CORROSION PRODUCT TRANSPORT IN WATER-COOLED NUCLEAR-REACTORS .3. BOILING WATER WITH INDIRECT CYCLE OPERATION

Corrosion products from out‐core surfaces are made radioactive when deposited in the core of a water‐cooled nuclear power reactor. Their release and deposition on out‐core surfaces causes gamma radiation fields to grow with time around these surfaces. Deposition and release of corrosion products in the reactor core is strongly influenced by the mode of heat transfer and by the water chemistry. Here, the deposition of corrosion products from boiling water onto nuclear fuel sheaths was studied in a water loop and in the CANDU Nuclear Power Demonstration (NPD) reactor as a function of possible water chemistries for indirect cycle operation. Deposits on sheaths in the boiling water region of test sections were very heavy (35 g Fe/m2) when ammonium hydroxide at 10 to 20 mg NH3/kg controlled the pH, or when the pH was controlled with 0.02 mg Li/kg added as LiOD. Deposits were light (∽ 50 mg Fe/m2) if the pH was controlled with at least 1 mg Li/kg. A mathematical model for deposition and release of corrosion products at fuel sheaths in non‐boiling water was modified and found to apply also in boiling water for the high pH test. Copyright © 1979 Canadian Society for Chemical Engineering