A demonstration of reduced temperature return-to-power was performed at the 920-gross-MW(electric) Tihange nuclear station in Belgium. A rapid power escalation of 320-MW(electric) in gross output was achieved using control rod withdrawal and moderator temperature reduction. Of that total, 230 MW(electric) was achieved on a core reactivity increase provided by a 9 K (16°F) drop in moderator temperature. Digital computer calculations and analog simulations accurately predicted both core and systems response.