Tuesday, January 7, 2014

Polar Vortex Vs. Nuclear Plant

Exelon Nuclear's Limerick Generating Station
Blogger's Note: It's not often we get guest bloggers on The Digital Notebook, although your submissions are always welcome.

In fact, we've never had one.

And this is only kind of one.

You see, the Nuclear Regulatory Commission has its own blog, which I read, and they had a post Monday which seemed relevant given today's weather. Further, it's written by Neil Sheehan, a fellow with whom I have regular contact for stories about the Limerick Generating Station and I have always found him to be well-informed.

So, I figured, what the hell? This is what he has to say on a subject I thought you might find interesting. You can click the link above and read it there, or read it here.

When the temperatures plunge into Arctic territory, there are few parts of the infrastructure not impacted in one way or another. Pipes can freeze, roads and bridges can quickly ice over and car batteries can go dormant.

Now, with what meteorologists are calling a “polar vortex” flooding much of the country with a blast of frigid air, precautions are being taken to guard against potential effects. Count U.S. nuclear power plants among those facilities gearing up for the 2014 version of the Big Chill.

As of Monday afternoon, no plants were reporting any problems of note related to the frigid extremes, but ongoing checks will be in order to ensure that remains the case.

The NRC’s regional offices in the Midwest and Northeast are keeping an eye on plant owners’ responses to the unusually low temperatures. Plants in the affected areas have entered off-normal procedures that entail minimizing regular surveillance activities and increasing the frequency of checks and walkdowns (visual evaluations) of equipment that could be impacted by the temperatures.
Beaver Valley Nuclear Power Plant

NRC Resident Inspectors, who are assigned to specific sites, will continue to monitor the situation. The inspectors use an “Adverse Weather Protection” inspection procedure to guide their assessments of whether plants are ready for extreme temperatures, including the bitter cold. Those reviews are typically done at the start of the season.

“As applicable, verify cold weather protection features, such as heat tracing, space heaters, and weatherized enclosures are monitored sufficiently to ensure they support operability of the system, structure or component (SSC) they protect,” the procedure states in part.

It also instructs inspectors to perform walkdowns to verify the physical condition of weather-protection features.

The NRC has long recognized the need for nuclear plant owners to be on guard for extreme cold-related issues. Along those lines, the agency in January 1998 issued anInformation Notice on “Nuclear Power Plant Cold Weather Problems and Protective Measures.” Although such notices do not require a specific action or written response, they do serve to make plant owners aware of possible concerns.

For example, the Information Notice discussed an ice plug that formed on Jan. 8, 1996, at the Millstone Unit 2 nuclear power plant in a service water strainer backwash drain line. Service water refers to water taken from a nearby source of water -- be it the ocean, a lake or river -- used for cooling purposes in the plant and then returned.

To prevent a recurrence of the problem, the plant owner changed an operating procedure to ensure closer monitoring when service water intake structure temperatures drop below 40 degrees Fahrenheit and to make use of portable heaters or go to manual operation of the strainers.

Nuclear power plants are designed to withstand weather extremes. Nevertheless, NRC inspectors will be on hand to keep a close watch on plant conditions during the “vortex” and beyond.

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