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REFRESH: The Power of Power Uprates

Since this blog post first ran in December 2011, the NRC staff has approved 16 additional power uprates, increasing the nuclear fleet’s output by an additional 1300 megawatts electric. An additional three are under review (for the three reactors at Browns Ferry), and the staff expects to receive an additional 10 uprate applications through the end of September 2017.  David McIntyre

Neil Sheehan
Public Affairs Officer
Region
I

refresh leafMuch news space has been devoted over the years to the prospects for new reactors in the U.S. However, new reactors are not the only way the nation’s share of nuclear-generated electricity can be increased — and it doesn’t involve earth-movers, the construction of new buildings or other changes visible to the casual observer.

Another option available to nuclear power plant owners is to pursue a power uprate, which essentially means an increase in the maximum amount of power a reactor can generate. But before a power uprate can be implemented, it must first undergo a thorough review by the NRC.

Take for example, the NRC’s approval of a 15 percent power uprate for the Nine Mile Point 2 nuclear power plant in upstate New York. That approval was the culmination of an NRC review that began with the submittal of the application on May 27, 2009.

During the course of the agency’s evaluation of the proposal, NRC staff scrutinized data regarding the proposal and posed dozens of technical questions to the plant’s owner, Constellation. They included queries about the effects of greater stresses on piping and the plant’s steam dryer, a component at the top of the reactor vessel, as a result of operations at higher power levels.

Power_Uprates_past-current-future (002)The NRC does not proceed to a final decision until all such questions are answered to our full satisfaction.

Uprates are not a new development. In fact, the NRC approved the first uprate back in 1977 and has to date approved 140 such applications. All told, the uprates have led to an increase in power output nationwide of about 6,000 megawatts electric.

There are three different kinds of power uprates: “measurement uncertainty recapture” uprates, “stretch” uprates and “extended” uprates. Here’s a brief description of each:

Measurement uncertainty recapture uprates – They involve an increase of less than 2 percent and are achieved by implementing enhanced techniques for calculating reactor power levels. State-of-the-art devices are used to more precisely measure feedwater flow, which is used to calculate reactor power.

Stretch uprates – The increases are typically between 2 and 7 percent and usually involve changes to instrumentation settings but do not require major plant modifications.

Extended uprates – Power boosts of this type have been approved for increases of up to 20 percent. They usually involve significant modifications to major pieces of non-nuclear equipment, such as high-pressure turbines, condensate pumps and motors, main generators and/or transformers. The Nine Mile Point 2 uprate would fall into this category.

For more information on power uprates, visit the NRC web site.

7 responses to “REFRESH: The Power of Power Uprates

  1. Anonymous August 1, 2016 at 9:13 pm

    I think for all of you agitated commenters – it is time that I redirected you to go read the NRC Regulations under Title 10, I did:

    i. Regarding “erroneous assumption that no maintenance or improvements are ever done” active components vs. passive components (components that are amenable for replacement) vs. (components that are not amenable for replacements) i.e. installed once and embedded in concrete for life time otherwise, such as drywell, torus, re-circulation, injection, Cold and Hot leg piping with the integral dissimilar metal welded piping and appurtance). Forget about maintaining these, they can’t even be inspected in successive 10-year inspection cycle intervals, as mandated by regulations such as 10 CFR 50.55a; and how much staff have to twist the licensees around to make them comply with it. You have to live their miserable lives in fighting in, how not grant endless reliefs and exemptions and make them at least, look at these components, leave alone remediating or replacing. We know all about that too!

    ii. The assumption that Nuclear reactor components life is limitless, is such a wrong notion and that these can be safely licensed for 80 years end-of-cycle, as surmised is not true, may just be! Mr. Poet go read Regulation 10 CFR 54.3, especially § 54.4(a) and (b) and how on TLAAs are analyzed and power uprate (it is termed re-rated power) plays crucial role in reducing the USE (Upper Shelf Energy, that is) which reduces licensable life. So your argument, that I made a rush to judgment was rash, rather, I was qualified to comment on it (I have studied two Shakespeare’s dramas, Othello and Tempest, as a degree subject in English, all within a prescribed curricula, for an advanced degree in English too).

    iii. Now regarding “Perhaps cognitive-behavioral therapy, combined with visits to radon-rich hot-spring spas and tours around actual nuclear plants as they carry dosimeters.” In my 40 odd years of engineering career (nuclear, that is), I had the privilege to wear vintage dosimeters(1960-70s) (incorporating α, β, ϒ radiation filters), received occupational doses, annually measured, working in radiation environment, (in at least, 6 reactor units overseas ) and countless tours in the continental U.S. wearing thermo luminescent dosimeters (TLDs). These therapies don’t have an effect on me anymore. Please, suggest something else. The point that I was making here was – don’t blanket embrace the regulator, but just adopt a balanced approach, especially in a topic such as power uprate – these things makes them rave on a topic, which is meaningless, when you think of reactors shut down (Crystal River, Vermont Yankee, SONGS U 1 & 2 etc.) and ones that are scheduled to shut down (Quad Cities U 1&2, Clinton, Oyster Creek, Pilgrim, TMI etc.) – for these, it is not only the uprated power they take down with, but their licensed power levels as well.

    iv. Finally, I am on the side of Regulations, Good Regulation – all the time! Sorry moderator, I have to set the score straight here, for these folks!

