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  1. Other than a required ancillary services market and stated reserves, ERCOT runs an energy-only market. There is no market for capacity.

    For details, see

    This has worked for the expected summer high load. Since adopting the energy-only rules for bidding by generators there have been no rolling blackouts. Until this February.

    I don’t particularly blame ERCOT or even the insufficient winterizing by the generating companies. I do blame, in retrospect, the Texas Railroad Commission for failing to insist that natural gas pumping and piping companies be capable of JIT delivery despite the unprecedented cold.

    As a footnote, I point out that the nuclear power stations in ERCOT Texas compete quite well in the energy-only market; there’s no need for a capacity market.

    1. @David B. Benson

      I don’t think capacity markets are a solution. As you noted, nuclear plants can comfortably serve in energy-only markets (they produce massive amounts of energy over extended periods) as long as energy prices are high enough for enough hours every year. But if energy prices are too low or too unpredictable, new cones won’t be built.

      Current nuclear plant owners in Texas are rewarded handsomely and more frequently under conditions where the system approaches instability. Scarcity pricing is good for their revenue.

      Question I am posing in this piece is whether or not that situation is acceptable to electricity customers. Does it produce the results that they want from electricity supply system?

      1. ERCOT Texas is also unusual in enabling a multiplicity of retail plans. Some do dollar cost averaging over a year. Customers with such plans won’t notice, much, this fiasco in their electricity bills.
        Others choose wholesale+ plans. They are the ones stuck with very large electricity bills.

        Many were seriously affected by the inability of the rolling blackouts to actually roll. The lack of generation was too severe.

      2. Capacity markets provide money for new power plants to be built. These are (surprise) inexpensive gas-fired plants…that’s all the money capacity markets can supply. So now you have an extra power plant. What about the fuel supply for that plant?

        My recent book, “Shorting the Grid,” describes how capacity markets do nothing, nada, zero—for winter fuel security.

        In a short form, this November blog post updates “Shorting,” and gives somewhat of an overview of earlier material. In “Shorting,” the section on winter reliability starts with the chapter: Winter Lights. Meanwhile, here’s the blog post.

        People constantly think that a new auction (capacity! pay for performance!) will solve the reliability problem. New auctions are bandaids, and they are kludges. They are part of the problem, and not the solution.

      3. While I am a staunch free-enterprise, the whole capacity market scheme (aka price gaming) is Enron all over again. No reinvestment of windfall gains in better capital or utility debt management. No consumer choices to upgrade to efficient and cost effective arrangements. No real wisdom of utility choices in energy mixes and technology. Certainly no investment in a truly cost effective national grid. Just price gouging when consumers least need it, and hidden utility cosys.And where do you think Enron decided to build it’s new corporate campus before they went belly up?

  2. Will the lessons be learned? It seems to survive an event like this in the future natural gas storage at some number of strategically located gas plants would be the solution. Texas relies so much on natural gas that you have to be able to heat and generate through the duration of the vent. Not sure this is practical.

    During the extreme polar vortex , I think it was 2014 a lot of gas plants in the NE were dual fuel and switched to oil. There were also reserve oil burners used.

    And if gas was available for the generators would that have been enough with near zero wind? How much does Texas credit wind in their planning?

    But the heavily politicized finger pointing won’t solve anything

    1. Apparently their LNG plants were disabled too. We hear that Boston again had to import it from Russia despite the much vaunted capacity of TX to export cheap gas via fracking. Since the EROIA of LNG is very low compared to modern nuclear or even wind, I suggest using nuclear with cogen to process the gas would have been very shrewd. Better yet ethane, which is ordinarily burned off. It is easier to liquify than methane and contains more heat content per tanker, and turbines have now been designed to burn it. Much propane and butane would have been obtained for auto gas, a clean gasoline substitute, well within the reach of Texans.

  3. Excellent point about the waste heat.  It’s a much-overlooked resource which really ought to be included in integrated resource planning.

    The Chinese and Russians are more forward-looking than we’ve been.  The AP1000s at Haiyang are being connected to a district heating system, and the floating NPP Akademik Lomonosov is supplying heat as well as electric power.

