Experimental tests and validation of calculation criteria of acceptable Tk shift with respect to PTS at VVER

The following topics were examined: (i) Methodology of fracture tests at temperature gradients and pressurized thermal shock (PTS) cooling tests on large specimens (1500x1200x140 mm) with a designed postulated crack and other smaller cracks in the cooled area (test performed on a ZZ 8000 (80MN) loading stand); (ii) simulation of radiation embrittlement of tested material near the end of the RPV designed life, the material is subjected to standard mechanical property tests and fracture tests of standard test specimens modelling the PTS regime of material loading; (iii) 100% NDT tests of a specimen before the beginning of tests and μTOFD before and after each particular test of a specimen; (iv) on-line monitoring of the test conditions based on instrumentation of a specimen with thermocouples, COD and strain gauges together with on-line monitoring of Acoustic Emission during the tests; (v) calculation of Kl at the critical points of the crack front during the test, based on monitored boundary conditions; (vi) fractographic analysis after the fracture of a specimen and evaluation of the whole test. (P.A.)