Russian WWER Surveillance Specimen Programs

International Review of Nuclear Reactor Pressure Vessel Surveillance Programs

2018

Water-water energetic reactors (WWERs) are, in principle, pressurized water reactors but designed and manufactured from Russian-type materials and operated according to former Soviet/Russian rules, standards, and requirements. Their surveillance specimen programs are designed, manufactured, operated, tested, and evaluated with the same purpose but with some differences given by different codes and approaches used in individual countries. This paper describes standard as well as all supplementary and extended surveillance programs in WWER-440/V-213- and WWER-1000/V-320C-type reactors.

WWER RPV Surveillance Programs

International Review of Nuclear Reactor Pressure Vessel Surveillance Programs

2018

Structural Integrity Lessons Learned in WWER RPV Surveillance Specimen Programs

International Review of Nuclear Reactor Pressure Vessel Surveillance Programs

2018

Surveillance specimen programs in reactor pressure vessels (RPVs) are an important part of monitoring material property changes during reactor operations. Results of testing such specimens in surveillance programs, if properly designed and operated, should be the basis for assessing RPV integrity and lifetime. This paper describes special features of surveillance programs in individual water-water energetic reactors (WWERs)—V-230 and V-213 for WWER-440s and V-320 for WWER-1000s—that lead to changes in normative embrittlement trend curves of base and weld metals in these RPVs. Finally, VERLIFE procedures for evaluating test results of surveillance specimens are described together with their application to RPV integrity assessment with the use of both types of transition temperatures: critical temperature of brittleness, Tk, and reference temperature, T0.

Neutron Dosimetry Overview for WWERs

International Review of Nuclear Reactor Pressure Vessel Surveillance Programs

Marek

2018

Neutron dosimetry is a mandatory part of the monitoring of irradiation conditions within the reactor pressure vessels (RPVs) of all type of reactors, including water-water energetic reactors (WWERs). The main experimental part is connected with the surveillance specimen programs because the determination of neutron fluence in each of the surveillance specimens is required for the evaluation of radiation damage in RPV materials. Ex-vessel (cavity) neutron dosimetry is practically mandatory for all WWERs because it serves as the basis for fitting results from calculations of neutron fluence in the RPV wall. In addition, retrospective neutron dosimetry in WWER RPVs is supported by a high content (approximately 1 wt.%) of niobium in the upper layer of the austenitic cladding on the inner RPV surface. This paper describes the main principles of experimental neutron dosimetry in WWER RPVs and some specific results for different types of their units and different surveillance specimen programs. Some discussion is also held regarding different approaches for neutron fluence determination, i.e., for a differential threshold energy equal to 0.5 MeV in WWER studies.