    Nuclear district heating systems would go a long, long way to displace natural gas.  I ran the numbers once, and an all-nuclear USA would have more than enough waste heat to replace every bit of NG burned in the country even in January.  As in, several times as much.

    1. Don’t need nuclear to follow your idea. A CAES concept developed in Macintosh AL was ready in the 90’s but was deemed too thermally inefficient to replicate. It now turns out that seperating the heat from the compressed air brings the thermal efficiency up to modern gas turbines, and certainly warrants underutilized off peak electricity to compress the air. Salt deposits from Texas to Alabama provide endless opportunity to site CAES adjacent toelectris and gas grids. Would have saved a $60 bil effort to create a Sourhern gas grid in the late 90’s, which was stranded when Bush II decided to grant coal a moratorium on clean air regs for 15 years! Texas of course, rejected investment in CAES, preferring dodgy wind, for the pleasure of subsidizing Texas folk to use their washing machines and TV’s at night when wind was strongest.

  4. So basically, wind and solar were not to blame because we already knew beforehand they’d be useless in a blizzard. Got it. I guess it takes a Ph.D to explain that. They are useless but its ok because we knew that already.

    Here in Holland the capacity factor of solar PV averaged around 2% the last 3 months. No blizzards, maybe 4 days of snow. Quite a mild winter otherwise.

    Hey its ok because we already knew solar PV wouldn’t be there 98% of the time. Cue the Ph.D.

  5. The news media is reporting that the two-unit Comanche Peak nuclear power plant was as little as 3 minutes away from automatic reactor shutdown, and the entire grid as little as 4 minutes and 37 seconds away from total collapse, according to ERCOT. These statements raise more questions than they answer.

    There are a number of potential reactor trips that could have been experienced, e.g. loss of load/turbine trip or loss of offsite power leading to any of a number of trip functions. During the 2003 Northeast Blackout event, nine US nuclear power units experienced rapid shutdowns (reactor trips) as a consequence of the power outage while six nuclear units experienced significant electrical disturbances but were able to continue generating electricity. Indian Point Units 2 and 3 tripped on under-frequency to the reactor coolant pump buses at around 58 Hz. This trip is a design feature to protect against unacceptably low core flow and to prevent the nuclear fuel rods from experiencing localized fuel failures (departure from nucleate boiling). It is public knowledge.

    It is also public knowledge that ISO New England has emergency operating procedures and training to shed up to 50% of the load in 10 minutes to respond to catastrophic natural gas pipeline events. It is not clear under what set of circumstances and what combination of equipment failures and human errors that frequencies as low as 58 Hz might be reached, resulting in the automatic trip of the Seabrook and two operating Millstone Units. Whatever analyses might have been performed by national labs remain FOR OFFICIAL USE ONLY.

    Suffice to say that the key lesson to be learned from all of these experiences is that intermittent sources of electricity such as wind and solar AND just-in-time fuel sources such as natural gas are unreliable and/or not resilient. Ironically, FERC just closed the docket on resilience. A half-dozen nuclear units may close this year, and up to one dozen units by 2025. You be the judge on the wisdom or lack thereof regarding our nation’s grid.

    Note: the commenter is a former manager of safety analysis, previously responsible for LOCA analysis, non-LOCA analysis, containment analysis, and risk assessment for the Connecticut Yankee and three Millstone units. Opinions expressed are those of the author and do not reflect the views of past or current entities.

    1. The wind and solar enthusiasts defence is rather hilarious. Oh yes, our energy sources, which are dependent on the WEATHER, and are by definition unreliable (ZERO dispatchability on demand) are in no way responsible for issues during extreme WEATHER. They need Ph. D.s to explain this.

      The nuclear plants seem to me a classic case of insufficient design basis – equipment, insulation, heat tracing, HVAC etc. were simply not designed for such temperatures/wind speed combination, so unsurprisingly there will be failures when one goes far outside the design range. Anything can be designed for – 100 year blizzard, 1000 year blizzard, 10000 year blizzard. Just costs ever more money. At some point one has to decide on a residual risk level. If solar panels and wind turbines must be designed for a 1 in 10000 year blizzard, rest assured they wouldn’t be cheap. Looking at some photos of damaged solar panels from hailstones, its pretty clear they aren’t even designed for a 1 in 20 year hailstorm.

