Northwest wind takes a week-long vacation 1


  1. There is a good article at IEEE Spectrum by two engineers associated with Google’s renewable energy program. They realize now that the traditional renewable energy approach isn’t going to work to substantially reduce CO2 emissions. According to them, “we need a fundamentally different approach”.

    Compare nuclear-heavy France to renewables-heavy Germany, and it is easy to see which approach works better.

      1. It must be nice to have plenty of reliable nuclear energy capacity that you can make a mint off of exporting the electricity to all your neighbors chasing butterflies. 😉

  2. Rod – On the BPA wind page titled “WIND GENERATION & Total Load in The BPA Balancing Authority”, item 12 “Data for BPA Balancing Reserves Deployed and BPA State(s)” allows the user to download a spreadsheet for each year which shows the oversupply mitigation states (aka curtailment) in 5 min intervals. there is one tab for Jan-Jun and a second tab for Jul-Dec. Review of that data shows no curtailment on Nov 22.

    1. @Paul Lindsey

      Thanks for the information. I went back to the dynamic graph where I can currently see Nov 19-Nov 25. What I saw as potential curtailment was simply indication of the start of some rather wide fluctuations that are continuing through today. Of note, there was another nearly complete disappearance of wind just as demand began ramping up with the start of the work week. That required the hydro generation to increase rather quickly from 5200 to 10000 MWe over the space of just a couple of hours.

      BPA load and production Nov 19 - Nov 25

      1. Aside from curtailment, there is another event which causes wind turbines to suddenly stop producing electricity even while the wind is blowing, namely when they shut down due to excessive wind speeds or gusts. Might that have been a factor here?

        1. I’ve never understood why they would completely shut down (except maybe in a hurricane or tornado situation). Can’t they ‘feather’ the blades, to allow wind to spill off of them, so that they don’t experience as much torque, and can operate within the designed energy ranges?

      2. I have a question for the engineers (Maybe Rod can reply): It seems like I’ve heard before that on mechanical systems (particularly spinning systems like water turbines and natural gas turbines, etc), that frequent hard ramp-ups, and ramp-downs, like depicted in that graph, are very hard on the system mechanically, and can pretty significantly reduce the mean time between failures requiring repairs and overall system lifetime? Is that correct?

  3. I’ve been sending around the BPA link for years. That is a great way to look at wind. You can even download an Excel file for data every 5 minutes for months, if you want to do some analysis. You’re right Rod, the flat line isn’t the most discouraging. Pick a week when it is gyrating like crazy. I’ve often told people that if you take one look at that graph, you know why wind is a problem. BPA can get away with this because they have a huge amount of hydro that can be ramped up and down quickly. Not everyone is so fortunate, and even for them it is difficult. I wonder if they have any plans to add wind, or have reached the limit.

  4. Something about the graphs I don’t understand. Is the red line labeled “load” just the load on the BPA distribution system alone? Easiest to see at left side, but the total generation exceeds the load by about 3500 MW. Are they pumping up storage, selling outside of their system, etc? That’s quite an excess of generation over what they call “load.”

  5. OK, the link at EntrepreNuke above explains BPA is a net exporter of energy, so that explains it. Hmmm… BPA web site says they are a non-profit federal agency; complicated.

  6. What this leaves unaddressed is that ‘unreliable’ is still a description of our relationship to fluctuating energy sources, and not a description of the energy production profile. A graph can capture the output profile, but it does not convey the degree to which anyone was depending on it having a different production profile.

    But when I point to a wind production graph from my state, such as this one:

    I think it would be fair to describe that as spasmodic or erratic without including the value-laden implication that such a production profile let anyone down–an implication I would not be able to substantiate from any information given in the graph itself. And if anyone did object to the use of ‘spasmodic’ or ‘erratic’, the obvious reply would be to challenge them to cite or produce an illustration of a production profile which *could* be fairly described as spasmodic or erratic and then they can point out how their sample profile is qualitatively or categorically distinguishable from the actual recorded profile given.

