Best New Reactor Design

[Roll Tide]

Roll Tide,

I could go on and on with specific details but until you get a BWR license it would be pointless.  Forgive my lack of patience... I have a small pet peeve about people speaking about subjects they know little about.

Both reactor designs are safe.  I take professional exception to your comment of your community not wanting a BWR in their backyard.

As a previously PWR licensed RO, my understanding of a BWR is greater than that of the general public. I also have worked at a BWR, but not in OPS. When I was a contract HP tech, I experienced a vast difference in dose received by the workers at BWRs vs. PWRs. PWR off-gas releases should have more impact than BWR liquid releases, though both have been evaluated as acceptable levels.

As a former Navy Nuke, I realize that I am prejudiced against intentionally boiling in the core. Based on much of the PR from the Navy's days of building a nuke fleet, there is a similar consensus among relatively informed members of my community.

You are free to take professional exception to my preference for an AP1000 over an ABWR in my community, but the community already has their own desires. Before you ignore this group as an ignorant bunch of farmers, realize that many retired there after construction halted on Bellefonte. Few are operators, but many participated in construction of TVAN and other nuclear plants. Some came out of retirement to work the Browns Ferry Unit 1 Restart, along with the children and grandchildren of that generation of nukeworkers.

You don't have to be patient with me. But with the general public it would be useful. And these threads can be researched by members of communities considering new nuclear plants. A proponent of the ABWR should provide a defense of that design that could be followed by the general public, or at least by a Nukeworker.

[BuddyThePug]

If you're talking Gaseous release the release rate at most BWRs is roughly the same as at a PWR. Liquid releases are not even close as most BWRs never have to release liquid to the environment.

As for dose, hmmmm, I can tell you this, the BWR I came from had far lower doses than the PWR at which I currently work, and we never came near the total dose that I've seen in two outages here. I get more dose in an Aux Building tour than I'd get in a week of reactor building tours at my old BWR.

If you pop a fuel rod at a BWR its not all that major and doesn't effect outage dose rates like in a PWR.

I also got a lot less dose from being up-close and personal on the BWR turbine, than I did in the world of tiny boric acid leaks bringing CRUD to ya in the PWR world.

Once H2 injection went in, there were some streamers and higher dose rates in a few select portions of the BWR piping.

My major concern with BWR over PWR comes from the scenario where a BWR has been running a 24 month cycle MOX fuel, you're at EOL, and a 100% load reject occurs. Seems that with voids gone, the SDM is really low. Yes,a  PWR under similar scenario with a MS line break could get there as well, but load rejects are a lot more common.

Another minor feature about PWRs is that with the Rx vessel slightly below ground level, is the ability to gravity feed additional borated water sources.

Overall, having worked a bit in both types, I wouldnt have a problem living at 5281 ft from vessel center on either design. Remember, TMI and Davis-Besse are both PWRs. It depends more on diligence of Maint. and Ops. , we have good plant designs and containments.

On a side note, nuclear side VPs like to push for large units (1300MW if we can get it , yessiree) for perceived economies of scale (fewer bodies/MW). Which is fine, but it means that 1. You are the MSSC in your reserve sharing group, and someone is burning a lot of coal to provide spinning reserve, and 2. An extended outage at a 1300MW is much pricier than buying replacement power for a 600MW unit. If memory serves me right, most of the 6 to 9 month outages from hell have been at large PWRs, yes?

[M1Ark]

As a previously PWR licensed RO, my understanding of a BWR is greater than that of the general public. I also have worked at a BWR, but not in OPS. When I was a contract HP tech, I experienced a vast difference in dose received by the workers at BWRs vs. PWRs. PWR off-gas releases should have more impact than BWR liquid releases, though both have been evaluated as acceptable levels.

As a former Navy Nuke, I realize that I am prejudiced against intentionally boiling in the core. Based on much of the PR from the Navy's days of building a nuke fleet, there is a similar consensus among relatively informed members of my community.

You are free to take professional exception to my preference for an AP1000 over an ABWR in my community, but the community already has their own desires. Before you ignore this group as an ignorant bunch of farmers, realize that many retired there after construction halted on Bellefonte. Few are operators, but many participated in construction of TVAN and other nuclear plants. Some came out of retirement to work the Browns Ferry Unit 1 Restart, along with the children and grandchildren of that generation of nukeworkers.

