(a)When the reactor power is increa

(a)When the reactor power is increased, Xenon concentration initially decreases. The burn up is increased at the new higher power level, 95% of the Xenon production is from Iodine-135 decay, which has a 6 to 7 hour half-life, the production of Xenon remains constant for several hours. After a few hours (roughly 4 to 6 hours depending on power levels) the rate of production of Xenon from Iodine and fission equals the rate of removal of Xenon by burnup and decay. At this point, the Xenon concentration reaches a minimum. The Xenon concentration then increases to the new equilibrium level for the new power level in roughly 40 to 50 hours. The Xenon concentration change is greater for a larger change in power level.When reactor power is decreased, the process is reversed: There is an immediate decrease in Xenon burnup, which results in an increase in Xenon-135 concentration. The Iodine-135 concentration is still at the higher equilibrium level and is therefore still producing Xenon-135 at the higher rate. The Xenon-135 concentration continues to rise until the rate of production of Xenon-135 becomes equal to the rate of removal (roughly 7 to 8 hours). The Xenon-135 concentration then gradually decreases to the new lower equilibrium level. The magnitude of the Xenon peak is greatest if the initial power level is very hig