Advanced Reusable Mandrel for Ceramic Cladding Fabrication

The use of advanced ceramic materials for light water reactor fuel cladding is being investigated, in part due to increased safety margins over conventional metallic claddings. In light of the Fukushima events, safety concerns have come to the forefront of public scrutiny of commercial nuclear generated power, spurring activity in this arena. While the safety benefits of advanced ceramics are alone attractive, there are other desirable characteristics including the maintenance of strength and neutron (and thus power generation) efficiency which have their own benevolent cascades. A deterrent, however, is the current cost of production of these materials. In the research quantities currently produced, ceramics are an order of magnitude more expensive than standard metallics on a per-length basis. For commercial introduction, economy of scale alone cannot be expected to narrow this cost differential. Decreasing the cost of production and establishing a uniform process that produces material of consistent quality will make advanced ceramics a more cost-competitive technology for fuel cladding. The reusable mandrel proposed in this project is an enabling technology for the fabrication of a full length 14-foot tube ceramic tube, which has to-date not been demonstrated. Demonstrating this mandrel, its potential cost saving, and in-pile performance of material fabricated is an another incremental step addressing large-scale manufacturing challenges increasing the chances that advanced ceramic claddings can be introduced commercially. In Phase I, a number of small reusable mandrels were fabricated with the survivability of these items throughout the process of fabricating silicon carbide, and afterwards, was demonstrated. The capability of re-use of these mandrels was suggested when it was shown that a silicon carbide layer could be successfully removed from an apparently undamaged mandrel. If successful in Phase II, a mandrel technology will be demonstrated with the capability of producing 14-foot lengths of tubing, a major milestone, and enabling technology for the production of advanced ceramic cladding. The technology of this product is not limited to any of the specific designs currently proposed, and is thus applicable for use with any of the expected ceramic fuel clad manufacturers. The current market for cladding is over 150,000 linear feet annually for each light water nuclear reactor, with a fleet of over 300 reactors worldwide. This reusable technology reduces the cost of production, and alone could be worth a minimum of $750,000 in cost reductions to the price of fuel annually for each reactor that adopts ceramics for their safety benefits. Over the entire fleet, this is a considerable savings of over $33 million annually.