Lumped thermal capacitance analysis of transient heat conduction and induced stresses in Ghana research reactor vessel

Abstract

Lumped thermal capacitance analysis has been undertaken to investigate the transient temperature variations, associated induced thermal stress distributions, and the structural integrity of Ghana Research Reactor-1 (GHAR R-1) vessel after 15 years of operation. The beltline configuration of the cylindrical vessel of the Miniature Neu-tron Source Reactor (MNSR) was based on thin-shell and axi-symmetric assumptions with small  temperature gradient and low Biot number. The thermal energy transferred by unsteady flow of the coolant to the vessel was determined as internal energy change. Numerical algorithms for Matlab Code were implemented to generate data for transient analysis and simulation. The simulations indicated that the temperature variations and the the-rmal stresses were below the limits imposed by the vessel material (Aluminium alloy LT 21) specifications of 933 K melting point and allowable yield stress of 480 MPa. The low level of induced thermal stresses indicated that the structural integrity of the reactor vessel has been maintained to forestall any incidence of crack propaga-tion and fatigue failure over the operation period.