    1. I put it to you that “having it there when you throw the switch” is the very essence of power as we understand it. That is our “relationship” to energy sources of any kind ; a source which produces without correlation to demand is inherently unsuitable.

  7. Way to make something of nothing. Please tell us something we don’t already know.

    a week-long vacation

    WNP-2 takes a longer vacation every year or two. What ever happened to WNP-1,3,4 and 5?

    During part of that time, the slope of increased generation approached a vertical line.

    This is just whining. Hydro generation increases exhibit the same behavior, as frequently, or more, than wind. I suspect gas turbine generators, diesel generators, solar photovoltaic or thermal, and even nuker generators can exhibit the same response, although nukers would be primarily in the downward direction after a trip.

    In fact, I suspect that the dip in wind production at midnight on November 22 came as a result of curtailing wind generators to prevent grid instability as the wind generation approached 75% of the total load

    Suppositions are not worthy of the “in fact” preface, as they are, in fact, only guesses. This is where an actual investigative journalist might seek an informed source and include a quote from a dispatcher, rather than guessing.

    1. @Not CR

      The difference with WNP-2 is that it is a single plant whose every 18 month “vacations” are normally scheduled well in advance. The wind vacation I am pointing out in this post affected a geographically dispersed set of several thousand wind turbines with a total nameplate capacity of 4,500 MWe. When they simultaneously stopped spinning and remained still for a week, there was little advance notice to the grid operators. Their return was also not predicted more than a few days in advance.

      I accept your criticism of my use of the “in fact” preface. It was not appropriate to use when offering an opinion.

      In my defense, I have never claimed to be a journalist. I’m an opinionated writer who bases his opinions on a reasonably deep well of personal experience supplemented by extensive, but not perfect, research.

      1. In addition to having the outages of WNP-2 scheduled well in advance, they are scheduled for times when demand is low (Spring and Fall) so that impact to the grid is minimized due to ample excess generating capacity. Wind “outages” can easily happen during times of maximum demand when spare generating capacity is scarce.

        I live in the Northwest, and part of my electrical energy comes from BPA. There is a good deal of electrical heating here (I have an electric heat pump). A common Winter weather pattern here is cold, stagnant air for a week or two — lots of electrical demand while wind generation is “on vacation”.

        1. I have been corrected when I referred to “Columbia Station” as Whoops-2. I can understand why as this name is similar to calling wind energy unreliable.

          Question: Are all the peaks and valleys in the chart caused by changes in wind or is BPA changing the pond level at some of its dams to account for the different value of electricity at different times of the day? Some dams are run of the river and some let the pond level be raised and lowered.

      2. Hi Rod – In the context of this discussion, can you perhaps address the point I frequently hear from proponents of wind – that the wind is always blowing somewhere? That is, they’ll show you a national wind map, and show how even when it’s calm somewhere, it’s windy somewhere else. Which is true.

        My thoughts on that are that it requires a massive overbuild of both generation, and transmission capacity, as every “locality” would be required to provide something like 50% or 100% more peak generation capacity than needed locally, in order to be ready to supply a becalmed neighboring region, and massively excess transmission capacity to transmit that large over-supply of local power to the localities where it’s needed?

    2. WNP-2 takes a longer vacation every year or two.

      Anyone who’s ever worked in a technically-oriented team with procedures and deadlines etc. will know of the aggravation of a team member unexpectedly taking leave with little or no notice. Productivity is optimised when all team members are professional enough to book their leave well in advance, and for reasonable periods.

      It is a nightmare to have a colleague who is unexpectedly absent a large chunk of the time, and often won’t pull his weight when he does turn up.

