Critical Phenomena Experimental Situation

In general, in the modern theory of phase transitions, the energy of deformation of the director has to be taken into account, and 

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This situation of a non-perpendicular crack producing a weaker specimen has occurred in other studies. Indeed, Palaniswamy and Knauss (Ref. 14), in a tour de force, examined the angled crack phenomenon analytically and numerically. Their results approximated very closely to an equation of the form of (19). Moreover, in a plot (Figure 10) of normalized critical stress versus orientation, the "dip" situation occurred, i.e., rotating the crack from normal would then produce a weakened specimen. Palaniswamy and Knauss (Ref. 14) also obtained experimental data from polyurethane specimens. It is hard to ascertain froni a plot of the data (Figure 18) if... 

While the criticisms outlined above imply that the Rasmussen analysis underestimates the hazards of nuclear power plant accidents, there is also evidence which suggests that in some respects the opposite may be true. In particular, recent research indicates that the volatility of iodine may have been greatly overestimated in situations where substantial amounts of water are present. In LWR fuel, the iodine is largely in the form of cesium iodide, which dissolves readily in any water present, leaving only a small concentration in the gas phase. It is this phenomenon that is thought to account for the unexpectedly low release of radio-iodine in the Three Mile Island accident, which is described in Section 12.3.2. Another area in which the analysis may be overconservative is in dealing with the possibility of pressure vessel or containment failure from a steam explosion recent experimental work suggests that the probability of failure is considerably less than was assumed in the Rasmussen model. 

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