The Nuclear Power Thread

[jim hardy]

HIJACK ALERT wasnt on purpose though

I can. Airspeed indication is critical to aircraft control, for pilots and autopilot. If the sensors , pito tubes or alternatives, can't somehow be made absolutely impervious to ice under all possible flight conditions, then flying at night at cruise altitude into thunderstorms becomes off limits. Carry fuel to allow deviation or return. If this breaks some 13 hr flights into two hops, tough. Start with that. Then move on to fixing control law governance in that Airbus, so that it can not automatically switch from one mode to the other without crew acceptance.

I'll add that tactile feedback is necessary. Technology as with all things is good in moderation.
An old fashioned yoke connected to the controls by cables gave the pilot a feel for the force of air flowing over his control surfaces.
Howard Hughes built into his Spruce Goose's hydraulic controls a servo "backdrive" mechanism that returned to the yoke and rudder pedals some of the force from air over the control surfaces.
That way the plane would have "Tactile Feedback" and feel to the pilot like a normal plane of the day .

Does that Airbus joystick provide tactile feedback? I don't know. Does Airbus have rudder pedals? I don't know.
Being the almost quadrapeds we are, i'd say
when the computers give up the ghost
"Feel" for the airplane should be transmitted both to a pilot's hands and feet by Tactile Feedback.

Appropriate degree of automation.
Boeing flight decks are designed to provide automation to assist, but not replace, the flight crew member ...
...In the fly-by-wire 777, visual and tactile motion cues are provided by backdriven controls. These controls reinforce situational awareness and help keep the flight crew fully aware of changes occurring to the airplane’s status and flight path during all phases of automated and manual flight.
http://www.boeing.com/commercial/aeromagazine/aero_08/human_textonly.html

I suggest there is still a bit of cowboy remnant in passenger aviation,

Yer' De\arn tootin' there is.
I once lived on an airstrip in the Florida Keys. A half dozen of my neighbors were airline pilots.
They had a saying: "If it ain't Boeing I ain't going."a feeble attempt to get back on topic

I put the loose parts monitor" for our reactor within earshot of the operating console. Operators could hear the KaLanka-KaLanka-KaLanka of control rods in motion on the speaker. It was reassuring to hear them stepping correctly.
Around big machinery little things mean a lot.

old jim

"loose parts monitor is an electronic stethoscope that listens for anything rattling around .

 

[xpell]

I can. Airspeed indication is critical to aircraft control, for pilots and autopilot. If the sensors , pito tubes or alternatives, can't somehow be made absolutely impervious to ice under all possible flight conditions, then flying at night at cruise altitude into thunderstorms becomes off limits.

It's common procedure and it's actually not dangerous. Hundreds of jetliners do it routinely every day without trouble. In that very moment there were 12 more jetliners before and behind the AF447 crossing the very same Intertropical Convergence Zone. That includes AF459, following the same route from São Paulo 30 minutes behind with exactly the same aircraft model, an Airbus A330-203 (it was the first aircraft trying to contact AF447 after it "vanished".) Nothing happened to any of them. The ITCZ crossing is routinely done every day by many planes flying between the Northern and Southern Hemispheres, thunderstorms or not. I guess the AF447 was pretty unlucky: every possible thing which could go wrong went wrong for them.

Carry fuel to allow deviation or return. If this breaks some 13 hr flights into two hops, tough. Start with that.

That wouldn't be competitive at all, especially in long-haul oceanic intercontinental routes. Actually it wouldn't have helped the AF447 in any way: they crashed barely 5 minutes after the problem started. They still had enough fuel to return to South America or deviate to Africa or wherever if needed. Actually they had left Brazilian airspace barely 1 hour before and carried fuel to continue to their destination, Paris, over 3,000 nautical miles away.

Then move on to fixing control law governance in that Airbus, so that it can not automatically switch from one mode to the other without crew acceptance.

The autopilots must shut down automatically if the on-board computers are no longer able to provide them with consistent information. Doing it otherwise would be way more dangerous: you would have an airplane controlled with false/contradictory information while the pilots decide what to do. And that's how it was, with the appropriate autopilot disconnection alarm sounding. Then the crew reacted immediately... but wrongly, out of surprise and confusion. Then things started to go south very, very fast.