    3. Not CR,

      The fluctuations of the hydro generation within BPA’s balancing authority are CLEARLY to balance the sporadic nature of wind. If not for the quick ramping ability of the hydro generation and the reliable presence of stored water behind Columbia River system dams, BPA would not be able to successfully manage the 4,500 MW of wind capacity.

      California is lucky to be able to import some electricity from the BPA region.

      1. EntrepreNuke,

        Wind fluctuations CLEARLY have nearly NOTHING to do with hydro fluctuations, because the same LARGE daily “molar tooth shape” hydro fluctuations occurred on November 19 AND 20, when wind was still “on vacation,” as shown in the chart “captured for posterity” ABOVE.

        And by the way, wind power systems do have automated controls and human operators.

        1. Have a better look, and at the graph Rod shows in his November 25, 9:59 AM post too.
          Hydro is clearly demand-following on 19 and 20 November, but reacting to balance the irregularity of the wind power on 22 trough 25 November. Their curves are more or less mirror images.
          Hydro fluctuations CLEARLY have everything to do with wind fluctuations.

    4. @ Not CR

      Are you implying you don’t know the difference between planned shutdowns for maintenance (“every year or two”) and unplanned UNavailablility of power a company was hoping to exploit? How many weeks a year is this wind power unavailable or severely limited?

    5. @ Not CR

      “Way to make something of nothing. Please tell us something we don’t already know.”

      That is my exact sentiment when I read or hear anti-nuclear criticism of nuclear power. In addition to the usual exaggerations are the outright lies, falsehoods, and appeals to bogus studies which have become standard fair in the anti-nuclear community.

      “This is just whining”

      Oh, how ironic this statement is given the history of the anti-nuke movement.

      “Suppositions are not worthy of the “in fact…”

      It would be grand if anti-nukes took your advice on this statement, but to do so, would completely undermine the movement.

      1. @ Bonds 25

        Hey, at San Onofre we had two runs that were 600+ days! Oh, for the good o’l days of actually working on a running unit. Just another victim of anti-nuclear hysteria and lies (and madame Boxer, the master of disaster).
        Good luck there at WNP-2.

        1. Our record was 505……and like 170 coming out of an outage. I’m sorry for your loss. Hopefully the local Anti-nukes will never be able to grasp their teeth in our skin.

        2. I don’t understand why the SCE management, at the top, as well as in the SONGS staffing, blame everyone else for the shutdown. Its obvious that bad decisions and poor oversight of the retrofit led to major costly problems. The shutdown of SONGS has its origin in SCE management. Had the retrofit been well managed by both engineers and management, resulting in a functioning system sans leaks, seems to me that Boxer and her ilk would have lacked the ammo to launch an offensive.

          1. They were ready to use anything as ammo, there was bound to be one day a bump in the road that would provide the ammo they needed. As Rod made clear, many reactor have had similar minor leaks in the past, plugging the defective tubes, running the reactor at a lower power would have been perfectly effective and reasonable solutions.

          2. @poa

            My understanding of your comment is along the lines of “why wasn’t SCE management and engineering perfect? If they had not made any errors, the people opposed to nuclear energy would have left them alone.”

            In answer to that position, I’ll point to the current effort to force a shutdown of Diablo Canyon. Even if corporate management and local engineering does not make a small error, the organized forces against nuclear energy will make something up to use as a pressure point against nuclear power.

            I say again, the closure of Diablo Canyon came as a result of a single U-tube leak that resulted in about 75 gallons of virtually pure water per day seeping from one closed system to another in a very valuable and productive ultra-low emission nuclear power plant. While I admit that the leak should not have happened, I would hope that a guy who makes things for a living would understand why my reaction to the situation would be to promptly fix the problem and restart the plant.

            I’ve written several more detailed explanations for why I believe there was so much overreaction by nearly everyone involved. I do not hold the management blameless, but they were not the only people who reacted poorly and contributed to the loss, which has been computed to carry an eventual price tag of something like $13-$15 billion.

