Collaborative Project Proposal (IND5)

1. Collaborative Project Proposal(IND5) Integrated Approach for the Design of Safety Grade Decay Heat Removal System for Liquid Metal Reactor INDIRA GANDHI CENTRE FOR ATOMIC RESEARCH KALPAKKAM, INDIA

2. -Atmospheric wind conditions -Natural convection stability -Flow reversal -Sodium freezing -Multidimensional thermal hydraulics -Structural integrity -Atmospheric wind conditions -Multidimensional thermal hydraulics -Structural integrity -Hot and Cold pool temperature limits -Pool hydraulics -Decay power evolution -Fuel, Clad & Coolant temperature limits -Interwrapper flow Issues involved in SGDHRS design

3. Air outlet Air inlet AHX Subassemblies Inter-wrapper gap (~3 mm) Hot leg Cold leg DHX Primary inlet Primary outlet Issues involved in SGDHRS design – Contd. Inter-wrapper flow has a potential to absorb significant fraction of decay heat Minimum flow required to avoid flow reversal & stability of the intermediate loop need to established.

4. Objectives • To identify various design options including choice of coolant in the intermediate circuit • To develop matured analysis methodologies for pool hydraulics, heat transfer in liquid metal heat exchangers and air heat exchangers • To arrive at an international benchmark for safety grade decay heat removal system applicable for pool type LMR • To address critical issues involved in the structural integrity of the system • To identify relevant R & D areas

5. Design and Analysis Duration – 2 years Resources India is pursuing development of LMR system as a part of the three stage activity of Indian nuclear power program. LMR systems are to be deployed on a commercial scale in India. Extensive analytical and experimental studies have been planned as a part of this program. Well equipped laboratories, in-house developed computer codes and well trained man power along with state of the art library facility subscribing to most of the reputed International Journals are available. Procedure for Implementation CRP Participants and Observers Other member states (MS) pursuing LMR development and interested in carrying out the entire study or a part of it are invited to join the project Funding Each MS is expected to meet its own expenses including man power deployed for this purpose Nature of Project Proposal

6. Content and Work plan Phase-0 (Pre-project stage) Formulation of scope, schedule and responsibilities for the entire project duration Approval at institutional levels Approval of detailed structure of activities and detailed responsibilities through e-correspondence Monthly exchange of newsletters giving information on status FIRST YEAR

7. FIRST YEAR – Contd. • Phase-1 • Critical review of various design options and arrive at an international benchmark problem for detailed investigations • Identification of various parameters such as coolant in the intermediate circuit, diversity in heat exchanger design, thermal center difference, ambient conditions etc. • Identification /establishment of analysis methodology for hot pool hydraulics including inter-wrapper flow, thermal hydraulics of intermediate circuit and heat transfer process in air heat exchangers • E-correspondence and exchange of initial responses • Review meeting to exchange views and midcourse corrections if any

8. SECOND YEAR • Phase-2 • Inter-comparison of results predicted by various codes available in the participating countries • Further activities by MS at their respective work places • E-correspondence and exchange of results • Review meeting to exchange views and midcourse corrections, if any • Phase-3 • Validation of results based on the availability of bench mark problems in participating countries • Compilation of results • Identification of R&D areas and long term R&D collaborations among countries • Preparation of related documents

9. Expected Outcome and Deliverables • A robust decay heat removal concept for LMR and an international benchmark • Arrival of design basis limits for various components • Establishment of decay heat removal capability of the natural convection system involving sodium and air circuits by an integrated study • Prediction of temperatures of various systems during decay heat removal with primary circuit either under forced flow or under natural convection condition • Demonstration of the development of inter-wrapper flow and its effectiveness in decay heat removal • Suitable design for wind barriers around AHX inlet • Optimization of SGDHRS, its location, number of loops and sizing • Margins to be considered on various parameters such as heat removal capacity, pressure drop coefficients and heat transfer coefficients in the process design

10. Air outlet Primary Sodium Inlet through porous shell Air inlet Buoyancy induced air flow in sodium to air heat exchanger, with optimized deflector (CFD study) Primary Sodium Outlet A – Central Subassembly B – Storage Subassembly Flow and temperature distributions of primary sodium in sodium to sodium heat exchanger (CFD study) Evolution of clad temperature during Safety Grade Decay Heat Removal operation (1-D study) Thermal Hydraulic studies carried towards Decay Heat Removal System