      But the reactor DNB thing – are you saying that a few percent drop in the coolant flow rate causes issues with critical heat flux?!

      Surely these plants aren’t designed with such poor thermalhydraulic margins?

      Also, instead of tripping the reactor, wouldn’t it be better to decouple from the grid and run on islanding mode with the reactor throttled down automatically?

      Throwing out your main energy source (reactor) as soon as external energy (grid) is not available seems to me a poor design philosophy. Similar to the Japanese plants automatically tripping on seismic – not smart as large seismic likely trips the grid, now you lose 2 sources of energy and are dependent on the plant diesels.

      1. Nuclear power plants are designed to have 95% confidence or greater of 5% probability or less that an anticipated design basis transient such as a loss of coolant flow would result in DNB. And that is typically to the worst location of the hottest fuel rod in the hottest fuel assembly.

        Some plants are designed to ride out a loss of grid event, but for how long, and to what purpose if they are not generating power? Plants will typically disconnect from the grid on under/degraded voltage to protect safety equipment. I can not describe 60 years of nuclear reactor safety philosophy in 250 words or less. Not tripping the reactor when safety limits are challenged is against all good principles of safe operation for fuel, equipment and the public.

      2. Don’t get me wrong, I’m not saying don’t trip if there’s a risk of core damage, rather the limits being (apparently) rather fragile.

        This seems like a poor design to me – this shouldn’t be a twitchy formula 1 racing car where everything mechanical and thermal is designed at 95% of the limit. This should be more like a reliable long haul diesel truck with big margins on engine mechanics and cooling.

        Don’t get me started on the probabilistic stuff, claiming a 1 in 10000 year core damage frequency and then saying there’s a 1 in 20 we’re wrong due to uncertainties. Not a convincing argument to me. Your core damage frequency is now determined by the uncertainty.

        I’m a thermal-hydraulics guy. When I see a 5% margin to critical heat flux I nearly get a heart attack. Not what I want to see in a design. If my car has a slight cooling flow blockage and gets 95% of the normal cooling flow and that overheats the engine I’m not going to be a happy customer.

        These PWRs have very high power densities and seem to be a glass giant operating right up to the margins. Given uncertainties in local power production (changing fuel isotopics with burnup, control rod movements etc.) and local flow (complex fuel assembly design, fixed orificing) this is clearly an area where we want to use big margins.

        The more I learn about PWR the more I think they are formula 1 racing cars operating close to various limits, rather than the gentle giant long range diesel trucks they should be.

  6. “To what purpose?”. Don, wouldn’t a progressive power-down allow the operator to burn away any accumulation of I-135? Tripping the reactor from full power and staying down for several hours would (allow accumulated I-135 to decay to the neutron poison Xe-135 and) remove its capacity to generate for several days.

    1. Exactly – avoid iodine pit. Also a power operating plant (even just on house load supply) can get back on the line faster.

      From a safety viewpoint I think this is much superior to just a knee-jerk trip of the reactor as a “precaution” to every upset condition.

      Islanding with throttle back on power will increase thermal margins, not decrease them, as coolant flow per unit thermal output is increased. For PWR it would be likely on constant coolant flow so a low core dT and very high T/H margins. For a BWR you can eventually just trip the recirc pumps and run on natural circulation (need small feedwater supply of course).

      Secondly, islanding allows another layer of defence in depth for both the heat sink and plant power supply. That is a huge deal in safety terms. The islanding/throttle back can be fully automatic and can be a non-safety system. If it fails (or if an upset condition is so severe as to exceed trip points) then the safety systems could still trip the reactor as a safety backup.

      Costs of this option are typically low since systems are required for startup and shutdown anyway (like aux/startup FW/boilers and so on).

      For LWRs, loss of plant power and loss of heat sink are proven to be much bigger risks than reactor criticality control. Can’t shut off decay heat… or run important emergency systems on fairy dust imaginary electrons.

