A digital controller controls discharges of a utility from a reservoir to a plant during a first time period and recharges of said utility from the plant back to the reservoir during a second time period. The reservoir can be any storage device. When the utility is electric power, the discharges make up for the power not generated by the plant due to an accident. The digital controller may use a balanced nonlinear transfer function to control the recharges based on the discharges. If there is a long duration discharge that extends beyond the end of the first time period, the digital controller may use a Monte Carlo simulation along with a tail distribution for the long duration discharge and the balanced transfer function to forecast the recharge required during the second time period.