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North American construction is back—smaller and faster—at OPG’s Darlington
“The nuclear renaissance is real here,” said Ontario Power Generation’s Subo Sinnathamby on May 8, one year to the day after OPG secured a final investment decision to build the first of four planned BWRX-300 reactors at its Darlington nuclear power plant, and shortly after the new reactor’s foundation was lifted into place. “We got our license to construct in April and our [final investment decision] in May, and we’ve been off to the races since.”
L.-Y. Cheng, J. S. Baek, A. Cuadra, A. Aronson, D. Diamond, P. Yarsky
Nuclear Technology | Volume 196 | Number 2 | November 2016 | Pages 238-247
Technical Paper | doi.org/10.13182/NT16-29
Articles are hosted by Taylor and Francis Online.
A TRACE/PARCS model has been developed to analyze anticipated transient without scram (ATWS) events for a boiling water reactor (BWR) operating in the maximum extended load line limit analysis-plus (MELLLA+) expanded operating domain. The MELLLA+ domain expands the allowable operation in the power/flow map of a BWR to low flow rates at high-power conditions. Such operation exacerbates the likelihood of large-amplitude power/flow oscillations during certain ATWS scenarios. The analysis shows that large-amplitude power/flow oscillations, both core-wide and out-of-phase, arise following the establishment of natural-circulation flow in the reactor pressure vessel after the trip of the recirculation pumps and an increase in core inlet subcooling. The analysis also indicates a mechanism by which the fuel may experience heatup that could result in localized fuel damage. TRACE predicts that heatup will occur when the cladding surface temperature exceeds the minimum stable film boiling temperature after periodic cycles of dryout and rewet, and the fuel becomes locked into a boiling-film regime. Further, the analysis demonstrates the effectiveness of the simulated manual operator actions to suppress the instability.