻĴŇ ŀňņŇ ĸŁņňŅĸ ŇĻĴŇ ļŇņ ĹĴĶļĿļŇļĸņ ĴŅĸ ĴʼnĴļĿĴĵĿĸё more specifically the secondary system, before carrying out the divergence and power increase transients. With regard to the fabrication of fuel assemblies, ASN is maintaining its vigilance following the anomalies on assemblies ĶłŁŇĴļŁļŁĺ ĸŁĶłňŁŇĸŅĸķ ļŁ ӅӃӄӊׇҎŃŅĸņĸŁĶĸ łĹ ĿĴŅĺĸі ņļōĸķ ŃĿňŇłŁļňŀ ĸŁŅļĶĻĸķ ļņĿĴŁķņҏё ŊĻļĶĻ ĻĴŃŃĸŁĸķ ĴĺĴļŁ ļŁ ӅӃӄӌׇķĸņŃļŇĸ ŇĻĸ ņŇĸŃņ ŇĴľĸŁ ĴŇ ŅĴŁł ŌĶĿĸѡņ ĸĿłŋ ŃĿĴŁŇє reported a significant event concerning a neutron flux increase phenomenon at the bottom and at the top of the fissile column łĹ ĹňĸĿ ĴņņĸŀĵĿļĸņё ŊĻļĶĻ Ŀĸķ Ňł Ĵņľ ļŁ ӅӃӄӋׇĹłŅ compensatory measures pending a change to the design of these assemblies and a complete demonstration of the corresponding Ņļņľņє Ļĸņĸ ĶłŀŃĸŁņĴŇłŅŌ ŀĸĴņňŅĸņ ŊĸŅĸ ķĸŃĿłŌĸķ ļŁ ӅӃӄӌׇĹłŅ ŇĻĸ ĿłŊĸŅ ŃĴŅŇ łĹ ŇĻĸ ĹļņņļĿĸ ĶłĿňŀŁ ĴŁķ ŊļĿĿ ĶłŁŇļŁňĸ ļŁ ĸĴŅĿŌ ӅӃӅӃׇĹłŅ ŇĻĸ ňŃŃĸŅ ŃĴŅŇє Ň ŇĻĸ ņĴŀĸ Ňļŀĸё ņŇňķļĸķ ŀłķļĹļĸķ fuel assemblies reducing the impact of this design anomaly and ĵĸĺĴŁ Ňł ĿłĴķ ŇĻĸŀ ļŁŇł ŇĻĸ ŅĸĴĶŇłŅє ŊļĿĿ ĴĿņł ĵĸ ĴķłŃŇļŁĺ particular operating measures for reactors containing MOX fuel as of the beginning of 2020. א ِ א zɖƬǼƺƏȸ ȵȸƺɀɀɖȸƺ ƺȷɖǣȵȅƺȇɎ ٢z¨0٣ א ِ א ِ׏ xȒȇǣɎȒȸǣȇǕ Ȓǔ Ɏǝƺ ƳƺɀǣǕȇ ƏȇƳ ȅƏȇɖǔƏƬɎɖȸǣȇǕ ƬȒȇǔȒȸȅǣɎɵ Ȓǔ zɖƬǼƺƏȸ ¨ȸƺɀɀɖȸƺ 0ȷɖǣȵȅƺȇɎ ASN assesses the compliance of the NPEs which are most important in terms of safety, said to be “level N1”, which are the reactor pressure vessel, the SGs, the pressuriser, the reactor coolant pumps, the piping and the control valves and relief valves. These regulations are a guarantee of their safety. They are defined by a European Directive on NPE and are supplemented by requirements specific to NPE. This conformity assessment concerns the equipment intended ĹłŅ ŇĻĸ ŁĸŊ ŁňĶĿĸĴŅ ĹĴĶļĿļŇļĸņ ҎŀłŅĸ ŇĻĴŁ ӅӃӃׇĸńňļŃŀĸŁŇ ļŇĸŀņ ĴŅĸ ĶłŁĶĸŅŁĸķ łŁ ŇĻĸ ĿĴŀĴŁʼnļĿĿĸ ҏ ĴŁķ ŇĻĸ ņŃĴŅĸ equipment intended for nuclear facilities already in service (notably the replacement SGs). ASN can be assisted in this task by organisations that it approves. These latter can be mandated by ASN with performance of some of the inspections on the “level N1” equipment and are tasked with assessing the regulatory compliance of the NPE less important for safety, ņĴļķ Ňł ĵĸ ѢĿĸʼnĸĿׇ ӅׇłŅ ӆѣє Ļĸ łʼnĸŅņļĺĻŇ ĵŌ ĴŁķ ŇĻĸ 282 ASN Report on the state of nuclear safety and radiation protection in France in 2019 ׏׎ ٲ THE EDF NUCLEAR POWER PLANTS