Xenon Transient Behavior

The present study represents an attempt to study the problem of control rod calibration during a xenon transient from a purely analytic point of view and then correlate theory with experiment to obtain the desired results in the best possible approximations. Particulars of the problem are described as follows. Suppose that a thermal reactor, fueled homogeneously with uranium-235, is maintained at criticality during the rising phase of a xenon transient by the continuous motion of a control rod. Then a control rod (or set of control rods) is suddenly pulled at = o- The approximate subsequent behavior of the flux has already been described. It is desired to find the reactivity thus introduced by pulling the rod x inches. 

To illustrate the concept of the target manifold, in this example a target curve, it is convenient to picture the behavior in the xenon-iodine phase plane (Fig. 1). For specified fluxes, trajectories in the phase plane trace the state of the system from given initial conditions. In particular, if the flux is put to zero at the end of the control period, a series of shutdown curves can be traced, covering different terminal points, to represent the xenon transient or shutdown peaking. Each such curve in Fig. 1 has a... 

Thermal power was to be reduced in stages from 3200 MW to 700 MW (MW). Operator error caused the power to undershoot to 30 MW, and the consequent increase in xenon poisoning meant that the operators could only manage to raise the power back to 200 MW. This power level was lower than stipulated in the test instructions. The operators should have abandoned the test at this point. ( Xenon poisoning is a transient behavior of nuclear reactors during power reductions. Xenon-135 is a fission product that absorbs neutrons, and which decays with a half-life of about 9 h. When power is reduced, xenon-135 levels increase, which makes it difficult to increase power until the xenon-135 has decayed.)... 

Describe xenon and samarium transient behavior for the following power histories (1) startup to steady state power ( ) shutdown from steady state (3) startup near peak shutdown concentration (4) decrease in power after prolonged operation at steady state and (5) Increase in power after prolonged operation at steady state,... 

---