[en] The perturbation technique described in this supplement to the Westinghouse ECCS Evaluation Model is a method which uses overall sensitivities which are known to be conservative based upon the results of analyses presented to the NRC in connection with the review and approval of the current Westinghouse Evaluation Model and in connection with approval of ECCS designs since the adoption of 10 CFR 50.46 and 10 CFR 50 Appendix K. The use of these sensitivities permits the calculation of the limiting peak clad temperature (PCT) and the limiting total peaking factor (F/sub q//sup T/) by calculating the change in these factors relative to certain key parameters and adding these changes to the results of the ECCS cooling performance calculated with the current approved Westinghouse Evaluation Model