Integrated Approach for the Modelling of Safety Grade Decay Heat Removal System for Liquid Metal Reactors (DHR)
Decay heat removal (DHR) after the reactor shutdown of a fast reactor is one of the most important safety functions which must be accomplished with a very high reliability. For a typical pool or loop type Na-cooled fast reactor, one of the safety grade decay heat removal system (SGDHRS) designs is based on the heat rejected to the atmospheric air as an ultimate heat sink from the reactor pool system via an intermediate loop having sodium or NaK as the coolant. This system can be designed on the principle of natural convection in main Na circuit, intermediate coolant circuit and on air side for enhanced reliability. This INPRO Collaborative Project provides a forum for inter-comparison of results for a benchmark exercise for SGDHRS of a typical Na-cooled fast reactor.
Inter-coupled features of SGDHRS considered
Inter-comparison of results of a candidate robust SGDHRS of liquid metal reactors (LMR).
PURPOSE OF THE CP (SPECIFIC OBJECTIVES)
- To arrive at an international benchmark for SGDHR system applicable for pool type LMR.
- To develop matured analysis methodologies for pool hydraulics, heat transfer in liquid metal heat exchangers and air heat exchangers (AHX): Identify / establish analysis methodology for pool hydraulics including inter-wrapper flow (IWF), thermal hydraulics of intermediate circuit and heat transfer process in AHX.
- To determine the performance of NaK versus Na in the intermediate circuit.
- Inter-comparison of results generated by the partners using the codes available with them.
- To identify relevant R&D areas related to natural convective heat transfer.
For the benchmark studies, the following parameters will be suitably defined:
- Events for which SGDHR operation will be analysed (for example, offsite power failure).
- Initiation logics of SGDHR system (e.g. time at which SGDHR dampers are opened and degree of opening of dampers with respect to time)
- Initial conditions (e.g. flow rates and temperatures of primary Na, secondary Na, intermediate Na and AHX air flow)
- Boundary conditions (e.g., number of SGDHRs put in operation)
- Pump coast down characteristics (primary flow reduction as a function of time)
IGCAR/India (lead), CIAE/China, KAERI/Republic of Korea, IPPE/Russian Federation, JRC/European Commission and IAEA (Secretariat).