Aluminium cladding

Loft space between flat celling and pitched roof of aluminium cladding, or low-emisslvlty upper surface on celling... 

Aluminium cast onto steel or cast iron is used to produce integral aluminium/steel drums and bimetallic pistons. Aluminium clad onto other metals by mechanical bonding is used in heat-exchanger systems subject to multiple atmospheres or environments. The clad products are also used for cooking utensils and functional press work. 

In the second paper [118] tin, iron and nickel organometallic compounds were separated using aluminium-clad high temperature columns coated with 0.1 xm films of HT-5. Various column lengths and temperature gradients were used to separate the species. Helium was used as the carrier gas. The same GC-ICP-MS set up was used as in the previous paper with slight modification of the transfer line for the analysis of nickel diethyldithiocar-... 

A common method of maintaining high corrosion resistance of aluminium alloys is to clad the alloy with pure aluminium. Subsequent to cladding, the alloy cannot be heat treated as diffusion of alloying metals into the pure aluminium cladding will again reduce corrosion resistance. 

External insulation of optimum thickness and aluminium cladding. 

Aluminium clad spent nuclear fuel from research and test reactors worldwide is currently being stored in water filled basins while awaiting final disposition. Much of this fuel was provided to the various countries by the United States of America as part of the Atoms for Peace programme in the early 1950s. Other fuel was provided by the former Soviet Union. The spent fuel has been in water at the reactor sites for up to 40 years, in some cases, awaiting shipment back to the USA or to the Russian Federation. 

A large database on corrosion of aluminium clad materials has been generated from the CRP and the SRS corrosion surveillance programme. An evaluation of these data indicates that the most important factors contributing to the corrosion of the aluminium are ... 

With aluminium clad fuel corrosion issues starting to appear in wet spent fuel storage basins around the world, the IAEA formulated a corrosion surveillance programme in late 1994. This scientific investigation was implemented in 1996 as part of an IAEA Co-ordinated Research Project (CRP) on Corrosion of Research Reactor Aluminium Clad Spent Fuel in Water. Scientists from countries worldwide were invited to participate [1.2]. The results of the CRP were presented at a final research co-ordination meeting (RCM) in Bangkok, Thailand, in October 2000 and are documented in Chapters 5-13. 

This report is a summary and overview of the scientific investigations of this CRP as carried out in the nine participating countries. The results of corrosion surveillance activities in the individual fuel storage basins of these countries are discussed in detail. On the basis of the knowledge gained from the overall results of this project, a set of Guidelines for Corrosion Protection of Research Reactor Aluminium Clad Spent Nuclear Fuel in Interim Wet Storage were developed and are presented in Chapter 3. 

Removal of the nodules revealed extensive pitting corrosion that had breached the 0.375 mm aluminium cladding. Pitting corrosion that had penetrated the aluminium cladding to the fuel meat was found on approximately 7% of the total number of assemblies inspected by SRS. 

An IPEN rack containing 1060, 6061 and 6262 alloys, used in fuel assembly manufacture, was also immersed in the basin. After 16 months of exposure, it was observed that some pitting had occurred on the uncoupled coupons, mostly on the top surfaces. The aluminium couples were stained inside the crevices but were not pitted. The stainless steel-aluminium galvanic coupons were much more severely corroded. Additional laboratory tests were conducted to determine whether increased levels of silver in the basin water could have increased the corrosion of the aluminium cladding in the IPEN basin. Results indicated no pitting but an increase in darkness of the surface oxide colour with the increase of silver concentration. 

FIG. 1.3. Nodular corrosion on aluminium clad U-Al alloy fuel. 

Continuation of this CRP concentrating on fuel storage basins that have demonstrated significant corrosion problems will provide additional and much needed insight into this issue. The final results wiU enable storage pool operators to better control those environmental parameters key to long term storage of aluminium clad spent fuel. 

This chapter presents a discussion of the fundamentals of aluminium alloy corrosion applicable to the wet storage of spent nuclear fuel throughout the world. It examines the effects of variables on corrosion in the storage environment and presents the results of corrosion surveillance testing activities at SRS, as well as discussions of corrosion at fuel m storage basins at other production sites of the USDOE. Aspects related to the corrosion of aluminium clad fuel at SRS apply to research and test reactor fuel worldwide. 

There are a number of factors that affect the corrosion of aluminium clad spent nuclear fuels in wet storage. 

In wet storage of aluminium clad spent nuclear fuel, different types of corrosion can occur. A short discussion of the more important types of corrosion as they pertain to the aluminium alloys is provided below. 

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