| Popis: |
The thermal conductivity of UO 2 and mixed oxide light water reactor (MOX LWR) fuels decreases as a result of reactor burnup. In this chapter, the phenomena causing this degradation are presented, and the effect of the most influential parameters is discussed. Information useful for the interpretation and comparison of in-pile or out-of-pile measurements is given, especially as a function of burnup and for samples having different irradiation temperatures, in-pile histories, and microstructures. The impact of the introduction of plutonium or additives (Gd, Cr) in standard UO 2 is also addressed. The evolution of the thermal conductivity as a function of burnup is nonlinear, and the numerous approaches and approximations that are used to obtain thermal conductivity correlations are summarized and compared. |
