Intermediate size pressure vessel programme (ZB 1)

One of the focal points in the discussion about the safety of nuclear power plants is the integrity of the reactor pressure vessel. In order to prove its integrity tests are in progress in an underground test facility of the main power station in Mannheim with an intermediate size vessel from the research programme “Integrity of Components”. Patches of A 533 B and modified A 508 B material were welded into the vessel ZB 1, the test temperatures are approximately 70 and 290°C. The main goal of the tests is to measure the behaviour of artificial and natural flaws during static hydrotests and simulated operational (cyclic) conditions. In the first half of the research programme the objective is to produce a crack growth of some centimetres by cyclic loading between a variable minimum pressure and a maximum pressure of about 24 MPa. The total number of load cycles will be approximately 30 000. In the second half of the tests the vessel will be loaded by a number of pressure cycles which correspond to the loading a reactor pressure vessel experiences during 40 years of operation. During the static and cyclic loading acoustic emission monitoring is being made by German and American laboratories. This paper presents details of the vessel, the test loop, results of the nondestructive examinations conducted to quantify the crack depths and results of the acoustic emission monitoring.