Review Analysis of cold leg LOCA with failed HPSI by means of integrated safety assessment methodology J. Gonzalez-Cadelo ⇑ , C. Queral, J. Montero-Mayorga Universidad Politécnica de Madrid (Technical University of Madrid), C/Alenza 4, 28003 Madrid, Spain article info Article history: Received 9 January 2013 Received in revised form 29 November 2013 Accepted 6 February 2014 Available online 4 March 2014 Keywords: Accident management Emergency operating procedures Integrated safety assessment Probabilistic safety assessment Small-break LOCA TRACE code abstract The integrated safety assessment (ISA) methodology, developed by the Spanish Nuclear Safety Council (CSN), has been applied to a thermal–hydraulic analysis of cold leg LOCA sequences with unavailable High Pressure Injection System in a Westinghouse 3-loop PWR. This analysis has been performed with TRACE 5.0 patch 1 code. ISA methodology allows obtaining the Damage Domain (the region of space of parameters where a safety limit is exceeded) as a function of uncertain parameters (break area) and oper- ator actuation times, and provides to the analyst useful information about the impact of these uncertain parameters in safety concerns. In this work two main issues have been analyzed: the effect of reactor coolant pump trip and the available time for beginning of secondary-side depressurization. The main conclusions are that present Emergency Operating Procedures (EOPs) are adequate for managing this kind of sequences and the ISA methodology is able to take into account time delays and parameter uncertainties. Ó 2014 Elsevier Ltd. All rights reserved. Contents 1. Introduction ......................................................................................................... 145 2. Materials and methods ................................................................................................ 146 2.1. Almaraz Unit I TRACE model ...................................................................................... 146 2.2. General overview and application of ISA methodology ................................................................. 147 2.2.1. Block A ................................................................................................ 147 2.2.2. Block B ................................................................................................ 148 2.2.3. Block C ................................................................................................ 148 2.2.4. Block D ................................................................................................ 148 3. Path analysis with respect to the break size and depressurization delay......................................................... 149 3.1. Damage domain for sequences with RCP trip concurrent with break ...................................................... 150 3.2. Damage domain for sequences without RCP trip ...................................................................... 152 3.3. Damage Domain comparison (RCP ON/OFF) .......................................................................... 155 3.4. Comparison between ISA and PSA available time ...................................................................... 156 4. Analysis with respect to the break area size and RCP trip delay ............................................................... 156 4.1. Damage domain for sequences without secondary side cooling .......................................................... 157 4.2. Damage domain for sequences with secondary side cooling ............................................................. 158 5. Probability density functions of uncertain parameters ....................................................................... 159 5.1. Break size PDF .................................................................................................. 159 5.2. Beginning of secondary side cooling and depressurization PDF ........................................................... 159 5.3. RCP trip PDF ................................................................................................... 162 6. Risk assessment. Integration of damage domains ........................................................................... 164 6.1. Damage Exceedance Probability calculation .......................................................................... 164 http://dx.doi.org/10.1016/j.anucene.2014.02.001 0306-4549/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +34 913367061. E-mail addresses: j.gcadelo@alumnos.upm.es, jgcadelo@gmail.com (J. Gonzalez-Cadelo). Annals of Nuclear Energy 69 (2014) 144–167 Contents lists available at ScienceDirect Annals of Nuclear Energy journal homepage: www.elsevier.com/locate/anucene