      1. I will not perpetually argue with you except to say that I have 40 years of nuclear reactor safety analysis including conventional design basis safety analysis and risk assessment at a nuclear utility and regulatory body. The trade-off in risk between reactor trip and loss of heat sink is minor and is not a reason for not tripping the reactor or separating from the grid on degraded/undervoltage. The risk of permanently damaging safety equipment due to undervoltage conditions, and the equipment being damaged and not being available should the transient progress, far outweighs what benefit of islanding might afford. The reaction is not knee-jerk. I have been talking about an automatic reactor trip at 58 Hz that occurs in minutes due to a degraded grid. You can not manually override it. These trips have been established on sound engineering basis by the NSSS vendors, and approved by the US NRC and its predecessor. You’ve nit-picked on some minor point of my comment, while missing the forest for the trees “…intermittent sources of electricity such as wind and solar AND just-in-time fuel sources such as natural gas are unreliable and/or not resilient…” compared to nuclear power plants. If you want to argue that point, fine.

      2. @Cyril R

        Please avoid making judgmental comments that include phrases like “knee jerk trip of the reactor as a precaution to every upset condition.” That statement cannot be true, given the decade+ record of a US fleet-wide average of about 0.5-1.0 unplanned scrams/year.

        There are plenty of upset conditions that do not initiate a shut down signal. Many have time delays that allow temporary conditions to be cleared without scram.

        But when you have a very large, high value unit, you work hard to make sure that it doesn’t suffer permanent damage. Professionals like Don have played a huge role in creating nuclear energy’s incredible record of safety and reliability. Their work and success is what allows us to be ready to evolve into slightly less restrictive paradigm.

  7. Let me describe a success story that, while not a station islanding situation per se, perhaps gets to the point that several commenters wish to make.

    During the 2003 Northeast Blackout, power flows went back and forth between New England, New York, and New Brunswick. The grid frequency was oscillating. Interties with New York were cut by relay action. Most of New England and the Maritime Provinces islanded.

    I next refer to publicly available testimony of the September 11, 2003 Energy & Technology Committee of the Connecticut State Legislature to describe the response of Millstone operators.

    The first indication in the Millstone Units 2 and 3 control room occurred at 4:11 pm when numerous internal indicators and alarms began showing significant grid instability on the 345 kV system. Both units noted large swings in grid frequency and voltage. When the operators saw the grid frequency changing the way it did, they knew that they were one of the few generators left on the grid in the area. To be able to change grid frequency, the operators have to change turbine speed by changing the control valve position. These are situations that the control room operators train on and they responded extremely well in that critical first couple of minutes. As part of the plant’s stabilization, Units 2 and 3 operators took manual control and reduced power respectively to 98 and 83 percent. This reduction in power helped to match station generation with system load and thus helped to reduce grid oscillations all across New England.

    The Chairman of the Department of Public Utilities Control, Donald Downes, states that “Millstone stood like a rock and was probably one of the main reasons that the system here survived as well as it did under the circumstances.”

    So, yes, there is capability to affect the course of a Blackout. No automatic reactor trip setpoints were reached in New England that day. Seabrook stood. Setpoints were not reached to separate power to emergency buses from the grid. But run a thousand different scenarios in different parts of the country under different circumstances would there be the same outcome? Yes, it would be great if the next generation of nuclear plants were specifically designed and licensed for islanding.

    So, my apologies to Roger Clifton and Cyril R. if I did not listen closely enough to your comments.

    Full disclosure: I left Northeast Utilities and my affiliation with Millstone prior to the 2003 Blackout

  8. Thanks Don. That’s an encouraging story.

    You’re right we were talking past one another, actually seem to agree on just about anything really.

    Islanding mode seems like a great capability to have as an add-on to more safety-related/limited systems, and to prevent such systems from being called on for the more common and expected transients. It won’t deal with all scenarios but will help a lot in the more common ones.

    The newly proposed plants all seem to claim such capabilities – though it is of course a case of “so they may claim” at the moment.

    How does NuScale or BWRX300 do in terms of islanding or self standing operations? Black start capabilities?