You don't have to be patient with me. But with the general public it would be useful. And these threads can be researched by members of communities considering new nuclear plants. A proponent of the ABWR should provide a defense of that design that could be followed by the general public, or at least by a Nukeworker.

I am also a former navy nuke and former BWR SRO and curently a PWR SRO working with RO's like yourself and if you knew twice as much as them on BWR operations you'd still know next to nothing.

I accept that your biased towards PWR.  I'm telling you both designs are good.

[M1Ark]

My major concern with BWR over PWR comes from the scenario where a BWR has been running a 24 month cycle MOX fuel, you're at EOL, and a 100% load reject occurs. Seems that with voids gone, the SDM is really low. Yes,a  PWR under similar scenario with a MS line break could get there as well, but load rejects are a lot more common.

Most PWR people equate voids with boron concentration where boron concentration gets really low at EOC.  Voids never really go away.  BWR's have twice the number of control rods as a PWR and SDM is never an issue as it pertains to your scenario.  BWR Rx Power goes down on a MS Line break (it shuts itself down).  BWR Rx Power goes down when it losses vessel inventory such as a LOCA (it shuts itself down).

Another minor feature about PWRs is that with the Rx vessel slightly below ground level, is the ability to gravity feed additional borated water sources.

BWR's do not use boron.  SDM acomplished by rods.

Overall, having worked a bit in both types, I wouldnt have a problem living at 5281 ft from vessel center on either design. Remember, TMI and Davis-Besse are both PWRs. It depends more on diligence of Maint. and Ops. , we have good plant designs and containments.

Absolutely agree.

On a side note, nuclear side VPs like to push for large units (1300MW if we can get it , yessiree) for perceived economies of scale (fewer bodies/MW). Which is fine, but it means that 1. You are the MSSC in your reserve sharing group, and someone is burning a lot of coal to provide spinning reserve, and 2. An extended outage at a 1300MW is much pricier than buying replacement power for a 600MW unit. If memory serves me right, most of the 6 to 9 month outages from hell have been at large PWRs, yes?

Right again.  ESBWR designs only advantage is it's 1500 mw vs. 1000 mw for the AP1000

Which one flies better?  A helicopter or an airplane?  Depends on the application and what you are trying to accomplish.  This is similar to the BWR vs. PWR argument.  Both Rx designs are brilliant.  Really knowing both designs at a level higher than what's listed on Wikipedia allows one to appreciate the finer points of both designs.

[BuddyThePug]

If you are going to quote, please dont MISquote. OF course an MS line break lowers BWR power due to voids, that why I used it as a PWR example. No one said BWRs use boron, was used as a PWR example. NO one cited Wikipedia. -5 for some lack of reading comprehension there shipmate.

[Charles U Farley]

All right, Susies, this is almost like a Navy 8G versus 6G "You guys do what with your reactor?!?!" argument---I was hoping to never have one or hear one again.   

[Roll Tide]

I am also a former navy nuke and former BWR SRO and curently a PWR SRO working with RO's like yourself and if you knew twice as much as them on BWR operations you'd still know next to nothing.

Your Honor,
I motion that you strike the last from the record as non-responsive.


OK, lacking Judge Wapner's input, let's try again. You consider the BWR at least as good overall as the PWR. But you either can't explain it to a Nukeworker (typical or otherwise) or just consider it beneath you. Put a little effort into it, because I am sure I am not the only one who really would like to hear this.

[Roll Tide]

As for dose, hmmmm, I can tell you this, the BWR I came from had far lower doses than the PWR at which I currently work, and we never came near the total dose that I've seen in two outages here. I get more dose in an Aux Building tour than I'd get in a week of reactor building tours at my old BWR.

You must have used a lot of cameras on the BWR, and gone a lot of out of the way places on the PWR to get those results.