    • Engineer-Poet August 4, 2016 at 1:26 pm

      This is why anonymous comments should be prohibited:

      The assumption that Nuclear reactor components life is limitless, is such a wrong notion

      Here we have an assertion made from whole cloth that is blatantly false.  NOBODY said that life is limitless (just longer than worst-case), but we have “Anonymous” claiming that someone did… and we have no one to point to for fabricating that assertion.

      power uprate (it is termed re-rated power) plays crucial role in reducing the USE (Upper Shelf Energy, that is) which reduces licensable life.

      So they squeeze out the total energy output of the unit in less time.  I’m supposed to be worried if 20% higher power means it has to be retired after 75 years and not 80?  Every kWh we can get out of it NOW is natural gas that’s not burned and carbon that’s not emitted.  It’s methane that doesn’t leak, fracking water that never contaminates wells and streams, and radium-filled scale on piping that never needs isolation from the environment for 20,000 years.

      The point that I was making here was – don’t blanket embrace the regulator

      The amount of engineering documentation associated with just about any modification of a plant shows that you’re living in a fantasy world.

      just adopt a balanced approach, especially in a topic such as power uprate

      Just as soon as you adopt “a balanced approach” to radiation safety, such that levels that people have been living in for centuries in perfect health (Ramsar, Kerala, Guarapari) are designated “below regulatory concern” and ALARA is abandoned.

      But we have no idea who you are or if your claims are bogus, because “Anonymous”.

  2. Anonymous July 29, 2016 at 11:47 am

    Safety is a class of engineering in which one believes in the founding assumptions – that original assumptions and factors of safeties remain un-violated and realizing that these were put in place for a specific purpose – which is to take care of imponderables and unforeseen circumstances on the way. These are 40 years of licensed plant life limit based on endurance for nuclear reactors core hardware plus wear and tear. Please, don’t stretch these beyond a limit. The agency gets too cozy with the operators and have been granting power uprates indiscreetly and in one case (at least) the operator had to surrender their uprated capacity being unable to restart the unit to its original licensed power level, while satisfying a stipulated license condition of restart/uprate.

    At the least, don’t add up the uprated power totals and show cumulatively it is equal to 6 new operating units. It is fool hardy to gloat, lest, something blows on your face!

    • Paul Lindsey July 29, 2016 at 5:09 pm

      Anon – you fail to take into account improvements in analysis and computer models of core neutron flux, power output and temperatures. What was available for performing finite element analyses over 40 years ago is nothing like what is available today. Your comment is also based on the erroneous assumption that no maintenance or improvements have been performed, that a nuclear power plant is somehow like a aging 1960’s sow car, shiny on the outside and pretty leather on the inside, but don’t drive it lest it fall apart.

    • Engineer-Poet July 29, 2016 at 9:22 pm

      I wish the moderators would disallow anonymous comments.  People should at least have to adopt pseudonyms so they can be distinguished from one another.

      Safety is a class of engineering in which one believes in the founding assumptions – that original assumptions and factors of safeties remain un-violated and realizing that these were put in place for a specific purpose – which is to take care of imponderables and unforeseen circumstances on the way.

      This is a bunch of word salad which means roughly nothing.

      The safety of major parts of nuclear plants is determined by the stresses imposed by certain events, e.g. the thermal shock as cold emergency core-cooling water replaces warm steam generator return water.  The reactor vessel and piping are designed with margins of strength and ductility to withstand such stresses without damage.  Reactor designers have ways of measuring the qualities of the metal, such as using material samples placed in the reactor vessel and subjected to the same neutron bombardment and damage as the vessel itself.

      The original design specifications for reactors, especially early ones, made some worst-case assumptions and made certain that the design margins were sufficient to handle them over the initial 40-year licensing period (which is the duration they were expected to be financed).  As it turns out, those worst-case assumptions were often very pessimistic and the rate of deterioration is far lower than the 40-year numbers assumed.  If neutron embrittlement is the limiting factor and it is going at half the rate assumed for the original 40-year license, the unit can potentially run for 80 years.  It will still be safe at the end; it will have the margins to handle worst-case events.

      There is so much hysteria on the anti-nuclear side that I am rapidly coming to the position that these people need counseling.  Perhaps cognitive-behavioral therapy, combined with visits to radon-rich hot-spring spas and tours around actual nuclear plants as they carry dosimeters, could get their thinking aligned with reality and relieve them of their unwarranted and unhealthy stress.

    • gmax137 July 30, 2016 at 10:07 am

      “These are 40 years of licensed plant life limit based on endurance for nuclear reactors core hardware plus wear and tear.”

      This is entirely incorrect. The 40 year license term was selected to match the license term of large hydro dams, and to avoid giving the new nuclear licensees an unfair advantage over their coal and oil burning competitors. Fatigue analysis of the reactor components that can’t reasonably be replaced (like the reactor vessel) show that they will last far in excess of 40 years.

  3. Engineer-Poet July 28, 2016 at 11:42 pm

    For those who wonder how nuclear power has continued to provide such a large amount of energy even as plants have shut down, here’s your answer:  the hard-working people of the nuclear industry have worked both harder and smarter to make their units better.

    I’d like to see the NRC visit the issue of re-commissioning.  It is quite possible to do the engineering to bring Vermont Yankee back up to spec and turn it on again, but the NRC won’t allow it without going through the new-plant licensing process.  This is a paperwork problem.  The growing climate crisis does not allow us to put paperwork ahead of the needs of the planet; this will eventually be viewed as a crime against humanity.

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