Solubility of simulated PWR primary circuit corrosion products

Technical Report · Fri Aug 01 04:00:00 EDT 1986

OSTI ID:5411485

Kunig, R H; Sandler, Y L

The solubility behavior of non-stoichiometric nickel ferrites, nickel-cobalt ferrites, and magnetite, as model substances for the corrosion products (''crud'') formed in nuclear pressurized water reactors, was studied in a flow system in aqueous solutions of lithium hydroxide, boric acid, and hydrogen with pH, temperature, and hydrogen concentrations as parameters. Below the temperature region of 300 to 330/sup 0/C, at hydrogen concentrations of 25 to 40 cm/sup 3//kg H/sub 2/O as used during reactor operation, the solubility of nickel-cobalt ferrite is the same as that of Ni and Co/sub x/Fe/sub 3-x/O/sub 4/ (x << 1) which are formed at the surface by dissociation in hydrogen. In experiments related to reactor shutdown, with 0.2 M boric acid and 3 cm/sup 3//kg of hydrogen, the equilibrium iron and nickel solubilities increase congruently down to about 100/sup 0/C, in a manner consistent with the solubility of Fe/sub 3/O/sub 4/, but sharply decline at lower temperatures, apparently due to formation of a borated layer. A cooldown experiment on a time scale of a typical Westinghouse reactor shutdown, as well as static experiments carried out on various ferrite samples at 60/sup 0/C show that after addition of oxygen or peroxide evolution of nickel (and possibly cobalt) above the equilibrium solubility in hydrogen depends on the presence of dissociation products prior to oxidation. Thermodynamic calculations of various reduction and oxidative decomposition reactions for stoichiometric and non-stoichiometric nickel ferrite and cobalt ferrite are presented. Their significance to evolutions of nickel and cobalt on reactor shutdown is discussed. 30 refs., 38 figs., 34 tabs.

• Research Organization: Westinghouse Electric Corp., Pittsburgh, PA (USA). Research and Development Center
• OSTI ID: 5411485
• Report Number(s): EPRI-NP-4248; ON: TI86920444
• Country of Publication: United States
• Language: English

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21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
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36 MATERIALS SCIENCE
360105 -- Metals &amp; Alloys-- Corrosion &amp; Erosion
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
COBALT
COOLING SYSTEMS
CORROSION
CORROSION PRODUCTS
ELEMENTS
ENERGY SYSTEMS
ENERGY TRANSFER
FERRIMAGNETIC MATERIALS
FERRITES
FLUID MECHANICS
HEAT TRANSFER
HYDRAULICS
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IRON
IRON COMPOUNDS
IRON ORES
IRON OXIDES
MAGNETIC MATERIALS
MAGNETITE
MATERIALS
MECHANICS
METALS
MINERALS
NICKEL
NONMETALS
ORES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PRIMARY COOLANT CIRCUITS
PWR TYPE REACTORS
RADIOACTIVITY
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REACTOR COOLING SYSTEMS
REACTORS
SIMULATION
SOLUBILITY
TRANSITION ELEMENT COMPOUNDS
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