Mirna Urquidi-Macdonald, Stefany Lyn Jacesko, Digby D. Macdonald, and Monica Salter-Williams

Importance of ECP in the Prediction of Radiation Fields in PWR and VVER Primary Circuits

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A model has been developed for predicting mass and activity transport in the primary coolant circuits of PWRs and VVERs with the objective of demonstrating and quantifying the importance of the electrochemical corrosion potential (ECP) in determining the impact of both processes on reactor operation. The model initially employs a radiolysis/mixed potential code to calculate the ECP at four locations (core, hot leg, steam generator, cold leg) and the ECP is then used to estimate the local magnetite solubility. The solubility is then averaged around the loop to yield the "background" solubility. Comparison of the background solubility with the local solubility determines whether precipitation or dissolution will occur at any given point in the circuit under any given set of conditions. It is further assumed that the concentration of ⁵⁹Co in the coolant is given by the isotopic fraction of this species compared with iron averaged over all materials and weighted by the respective wetted areas. Activation of ⁵⁹Co to ⁶⁰Co is assumed to occur in the coolant phase by fast, epithermal, and thermal neutron capture. The calculated activity is then used to train an artificial neural network (ANN) to establish relationships between activity at any given location and the operating properties of the reactor, including coolant pH, ECP, temperature, power level, etc. The model predicts that during shutdown, magnetite (and hence ⁵⁹Co) migrates to the core, where it is irradiated and activated, particularly during subsequent startup. During startup, the magnetite (and hence ⁶⁰Co) migrates from the core to out-of-core surfaces, where it establishes the radiation fields.

PowerPlant Chemistry 2002, 4 (7)

Craig Torville

Power Station Chemists - Recent Past, Present Life and Visions of the Future

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Challenges and key result indicators for power station chemists are economic, technical and managerial. What should we carry from the past, to manage the present and meet future economic, technical and managerial challenges? The results of an Australia-wide survey are presented in an attempt to develop a view of future impacts on the power station chemist's role.

PowerPlant Chemistry 2002, 4 (7)

Sallie Fisher

My Dream Plant

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A chemist with over 50 years experience in systems design for and monitoring the performance of high purity water production systems puts together pieces for primary treatment and condensate polishing for a future power plant with emphasis on reliable performance rather than capital cost.

PowerPlant Chemistry 2002, 4 (7)

Sallie Fisher

Spotlight on the Cation Resin

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A review of the overall dependence of sulfonic acid resin performance on divinylbenzene content shows that resin selection based on a single property is probably unwise.

PowerPlant Chemistry 2002, 4 (7)

Geoff Spowart

Legionella - An Appendix to the Saga

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This paper deals with the issues facing power stations attempting to manage Legionella in large scale cooling water systems. Australian power stations are keen to minimise Legionella levels and therefore are seeking to establish a standard suitable for the industry without the prescriptive requirements of the existing air conditioning standard. The issues surrounding metallurgy, environmental discharges, system complexity and makeup water quality and quantity are examined. The work that has been done over the past two years is detailed.

PowerPlant Chemistry 2002, 4 (7)

David Knights

Reducing the Volume of Water in Tarong Power Station's Ash Dam

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Tarong Power Station, a major supplier to Queensland's electricity grid, recently faced a potentially severe operational problem. A prolonged drought in the first half of the 1990s significantly depleted supplies of raw water. Water conservation measures were implemented, but required cooling tower blowdown to be stored in the on-site ash dam. Consequently, rising water levels in the ash dam posed a significant environmental risk. Several methods of water removal were considered, but a novel approach, using installed plant, was eventually chosen, with a very successful outcome. This paper traces the problem and its eventual solution.

PowerPlant Chemistry 2002, 4 (7)

Graeme E. Batley and Kenneth W. Riley

Power Stations and the ANZECC/ARMCANZ Water Quality Guidelines

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The release of waters from coal-fired power stations may be of environmental concern in some environments. The management of large volumes of ash dam water can be particularly difficult. "Dry" landfill sites may also release trace elements where groundwater or rainwater comes into contact with the ash residue. A number of these elements are toxic or accumulate in organisms to an extent that biological function is impaired. The biological activity of the leached elements is a function of factors such as speciation (including organic complexation), pH and water hardness. Simple limits of water release based on concentration alone are often used in the licensing of power stations but are an inadequate parameter with which to manage water quality. The Australian and New Zealand Environment Conservation Council Water Quality Guidelines provide broad holistic guidance on discharge limits as well as detailed advice on the monitoring and assessment of environmental impact.

PowerPlant Chemistry 2002, 4 (7)