Palo Verde settles with NRC over apparent spent fuel storage violations

The Palo Verde nuclear power plant in Arizona.

A confirmatory order issued by the Nuclear Regulatory Commission to Arizona Public Service Company documents the commitments the company has made as part of a settlement agreement with the agency. The settlement agreement stems from two apparent violations of NRC regulations involving spent nuclear fuel at APS’s Palo Verde nuclear power plant in Tonopah, Ariz.

The apparent violations involved APS’s failure to (1) perform a written evaluation for a change to the NAC MAGNASTOR dry cask storage system for spent fuel and obtain a license amendment for a change in methodology for performing tip-over calculations and (2) adequately analyze the consequences of a hypothetical MAGNASTOR CC5 spent fuel cask tip-over accident on the plant’s independent spent fuel storage installation pad.

The confirmatory order was issued on November 17. The apparent violations are described in a July 6 NRC inspection report.

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Robotics at Palo Verde

The Zephyr system uses probes for steam generator inspections. Photos: APS

The Palo Verde Nuclear Generating Station, a three-unit pressurized water reactor plant operated by Arizona Public Service Company, has started using an inspection technology relatively new to the nuclear industry. The technology, called smart pigs (an acronym for “piping inline gauges”), has previously been employed by oil and gas companies for inspecting and cleaning underground pipes. After testing and analyzing smart pig products from several companies, Palo Verde’s underground piping consultant, Dan Wittas, selected a smart pig suitable for navigating the tight-radius bends in the plant’s spray pond piping. The spray pond system consists of piping, a pump, and a reservoir where hot water (from the Palo Verde plant) is cooled before reuse by pumping it through spray nozzles into the cooler air. Smart pigs work by using the water’s flow through the piping to move an inspection tool within the pipe itself. The technology replaces the previous method of pipe inspection, in which various relatively small sections of piping were unearthed and directly inspected, and were considered to be representative examples of the overall piping condition. In contrast, the smart pigs obtain corrosion levels for the length of piping traveled through and allow a corrosion baseline to be established.

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EIA: Nine of top 10 electricity generators in 2019 were nuclear plants

Graph: EIA

Of the 10 U.S. power plants that generated the most electricity in 2019, nine were nuclear plants, a recent report from the U.S. Energy Information Administration states.

These 10 facilities produced a combined 230 million megawatt hours of electricity last year, accounting for 5.6 percent of all electricity generation in the United States, according to the report. The report also notes a shift in the makeup of the top plants over the past 10 years, from a mix of nuclear and coal-fired generators in 2010 to nearly all nuclear in 2019.

Coal’s share of U.S. electricity generation dropped from 45 percent in 2010 to 23 percent in 2019, the reports says. Stricter air emission standards and decreased cost competitiveness relative to other generators are given as the key reasons for coal’s decade of decline.