Complex sentence: An operational improvement would result from increased fuel burnup; it provides fuel cost reduction because less uranium and fewer bundles are needed to fuel the reactor which in turn reduces the quantity of spent fuel and its subsequent management costs.
Split into simpler sentences: An operational improvement would result from increased fuel burnup; it provides fuel cost reduction because less uranium and fewer bundles are needed to fuel the reactor. This in turn reduces the quantity of used fuel and its subsequent management costs.