Experimental verification of the piping code ICEPEL has led to a modification of the elbow hydrodynamic model so that agreement in predicting uniform pressure across the elbow cross section is obtained. A rupture disk model is incorporated and used in modeling the MARK-IICB loop of the TREAT reactor to assess its structural adequacy during a postulated accident that results from fuel-sodium interaction. The analysis showed the loop remained elastic. A nonreflecting boundary is incorporated and can be used in elastically deforming regions of piping systems to allow for refined modeling of portions of interest without having to model the whole system.