According to INPO, there are very few US BWRs with lower dose than any US PWRs (would be 0, but SGRP and head inspections takes a toll). The "one year dose normalized for a full cycle" data looks like this:

Best 10%                           PWR 39Rem               BWR 90Rem
Best Quartile                      PWR 44Rem                BWR 108Rem
Median                              PWR 60Rem                BWR 133Rem


Glad you didn't pick it up, but somebody did!                         

[M1Ark]

If you are going to quote, please dont MISquote. OF course an MS line break lowers BWR power due to voids, that why I used it as a PWR example. No one said BWRs use boron, was used as a PWR example. NO one cited Wikipedia. -5 for some lack of reading comprehension there shipmate.

Sorry Buddy,


I tried to answer you and Rolltide at the same time. I didn't mean to upset you.  It's hard to get ones point across correctly in an email or forum.  I agreed with most of what you said.

The Wikipedia comment was for Rolltide along with the inherently conservative design of the BWR over the PWR on an ESDE and LOCA.

The only thing you said that was not true was that SDM was an issue for a BWR at EOC.

Rolltide,

License class is 18 months long and I will not argue the specifics with you.  If you really must know talk to Broadzilla.  He will tell you the merits of each design in excrutiating detail.  I am an amateur compared to him.  You are correct in that dose to employees is much lower on a PWR.  But please don't equate this to dose to the public.  Broadzilla is correct in that my previous BWR had lower dose than my current PWR. Some BWR's built their secondary like a PWR and some built their secondary like an Egyptian Pyramid.  4 to 8 foot thick concrete floors, walls and ceilings.

When you weigh all of the facts both designs are good and safe and the economy of scale will prevail as to which designs will be built.

P.S.  Thanks for the Karma, Rolltide.

[tr]

Just to clarify, the AP1000 is actually an 1150 MWe plant (http://www.westinghousenuclear.com/AP1000/index.shtm).   

Regarding which plant is safer, the PWR core damage frequencies are as follows per MIT (http://web.mit.edu/erc/docs/scourse/28.FridayPM.Buongiorno.pdf):

EPR:   4x10(-7)
AP1000:  5.09x10(-7)

The BWR core damage frequencies are as follows per a magazine article (http://ecow.engr.wisc.edu/cgi-bin/getbig/ne/550/witt/literature/esbwr_mps_2005.pdf):

ABWR:  2x10(-7)
ESBWR: 2x10(-7)

As a former BWR SRO/STA, and a current PWR safety analyst, I'll take the BWR with its 2000+ gpm of ECCS flow directly to the core at operating pressure over a PWR with its 0 (for CE plant) to 1000? (W plant) of ECCS flow to the loops (with the associated business of how much actually gets to the core).  You can actually keep a BWR cool with the entire bottom head of the vessel gone, if it weren't for the fact that the assemblies would fall out!

There's also something about a BWR where once you put the rods in, the thing stays shutdown.  No worries about having to borate to get down to cold shutdown.

[M1Ark]

Well stated tr.  You must have been at a small bwr.  The BWR I was at could inject 6000 gpm of ECCS flow at rated pressure and ~ 80,000 gpm at lower pressures using all available sources.  The point about not having boric acid to maintain SDM is also a big factor. My current CE plant CDF is ~3x10-5.

[Fermi2]

An RHR Pump at my old plant is bigger than the entire ECCS at a Westinghouse 4 Loop PWR. Of course the design analysis says you need that kind of flow the reactor and core is physically a LOT bigger. But so far as water sources there's a lot more available ones because most plants can inject their BOP water into the core.

As for Mixed Fuel EOL I don't understand the concern. Without being able to make the required Shutdown Margin and Rod SCRAM time post accident you couldn't operate the plant anyway. The concern isn't so much being able to hold the reactor SD, in a BWR they'll always be able to do that, the concern is being able to control the transient via a SCRAM before MCPR reaches certain limits. it's a rather moot point anyway as a BWR 4 operating in the MELL or MEOD region breeds quite a bit of Plutonium and and in fact roughly 60 to 70% of the fissions at EOL are Plutonium based anyway. One time Fermi didn't load enough fuel to make it to the end of a cycle without an early coast down so they intentionally operated high in the MELL/MEOD region very early in core life and performed Control Rod Pattern Adjustments with the intent of breeding even more Plutonium. That was a couple cycles before M1Ark got there and IIRC it didn't matter as that was the cycle we broke something which caused a SD of sufficient length that we'd have enough Uranium.

