Oyster Creek Cooling Towers

[ascend68]

The NJ state senate held a hearing on proposed legislation to force Exelon to build cooling towers. The committee was split 3-3 and postponed any final decision until February. Exelon stated that if forced to build cooling towers they would shut the plant down. I'd like to hear people's thoughts on this topic. Do you believe Exelon will shut down the plant? Is it economically feasible for them to actually build the cooling towers? Will the NJ senate force Exelon's hand? Many jobs and 321 million dollars of NJ tax revenue are on the line and I would be shocked if in this national economic climate they would force a shutdown. What are your thoughts?

[JustinHEMI05]

I think its clear, that if it isn't economically feasible to build cooling towers, they will shut the plant down. If it is, they won't. I also don't think Exelon would bluff by saying that they would shut the plant down if forced. They just announced the shut down a bunch of conventional units for economic reasons, so if forced to spend a ton of money on this plant, I could definitely see them shutting it down.

[HydroDave63]

The watermelon greenies are also aiming their cooling tower sights on a certain INPO 3 Region IV plant as well

[withroaj]

Alright, everybody.  Brace for ignorance.  I have questions.

Many of you out there already know my level of understanding of power generation.  I don't really know anything at all about "the grid," except that my lights turn on and I pay a bill to my local utility wherever I live. 

I wonder, as a response to this post, what happens when a big plant shuts down.  I know that plants shut down for outages or due to trips all the time, but is there an appreciable increased load on other plants/units when one plant/unit shuts down?

What is the long-term impact on other, nearby plants when a plant decommissions?

[thenuttyneutron]

Alright, everybody.  Brace for ignorance.  I have questions.

Many of you out there already know my level of understanding of power generation.  I don't really know anything at all about "the grid," except that my lights turn on and I pay a bill to my local utility wherever I live.  

I wonder, as a response to this post, what happens when a big plant shuts down.  I know that plants shut down for outages or due to trips all the time, but is there an appreciable increased load on other plants/units when one plant/unit shuts down?

What is the long-term impact on other, nearby plants when a plant decommissions?

Grid Load and power generation must be balanced.  When a plant goes down, the load dispatcher must get power from somewhere else.  There is some spinning reserve that can take the load in the event of a trip at a base load nuke.  If the spinning reserve can't pick the load up fast enough or there is not enough reserve, people will get cut off to maintain the grid.  Once the power on the grid is enough, the people can get put back on.  Remember the rolling blackouts in the early 2000's in California?

The 2003 blackout was a bad event that was caused by a cascading failure of the grid.  This is the worst case consequence of grid problem.  The thing that sucks about nukes is the reliance on offsite power to startup and in most cases run.  There are certain situations where you can get what is called a load rejection and still survive.  In this situation, your house loads are all on your own main generator and you are no longer on the grid.  I have only seen this on a simulator and it can't happen at 100% power for me.  In the event of a loss of offsite power at 100%, the RX would trip before it could get low enough in power to not cause an automatic trip by a safety system.

[HydroDave63]

I wonder, as a response to this post, what happens when a big plant shuts down.  I know that plants shut down for outages or due to trips all the time, but is there an appreciable increased load on other plants/units when one plant/unit shuts down?

Instantaneous trip, unscheduled...frequency changes based on load of generation as a percentage of its contribution to the inteconnection. Since that's the Eastern Interconnection, it wouldn't even wiggle the chart recorder pen. Drop something like STPEGS in the ERCOT, probably see frequency go to 59.5 for a minute or so before governor action and AGC push back to 60.

Long-term loss like a decommissioning: Depending upon the fuel profile of generators near major consumers, energy bid prices will go up based on what other fuel prices and capacity factors are nearby. Large baseload coal units can cost anywhere from $10-30/MWH, simple cycle gas with $6/MMBtu gas somewhere around $60/MWH, newer comb. cycle gas around $35/MWH, baseload nuke around $25/MWH. Since in the majority of energy markets a nuclear unit with decent capacity factor is one of the cheaper sources of power, the cost will go up.

[withroaj]

...
Long-term loss like a decommissioning: Depending upon the fuel profile of generators near major consumers, energy bid prices will go up based on what other fuel prices and capacity factors are nearby. Large baseload coal units can cost anywhere from $10-30/MWH, simple cycle gas with $6/MMBtu gas somewhere around $60/MWH, newer comb. cycle gas around $35/MWH, baseload nuke around $25/MWH. Since in the majority of energy markets a nuclear unit with decent capacity factor is one of the cheaper sources of power, the cost will go up.

