During the events of a reactor scram, the control room operators play a vital role in the diagnosis of the causes and control of the plant. It is critically important that the operators immediately detect an abnormal scram situation related to the plant protection system and take necessary actions to shut down the nuclear reaction safely. The present study develops a proof-of-principle prototype of a postscram analyzer. It is an operator aid information system designed to assist the operators in the recognition of possible abnormal scram situations immediately after a scram and to facilitate postscram analysis for diagnosis of root causes and for speedy plant restart. The resultant displays for man-machine interface demonstrate that a postscram analyzer can provide vital and concise information in the control room to enhance the productivity of the plant operators.