          3. Once upon a time, both Britain and France did it correctly. Nuclear power was a National property, “public sector” enterprise, or “public option” energy. Then Britain got Thatcher, and recently France got clobbered by EU idiocy, probably engineered in the Ruhr.

  8. I’m not sure I understand the problem here. If the “intermittent” wind patterns are sufficient enough to pump enough water into the holding resevoirs to supply hydro generated power during no or low wind periods, whats the beef?

    Besides, aren’t some of these wind/hydro systems set up where the wind turbines are specifically supplying power to the pumps, rather than contributing to the grid?

    1. @poa

      It is difficult, expensive, and environmentally damaging to build sufficient water storage to providing anything close to 1,500 MWe for 7 days. (That’s 1/3 of peak wind capacity in the Pacific Northwest.)

      I don’t have exact figures for the Bonneville system, so I will use a system local to me that I know pretty well. Smith Mountain Lake and Leesville Lake make up a 640 MWe pumped storage system that can store enough water to produce that power output for two days before the upper lake runs out of water. (It actually does not run out, but the level gets to the bottom of the range allowed by license and upsets all of the lakefront property owners.)

      The upper lake has 20,000 surface acres and a shoreline that is more than 500 miles long.

      You would need about 7 times as much water storage capacity to provide a week of 1,500 MWe average power.

      1. poa, rod,

        Rod doesn’t know, and thus assumes the worst, because it’s not nukers’ power.

        BPA clearly has enough hydro storage to produce from 5 to 10 GW, and ramp up or down between those values over short times, on a daily basis, whether wind is involved or not. Clearly, on November 24, as wind went down from about 2.0 to 0.5 GW, over about 12 hours, hydro increased from about 5.5 to 10 GW in a much shorter time, maybe 1-2 hours.

        Can you see how hysteria and FUD are being promoted intentionally by the nukers?

        1. @NCR

          I am a big admirer of the long term investment in hydroelectric dams made by my parents’ and grandparents’ generation. However, if BPA has the hydro power it needs “whether wind is involved or not” then why have the rest of us spend so darned much tax money in subsidizing the construction of 4,500 MWe of wind generating capacity?

          1. big admirer of the long term investment in hydroelectric dams made by my parents’ and grandparents’ generation.

            It is difficult, expensive, and environmentally damaging to build

            Admire the expensive damage… Inconsistencies abound.

            spend so darned much tax money in subsidizing the construction

            Why not. More is spent on defense nukes already.

            The subsidy is for energy produced, not construction, and nukers would accept the same, when any new plants are eventually built.

            (Attempt 2 at similar comment)

            1. @Not CR

              Your comment indicates little or no knowledge of the historical context in which the dams were built. Then, they were the best available option compared to continuing to burn massive quantities of coal. There was little natural gas available because distribution pipelines did not exist.

              In addition, the expense was far lower in an era where people were desperate for work of any kind. Many of the biggest dams were products of the Depression Era and built to provide productive jobs to people who might otherwise struggle to eat or who were more interested in making a living than in getting a handout.

              Land was cheaper and there was no organized, litigious Environmental Movement that would sue to delay and add cost to any project that would actually reduce the consumption of fossil fuel.

              As of 2009, nearly all of the wind and solar projects that have been developed in the US have taken the option provided in the Recovery Act to accept a 30% Investment Tax Credit in lieu of the Production Tax Credit. That option provides them with a 30% of project cost payment within one year of project completion. In other words, it is a construction subsidy, not a production subsidy. It is hugely popular among the financial folks that understand the time value of money and recognize that a subsidy distributed over the first 8-10 years of operation is a political vulnerability. No one is going to succeed in recovering those ITC payments, even if they managed to halt the PTC payments.

              (Note: The link I provided indicates that the ITC in lieu of PTC expired in 2011, but it was extended at least one time to 2013.)

