Description and Regulations of German RPV Irradiation Surveillance Programs
SourceThe reactor pressure vessel (RPV) irradiation surveillance programs applied in German light water reactors are described herein. These descriptions take into account the boiling water reactors and pressurized water reactors operated in Germany at the beginning of 2011. The reactor generations are introduced regarding dimensions, number of loops, and active core features; this introduction is followed by an overview of the codes and standards of the German Nuclear Safety Standards Commission (KTA). Based on the regulations stipulated in safety standard KTA 3203, which was issued in 2001, the scope and requirements of the standard RPV irradiation surveillance program are described in terms of materials and specimens, design and location of capsules, dosimetry, temperature monitoring, withdrawal scheme, specimen testing methods, and specific issues such as the reconstitution of specimens and alternative dosimetry methods. With respect to long-term operation, additional and modified surveillance programs are considered as well. Finally, the basic evaluation method of surveillance test data according to KTA 3203 and the use of surveillance data for RPV integrity assessment and long-term operation evaluation are explained. Because of the low neutron irradiation or use of well-designed RPV materials, or both, all reactors operated in Germany at the beginning of 2011 have demonstrated favorable irradiation behavior, allowing RPV long-term operation far beyond the 40 years of original design.