Light Water Reactor Applications Research Articles

Testing of high temperature reference electrodes for light water reactor applications

The main objective of the LIRES (light water reactor reference electrodes) project, supported by the EC within the EURATOM FP5, was to develop reference electrodes, which are robust enough to be used inside a light water reactor at temperatures up to 320 °C and pressures up to 120 bar. This contribution summarises the test of three types of reference electrodes developed within LIRES: (i) an external Ag/AgCl reference electrode from the NRI, Rez, Plc, (ii) a PtIr alloy hydrogen electrode from Studsvik Nuclear AB, and (iii) a Pd-hydride reference electrode—Pd(Pt) polarised active electrode pair—from the VTT Technical Research Centre of Finland. Our results are being compared, within a Round Robin test, with similar measurements of a number of laboratories to select the appropriate reference electrodes for long-term tasks, when the potential should be monitored for months under irradiating conditions.

Flaw evaluation of theramally aged cast stainless steel in light-water reactor applications

Cast stainless steel may be used in the fabrication of the primary loop piping, fittings, valve bodies, and pump casings in light-water reactors. However, this material is subject to embrittlement due to thermal aging at the reactor temperature, that is, 290°C (550°F). The Argonne National Laboratory (ANL) recently completed a research program and the results indicate that the lower-bound fracture toughness of thermally aged cast stainless steel is similar to that of submerged arc welds (SAWs). Thus, the US Nuclear Regulatory Commission (NRC) staff has accepted the use of SAW flaw evaluation procedures in IWB-3640 of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code to evaluate flaws in thermally aged cast stainless steel for a license renewal evaluation. Alternatively, utilities may estimate component-specific fracture toughness of thermally aged cast stainless steel using procedures developed at ANL for a case-by-case flaw evaluation.