I suggest there is still a bit of cowboy remnant in passenger aviation, that somehow "up there" the jets are above it all. I suggest this mentality allowed the AF Captain to be on break while his aircraft was flying through thunderstorms at night. Without apologizing for Putin in anyway, I suggest the *routine* flyover of a modern war zone in the Ukraine shoot down was part of the same recklessness. Flights don't enter the airspace now.

Captain Dubois (almost 11,000 flight hours) was resting in his scheduled break time. Two fully qualified first officers (one of them with 6,500+ flight hours, almost 4,500 of them flying those very Airbus'es) were in command. As stated, the ITCZ crossing is routinely done every day without trouble... so much that the least experienced first officer was the pilot-in-command in that moment because it's considered an easy, even boring job. There was no reason to be especially alert. In despite of that, Captain Dubois was back in the cockpit as soon as he realized that something was wrong (because of the weird initial movements) and stayed there until the crash. He wasn't able to understand what was happening either. All of them were totally confused from second zero, even after the Pitot tubes unfreezed and instruments went back to normal. But by then, they were too disoriented, too stressed and too deep into "tunnel thinking" to save the day.

Yer' De\arn tootin' there is.
I once lived on an airstrip in the Florida Keys. A half dozen of my neighbors were airline pilots.
They had a saying: "If it ain't Boeing I ain't going."

Yes, that's what many American pilots often say, at least until their employers tell them to do otherwise. All things considered including age of fleets etc., Airbus and Boeing safety records are pretty much the same. Actually, most modern air disasters are the result of a huge amount of complex causes and there are not so many strongly attributable to obvious aircraft's design flaws or failures. Even the infamous safety records of some other manufacturers are most often the result of their airplanes being usually operated in difficult areas and conditions by strongly substandard operators than of design or construction flaws.

That way the plane would have "Tactile Feedback" and feel to the pilot like a normal plane of the day. Does that Airbus joystick provide tactile feedback? I don't know. Does Airbus have rudder pedals? I don't know. Being the almost quadrapeds we are, i'd say when the computers give up the ghost "Feel" for the airplane should be transmitted both to a pilot's hands and feet by Tactile Feedback.

Here you can find a couple discussions including professional pilots who routinely fly both Airbus and Boeing:

http://www.pprune.org/tech-log/267468-difference-between-airbus-boeing-controls.html
http://www.airliners.net/aviation-forums/general_aviation/read.main/3018977/

The result? Mostly: both approaches have advantages and disadvantages. But most of those who have transitioned from Boeing to Airbus say it took them like 15 minutes to get used to the no-feedback sidestick and not a few of them also say they now find it safer and better.

Anyway, no modern fly-by-wire aircraft is going to provide you with real "cables and bolts" feedback. Some Boeings kept this "legacy hardware" as a backup mode, but they eventually gave into full digital with the B777 "simulating the feedback" (so if the computers go nuts, the feedback can go nuts too.) Same with the 787. Those "cables and bolts" were too heavy and lacking in flexibility to make competitive 21^st century aircrafts, and not really so more reliable. Now, even this "simulated feedback" is close to death too, because even that adds unneeded weight and complexity in this new world of highly optimized "flying robots" which are going fully electric, even discarding the control wires for fire-by-wireless and the hydraulics for power-by-wire.

HIJACK ALERT wasnt on purpose though

Certainly, but I'd say not so much. I find huge analogies in all kinds of technological disasters which can be quite interesting, especially when considering the human factor. Human psychology works pretty much the same on a jetliner at 40,000 ft, in a nuclear power plant firmly rooted on the ground, and anywhere else.

 

[mheslep]

Gorbachev said in Peristroika, to effect
'That project was considered best which consumed the most manpower, money and resources.'

BTW Jim, I think that description is apt for the goals for any bureaucracy. A bureaucracy may well attempt to operate safely, without accident, but the more staff, resources, the better I've observed in working with them.

 

[mheslep]

It's common procedure and it's actually not dangerous.

Common yes, but the accident demonstrates it none the less is dangerous under those conditions with equipment that can fail with ice accumulation.

Hundreds of jetliners do it routinely every day without trouble

And how often at night in thunderstorms at altitude. Its not the route, its the conditions.