...So you're saying that decommissioning has more of an impact on the energy market than on the generation/transmission hardware, right?  Does that mean that our general energy infrastructure is over engineered for the moment (however insufficient to cope with the expanding energy consumption that accompanies societal development)?

For some reason, this topic is one of the things that shows how NNPP operation is significantly less than a drop in the bucket.  When I think of dropping a generator I think of the plant/operator reacting to maintain continuity of power to...  Either way I can't even fathom ACTUAL energy infrastructure.

[thenuttyneutron]

I think of the plant/operator reacting to maintain continuity of power to...  Either way I can't even fathom ACTUAL energy infrastructure.

I can tell you how it is done for me.  I am going to make about 955 MWe on average.  On a good cold day I can get that to about 965 MWe and a hot summer day it goes down to about 950 MWe.  My house loads are about 40 MWe.  We use all we need and put the rest on the grid.  The load dispatcher talks to us every day.  We have a voltage schedule that we try to maintain.  I can try and meet it by changing the excitation on my main generator.  In some cases I can't meet it (very rare) because of limitations to my essential bus voltages or even my generator capability curves.

Since I work at a base load unit, I don't care what the frequency on the grid is.  I am maintaining a load on my generator and it won't go any faster or any slower than the grid.  Only when there is a major power/load imbalance (main turbine is not matched to the RX) will my turbine go to manual and then try to maintain a frequency.

I only react to problems by either punching out (trip) or trying to stabalize the plant during a transient.  I can not think of a situation where I would ever try to maintain the grid by trying to keep the power flowing from me to the grid.  I don't care about the grid if I am in a transient.  I only care about my plant and keeping the public around me safe.

[HydroDave63]

...So you're saying that decommissioning has more of an impact on the energy market than on the generation/transmission hardware, right?  Does that mean that our general energy infrastructure is over engineered for the moment (however insufficient to cope with the expanding energy consumption that accompanies societal development)?

In no particular order:

The electrical infrastructure has to have slightly more capacity, both in generation and transmission, in order to make up for changes in demand, trip of generation or relaying of transmission lines, planned transmission outages, etc. Overengineered...not by much. Basically, the guys with slide rules in the 60s who planned and built most of the major projects with tons of design margin, are the only reason we aren't living with rotating blackouts as in Iraq.

Energy market - after we take a cheap generation source out of the mix, prices go up. The bidding on energy goes on worldwide 24/7/365. PM if interested in details.

Decommissioniing affecting hardware - When decommissioning a generating station, some utilities remove some or all of the switchyard. There are some devices in the switchyard (capacitor banks, reactor banks) that are useful for the transmission folks to maintain control of system voltages at key locations. Not having voltage support at Point B can make it nearly impossible to supply point D from point A, despite what greenies and politicians and marketers think.

[HydroDave63]

Since I work at a base load unit, I don't care what the frequency on the grid is.  I am maintaining a load on my generator and it won't go any faster or any slower than the grid.  Only when there is a major power/load imbalance (main turbine is not matched to the RX) will my turbine go to manual and then try to maintain a frequency.

That's not quite correct, because:

1. To pick up load, you put more steam on your turbine, which puts more torque on a rotating mass, and for a fraction of time, your excess torque changes speed to affect the phase angle of the magnetic coupling of your generator to Das Grid. Mo trons flow out. When torque equals sync'd with the grid, stable at new power output. But yes, 99.999% of the time you are at grid frequency, which brings us to your first point of

2. Yes, you do care what the grid frequency is, but may not be aware why. If the grid was at 61 Hz, you have protective relaying that will open your output breaker within a couple seconds, not to mention your various mechanical overspeed devices. If the grid was 59.5 Hz, that timer is a few minutes long. Grid at <58.0  and the turbine will trip in a few seconds.  Those low frequency trips are to avoid the LP turbine blade root cracking from sub-synchronous resonance. A pretty good presentation on this theme can be found at http://www.midwestreliability.org/04_standards/drafting_teams/ufls/BarryFrancisPresentation081024.pdf

3. You also care about grid voltage, and more recently the grid ops guys have to care about your switchyard voltages. To state it in nuke terms, they have to care about the offsite source to your Vital Bus. For grid operators out there, thats why you have NERC Std. NUC-001-1

