Modeling local history effects in the nodal code ARTEMIS^TM

The insertion of devices like control rods and detectors during reactor operation induces a non-standard depletion of the surrounding fuel pins. During the insertion period the pins experience a reduced pin power density and, therefore, a reduced fuel burnup and an off-nominal actinide and fission product buildup. The major consequence of this special depletion is that when the device is withdrawn the power peak could be higher than the result of the standard de-homogenization model. Modeling this phenomenon demands to take into account the history of the presence of the device. This paper describes the methodology implemented in ARTEMIS^TM to evaluate the effect of these devices on the pin-wise power distribution. (authors)