a.r. zolfaghari

In designing the fuel rod, having a reliable prediction of fuel performance is of high importance in order to comply with safety principles. Various computer codes have been provided for this purpose. Each of these codes uses different mechanical models, numerical and analytical methods. Accordingly, the purpose of the present work is to develop Fortran computer software for mechanical and thermal analysis of fuel rods using numerical methods, especially applying the principle of virtual work in mechanical analysis of fuel rods in steady-state conditions. The finite element method is used to solve the equations. The mechanical analysis includes phenomena such as swelling and fuel density and clad creep. Through these phenomena and simultaneous performance of mechanical and thermal analysis, fuel-clad interaction, stress and strain rate in fuel and clad, fuel center temperature, oxide layer thickness, fuel, and clad temperature distribution during operation is obtained by the code. The results of the code are compared with the results of the analytical method which are available in other research works. Finally, for the VVER1000 reactor, mechanical and thermal analysis of the fuel rod was performed over a 1600-day interval. According to the simulation, the fuel-clad interaction occurs after 1250 days.

Providing the human thermal comfort, because of its impact on productivity and health is very important. This can be more challenging under extreme cold conditions and when the human body cannot adapt itself to the environment by using the physiological thermoregulatory mechanisms. Under these conditions, using protective clothing is one of the effective ways to protect the human body against the thermal injuries. In this study, the performance of protective clothing with a Phase Change Material (PCM) layer has been analysed by simultaneous modeling of physical and physiological mechanisms of the human under extreme cold conditions. For this purpose, multi-layer protective clothing with a PCM layer has been considered and its thermal performance has been investigated for two different arrangements of the layers. The results show that the middle layer of protective clothing is the best position for implementing the PCM layer and the best melting temperature for the mentioned PCM is about 10˚C. Also, using the PCMs in protective clothing can increase the thermal tolerating time from 4000 seconds up to 6000 seconds under extreme cold conditions.