[thenuttyneutron]

That's not quite correct, because:

1. To pick up load, you put more steam on your turbine, which puts more torque on a rotating mass, and for a fraction of time, your excess torque changes speed to affect the phase angle of the magnetic coupling of your generator to Das Grid. Mo trons flow out. When torque equals sync'd with the grid, stable at new power output. But yes, 99.999% of the time you are at grid frequency, which brings us to your first point of

2. Yes, you do care what the grid frequency is, but may not be aware why. If the grid was at 61 Hz, you have protective relaying that will open your output breaker within a couple seconds, not to mention your various mechanical overspeed devices. If the grid was 59.5 Hz, that timer is a few minutes long. Grid at <58.0  and the turbine will trip in a few seconds.  Those low frequency trips are to avoid the LP turbine blade root cracking from sub-synchronous resonance. A pretty good presentation on this theme can be found at http://www.midwestreliability.org/04_standards/drafting_teams/ufls/BarryFrancisPresentation081024.pdf

3. You also care about grid voltage, and more recently the grid ops guys have to care about your switchyard voltages. To state it in nuke terms, they have to care about the offsite source to your Vital Bus. For grid operators out there, thats why you have NERC Std. NUC-001-1

I think you are splitting hairs a bit too much.  You are right that I have protective relays for important motors when the frequency is not about 60 Hz.  What I am saying is that I don't control grid frequency.  For every day operations I do not give it any thought because it is out of my control anyway.  Also notice my last sentence about the main turbine.  That last sentence covers abnormal stuff.  Yes I have Overspeed, BU Overspeed, and electronic overspeed devices.  If those ever actuate, I will have a seriously bad day at the power house.  

The Power/ Load imbalance comes in fast and can catch turbine before I get a turbine overspeed trip.  What trips me is the RX trip due to a RPS actuation.  Regardless of what the turbine is doing, I have 2817 MWt to put somewhere.  I don't have the capacity to handle it all through my turbine bypass valves or safeties.  RPS will kick in probably on high pressure first.  It will catch other RPS setpoints but it is pointless to argue what setpoint hit first because the end result is the same.  The RPS then causes my turbine trip.  Don't confuse cause and effect.  The results however are the same.  I hear my safeties lift and have a pissed off plant in a transient.  I will do my immediate actions the same way for either case and then work the EP.

If my plant has a turbine trip at 100%, my RX will trip on a safety system called ARTS.  Same thing occurs for me, I do IA and then go to the EP.  Regardless of what does it to me, I react to symtoms.  If my RX trips, I will always have a turbine trip.  If my turbine trips above 40% power, I will always have a RX trip.  I will do the same thing regardless of what did it.  This is why I don't care what casued it.  No matter what situation I am in, I react to symtoms with my procedures as I was trained.

Yes I have performed offsite S.T. many times and called the system load dispatcher for info on offsite lines.  I think you are reading way too much into what "I don't care" means in this context.  I care about voltage and frequency on normal event free days.  My priorities are to operate the RX safely and protect the health and safety of the public.  I will never let generation concerns come before that.  If stuff is not going right on the grid, "I don't care" means that I am carrying out actions to keep the plant safe.  If I have to trip and use my onsite sources, so be it.  If I am on my diesels and have no offsite power, when I get everything stabilized on my end, I will eventually get to a spot in my procedures to try and recover the offsite sources.  Until these actions occur, I really don't care about the grid because I have other higher priorities.

I think it would be better if we argued about imaginary power.  Do I burn more uranium when my MVARS are higher or lower?  I think I burn more uranium when my MVARS are higher.  I bet that will overspeed trip many pure electrical theory guys out there  

[HydroDave63]

True, true...wasn't meant to criticize your view, just wanted to refine a bit for benefit of the readers.

I think it would be better if we argued about imaginary power.  Do I burn more uranium when my MVARS are higher or lower?  I think I burn more uranium when my MVARS are higher.  I bet that will overspeed trip many pure electrical theory guys out there 

I'd agree that when the generator runs at a lagging p.f. , more uranium is burned, but this depends on where on the 'D curve' the generator is operated. If your generator would support a .8 p.f. leading, then that will burn more uranium than .9 p.f. lagging. The answer lies in "which p.f. ( MVARS higher or lower) results in the largest Apparent power output. MVA is the bottom bottom line in your uranium question.

