Best New Reactor Design

[Fermi2]

I actually read the FSAR for Fermi and a bunch of other plants. Utilities that bought them did so with the intent of load following. I licensed at a BWR and I'm currently licensing at a PWR, I KNOW which is the better load follower and I'll stack a BWR 4 against any reactor in the world when it comes to following load.

As for efficency, I think it's a wash. B=W plants paid for the 1% with a MUCH smaller PZR and SG Water Volume so they don't respond well to transients. I think overall there's no real difference in the efficency between types except as designated by local preference. By that I mean Sequoyah is a VERY efficient plant. It reovers about every bit of waste heat that it can and it has 7 stages of feedwater heating, something that is very rare.

Mike

[wlrun3@aol.com]

   do frequent power level changes significantly impact maintenance costs...which design is superior in this respect...

[Fermi2]

Frequent power level changes impact Operating Costs not so much maintenance costs, a BIG reason all reactors are base load machines is the higher their capacity factor the less overall cost. From a maintenance perspective online maintenance on the Secondary/BOP side is easier in a PWR  simply because the equipment is accessible we do stuff at a PWR at power that we couldn't do at a BWR simply due to dose.

During an outage it's a wash. What surprised me is the Dose at a PWR. Coming from a very low dose BWR I've found PWR doserates to be incredible

Mike

[M1Ark]

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.

If you "knew" how fast a BWR can change power you wouldn't call a B&W or any PWR for that matter a hot-rod.

[Roll Tide]

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.

Human factors cannot be engineered out of reactor safety. Human incompetence is one of the difficulties that must be overcome. Look closer at the TMI event, and you will see humans making the situation worse. Look closer at Davis-Besse, and you have humans making poor decisions (utility and NRC).

People make mistakes. The solution must prevent those mistakes from causing a tragedy.

[alphadude]

-Dont get yer panties in a wad-im not calling anything anything- I just happen to be old enough to remember the sales pitch that was given to us while in ops in the early 70's . Personnally all the present plants operating are primative as hell- designed in the 50's and 60's, worked like a rented mule-and required hundreds more people than originally designed for. I remember when we pulled the drinking water fountains out of some containments because the newly created NRC didnt like that idea, and when we hired more than the 80 people projected to operate the plant- Not to mention Dixie Lee Ray! 

So I was just commenting- I never discussed the one situation where the president of the utility stood in front of the room and said " In about 20 years we will take this small device about the size of a coffee cup and put it in a unit in our back yard and get all the power we need from it."  We shook our heads and said, " Wow I cant wait until 1992!"

As as Roll Tide said in brief- "if designed by humans-humans can break it!"  The commercial factors will always come into play when purchasing an engineered item. Which are
1. Cost benefits analysis
2. Competition in the free market
3. We only know what we know-
4. Humans build it-humans can break it.

[rlbinc]

I have worked at both BWRs and PWRs. In my 30+ years of experience, I have come to believe that BWRs are safer than PWRs for the following reasons:

1. No reliance on Boric Acid concentration to maintain Shutdown Margin. PWRs require varying Boron concentrations in the RCS to maintain SDM. Unfortunately, item 2 below poses a considerable threat.
2. PWRs have Steam Generators. A leak can allow radionuclides access to the steam system - which really doesn't bother me. The same tube leak allows unborated water access to the reactor with flaw #1 - which really does bother me.

Just the humble opinion of an old and condescending operator.

[wlrun3@aol.com]

   so in the case of a tube rupture it is possible for the pressure in the secondary side to exceed that in the primary and allow secondary water into the primary system?

[wlrun3@aol.com]

   having personally been involved in the reintroduction of the hot midloop evolution...does this present a concern, to the those involved in this thread, in same manner that a concern for non borated water introduction into the primary was recently voiced?

[thenuttyneutron]

Human factors cannot be engineered out of reactor safety. Human incompetence is one of the difficulties that must be overcome. Look closer at the TMI event, and you will see humans making the situation worse. Look closer at Davis-Besse, and you have humans making poor decisions (utility and NRC).

People make mistakes. The solution must prevent those mistakes from causing a tragedy.

I disagree with not being able to engineer humans out of reactor safety.  The Generation 4 reactors very safe.  In the worst case accident conditions, the fuel will never melt.  The melt temperature of the ceramic fuel is higher than the highest temperature achievable.  Even with no control rods used, the negative temperature reactivity coefficient will shut the reactor down.  The temperature will stay high enough to prevent a restart but cool enough to avoid fuel damage.

