SYMPOSIA PAPER Published: 01 January 1996

Corrosion Behavior of Duplex and Reference Cladding in NPP Grohnde


The Nuclear Fuel Industry Research (NFIR) Group undertook a lead test assembly (LTA) program in NPP Grohnde PWR in Germany to assess the corrosion performance of duplex and reference (i.e., non-duplex) cladding. Two identical 16 by 16 LTAs, each containing 32 peripheral test rods, completed four reactor cycles, reaching a peak rod burnup of 46 MWd/kgU. The results from poolside examinations performed at the end of each cycle, together with power histories and coolant chemistry, are reported.

Five different cladding materials [three types of duplex (D1-D3) and two types of reference (R1, R2)] were characterized during fabrication. The corrosion performance of the cladding materials was tracked in long-term tests (∼900 days) in high-pressure, high-temperature autoclaves. The relative ranking of corrosion behavior in such tests corresponded well with the inreactor corrosion performance. The extent and distribution of hydriding in duplex and reference specimens during the autoclave testing has been characterized.

The in-reactor corrosion data indicate that the low-tin (1.3% Sn) Zircaloy-4 reference cladding, R2, had an improved corrosion resistance compared to high-tin (1.5% Sn) Zircaloy-4 reference cladding, R1. Two types of duplex cladding, D1 (Zr-2.5% Nb) and D2 (Zr-0.4% Fe-0.5% Sn), showed an even further improvement in corrosion resistance compared to R2 cladding. The third duplex cladding, D3 (Zr-4 + 1.0% Nb), had significantly less corrosion resistance, which was inferior to R1. The in-reactor and out-reactor corrosion performances have been ranked.

Author Information

Besch, OA
PreussenElektra AG, Hannover, Germany
Yagnik, SK
Electric Power Research Institute, Nuclear Power Group, Palo Alto, CA
Woods, KN
Siemens Power Corporation, Richland, WA
Eucken, CM
Teledyne Wah Chang, Albany, OR
Bradley, ER
Sandvik Special Metals Corp., Kennewick, WA
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Developed by Committee: B10
Pages: 805–824
DOI: 10.1520/STP16202S
ISBN-EB: 978-0-8031-5343-1
ISBN-13: 978-0-8031-2406-6