High pressures of the energy release are assumed to give rise to shock damage to the vessel in the radial and bottom head directions. The only experimental information comes from modeling and the use of scaled chem­ical explosive tests using TNT and pentolite. The models used included some welded, nozzled, and noncylindrical vessels to give some realism to the yield calculations (22). Some additional information may be gained from the SL-1 accident and the consequent residual strain which was measured in the vessel and core debris (25). The information is relevant, despite the fact that the SL-1 was a thermal light-water-cooled system.

Figure 5.8 shows a comparison to be expected from nuclear and chemical explosive results. The chemical explosion is faster and has a higher initial shock but a lower residual pressure than the nuclear explosion with the same integrated energy value.

Thus it is pessimistic to use the chemical explosion correlations produced for the initial radial shock deformation of the vessel. The residual pressures resulting from the explosion should be handled differently, and Section

5.5.2.2 indicates a method of reverting to a use of the total energy release for a hydrodynamic description of the excursion.