Multilayer (TiN, TiAlN) ceramic coatings for nuclear fuel cladding

Abstract

In an attempt to develop an accident-tolerant fuel (ATF) that can delay the deleterious consequences of loss-of-coolant-accidents (LOCA), multilayer coatings were deposited onto ZIRLO ® 1 coupon substrates by cathodic arc physical vapor deposition (CA-PVD). Coatings were composed of alternating TiN (top) and Ti 1-x Al x N (2-layer, 4-layer, 8-layer and 16-layer) layers. The minimum TiN top coating thickness and coating architecture were optimized for good corrosion and oxidation resistance. Corrosion tests were performed in static pure water at 360º C and 18.7 MPa for up to 90 days. The optimized coatings had no spallation/delamination and had a maximum of 6 mg/dm² weight gain, which is 6 times smaller than that of a control sample of uncoated ZIRLO ® which showed a weight gain of 40.2 mg/dm². The optimized architecture features a ~1µm TiN top layer to prevent boehmite phase formation during corrosion and a TiN/TiAlN 8-layer architecture which provides the best corrosion performance.

Steam oxidation behavior of Y-bearing cladding tube with aluminizing coating

“…According to the reports of the Fukushima Daiichi nuclear disaster, the oxidation of Zr cladding begins above 900°C and causes accelerated hydrogen generation above 1227°C [7][8][9]. For example, during the loss-of-coolant-accident (LOCA), cladding temperature will be increased up to 1200°C due to the decay heat from fuel accompanied by the evaporation of the cooling water, which results in the rapid steam-oxidation of Zr alloy and further produces significant and dangerous levels of hydrogen [10]. To improve the high-temperature steam oxidation, protective coatings on cladding tubes have been developed recently.…”

Development of Cold Spray Coatings for Accident-Tolerant Fuel Cladding in Light Water Reactors

“…In this regard, a variety of coating materials and coating techniques have been investigated. [2][3][4][5][6] The University of Wisconsin, Madison (UW-Madison), under the auspices of the DOE's ATF program, has been collaborating with Westinghouse Electric Company (WEC) for over 3 years to develop low-temperature cold spray powder coating technology for the deposition of ceramic and metallic coatings on Zr alloy fuel claddings for improved oxidation resistance at elevated temperatures (> 1200°C). Based on initial successes, this concept has been selected for Phase 2 work of the ATF program aimed at in-reactor testing of lead test rods (LTR).…”

Synthesis and characterisation of high-entropy alloy thin films as candidates for coating nuclear fuel cladding alloys

“…As a result, the nuclear community has recently initiated efforts to investigate new accident tolerant fuel (ATF) systems aiming at preventing and mitigating possible deleterious effects in structural nuclear materials under severe conditions [15,16]. One particular approach has been to coat zirconium alloys with hard thin films such as nitrides [17,18] and carbides [11,19]. Such ceramics are well known for their excellent corrosion resistance [20], chemical inertness [21,22] and reduced H pickup [23], however, their applicability is diminished in some cases where low ductility, reduced heat transfer rate and crack resistance are regarded as essential.…”