Abstracts ASN Report 2019

• Áǝƺ ȅƏǣȇ ƬǝƏǼǼƺȇǕƺɀ ǣȇ ȅƏȇƏǕǣȇǕ ƏǕƺǣȇǕ As with all industrial facilities, nuclear power plants are subject to ageing. ASN ensures that, in line with its general operating ĴŁķ ŀĴļŁŇĸŁĴŁĶĸ ņŇŅĴŇĸĺŌё ŇĴľĸņ ĴĶĶłňŁŇ łĹ ĴĺĸļŁĺіŅĸĿĴŇĸķ phenomena in order to maintain a satisfactory level of safety in the installations for their operating lifetime. To understand the ageing of an NPP, over and above simply the time that has passed since it was commissioned, a certain number of factors must be considered, more specifically the existence of physical phenomena which can degrade the characteristics of the equipment according to its usage or its conditions of use. • (ƺɎƺȸǣȒȸƏɎǣȒȇ Ȓǔ ȸƺȵǼƏƬƺƏƫǼƺ ǣɎƺȅɀ Equipment ageing is the result of phenomena such as the hardening of certain steels under the effect of irradiation or temperature, the swelling of certain concretes, hardening of polymers, corrosion of metals, etc. This deterioration is generally incorporated as of the design and manufacture of the facilities and then in a programme of monitoring and preventive maintenance, as well as of repair or replacement if necessary. • Áǝƺ ǼǣǔƺɎǣȅƺ Ȓǔ ȇȒȇ ٮ ȸƺȵǼƏƬƺƏƫǼƺ ǣɎƺȅɀ Non-replaceable items, such as the reactor pressure vessel ҎņĸĸׇŃłļŁŇ ӅєӅҏ ĴŁķ ŇĻĸ ĶłŁŇĴļŁŀĸŁŇ Ҏņĸĸ ŃłļŁŇ Ӆєӆҏё ĴŅĸ ņňĵĽĸĶŇ to close monitoring in order to check that they age as anticipated and that their mechanical characteristics remain within the limits allowing satisfactory behaviour. • …ƫɀȒǼƺɀƬƺȇƬƺ Ȓǔ ƺȷɖǣȵȅƺȇɎ ƏȇƳ ǣɎɀ ƬȒȅȵȒȇƺȇɎɀ Before it is installed in the NPPs, some equipment undergoes a qualification process designed to ensure that it is able to perform its functions in the stress and atmosphere conditions corresponding to the accident situations in which it would be GRAPH 6 Number and percentage of workers per dose range (in mSv) for 2019 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 15 to 20 10 to 15 6 to 10 5 to 6 2 to 5 1 to 2 0.5 to 1 0.001 to 0.5 10.12% 9.15% 0.33% 0.00% 3.31% 1.54% 9.31% 66.24% 4,586 4,149 151 0 1,499 697 4 ,220 30,030 Number of people Dose range (mSv) Source: EDF. GRAPH 7 Trend in mean individual dosimetry according to the categories of trades of the workers in the NPPs 0 0.5 1.0 1.5 2.0 2.5 3.0 Risk Prevention Welding Auxiliaries Mechanical Expert appraisal Tests Electricity Checks - inspections Thermal insulation Administrative 2016 2017 2018 2019 Source: EDF. Average Dose (mSv) 304 ASN Report on the state of nuclear safety and radiation protection in France in 2019 ׏׎ ٲ THE EDF NUCLEAR POWER PLANTS