[Roll Tide]

I am glad the Gen IV reactors will be safer.

Perhaps you are not familiar with the term, "Sailor-proof". One of my first instructors in the Navy used to say, "There's nothing Sailor-proof except a cement park bench." Then one day as he was walking through the base, he saw a maintenance crew lifting a replacement cement park bench into place. Reason? Some Sailor broke it!


Passive safety systems are great. How long until someone gets a "bright idea" that defeats those systems? Training and operations must never make the assumption that humans have been engineered out of safety. Operators will still be the first line of defense.

[ChiefRocscooter]

I am glad the Gen IV reactors will be safer.

Perhaps you are not familiar with the term, "Sailor-proof". One of my first instructors in the Navy used to say, "There's nothing Sailor-proof except a cement park bench." Then one day as he was walking through the base, he saw a maintenance crew lifting a replacement cement park bench into place. Reason? Some Sailor broke it!


Passive safety systems are great. How long until someone gets a "bright idea" that defeats those systems? Training and operations must never make the assumption that humans have been engineered out of safety. Operators will still be the first line of defense.

AAH yes, quite the delimia.  I think I will have to go with Tide on this one! (and that is always hard for a FL boy who tends to pefer Gator to Elephant, but that is another topic )  Nutty I think you are misunderestimating the lengths to which some operators will go to prove thier stupidity!  What may seem absolutly like a stupid idea can appear to some "cool way to maje it better" to a operator of questionable intellegence.
Perhaps it would be better if we could build a common sense detector and install it at entrance to plant we might be able to engineering out the worst human elements but I fear even then a few will slip through on the "OOPS factor"
Rob

[Charles U Farley]

Interesting.  Adm. Donald just stopped by work a little while ago.  Altough I declined the invitation to attend the all hands Admiral call, I am told one of his concerns was the sense of complacency operators get with respect to the rising capabilities of technology.  I mean, c'mon, why worry when you are always a scram or F.I. away from safety, right?

[thenuttyneutron]

Operators are rude/crude and socially unacceptable.  I know all too well what operators can/will do because you tell them "you can't".  That operator will go to great effort to prove you wrong.  One of the hardest things for me to do was to kill the engineer in me and learn to be an operator.  I have seen many weird/crazy things as an operator.  I have never seen sabotage or malicious compliance that could endanger plant equipment, compliance of standing orders that results in an inconvenience for a SRO is all fair game   Some of the experiments run for the development of the Gen 4 reactors show good results.  I don't know if it took into account intentional sabotage.  I was taught many things in school that turned out to be untrue because ot "special cases".

I want reactors so safe that the worst case accident/ best attempt at sabotage only results in a minor problem that won't result in core damage.

[Fermi2]

Interesting.  Adm. Donald just stopped by work a little while ago.  Altough I declined the invitation to attend the all hands Admiral call, I am told one of his concerns was the sense of complacency operators get with respect to the rising capabilities of technology.  I mean, c'mon, why worry when you are always a scram or F.I. away from safety, right?

TMI happened AFTER the plant was Shutdown, Chernobyl, during the shutdown, Winksdale AFTER the SD.

Mike

[Charles U Farley]

TMI happened AFTEr the plant was Shutdown, Chernobyl, during the shutdown, Wincsdale AFTER the SD.

Mike

Oh, we're both on the same page.  But, I look around at work an start to wonder

[Roll Tide]

I want reactors so safe that the worst case accident/ best attempt at sabotage only results in a minor problem that won't result in core damage.

Many of the best laid plans of yesterday have become the obstacles we work around today. PWR example: loops tap off only slightly below the head, and RHR (cooldown) taps off the RCS loops. These taps are below the S/G's. The industry result: we drop level to mid-loop (only half-full in the RCS) in order to install the head after refueling. To minimize the air in the U-tubes, we then place the RCS under 24" Hg vacuum prior to filling. What is the highest risk / lowest safety margin in the cycle? Vacuum fill. Certainly not sabotage, but an example where a "good design idea" is also a challenge to get around.

Complacency is the enemy.

[rlbinc]

   so in the case of a tube rupture it is possible for the pressure in the secondary side to exceed that in the primary and allow secondary water into the primary system?

Yes, it's mentioned in the TS Bases for Boric Acid concentration in the RWST used during Safety Injection. Safety Injection Systems can fail - the RCS will depressurize through the leak. When the SG PORV finally closes, equalization will commence, then dilution can start.