Actually it wouldn't have helped the AF447 in any way: they crashed barely 5 minutes after the problem started.

To the contrary, aircraft radar makes a storm warning available to the crew well in advance, enabling storm avoidance en-route or possibly even in pre-flight weather checks in Rio.

Actually they had left Brazilian airspace barely 1 hour before...

Well, 4 hrs, 15 min after take off.

That wouldn't be competitive at all, especially in long-haul oceanic intercontinental routes.

Why not, if enforced internationally? Nobody short cuts over eastern Ukraine now to save fuel.

The autopilots must shut down automatically if the on-board computers are no longer

Yes, but the control law to flight surfaces given inputs should not change immediately when the autopilot quits, as it did, immediately changing the responsiveness and feel of the aircraft.

As stated, the ITCZ crossing is routinely done every day without trouble...

Its not the crossing. Long trips don't ice pitot tubes, high altitude thunderstorms can. Airspeed indication was not just taken away, it was indicated erroneously. And at night. In daylight, some clear sky, that pilot induced pitch up never happens.

He [Captain] wasn't able to understand what was happening either.

Perhaps not, but his first command as recorded was none the less correct, drop the nose: “No, no, no… Don’t climb… no, no.” The officer at the controls failed to execute, or perhaps it was too late then, 45s to impact. This suggests that had this Captain remained in the cockpit the accident was less likely. I understand it was routine for this (or any?) Captain to be out of the cockpit for such a flight; I suggest under these conditions it should not be.

http://www.telegraph.co.uk/technology/9231855/Air-France-Flight-447-Damn-it-were-going-to-crash.html

 

[OCR]

http://www.dailymotion.com/video/x2zksq0_air-disasters-vanished-season-4-episode-13_tv ...

 

[nikkkom]

They didn't send them there without thinking.

Yes, they did sometimes sent people into high fields without proper dosimetric control. Sometimes even without any dosimetric control (proper or "improper").

We're talking Gorbachev's USSR, not Stalin's. But when the USSR collapsed, all of that was spread between 3 countries and critical information (like the radioisotopic measurements I was talking about before) seemed to vanish into thin air out of nationalistic concerns. Basically Russia says it was all fault of the (mostly Ukrainian) operators, Ukraine says that their operators were blameless and it was all fault of the USSR -> Russia, and Belarusians don't say much. As always, the truth is somewhere in-between.

You, a foreigner, think you know my country's recent history better than me? For one, operators were not "Ukrainian" operators. Neither Akimov, nor Toptunov, nor Dyatlov are Ukrainian surnames. Secondly, there is no active Russia/Ukraine/Belorussia blame game wrt Chernobyl, they all blame USSR for it, and generally have far more pressing and recent conflicts than now-historic disaster.

 

[xpell]

Common yes, but the accident demonstrates it none the less is dangerous under those conditions with equipment that can fail with ice accumulation.

And how often at night in thunderstorms at altitude. Its not the route, its the conditions.

Quite often. The ITCZ is very much defined by its violent thunderstorms and generally unstable weather:

https://en.wikipedia.org/wiki/Intertropical_Convergence_Zone
http://earthobservatory.nasa.gov/IOTD/view.php?id=703

...and aircrafts flying between the northern and southern hemispheres are constantly crossing it, day and night, every day of the year.

To the contrary, aircraft radar makes a storm warning available to the crew well in advance, enabling storm avoidance en-route or possibly even in pre-flight weather checks in Rio.

Actually state-of-the-art jetliners receive constantly updated weather information through a diversity of systems. The on-board weather radar is "the last line" of all them. But they still have to cross unstable weather areas or modern aviation would be impossible. Very busy routes following the great circle often go through Arctic areas, which use to be a mess especially in winter (and winter is looong there... ) "Bad weather" is fully expected and accepted in all of those flights... and there are hundreds of daily (and nightly) flights following those routes. After all, when you go stratospheric, most of the trouble is going to happen way below you. Most often, passengers don't even notice. It's a non-issue, except if conditions go really hellish... or an unlucky combination of circumstances kicks in.

Well, 4 hrs, 15 min after take off.

...and 6:15 to arrival, plus the reserve fuel. If they had felt like diverting, they could have basically gone wherever they wanted in South America, Africa, Western Europe or even the U.S. East Coast. But they didn't have any reason to divert, it was just a standard ITCZ crossing, just as the other 12 jetliners (including at least another aircraft of exactly the same manufacturer, model and airline) before and behind them did without trouble.

