Document n91x8wD4gJ3EXKLRmzMn5K0d2

CERN comments to PFAS restric3on consulta3on SPECIFIC INFORMATION REQUESTS 1) Sectors and (Sub-)uses I have informa-on on this topic The use of the F-gases in the par-cle physics experiments as gases for par-cle detec-on and related cooling is not included among the uses contemplated in Table 9 of the restric-on proposal neither in the list of proposed deroga-ons. 2) Emissions in the end-of-life phase I don't have informa-on on this topic 3) Emissions in the end-of-life phase I don't have informa-on on this topic 4) Impacts on the recycling industry I have informa-on on this topic An extension of the F-gases use for par-cle detec-on and related detector cooling is needed for the con-nua-on of the par-cle physics research ac-vi-es un-l the end of the current physics program of the HL-LHC, planned to end by the mid 2040s. Possibility to recycle the F- gases in use during- and at the end- of the use period should remain available. 5) Proposed derogaKons - Tonnage and emissions I have informa-on on this topic See request number 6 6) Missing uses - Analysis of alternaKve and socio-economic analysis I have informa-on on this topic Par-cle physics experiments, as those conducted at CERN's LHC, make use of F-gases for par-cle detec-on and related detector cooling. A wide range of gas mixtures is used for the opera-on of different gaseous detectors for par-cle physics research. Among them are F-gases like C2H2F4 (Norflurane 1,1,1,2Tetrafluoroethane - R134a), CF4 (Tetrafluoromethane - R14), C4F10 (Perfluorbuthane - R610) and C6F14 (Perfluorohexane - PFC-51-14), which are used because they allow to achieve specific detector performance that are necessary for data taking at the CERN experiments (i.e. detector sensi-vity, detector stability, long term performance, -me resolu-on, rate capability, etc.) in a very harsh environment (very low temperatures and high level of ionizing radia-on). The concomitant cooling of the detectors is essen-al for the appropriate process of par-cle detec-on. Several F-gases are used in the detector cooling systems and are mainly built in a cascading system to achieve temperatures around -50 C. The type of gases, their quan--es and the related number of systems are listed in the tables hereaZer. The detector gas systems of CERN experiments are equipped with gas recircula-on plants, i.e. systems where the return mixture from the detectors is collected, cleaned and then re-used. These plants allow to reduce the gas consump-on by at least 95%. The gas recircula-on cannot always be pushed to 100% because of two reasons: a) the accumula-on of Nitrogen in the gas mixture that cannot be filtered, and which causes the degrada-on of the detector performance, b) the presence of leaks at the detector level that are not accessible and therefore very difficult to repair. Point a) has been the subject of R&D studies for the development of specific gas installa-ons able to remove impuri-es not easy to filter. Indeed, the gas mixture used for par-cle detec-on purpose makes extremely difficult the recupera-on of the primary gases. Dedicated recupera-on plants have been developed by CERN for CF4, C4F10 and R134a and they are currently used. Concerning point b), CERN and the experiments are fully engaged in the research for specific techniques allowing to repair the faulty components in par-cle detectors. In addi-on, an intense R&D ac-vity is ongoing since many years in the detector community for finding environmentally friendly replacements of F-gases. However, finding a suitable replacement is par-cularly challenging because most of the experiment infrastructures (i.e. high voltage systems, cables, front-end electronics) as well as the detectors themselves cannot be replaced. Therefore, the R&D is focused on iden-fying new mixtures able to reproduce the same detector performance observed with the currently used mixtures. In one case, encouraging results have been obtained with a par-al subs-tu-on of the R134a with CO2. However, for the