Boilers are better because they shutdown on rods. Just my opinion. 

[wlrun3@aol.com]

Yes, it's mentioned in the TS Bases for Boric Acid concentration in the RWST used during Safety Injection. Safety Injection Systems can fail - the RCS will depressurize through the leak. When the SG PORV finally closes, equalization will commence, then dilution can start.

Boilers are better because they shutdown on rods. Just my opinion. 

   ...could you keep the secondary pressure well below that of the primary by venting the secondary...

 

[Fermi2]

   ...could you keep the secondary pressure well below that of the primary by venting the secondary...

 

No that's not what the WOG Say. You Cool down the intact SG until the Primary and Secondary Pressures in the ruptured SG are roughly equal. Then you fill the ruptured SG  a certain level and let it bleed to the Primary.

Dilution does occur. At this point of the game you're not taking suction from the RWST. You basically fill the VCT to a certain concentration then try to use it to maintain primary boron concentration.

Mike

[wlrun3@aol.com]

   "Shippingport and the 1953 National Security Council decision that brought it about were the first major steps towards nuclear power in the United States. But it is worth remembering that Shippingport was not the result of a stupendous technical breakthrough nor of a willingness on private industry's part to take a risk, but a national security decision to reassert American atomic superiority during the Cold War. In their hurry to get a reactor, any reactor, pumping out electricity, the government's atomic bureaucrats seized upon the handiest reactor design available, Rickover's light water reactor. Their choice gave the light water model a head start and momentum that others were never able to match and led the industry to base its commercial future on a reactor design that some experts have subsequently suggested was economically and technically inferior."   Nuclear Inc., Mark Hertsgaard

[rlbinc]

I was a big fan of the Shippingport Light Water Breeder Core. They used Thorium and U-233 and used neutron flux to create U-234 and U-235. The reactor operated throughout the demonstration period with a 1.01 conversion ratio. That means they created 1% more new fuel than they burned. This reactor did not need refueling. That's the type of nuclear power Admiral Rickover envisioned for the commercial industry. Not once through to the spent fuel pool.

This reactor required all of the separated U-233 in the known civilized world at the time, which made its core prohibitively expensive. Th-232 goes to U-233, so it would have been less expensive and less of a burden in following cores.

Had Admiral Rickover gained control of the civilian nuclear industry, as he requested following TMI, we would have seen this core again.

[wlrun3@aol.com]

   " In the fall of 1951 Rickover faced an AEC bureaucracy that was unenthusiastic about his new idea to develop nuclear reactors for aircraft carriers...It had not taken Rickover long to choose the design for his carrier reactor: the light water design had been his favorite since the nuclear submarine project, and by applying it to the carrier, he could save both time and money. In another carry-over from the submarine work, Rickover selected Westinghouse as his main contractor...It  was precisely the light water design's power applications that led the AEC to decide simply to arrange to reorient Rickover's carrier project to produce a commercial rather than a naval reactor."    Nuclear Inc., Mark Hertsgaard

   

[thenuttyneutron]

I was a big fan of the Shippingport Light Water Breeder Core. They used Thorium and U-233 and used neutron flux to create U-234 and U-235. The reactor operated throughout the demonstration period with a 1.01 conversion ratio. That means they created 1% more new fuel than they burned. This reactor did not need refueling. That's the type of nuclear power Admiral Rickover envisioned for the commercial industry. Not once through to the spent fuel pool.

This reactor required all of the separated U-233 in the known civilized world at the time, which made its core prohibitively expensive. Th-232 goes to U-233, so it would have been less expensive and less of a burden in following cores.

Had Admiral Rickover gained control of the civilian nuclear industry, as he requested following TMI, we would have seen this core again.

I agree all the way that a Th232/U235/U233 fuel cycle would be great for the United States of America .  We must also undo what Carter did in regards to fuel reprocessing.  If we breed U233 fuel from Th232 using thermal breeders, we will extend our fuel supplies by leaps and bounds.  I also support the fast breeder reactors using U238 to make Pu239.  With the right engineering we can make these newly created fuels very difficult to use for purposes other than power production.  India has large supplies of Th232 and would make a great supplier of this fertile substance.

[wlrun3@aol.com]

   ...in response to a question from a member of the public...

   ...what is the single most attractive feature of a bwr compared to a pwr...