Why not, if enforced internationally? Nobody short cuts over eastern Ukraine now to save fuel.

Yes, a very small area. Now try any flight between the northern and southern hemispheres without crossing the ITCZ, or restricting them only to the days with perfect weather, and only from dawn to dusk... You'd have to purchase Airbus A380's like popcorns and keep them landed until all those conditions are met... then rush the thousands of waiting passengers and cargo into them to fly in formation to their destinations. Same with all flights with Arctic or sub-arctic overflies (try NYC -> Tokyo on Christmas Eve for instance), and quite a few more. Nah, that's impossible.

Yes, but the control law to flight surfaces given inputs should not change immediately when the autopilot quits, as it did, immediately changing the responsiveness and feel of the aircraft.

Its not the crossing. Long trips don't ice pitot tubes, high altitude thunderstorms can. Airspeed indication was not just taken away, it was indicated erroneously. And at night. In daylight, some clear sky, that pilot induced pitch up never happens.

Actually it's a defensive approach after an unscheduled autopilot disconnection. You're giving the pilot more control by removing some limitations by switching from normal law to alternate law (it doesn't fall back to direct law, which could be dangerous, only to alternate law.) That doesn't change the "handling" or the "feeling" of the aircraft, it just changes the limitations ("protections"), and every Airbus pilot knows that. Obviously, by giving him more freedom, you're also giving him more freedom to screw things up big time, as the AF447 crew did.

Perhaps not, but his first command as recorded was none the less correct, drop the nose: “No, no, no… Don’t climb… no, no.” The officer at the controls failed to execute, or perhaps it was too late then, 45s to impact. This suggests that had this Captain remained in the cockpit the accident was less likely. I understand it was routine for this (or any?) Captain to be out of the cockpit for such a flight; I suggest under these conditions it should not be.

It was way more complex. I studied the full final report together with the entire CVR transcript and the FDR data. First the pilot-in-command inadvertently climbed while trying to correct a lateral inclination after autopilot disconnection, so hard that the plane went into full aerodynamic stall. Then the aircraft started to fall with a high angle of attack. But the wrong instrument readings didn't let them really get and internalize that. They think they're overspeeding instead of stalling (and that's why they keep trying to climb: to bleed speed; the "apparent symptoms" of overspeeding and stalling are very similar.) Then Captain Dubois enters the cockpit... and sees they're at their scheduled altitude (he can't know that they have climbed then fallen while he rushed to the cockpit), so he doesn't realizes they're stalling either ("how could we be stalling, if why are at the same altitude than when I left to rest?")

If you read the CVR transcript (the accident starts at 2h10' UTC), you'll see that there is a hell of a mess of confusion in that cockpit even after the Pitots unfreeze and computers and instrument readings go back to normal (but by then, they were no longer trusting them.) You can almost "feel" how they got totally disoriented. The Captain only says that "no, no, no, don't climb..." less than 45 seconds before the final crash, after the most experienced first officer has been telling the pilot-in-command to "climb, climb, climb!"... the Captain just realized then that they were really falling in despite of trying to climb at full power all the time. They... heck, those poor guys had fully lost contact with reality. Read the report or at least the last minutes of the CVR transcript, it's really worth the time and they're pretty much self-explanatory. And I personally felt all of it strangely "Chernobyl-ish": professional people who honestly believed they knew what they're doing, but actually so confused and disoriented and so deep into "tunnel thought" that they basically didn't understand anything and did everything wrong just because they were convinced it was the best they could do. Bang.

 

[PeterDonis]

All of these can be filtered or neutralized

But, as others have pointed out, in many (most?) cases they aren't. Just as there are things that can be done with nuclear plants, that in many cases aren't.

It seems to me that you are comparing the worst case for nuclear power with the ideal case for other forms of energy. That's not an honest comparison.

On average, people are not sufficiently honest.

Yes. But somehow, in the case of nuclear power, that means we should just abandon it, instead of taking steps to improve it, the way we do for all other technologies?

It seems to me that you are holding nuclear power to much stricter standards of risk than other technologies, and then saying it should be abandoned because it's too risky. That's not an honest comparison.

