Reactor aluminium

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. 

GUIDELINES FOR CORROSION PROTECTION OF RESEARCH REACTOR ALUMINIUM CLAD SPENT NUCLEAR FUEL IN INTERIM WET STORAGE... 

CORROSION OF RESEARCH REACTOR ALUMINIUM CLAD SPENT FUEL IN WATER AT VARIOUS SITES IN ARGENTINA... 

Aluminium and its alloys have low thermal neutron capture cross-sections, and good tensile strength and thermal conductivity. They are commonly used as fuel cladding and as construction materials in water cooled research reactors. Aluminium owes its excellent corrosion resistance in most environments to the protective barrier oxide film that forms and strongly bonds to its surface. This oxide film is relatively inert and tends to resist further oxidation. During wet storage of aluminium clad spent fuels, a number of corrosion mechanisms... 

The corrosion of aluminium alloy coupons in the light water fuel storage basin of the IR-8 reactor has been studied at the Russian Research Centre Kurchatov Institute [12.1]. This investigation was part of the IAEA CRP on Corrosion of Research Reactor Aluminium Clad Spent Fuel in Water. The main objective of this project was to determine the environmental conditions that accelerate the corrosion of aluminium alloys in spent fuel storage conditions, and to control the corrosion. 

On the basis of these results, the following activities can be recommended for the next stage of the IAEA programme on the corrosion of research reactor aluminium clad spent fuel in water ... 

Corrosion of Research Reactor Aluminium Clad Spent Fuel in Water... 

Corrosion of research reactor aluminium clad spent fuel in water. — Vienna International Atomic Energy Agency, 2003. 

This report documents the work performed in the IAEA Co-ordinated Research Project (CRP) on Corrosion of Research Reactor Aluminium Clad Spent Fuel in Water. The project consisted of the exposure of standard racks of corrosion coupons in the spent fuel pools of the participating research reactor laboratories and the evaluation of the coupons after predetermined exposure times, along with periodic monitoring of the storage water. The project was overseen by a supervisory group consisting of experts in the field, who also contributed a state of the art review that is included in this report. 

This report describes all of the work undertaken as part of the CRP and includes a review of the state of the art understanding of corrosion of research reactor aluminium alloy cladding materials a description of the standard corrosion racks, experimental protocols, test procedures and water quality monitoring the specific contributions by each of nine participating laboratories a compilation of all experimental results obtained and the supervisory group s analysis and discussion of the results, along with conclusions and recommendations. 

Cladding. The Magnox reactors get their name from the magnesium-aluminium alloy used to clad the fuel elements, and stainless steels are used in other gas-cooled reactors. In water reactors zirconium alloys are the favoured cladding materials. 

A similar catalytic dimerization system has been investigated [40] in a continuous flow loop reactor in order to study the stability of the ionic liquid solution. The catalyst used is the organometallic nickel(II) complex (Hcod)Ni(hfacac) (Hcod = cyclooct-4-ene-l-yl and hfacac = l,l,l,5,5,5-hexafluoro-2,4-pentanedionato-0,0 ), and the ionic liquid is an acidic chloroaluminate based on the acidic mixture of 1-butyl-4-methylpyridinium chloride and aluminium chloride. No alkylaluminium is added, but an organic Lewis base is added to buffer the acidity of the medium. The ionic catalyst solution is introduced into the reactor loop at the beginning of the reaction and the loop is filled with the reactants (total volume 160 mL). The feed enters continuously into the loop and the products are continuously separated in a settler. The overall activity is 18,000 (TON). The selectivity to dimers is in the 98 % range and the selectivity to linear octenes is 52 %. 

Chloroaluminate laboratory preparations proved to be easily extrapolated to large scale. These chloroaluminate salts are corrosive liquids in the presence of protons. When exposed to moisture, they produce hydrochloric acid, similarly to aluminium chloride. However, this can be avoided by the addition of some proton scavenger such as alkylaluminium derivatives. In Difasol technology, for example, carbon-steel reactors can be used with no corrosion problem. 

Videm, K., Pitting Corrosion of Aluminium in Contact with Stainless Steel , Proc. Conf. on Corrosion Reactor Mater., Salzburg, Austria, 1, 391 (1962) C.A., 60, 1412g Lyon, D. H., Salva, S. J. and Shaw, B. C., Etch Pits in Germanium Detection and Effects , J. Electrochem. Soc., 110, 184c (1963)... 

The question of the compatibility of metals and alloys with carbon and carbonaceous gases has assumed considerable importance in connection with the development of the gas-cooled nuclear reactor in which graphite is used as a moderator and a constituent of the fuel element, and carbon dioxide as the coolant. Tests of up to 1 000 h on a series of metals and nickel-containing alloys under pressure contact with graphite at 1 010°C" showed that only copper was more resistant than nickel to diffusion of carbon and that the high-nickel alloys were superior to those of lower nickel content. The more complex nickel-chromium alloys containing titanium, niobium and aluminium were better than the basic nickel-chromium materials. 

Daumengrofes Labor aus Aluminium-Folie, Blick durch die Wirtschafi, June 1997 Heterogeneous gas-phase micro reactor micro-fabrication of this device anodic oxidation of aluminum to porous catalyst support vision of complete small laboratory numbering-up development of new silicon device [225]. 

In the vapor phase experiments, the photograftings are carried out in specially designed photoreactor constructed and built in our laboratory (Figure 1). The reactor is equipped with a 1 kW high pressure mercury UV lamp (HPM-15 from Philips) which can be moved to vary the distance to the substrate. The grafting takes place in an atmosphere of nitrogen in a thermostated chamber closed with a clear quartz window. Sensitizer and monomer evaporates from a solution of a volatile solvent in an open bucket which is shielded from the UV-irradiation with aluminium foil. 

Erroneous use of aluminium instead of alumina pellets in a hydrogen chloride purification reactor caused a vigorous exothermic reaction which distorted the steel reactor shell. 

Dining outgassing of scrap uranium-aluminium cermet reactor cores, powerful exotherms led to melting of 9 cores. It was found that the incident was initiated by reactions at 350°C between aluminium powder and sodium diuranate, which released enough heat to initiate subsequent exothermic reduction of ammonium uranyl hexafluoride, sodium nitrate, uranium oxide and vanadium trioxide by aluminium, leading to core melting. 

Bromochloromethane was being prepared in a 400 1 reactor by addition of liquid bromine to dichloromethane in presence of aluminium powder (which would form some aluminium bromide to catalyse the halogen exchange reaction). The reaction was started and run for 1.5 h, stopped for 8 h, then restarted with addition of bromine at double the usual rate for 2.5 h, though the reaction did not appear to be proceeding. Soon afterwards a thermal runaway occurred, shattering the glass components of the reactor. 

The chloride is usually (but not always) stabilised in storage by addition of aqueous alkali or anhydrous amines as acid acceptors. A 270 kg batch which was not stabilised polymerised violently when charged into a reactor. Contact of the chloride (slightly hydrolysed and acidic) with rust led to formation of ferric chloride which catalysed an intermolecular Friedel-Craft reaction to form polybenzyls with evolution of further hydrogen chloride. Contact of unstabilised benzyl chloride with aluminium, iron or rust should be avoided to obviate the risk of polycondensation. See Benzyl bromide Molecular sieve... 

---