Improvement of the NSRR simulator

Prior to actual runs in the shaped pulse and combined pulse operations in the NSRR, the online simulation and offline simulation must be performed to examine safety and validity in terms of fuel temperature, integral reactor power, maximum power, rod position and rod speed. Actual reactor power of the NSRR can be well simulated in most cases, but a slight difference remains between the present simulation results and actual operation during the NSRR start-up phase under open loop control and power controlled operation under closed loop control. Regulating rod worth and fuel temperature feedback reactivity were re-evaluated and updated. As a result, the accuracy of the simulator was remarkably improved with respect to the transients of the reactor power during the start-up phase and control rod position under the closed-loop control, so that flexibility of the shaped and combined pulse operations were improved. (author)