Water Chemistry and the Deposition of Corrosion Products on Nuclear Reactor Fuel. A Summary of Experimental Results

摘要

Corrosion product deposits on nuclear reactor fuel sheaths become slightly radioactive. When released and redeposited out-of-core, they cause radiation fields to grow on pipes, valves, pumps and steam generators in the primary coolant circuit. A series of six-week tests were done in which uranium dioxide fuel with 0, 0.7 and 2.4 wt% U-235 inside zirconium-alloy sheathing was irradiated at CANDU operating conditions in the X-3 loop of the NRX reactor. The tests showed that water pH is the major variable which determines the deposit weight of corrosion products on fuel sheaths, while the remaining variables are of secondary importance: pH additive, dissolved hydrogen concentration, particle concentration in coolant, boiling or non-boiling coolant, surface heat flux and reactor radiation. Test results are consistent with the solubility behaviour of magnetite, and have been valuable in testing mechanisms proposed for the deposition and release of corrosion products from the fuel sheath deposits. (Atomindex citation 11:557883)