Non destructive examinations, fracture toughness measurements and burst tests on a pressure vessel

A pressure vessel, welded of Welmonil 43 (11 NiMoV 53) plate, mainly of 36 mm thickness, was withdrawn from service after several years in a big PWR plant. Non destructive examinations, MT and UT results according to different standards are presented. Shell plate and weldment were destructively tested in the following. impact and fracture mechanics testing included. The vessel was closed a gain and longitudinal crack-like defects were applied on the inner vessel surface. Stresses were calculated and verified under internal pressure. Experimental stress analysis especially of the nozzle areas was conducted using strain gauges. Based on stresses, fracture mechanics characteristics and on defect sizes. burst pressures were calculated. Two Leak-Before - Break tests and one Break test resulted by pressurizing between 14 and 19 deg. C. Calculated and effective burst-pressures were in good agreement. The Battelle formalism did also fit well. Defect depth, however, was underestimated by UT. (authors)