System and Methods for Optimizing Availability and Performance of Light Water Reactors

Tech ID: 25305 / UC Case 2016-014-0

Brief Description

More than a quarter of the world's carbon dioxide emissions come from burning fossil fuels to produce heat and electricity. Nuclear energy plants do not emit criteria pollutants or greenhouse gases when they generate electricity. Thermal-neutron reactors are the most common type of nuclear reactor, and light water reactors (LWRs) are the most common type of thermal-neutron reactor, which uses normal water as the primary coolant. Localized corrosion in the primary coolant circuits (PCC) is a big problem in LWRs. The rate of corrosion is often determined by certain electrochemical properties, such as the electrochemical corrosion potential (ECP), solution conductivity, temperature, pH, flow rate, and the kinetics of the reduction of a cathodic depolarizer (e.g. O2) on the surfaces external to the crack. Mechanical loading (stress intensity factor on the crack) and micro-structural/micro-chemical factors (e.g. grain size, precipitates, degree of sensitization) may also contribute to this problem. To address this problem, researchers at the University of California, Berkeley, have developed an operating protocol in which the PCC are protected over wide ranges of parameters as the reactor progresses through a fuel cycle, including: temperature, pH, ECP, solution conductivity, flow rate, and stress intensity factor. Laboratory models using Berkeley approach suggest significant LWR optimization while adding levels of safety and lowering operational costs (e.g., by avoiding primary water stress corrosion cracking in Alloy 600 steam generator tubes, which is a major corrosion phenomena in operating a PWR). In fact, Berkeley’s solutions require minimal modification to the reactor PCC, and in most cases, can be implemented with no modifications at all.

Suggested uses

  • Stationary LWRs e.g. power plant
  • Non-stationary LWRs e.g. marine propulsion

Advantages

  • Applicable to range of LWR applications (including PWR and BWR)
  • Plug and play with no modifications of reactor PCC
  • Improves safety and reduces operational costs (estimated that up to 80% of the loss of availability of LWRs is due to corrosion amounting to several billion dollars per year over the entire LWR fleet)
  • Enables engineers and operators to achieve longer lifetime of PCC, by inhibiting various forms of corrosion

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Inventors

  • Macdonald, Digby D.

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