        2. I live in NW Oregon and enjoy the power from the Columbia River. It is my understanding from local news articles that annually BPA runs into complications with balancing hydro with wind energy sources due to the erratic flow impacts to the salmon runs and habitat. Biologist in the area seem intent that there is a significant conflict of interest in using hydro to balance wind intermittency and sustaining the wild fish runs on the river.

    2. @poa,

      There are two general types of hydro dams. Run-the-River dams (otherwise known as diversion dams) and Storage Dams (technically known as impoundment dams)

      The majority of the dams BPA operates along the Columbia River are run-of-the-river dams, not impoundment dams. Run-of-the-river dams have some limited storage capacity but not as much as the typical impoundment dam.

      The major exception is the Grand Coulee dam. The Grand Coulee Dam is an impoundment gravity dam and is the 7th largest power producing facility in the world. However, Grand Coulee dam was not designed as a a pumped hydro facility.

      Pumped hydro requires a water source downstream and at a lower elevation then the upper water reservoir. They can be closed loop as shown by typical diagrams of pumped hydro or they can be open loops which is what BPA would need to do since they are run-of-the-river dams.

      However large scale pumped hydro also requires extensive pumps, penstocks/piping arrangements and valving which BPA does not have on any of their systems except at the Grand Coulee facility. That specific facility within the Grand Coulee installation, the John Keys pumped hydro facility, is used for irrigation support though not as a storage mechanism for wind generation. The Bureau of Reclamation is proposing to decouple that particular facility from Grand Coulee to use as a pumped hydro storage for wind generation. That plan is somewhere in the evaluation stage. But it is only about 300MW’s, under 10% of the existing wind generation on the BPA grid so a little but not much and it would have to maintain its support for irrigation first, wind storage second.

      So while there are some areas in the Pacific Northwest that have been surveyed and analyzed to meet the requirements for pumped hydro potential, they have not been developed due to cost, potential displacement of local citizens, and environmental issues such as salmon migration runs. My personal opinion is that if a large scale pumped hydro were to be used on the Columbia River there would be salmon migration and total dissolved gas issues to resolve before it could become fully operational.

      All of this discussion though means that currently BPA must use the wind on a real-time basis thereby knocking off other generation sources (hydro, natural gas and even reducing Columbia Generating Station output to 85%) as described in my other post on this article.

      Now we can circle back around to the fact that several of the preliminary pumped hydro projects were proposed decades ago as a means for nuclear power plants to do the very same thing that wind developers want to do: Use the excess power, typically at night, to run a pumped hydro facility.

      So the pumped hydro as a means of storage is not a new idea nor is it wind dependent. If large scale pumped hydro were brought onto the BPA grid I suspect that Columbia Generating Station, as well as all other non-wind generation, would legally be allowed to join that pool of generators who could store their generation.

      Since Rod’s article was discussing BPA and since this comment is already fairly long, I purposefully did not go into pumped hydro being discussed for the Midwest where ERCOT and others are considering if pumped hydro will work for that region of the US.

  9. The load profile of the BPA system during the weekdays is an upramp about 6am to ensure there is sufficient generation available for eveyone’s morning routines and as business start back up for the next day’s production. Then BPA downramps as evening progresses towards the late night hours. On the weekends, the overall power demand generally decreases even further unless of there is a big event such as a Superbowl.

    The cycle as shown by the days from Nov 16th-21st repeated itself for years.

    Smaller hydro generators such as Seattle City Light and Tacoma Power could ramp up and ramp down as needed by BPA thereby providing revenues to those respective utilities which kept rates low for their ratepayers compared to the rest of the nation. The paper mills could depend on the revenue from their thermal generation during the downtimes of the day thereby keeping the plants running as efficient as possible.

    Until wind 4.8GW’s of wind was put onto the BPA grid.