Again I like both Machines. A Westinghouse 4 Loop PWR is a wonderful reactor with a lot of design margin, but one thing I noticed, it seems there is always a crunch on making and finding sufficient borated Water to supply everything we use it for during an outage, in fact it seems the Operator who can figure out the where's and whens is somewhat a wizard. We didn't have that problem in a BWR. You made a water plan before the outage and so long as you stuck with it you'd be ok. Then again the plants on the great Lakes weren't allowed to discharge so we had to be good with the water plan.

PWR have a higher CDF mostly due to the fact they have to rely on more active components to align to the Containment Sump and they're subject to seal failures.

One thing I really liked about a BWR is the multiple water level indications you had for actual reactor water level without having to derive anything. Also given the design analysis supports having 1/3 of the length of the fuel assembly uncovered without causing significant core damage is a BIG Plus.

On the other hand, too many times the BWR 4 EOPs require prioritization especially due to containment issues. It can be hectic. I'll show you a difference, in the WEstinghouse PWR World if you get an ATWS the Analysis shows you have 10 minutes to shut down the reactor, if not you risk breaking the vessel. In the BWR world in some cases you have less than 2 minutes to complete a LOT of EOP Actions (ATWS with a closure of MSIVs or ATWS due to Turbine Trip W/O Bypass. Many of these actions are geared towards protecting the containment and get VERY VERY hectic. It's a reason ATWS Instrumentation and systems are in BWR TEch Specs and IIRC are the most limiting Instrumentation Specs (2 hours allowed out of service and 1 hour testing IIRC)

Personally I like both types of plants but if you are gonna compare the two in any reasonable fashion the only way to do so is to be licensed as either an RO or SRO on both types. opinions are all great an OK and of course welcome, but to state anything in absolute without having operated either type probably isn't the best way to keep an open mind.

Mike

[retired nuke]

Hmmm Broadzilla - you may be right about expressing opinions only if you are licensed in both. Your explanation was so far over my head that I didn't even feel the breeze as it went by.
Being a humble RP tech, I prefer plants that run continuously between outages, require minimal major online maintenance, and keep the utility's pocket full enough that my paycheck is always on time. About any approved design will accomplish that if properly run and maintained.

Thanks to all of you operator types for the opinions and explanations - I am slowly learning more about our industry future from this forum - much more than I am learning at my plant....

[tr]

M1Ark,

Actually, I was at the second largest US BWR (Perry).  Due to the BWR6 HPCS pump being motor driven, it gave less flow at rated pressure than the older HPCI systems did (qualification - it's been over 10 years since I was there, the memory cells for the actual numbers may have died!). 

[M1Ark]

Broadzilla,

Excellent writeup.  I understood it 100%.  I felt that as I was reading your comments it would go over even an licensed PWR guys head.  This is predominantly the reason that I refused to get into the real specifics with Roll Tide on the pros and cons of both designs.  The bottom line is that an approved design is sufficient and I would buy a house adjacent to either a PWR or a BWR.

[Roll Tide]

Excellent examination of current BWR vs. 4-loop W PWR.

Now if we could get some information that would cut through the fog in that manner comparing AP-1000 vs. ABWR vs. EPR I would really be stoked. After all, I won't leave this site for another site designed by someone wearing bell bottoms...

[M1Ark]

Excellent examination of current BWR vs. 4-loop W PWR.

Now if we could get some information that would cut through the fog in that manner comparing AP-1000 vs. ABWR vs. EPR I would really be stoked. After all, I won't leave this site for another site designed by someone wearing bell bottoms...

LOL.  I wish I could offer insight on the three competing design.  I do not have credible knowledge on those designs besides what I've gathered from google.com as compared to knowledge I have of current designs.  Any design engineers on nukeworker.com care to weigh in?

[wlrun3@aol.com]

   "Initially it was believed, due to the possibility of clad burnout, that water could not be permitted to boil in a reactor vessel...the boiling water reactor designs provide a system that produces reactivity changes varying inversely as a function of steam void content in the core. This provides the inherent safety feature of these systems. That is, a transient power increase will produce more steam voids, reducing reactivity, which reduces power and thus limits the excursion."     Light Water Reactor Systems Training Material, Bartlett Nuclear Inc.

