[en] In order to evaluate the consequences of potential failure of reactor pressure vessel (RPV) supports in pressurized water reactor nuclear power plants due to effects of irradiation embrittlement, the Nuclear Regulatory Commission has selected the Trojan nuclear power plant for a pilot study. The evaluation starts with the structural integrity assessment of the reactor coolant loop (RCL) system to determine whether the RCL piping is capable of transferring (or redistributing) RPV support loads to other component supports in the RCL system. Because of its close resemblance to the Trojan RCL design and because there is a readily available computer model for it, the RCL system of Unit 1 of Zion nuclear power plant has been analyzed to demonstrate the methodology as well as to obtain preliminary results regarding the structural evaluation. 13 refs., 12 figs., 8 tabs