    Then BPA had problems meeting the Endangered Species Act. Then BPA had problems with total dissolved gases (TDG) in the water which put them out of compliance with the Clean Water Act. Now admittedly, BPA was struggling with salmon migration and TDG before large scale wind arrived but the 4.8GW of wind means the challenges of managing the various requirements users of the Columbia River expect to be met are just that more complex.

    So the BPA is using and will have to continue to use hydro to ramp up and down. BPA is forcing and will have to continue to force thermal generation to ramp down and back up unexpectedly when wind ramps up and then down. Rapid power transients of thermal generators decreases their overall plant efficiencies. That are costs – sunk, lost opportunity, increased maintenance, etc – that the new Oversupply Management Protocols will begin to shake out.

    BPA and Energy Northwest have already taken Columbia Generating Station into load follow mode down to 85% of capacity due to oversupply from wind and hydro. It is an operating situation that is new for ENW and CGS. The 85% level is the minimum level of reliability for that type of plant design from what I have read.

    These actions are taken through the establishment of the BPA’s Oversupply Management Protocols which FERC just approved in October of this year.

    Bottom line is that while BPA is exhibiting full support to wind, there is a cost that is only now being recognized for adopting large scale wind generation on a system that was designed to use more stable generation inputs. The fact that BPA MUST consider the loss of the production tax credit (PTC) to wind generators as part of the cost of curtailing generation is an example of a subsidy program gone awry in my opinion. And just another reason the PTC must die once and for all.

    Wind is not a stand alone generation solution as is nuclear.

    1. Bill Rogers,
      Rapid power transients of thermal generators decreases their overall plant efficiencies

      Funny, you see more of those when wind was near zero, from the charts. Looks like wind helps slow those rapid transients.

      1. Planned transients were and are still expected. BPA has always adjusted system transients every 20 minutes. Transients of small generation sources were part of that normal adjustment process. But wind is now driving how BPA operates and how BPA strucures its rate cost programs. BPA drives how the entire West Coast operates from British Columbia to Mexico since electricity moves from Canada and the Pacific NW to Southern CA.

        CA utilities bought the green credits from NW wind generators to meet RPS requirements (which is another political program that favors wind) but did not actually taking delivery of the electricity until BPA had to go to court to stop that practice. Power was being dumped in the NW because it couldn’t be delivered to California because California didn’t need it at that specific point in time. However CA utilities had to prove to the politicians they were “generating”a certain percentage of their power from politically approved sources. IOW it has been a shell game for some time. BPA’S new over supply protocol management program may finally shed some light on those issues.

        BPA is in the process of a multi-year rate adjustment/realignment process specifically because of wind generation. That process will ultimately be felt negatively by Pacific NW rate payers.

        Rapid transients every 5 minutes due to constant readjustments because of a highly variable and unpredictable generation input was not originally planned nor designed into any grid system. Be it BPA or ERCOT or the Eastern seaboard.

        Just because just-in-time computers programs and weather forecasting are becoming better at controlling a system that has to account for a highly unpredictable input source doesn’t mean it is cost free. Why should traditional power generation sources and their ratepayers pay for BPA or any other grid operator for the system upgrades that only being put into place because of wind genetation? Why should we taxpayers be forced to pay the PTC which a wealth transfer program to wind developers when we the ratepayers are going to be stuck with a big bill once the wind towers reach their end of life in the next 10-15 years?

        And I haven’t even started discussing how former FERC chairman Wellinghoff was and still is actively pushing the Pacific NW region towards developing natural gas generation. Natural gas generation is the choice for wind and solar believers to provide the power for the other 70% of the time when wind is not available. That would be the Wellinghoff who has ties to Sen Reid who also doesn’t want any more nuclear power because it could mean used fuel storage in his home state.

          1. Generating electricity is not the same thing as going down to one’s local cell phone store, standing in line and trading in last year’s model for the latest Apple iPhone.

            Generation, transmission and distribution equipment are multi-decade, multi-generational infrastructure investments. We are benefitting from our grandparents and parents investment in the existing grid structure. Our current investments in wind and solar only ensure an even larger replacement bill will be handed to our children and their children.

