Abhishek Chakraborty
Nuclear Power Corporation of India Limited, Mumbai, Maharashtra, India
Suneet Singh
Dept. of Energy Science and Engineering,
Indian Institute of Technology Bombay,
Powai, Mumbai 400076, India
M.P.S. Fernando
Nuclear Power Corporation of India Limited, Mumbai, Maharashtra, India
Xenon Oscillations are one of the main sources of instabilities
in nuclear reactors operating in the thermal spectrum. Due to
economics of power generation, the power rating and the size
of the reactors are increased making them unstable towards
xenon oscillations. Conventionally, the study of xenon
oscillations is performed by solution of neutron diffusion
equation coupled with iodine concentration, xenon
concentration and thermal hydraulics equations for different
perturbations and core conditions, which is a very tedious
process. In this paper, an approach for carrying out linear
stability analysis of out of phase xenon oscillations using
multipoint kinetics coupled with thermal hydraulic and xenon
feedbacks is given. A large Pressurized Heavy Water reactor
in is considered for the analysis. The reactor core is divided
into two regions for the analysis to present a "proof of
principle" for this approach. However, extension of this model
for more regions, for better accuracy, though not trivial is
quite straight forward. The nature of these oscillations
depends on the operating power level and the magnitudes of
the different reactivity coefficients. Hence, the operating
power fraction (f), fuel temperature coefficient of reactivity
(αf) and coolant temperature coefficient of reactivity (αc) are considered as the parameters for the analysis. Eigenvalue approach has been adopted to evaluate the linear stability boundary. Numerical simulations are carried out in order to verify the stability boundary.