Evaluation of the HSST program intermediate pressure vessel tests in terms of light-water-reactor pressure vessel safety

Eight 6-in.-thick 39-in.-OD steel pressure vessels containing carefully prepared and sharpened surface cracks have been tested to provide an improved quantitative basis for evaluating the safety margins against fracture of nuclear reactor pressure vessels. The cylindrical regions of the test vessels were fabricated from either A508 class 2 forging steel or A533, grade B, class 1 steel plate. All the eight vessels tested were loaded to failure by internal hydraulic pressure. Flaws in the test vessels ranged from 1.20 to 5.30 in. in depth, and test temperatures ranged from 32 to 1960F. Extensive fast fracture was observed, as expected, at 320F at a pressure near the gross yield pressure of the test vessel, and two vessels leaked without fracturing at or slightly above 1900F. One of these vessels contained a flawed nozzle, and the other contained a very deep external surface flaw. Another vessel containing a smaller external surface flaw achieved 2 percent strain in the plastic range at 1900F before developing a shear fracture that arrested before reaching the ends of the vessel. Extensive pre- and posttest fracture analyses have been performed for all the intermediate vessels tested. 11 references