Review of failure rate input parameters to risk analysis of cryogenic systems

1. Review of failurerateinputparametersto riskanalysis of cryogenicsystems Maciej Chorowski, Agnieszka Piotrowska, Laurent Tavian* Wrocław University of Technology, Poland CERN, Switzerland* CEC-ICMC2015

2. Outline • Introduction • Methodology of riskanalysis • Failurerate data availibility • Conclusions

3. Karol Olszewski and Zygmunt Wróblewskiair, nitrogen, oxygen liquefaction in 1883 1846-1915 1845-1888 Jagiellonian University, Cracow, Poland ~102 of components

4. Equipment of H. KamerlinghOnnes (1908) – hundreds of components Helium liquefaction stage Leiden « cascade » to produce liquid hydrogen ~103 of components

5. ITER Cryogenic System Cryodystribution lines and boxes in the tokamak building Main cryogenic transfer lines Helium and nitrogen liquefiers in the cryoplant buildings ~106 of components

6. In LHC – to header D In LHC – to header D Possible failures of cryogenic node followed by the cryogen discharge qm qm • Mechanical break of warm vacuum vessel • Fast degradation of vacuum insulation with air • Intensive heat flow to the cryogen • Magnet quench (optionally) • Pressure increase of the cryogen • Opening of the safety valve • Cryogen discharge through the safety valve p • Mechanical break of cold vessel • Fast degradation of vacuum insulation with cryogen • Intensive heat flow to the cryogen • Magnet quench (optionally) • Pressure increase of the cryogen and in the vacuum space • Opening of the rupture disk and/or safety valve • Cryogen discharges through the rupture disk and/or safety valve

7. Defects leading to cryogenic systems failures Coldweldrupture Coldpipeleakage Coldpiperupture Coldbellowsrupture Vacuumjacketrupture Electrical joint failure Capilary break Warm line leakage

8. RAMI approach – categorization of the failures with respect to their criticality for the following features: D. Van Houtte, K. Okayama, F. Sagot, RAMI approach for ITER, Fusion Engineering and Design 85, Elsevier, 2010

9. RAMI analysis – proposal of criticality Criticality rate of the failure severityrate to thepersonnel (based on oxygendeficiency hazard) failureoccurencerate (based on probability data and numer of components) severityrate to themachine (based on thelocation of defected element) Reference: Chorowski M., Fydrych J., Grabowski M., Risk analysis of the ITER cryodistribution system, Technical Report WUT-IO_TR_015-1010

10. Failure criticality rate CFR - the cumulative failure rate is described by the product of the quantity of elements that can fail (e.g. number of valves, length of the welds) and the probability of the defect occurrence.

11. RAMI Risk Analysis – a need for reliable failure rate data allowing OCC estimation Exemplary RAMI output for LHC cryogenic system

12. RAMI Risk Analysis – we can reduce SEVERITY by imposing procedures

13. RAMI Risk Analysis – we can reduce SEVERITY by imposing procedures Personnel access restrictions

14. Failure rates proposed in 1991 Probabilities of defect occurrence (failure rates) of the most common defects: Would lead to overconservative conclusions concernin mean time between failures T. Peterson, Helium and nitrogen ODH analysis for ICB Engineering Laboratory, Fermilab, 1991

15. Failure rates of the welds, according to [1] [1] Cadwallader L.C., Cryogenic System Operating Review for Fusion Application, Idaho National Engineering Laboratory, USA, 1992

16. CASE study – LHC welds reliability Weld rupture corresponding to the release of 100% of pipe flow can be expected 1 time per 275 years.

17. Pipes - potential sources of failure rate data Nuclear industry Chemical industry LNG industry Recommended Not recommended Recommended

18. Failure rates for process pipes

19. Failure rates for process pipes

20. Updated probabilities of defect occurrence (failure rates) of the most common defects • Cadwallader L.C., Cryogenic System Operating Review for Fusion Application, Idaho National Engineering Laboratory, USA, 1992 • Failure Frequency Guidance, Process Equipment Leak Frequency Data for Use in QRA, http://www.dnv.com/services/software/products/phast_safeti/safeti/leak_frequency_guidance.asp • Cadwallader L. Vacuum Bellows, Vacuum Piping, Cryogenic Break and Copper Joint Failure Rate Estimates for ITER Design Use, Idaho National Laboratory, USA, 2010 • Chorowski M., Fydrych J., Grabowski M., Risk analysis of the ITER cryodistribution system, Technical Report WUT-IO_TR_015-1010 • Peterson T., Helium and nitrogen ODH analysis for ICB Engineering Laboratory, Fermilab, 1991

21. Summary • Large helium cryogenic systems are characterized by big numer of welds (~ 105 in case of LHC) and long mean time between failures. • Categorization of potential cryogenic system failuers with respect to their criticality requires reliable failure rate probability data. • The data can be gathered on „learning from the past” basis, but there is a lack of the „past”. • The data can be trnsferred from other domains especially LNG industry. • It is recommended to create a global data base covering the failures of big helium cryogenic systems in Europe, USA and Asia.