    Gen IV seems well suited to a more robust and tolerant architecture. There’s typically a lot more margins on the fuel, with either high temperature capable fuel or liquid fuel design, the latter being my own speciality. Getting rid of fuel thermal and critical heat flux limits altogether is a big deal, I’ve found. The reactor core becomes just a glorified heat exchanger with internal heat generation in the liquid, a well understood though bit peculiar science. Such reactors are much more amenable to rapid load changes and frequent stop/starts, part of the reason for their focus during the aircraft reactor program… back when people were still pioneering and innovation wasn’t just miniturizing an old school PWR and call that novel.

    I’m forward looking and often lament the paths not taken. The smartest and talented people I know are nuclear engineers, but we are stuck in a path dependency and saddled with baggage like a mule, stuck in a system that neither wants nor accomodates real change, and rewards process and red tape over real innovation and progress.

    I’m sure you’ll agree, wind and solar offer no real alternative… with zero dispatchability, low capacity factors and high use of land and nonrenewable resources, these are not practical energy sources for a modern industrialized civilization. Increasing our dependence on the weather is backwards, running contrary to the most major of achievements of humanity the last millennia.

    1. Cyril R. —- NuScale Power states that their SMR has cold start capability using a small on-site startup unit.

  9. Don
    From what you describe, it reads like the islanded part of the grid was dealing with an over-frequency. What would be the operators’ procedure for dealing with an underfrequecy, which is generally more common event?

  10. After New England and New Brunswick islanded during the 2003 Blackout, frequency oscillated between 60.4 and 59.6 Hz as measured at the Northfield Mountain pumped-storage facility in western Massachusetts. The Connecticut transmission voltage reached high levels: more than 385 kV on the 345 kV system, and 130 kV on the 115 kV systems. Some minutes later in the Blackout, when other equipment was lost and loads came back on, the voltage on the 115 kV system fell to approximately 100 to 105 kV. The Connecticut Valley Electric Exchange (CONVEX) eventually ordered manual load shedding to bring generation and load into balance.

    In direct response to your question, I do not currently have access to nuclear power plant abnormal/emergency operating procedures for under-frequency/degraded grid events. Available options to plant operators are much more limited since the concern becomes primarily one of mitigation and protecting plant equipment.

    My concern goes back to the original February 25th posting regarding catastrophic gas pipeline events in New England. The just-in-time aspect of natural gas generation, combined with the fact that gas now represents about 50% of the electricity production here, but at times as high as 70%, creates an inherently unstable situation against catastrophic gas pipeline events. That was the main message.

    1. I am curious about the “islanding” comments. Are there new equipment designs that make it easier for Operators to battle Xe transients? BOL vs EOL significantly different and probably not trained on these days due to the lack of transients experienced now.
      Last training I was aware of on Reactivity control you would never get a supervisor to buy in on what it took to manage a large Xe transient. Mid cycle to EOL, Go from 100 to 30% rapidly and maintain it? Put on your hat and spurs and giddy up.
      Is life better now with new designs which can be retro fitted?

  11. Thank you for that Don.
    I agree with you about plant not realising their risks, but many don’t know about things until it happens. Fukishima and the tsunami is a case in point, though that is more a black swan event. I can relate a lot smaller one from my own experience. I had hooked up an atmospheric pressure transmitter at a remote site. This was to monitor a minor piece of equipment. The readings back was by a radio link. When they did an instrumentation on pumps upgrade a year later, they needed atmospheric pressure. They just used the signal from my transmitter without looking where it came from. Then the radio link went down. All hell broke loose (fortunately nothing tripped, until they got everything back under manual control. Now there are two hardwired transmitters with voting.

  12. I agree that nuclear is caught in a mindset. For one thing, liquid air energy storage can increase the effective thermal efficiency of PWR and meet rapid demand response, in a way to anticipate ‘islanding’, scrams, load shedding, and the inconvenience of ramping instead of utilizing the reactor at maximum capacity factor. I have considered reviving the famous Oyster Creek reactor in NJ on this basis, which was shuttered for unwillingness to build a long overdue cooling tower. Your thoughts?

  13. Exelon filed a permanent cessation of operations letter for Oyster Creek. This is a one-way door; it is not possible to “revive” an operating license for a plant that has filed a cessation letter. They could conceivably apply for a new license but considering the plant began commercial operation in 1969 there is no way such would be approved.

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