[thenuttyneutron]

More Uranium is burned with higher MVAR because the currents are higher on the main generator.  (I^2)R losses means that I have to burn more to keep my same real power output

[thenuttyneutron]

I have heard of times for when Tukey point tripped and it caused a slight sudden change in the sound of the steam lines and turbine.  The plant was running fine and nothing bad happened on our end.

[HydroDave63]

Based on this discussion..it seems as if slight demand changes in the grid (within specific parameters) could actually be identified in the monitoring of plant systems, without actually looking at grid demands..Is this correct?

Grid demand to generator to turbine to steam to Rx..

I'd venture to say the closest correlation and rapidly changing parameter, looking at a  strip chart record over time, would be HP turbine outlet pressure. Rx power would follow, yes, but there will be time lag, with variables all throughout the secondary cycle such as MSR levels, feed heaters, etc.

Going back to nutty's bar bet on MVARs, one could probably use stator water cooling temp or H2 temp/pressure to get some weakly correlated data as well.

[LaFeet]

Basically  if we do not have the capability to generate sufficient power (including transmission loss, I squared R, and so on, etc.) than rolling blackouts and grid failures will occur.  Our current "Grid" system is woefully inadequate.... especially in handling losses from unit shutdowns during high power demands.

Either we revamp the grips AND build more power plants....... or we DRAMATICALLY reduce or loading on the system.

Come on WE are Americans     we gotta up the ante.  We have the technology to rebuild and improve the grids.... and we now how to build SAFE and reliable power plants ....

Nuff said  

[Fermi2]

Not really.

Having been at Fermi during the blackout period of 2003 about the only thing you see is Frequency Changes and maybe some turbine speed changes that are driven by frequency.

That's about it. I've been on a Unit when another Unit on the grid rejected about 800 MWe and to be honest outside of a blip on frequency that lasted about .00000001 seconds we didn't see it, and we were about 7 miles from that unit.

So far as spinning reserve. IIRC it's a NERC regulation you have to have either spinning or Connected via 2 "Hard" ie separate connections to 2 independent grids the ability to hanbdle the trip of your largest unit plus 10%.

So far as your own plant staying up after a 100% Load rejection, I know there are plants designed for it but I'm guessing they wouldn't be able to survive it.

[HydroDave63]

Indeed... Eastern Interconnection carries about 1,000,000 MW summer peak, so losing an 800 MW unit might run ya down to 59.99, just statistical noise lost in the grass. Losing 800 MW out West would run down to 59.96 or so.

[Fermi2]

Indeed... Eastern Interconnection carries about 1,000,000 MW summer peak, so losing an 800 MW unit might run ya down to 59.99, just statistical noise lost in the grass. Losing 800 MW out West would run down to 59.96 or so.

Good point. Not many know the Eastern and Western Grids are not connected.

By the way, Nutty Neutron is not entirely correct. The 2003 Blackout was not a classical cascading failure.

Mike

[thenuttyneutron]

Good point. Not many know the Eastern and Western Grids are not connected.

By the way, Nutty Neutron is not entirely correct. The 2003 Blackout was not a classical cascading failure.

Mike

So what was the 2003 black out then?  A power plant goes down.  Lines near a dirt burner sagged and caused a fault.  The fault caused other parts to overload and trip.  There was a computer problem that made things worst.  In the end it was a cascading failure.

http://en.wikipedia.org/wiki/Northeast_Blackout_of_2003

Read the time stamps of the entires.  

Captain Sully's plane event was not a "classical" Plane crash, but it was still a plane crash.

[HydroDave63]

So what was the 2003 black out then?  A power plant goes down.  Lines near a dirt burner sagged and caused a fault.  The fault caused other parts to overload and trip.  There was a computer problem that made things worst.  In the end it was a cascading failure.
http://en.wikipedia.org/wiki/Northeast_Blackout_of_2003

- Referencing the Wikipedia sequence of events, most of which is correct -

Well, the power plant trip was in about the 4th inning. Hours before that, even before the computer lockup at lunchtime....planned outage work began on one of the 345 kV lines in parallel with the Sammis-Star 345 that was the beginning of the cascade. Point being that the other two lines in parallel weer running at or above their 100% summer continuous ratings for an extended period of time. (inspiring NERC Std. TOP-007). The state estimator tool did not give a proper N-2 analysis [ there is still opportunity for anyone to make their first billion $ writing code for a state estimator that works correctly, btw ].