   From a licensed reactor operator's perspective, is there an inherently superior light water design.

[Fermi2]

   "Initially it was believed, due to the possibility of clad burnout, that water could not be permitted to boil in a reactor vessel...the boiling water reactor designs provide a system that produces reactivity changes varying inversely as a function of steam void content in the core. This provides the inherent safety feature of these systems. That is, a transient power increase will produce more steam voids, reducing reactivity, which reduces power and thus limits the excursion."     Light Water Reactor Systems Training Material, Bartlett Nuclear Inc.

   From a licensed reactor operator's perspective, is there an inherently superior light water design.

No not really.


Mike

[thenuttyneutron]

I have only worked at a PWR and only know "theory" for how a BWR works.  In layman terms this means I know nothing about the BWR    I hope that we choose 2-3 designs and focus on making them standard.  I don't want to see a repeat of the last build out.  We can't afford to have "new" designs on every plant and basically run an experiment every time a new plant is built.  Deregulation will be more punitive than the regulated industry of the past.

Is it possible that we can get both a PWR and BWR design standardized and build lots of them?

[alphadude]

you must remember the original ideas behind the current reactor designs- boilers were base load systems to be situated near large cities and be kept on line. PWRs were the hot rods (B&W expecially) that were load followers- quick to change power levels.  The integrator controls systems were originally designed to be operated by  a dispatcher from some office located elsewhere.

[wlrun3@aol.com]

you must remember the original ideas behind the current reactor designs- boilers were base load systems to be situated near large cities and be kept on line. PWRs were the hot rods (B&W expecially) that were load followers- quick to change power levels.

    does this dynamic aspect of pwr design intention favor its selection in the current new reactor design/construction environment...

[Fermi2]

you must remember the original ideas behind the current reactor designs- boilers were base load systems to be situated near large cities and be kept on line. PWRs were the hot rods (B&W expecially) that were load followers- quick to change power levels.  The integrator controls systems were originally designed to be operated by  a dispatcher from some office located elsewhere.

HUH? Its much easier to follow load in a BWR than a PWR, in fact if you read the Grid Analysis of some of the utilities that invested big into BWRs they chose the design for that very reason. You can load follow a BWR down to about 55% power using nothing but flow control. Its not that easy with any PWR and never really was.

Mike

[alphadude]

How many subs have boilers-duh- The boilers and the PWRS completed the demand cycle of the then unstable grid. You may be too young to remember but back in the 60s and 70s the grid was not stable nor did it exist- as today.

So dont confuse what happens now with the original sales pitch we got from vendors in the 70s. Boilers were the "tea kettle" of power plants -set them up around cities and run them cheap and use them for base load- Cities had a stable system of power-not usually connected to a national grid (it didnt exist)

PWR (B&W) mainly were load followers and provided high efficiency, fast response, more power per smaller site etc-(sales pitch)For example, the B&W design was extremely responsive (called the corvette of power plants by salesmen) but the grid and other situations negated the very efficient design of B&W. Superheat and economizer regions- no other like it. The ICS was set up to load following.  The dispatcher would take control of the ICS not the senior reactor operator. So the dispatcher would change reactor power levels.

The Westinghouse design was put on the market to provide a base load unit to compete with the boiler base load market. 

PWR- its all about load following and eff.

[thenuttyneutron]

In theory I know PWR is about 1% more efficient than a BWR.  Is this true in practice?  I paid to have things taught to me that turned out to be untrue.  I was always taught in school that superheated steam was not possible with nuclear reactors.  It was not until I got in the industry that I learned the way things really work.  While OTSG are not common, they do give a nice 50 degree F or more superheat.

I like the idea of the ICS, you have to watch the power though and adjust the ULD a few times a shift.  It can be simple things like a temperature change outside that causes it.  I have heard other plants are not as easy to move around.

I don't like the fact that 3 major events in the industry occured at B&W reactors.  I want reactors so safe that the human factor is engineered out of the reactor safety.