            Dams and traditional power plants last upwards of 60-80 years with proper care and maintenance. Some dams are approaching 100 years on the BPA system. Other dams need to come out due to both upstream and downstream damage that is now known in better detail. Finally there are the dams that enviros are clamoring to have constructed and put on-line as pumped hydro which should never be built. Nuclear power plants are expected to last 60 years and still remain less per kwh delivered to the customer then wind or solar.

            Wind towers and solar panels whose life expectancy is measured in less then 2 decades thereby requiring full replacement of the nacelles and panels do not classify as an multi-generational infrastructure investment in my book. Especially when those industrial wind and solar generation sources require a hard investment hundreds of millions of dollars for new pipelines and pipeline capacity for the natural gas power plants that would be required to make up the 70% delta between what wind and solar can produce and what is needed.

            And when those wind towers and solar panels are causing a destruction of wild life that has yet to be fully understood and classified then we are leaving the world a little less desirable for future generations. I shake my head when I hear wind/solar advocates trying to reconcile Fukushima, where radiation is naturally decaying away and except for very well defined hot-spots could be repopulated, and the permanent loss of wildlife and wildlife habitat due to industrial wind and solar installations.

            The only thing being left to future generations in that scenario of being relying on a weather dependant system of industrial wind and solar generation sources is natural gas pipelines, natural gas power plants and a loss of wildlife that may drive certain species of predatory birds closer to being endangered if not extinct.

          2. One last comment on multi-generational investments.

            Geologists are estimating available natural gas that can be brought to the surface with existing technology will last 100 years at current burn rates. That is not a cost based assessment that is just an assessment based on the best data they currently have regarding in-ground inventory

            Increasing our dependency through the increased installation of large scale industrial wind and solar with natural gas plants will only increase our burn rate. Lets say the inventory drops from 100 years to 80 years for discussion purposes based on an ever increasing burn rate.

            So how does purposefully decreasing the existing supply of natural gas from 100 years from 80 years represent an investment for our children? Wouldn’t it be better to leave that natural gas in the ground as long as possible since natural gas is a multi-purpose resource? We use natural gas as an industrial feed stock for many things we now take for granted in our daily lives.

            Burning natural gas faster now may mean we are potentially setting up a world for future generations where their quality of life will decrease not increase.

            Just some things to consider………

    2. We call the lowering of reactor power to 85% “Economic Dispatch” and it usually happens on weekends in May-ish.

      1. @Bonds 25,

        Thanks for the clarifications.

        I was wondering if that decrease to 85% had to be approved by the NRC or is that operational mode already included in the license basis? And apologize if this question has been asked before.

        1. 85% is the magic number because lowering Reactor power beyond that involves taking feed water heaters off line. Being a BWR, we can achieve 85% with just adjustments to recirc flow. So its not a change to “mode” per say, just an adjustment to recirc flow thus reducing RX power……..and of course megawatts.

          I’m an HP, so this is knowledge I’ve attained from past “Economic Dispatches” and my introduction to boiling water reactor systems class. We usually take this opportunity to do some needed maintenance in steam effected areas for ALARA purposes (example being Furmanite leaking valves in the heater bays) since dose rates are lower at 85% compared to 100%.

          As for the NRC approval need……that I’m not sure of. Sorry

          1. Thanks for the info. I have been wondering about the methods used to get down to 85%.

            Appreciate the insight.

          2. I’m guessing the May power reduction is due to Spring runoff. (Snow melting in the Spring) Is this accurate?

  10. There are also Environmental restrictions on when and how much water can be or must be allowed to go past the dam(s). Thus, there could be times when the dams could not pass any more water or even time when the dams are dumping water and not even making electricity from the dumped water. Electrical generation charts do not show everything and can not be exactly correlated – as the fish are more important than electrical generation.

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