Anywho...the remaining lines in parallel load up and sag into the trees (vegetation management, one of the first places corporate beancounters everywhere cut back, that and equipment maintenance) and relays off as a hard ground fault. As more lines sag into the trees, the remaining lines in other loops to serve the Cleveland area carry more current, I²R builds up heat, more lines trip off.  From there, the Wiki timeline is essentially correct.

The point being that the Blackout didn't start as a computer glitch, a single faulted line finding a single lonely tree, one obscure coal plant tripping offline, etc. as various anecdotal stories would convey. This had several contributing root causes, well identified in  http://www.nerc.com/docs/docs/blackout/ISPE%20Annual%20Conf%20-%20August%2014%20Blackout%20EPA%20of%202005.pdf

[thenuttyneutron]

- Referencing the Wikipedia sequence of events, most of which is correct -

Well, the power plant trip was in about the 4th inning. Hours before that, even before the computer lockup at lunchtime....planned outage work began on one of the 345 kV lines in parallel with the Sammis-Star 345 that was the beginning of the cascade. Point being that the other two lines in parallel weer running at or above their 100% summer continuous ratings for an extended period of time. (inspiring NERC Std. TOP-007). The state estimator tool did not give a proper N-2 analysis [ there is still opportunity for anyone to make their first billion $ writing code for a state estimator that works correctly, btw ].

Anywho...the remaining lines in parallel load up and sag into the trees (vegetation management, one of the first places corporate beancounters everywhere cut back, that and equipment maintenance) and relays off as a hard ground fault. As more lines sag into the trees, the remaining lines in other loops to serve the Cleveland area carry more current, I²R builds up heat, more lines trip off.  From there, the Wiki timeline is essentially correct.

The point being that the Blackout didn't start as a computer glitch, a single faulted line finding a single lonely tree, one obscure coal plant tripping offline, etc. as various anecdotal stories would convey. This had several contributing root causes, well identified in  http://www.nerc.com/docs/docs/blackout/ISPE%20Annual%20Conf%20-%20August%2014%20Blackout%20EPA%20of%202005.pdf

All of these things occuring by themselves would never end up being so bad.  The combination of events is what did it.  Any large complex system can be brought down if you hit it hard enough in the right spots in a short amount of time.  At some point the stress on the system was too much for it to handle and it all unravelled.

On Wiki they mentioned that they may have saved the grid if they had cut off Cleveland.  How often do large areas have to be cut off for the grid?  I do know that there are days in the summer where they have "orange grid risk" days.  On those days, we will stop some jobs in the power house just to reduce the risk of a plant problem.

I was in Texas when this all went down and I remember seeing the carpet of people on the bridges of New York all trying to get off the island on the TV.

[HydroDave63]

On Wiki they mentioned that they may have saved the grid if they had cut off Cleveland.  How often do large areas have to be cut off for the grid?  I do know that there are days in the summer where they have "orange grid risk" days.  On those days, we will stop some jobs in the power house just to reduce the risk of a plant problem.

Although the  Regional Reliability Organizations, Balancing Authorities (one or more member utilities) and even the lone Dispatcher have the legal authority to shed firm load as needed to maintain system stability ( fancy terms for turning off a lot of people's power ), it is not a decision taken lightly or quickly. Paralysis by analysis. In addition to lots of angry phone calls, there is DOE reporting if the manual load shed was 100 MW or greater. No one likes to have to spend a lot of time talking to D.C. after one of these.

To avoid this hassle, and also improve grid stability, smaller blocks of load are spread in non-contiguous areas. After an hour or two, rotate the load shed to other blocks, and restore the first, etc. Doesn't happen too often. Back in the Enron-induced Calif. energy crisis of 2000-2001, there were some rotating load sheds, but I'm not sure if there are any news stories that could be Googled to show how many were affected at the time.

[Rennhack]

BEST DARN THREAD IN YEARS!!!!!!!!!!!!!!,...THANK YOU EVERYBODY

Usually my IQ drops when reading the PolySci.  I just gained a few points back.

[JustinHEMI05]

The watermelon greenies are also aiming their cooling tower sights on a certain INPO 3 Region IV plant as well

I agree with Marssim because this thread has been very educational for a rookie like me.



And to Dave's statement above, there is grapevine talk about making my plant turn their cooling towers back on, even though we had planned to tear them down. The greenies really need to get educated, but considering I have yet to meet a rational greenie, that isn't likely to happen.