PSI - Issue 60

Keshav Mohta et al. / Procedia Structural Integrity 60 (2024) 36–43 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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6. Conclusion The structural integrity assessment of Calandria assembly of PHWRs under postulated severe accident conditions has been carried out using the analysis method described in the paper. The used method is based on the sequentially coupled thermo-mechanical analysis, and accounts for the different requirements for thermal and structural assessment. The analysis has brought out the advantages of the inherent design features of PHWRs such as several heat sinks and low power density. It has shown that the in-Calandria retention of core debris provides a reasonably extended time frame (~ couple of days for Standard 220 and 540 MWe Indian PHWRs) for taking the accident management actions. In absence of any management action, Calandria would undergo plasticity and creep induced failure. Acknowledgement The authors are thankful to Department of Atomic Energy Steering Committee to Coordinate Safety Research, Atomic Energy Regulatory Board, India and Nuclear Power Corporation of India Limited for their support towards International Atomic Energy Agency, 2008. Analysis of Severe Accidents in Pressurized Heavy Water Reactors. IAEA-TECDOC-1594, Vienna. International Atomic Energy Agency, 2009. Severe accident management programmes for nuclear power plants. Safety Guide No. NS-G-2.15, Vienna. Koundy V., Hoang N. H., 2008, Modelling of PWR lower head failure under severe accident loading using improved shells of revolution theory, Nuclear Engineering and Design 238, 2400–2410. Kulkarni, P.P., Prasad, S.V., Nayak, A.K., Vijayan, V.K., 2013, Thermal and structural analysis of Calandria vessel of a PHWR during a severe accident, Nuclear Engineering and Technology, 45 (4), 469–476. Mao J., Hua L., Bao S., Luo L., Gao Z., 2017, Investigation on the RPV structural behaviors caused by various cooling water levels under severe accident, Engineering Failure Analysis 79, 274–284. Mohta K., Gokhale O. S., Gupta S. K. Gupta, Mukhopadhyay D., Chattopadhyay J., 2020, Structural integrity assessment of Calandria of 540 MWe PHWR for in-vessel corium retention, Nuclear Engineering and Design 367, 110791 Mohta K., Gokhale O. S., Gupta S. K. Gupta, Mukhopadhyay D., 2017, Structural Integrity Assessment of Calandria of Standard 220 MWe PHWR for In-Vessel Corium Retention without SAMG Action, BARC External Report (BARC/2017/E/005). Mohta K., Gupta S. K., Soupramanien C., Jaganathan S., Chattopadhyay J., 2020, High temperature deformation behavior of Indian PHWR Calandria material SS 304L, Nuclear Engineering and Design 368, 110801 Prasad, S.V., Nayak, A.K., 2017, Investigation of thermo mechanical behaviour in the scaled PHWR stepped calandria vessel during severe accident, Nuclear Engineering and Design 322, 591–602. Rempe J. L. Chavez S.A. Thinnes G.L., 1993, Light Water Reactor Lower Head Failure Analysis, NUREG/CR-5642, U.S. Nuclear Regulatory Commission. Sehgal B. R., Nuclear Safety in Light Water Reactors Severe Accident Phenomenology, ƒ†‡‹ ”‡••ǡ ͻ͹ͺǦͲǦͳʹǦ͵ͺͺͶͶ͸Ǧ͸Ǥ Singh, B.K., Kumar, R., Singh, R.J., Baburajan, P.K., Rao, R.S., Gaikwad, A.J., 2017, Coupled thermo-structural analysis for in-vessel retention in PHWR using ABAQUS, Nuclear Engineering and Design 323, 407–416. Yoshihito Y., Jinya K., Yoshiyuki N., Yoshiyuki K., Hiroyuki Y. and Yinsheng L., 2017, Development of failure evaluation method for BWR Lower head in severe accident; high temperature creep test and creep damage model, Mechanical Engineering Journal, Vol.4, No.6 the activity. References Chatelard, P., Belon, S., Bosland, L., Carénini, L., Coindreau, O., Cousin, F., Marchetto, C., Nowack, H., Piar, L., Chailan, L., July 2016. Main modelling features of ASTEC V2.1 major version, Annals of Nuclear Energy 93, 83–93.