moment the full replacement of F-gases within the exis-ng detectors is not possible. Therefore, the economic impact of the subs-tu-on process cannot be es-mated. Regarding detector cooling, alterna-ves were found for some of the systems, that will result in a dras-c reduc-on of the F-gases used. The implementa-on of the alterna-ve system using CO2 instead of F-gases is planned by 2028. The residual quan-ty of F-gases is shown in the table hereaZer. R&D was also conducted in recent years to replace some exis-ng F-gas detector cooling systems that cannot be ficed by the CO2 system men-oned above. HFOs and FKs were the main candidates under test, following the recommenda-ons of the F-gas Regula-on EU No 517/2014. The valida-on process of any new gas would require in depth tests for assessing the safety, the efficiency, and the reliability in the challenging radia-on environment. Thus, es-ma-ng the economic and technical feasibility is impossible at this stage. Furthermore, the schedule of the accelerators dictates strict -me lapses for interven-on on the gas systems located within the detectors. The next possible interven-on slot will be in several years from now, namely aZer 2033. In the light of the above CERN requests the following to be considered for the future regula-on: CERN research ac-vi-es require an exclusion of F-gas restric-ons un-l the end of the current physics program linked to the opera-on of HL-LHC, provided alterna-ve detector technologies for future research programs are available in due -me. An addi-onal deroga-on for research ac-vi-es and, in par-cular par-cle detec-on and related cooling is required in this context. F-gas quan--es used at CERN are: The total quanKty of each F-gas contained within the detector gas systems of CERN experiments is listed below: F-gas Number of installa3ons where Total quan3ty present inside it is used detectors (kg) Norflurane 1,1,1,2- 7 250 Tetrafluoroethane - R134a Tetrafluoromethane - R14 5 420 Perfluorbuthane - R610 1 64 Perfluorohexane - PFC-51-14 1 350 The total quanKty of each F-gas contained within the detector related cooling systems of CERN experiments is listed below: F-gas/HFO/FKs Number of Total quan3ty Total quan3ty installa3ons where it is present inside inside detector used detector cooling cooling systems as systems (kg) of 2028 (kg) Trifluoromethane R-23 1 40 0 HFC-404a 6 204 0 HFC-407c 2 3 3 HFC-410a 3 16 0 HFC-507 5 158 0 Norflurane 1,1,1,2- 6 17 0 Tetrafluoroethane - R134a HFO/HFC-449 2 150 150 Perfluoro(2-methyl-3- 2 884 884 pentanone) NOVEC 649 Hexafluoroethane PFC- 1 2 2 116 Octofluoropropane PFC- 5 4140 600 218 Perfluorohexane PFC-51- 20 27103 4000 14 The total quanKty of each gas typically emiSed by the detector gas systems of CERN experiments per year is listed below: F-gas Number of Total quan3ty tCO2e installa3ons where it emiFed by detectors is used per year (kg) Norflurane 1,1,1,2- 7 56000 80080 Tetrafluoroethane - R134a Tetrafluoromethane - R14 5 1290 9533 Perfluorbuthane - R610 1 41 363 Perfluorohexane - PFC-51- 1 410 3813 14 The total quanKty of each gas typically emiSed by the detector related cooling systems of CERN experiments per year is listed below: F-gas Number of Total quan3ty emiFed tCO2e installa3ons where it by the detector is used cooling systems per year (kg) Trifluoromethane R-23 1 7 104 HFC-404a 6 1.5 6 HFC-407c 2 0 0 HFC-410a 3 0 0 HFC-507 5 0 0 Norflurane 1,1,1,2- 6 0 0 Tetrafluoroethane - R134a HFO/HFC-449 2 141 197 Perfluoro(2-methyl-3- 2 56 0.1 pentanone) NOVEC 649 Hexafluoroethane PFC-116 1 0 0 Octofluoropropane PFC- 5 616 5435 218 Perfluorohexane PFC-51-14 20 4804 44674 7) PotenKal derogaKons marked for reconsideraKon - Analysis of alternaKves and socio-economic analysis I don't have informa-on on this topic 8) Other idenKfied uses - Analysis of alternaKves and socio-economic analysis I don't have informa-on on this topic 9) DegradaKon potenKal of specific PFAS sub-groups I don't have informa-on on this topic 10) AnalyKcal methods I don't have informa-on on this topic