 

[Astronuc]

GE/GEH in 2008
http://www.nuke.hacettepe.edu.tr/tr/webfiles/Activities/wnu/wnu/18%20sept/Birol%20Aktas/GEH-Fuels_ABWR%5B1%5D.pdf

GEH in 2015
https://www.oecd-nea.org/ndd/workshops/innovtech/presentations/documents/ii-1b-powell.pdf

GNF2 is the latest 10x10 BWR fuel design in reload quantities. It appears that GNF2 has been adapted to the ESBWR as GNF2e.
GNF2 is replacing GE14 as the standard fuel assembly, and GNF3 LUAs are now in two reactors, River Bend (4) and LaSalle 2 (4) since Spring of 2015.

 

[nikkkom]

>>On average, people are not sufficiently honest.

Yes. But somehow, in the case of nuclear power, that means we should just abandon it, instead of taking steps to improve it, the way we do for all other technologies?

Let's review the history.

Nuclear power people said that their stations are safe.
Then disasters happened.
Then nuclear power people swore before God that now they "learned from past mistakes" and their stations are positively, definitely quite safe, barring improbable events such as asteroid impacts or ICBM attacks.
Then disasters happened *again*.

Sorry, but my personal credit of trust towards nuclear power has been exceeded by this last step. They can't make it safe enough. My opinion.

It seems to me that you are holding nuclear power to much stricter standards of risk than other technologies, and then saying it should be abandoned because it's too risky. That's not an honest comparison.

"Other technologies" do not leave thousands of square kilometers uninhabitable for centuries, therefore I have all reasons to hold nuclear power to much stricter standards of risk .

 

[PeterDonis]

They can't make it safe enough. My opinion.

Well, that makes your opinion clear, yes. It also confirms what I said.

"Other technologies" do not leave thousands of square kilometers uninhabitable for centuries

No, other technologies just kill or harm orders of magnitude more people when you total everything up. But they don't make any areas of land uninhabitable, that's true--at least not if you don't count air that you can breathe without taking in coal dust, for example, in your criteria for habitability.

I have all reasons to hold nuclear power to much stricter standards of risk .

Yes, as above, you've made it clear that this is your opinion. Others (including me) have a different opinion. But there seems to be little point in arguing about it since we simply have different standards of risk for this particular case.

 

[mheslep]

...
"Other technologies" do not leave thousands of square kilometers uninhabitable for centuries, therefore I have all reasons to hold nuclear power to much stricter standards of risk .

There are no such areas, "thousands of square kilometers uninhabitable for centuries", not at Chernobyl, not even at Hiroshima and Nagasaki. There have been and are inhabitants there. The other Chernobyl reactors kept operating with staff on site every day for years.

 

[Jon Richfield]

...
Then disasters happened *again*.

...

"Other technologies" do not leave thousands of square kilometers uninhabitable for centuries, therefore I have all reasons to hold nuclear power to much stricter standards of risk .

I actually have considerable sympathy with this complex of points of view, but there are differences between on the one hand holding one technology to stricter standards than another, and on the other, forbidding that one on a blanket basis. That amounts to making the standard "no nukes", which is not a rational standard. It actually is quite simple in principle to establish standards that would reduce risks to the point that nukes are not the operative concern. TMI would meet such standards comfortably. The Japanese nukes did not. I suspect that the majority of existing PWRs and a number of other plants do not either, and for the same reasons, but that they happen to be in safer situations, so that it doesn't matter (yet? Cross fingers! What should we do about such concerns?)

The thousands of square km remark however, leaves me nonplussed. Which thousands of square km would those be? Windscale? TMI? Chernobyl? Fukushima?
I don't think so, not yet anyway!
In fact, compared to what coal and oil already have done for the environment and people's life and health, nukes are not even in the same category.
And that is before we even get into discussing climate change. I am neither a climate change apologist nor denialist, but the sheer scale of the topic makes it so important that to ignore it and the technologies that affect it, or to refuse to compare its evaluations, would be irresponsible. I grant that all the CO2 from nukes (the concrete and the operators' respiration and commuting etc) are regrettable but really, compared to fossil chemical fuels, I think we could instance more dramatic climatic change scapegoats than nukes, don't you?
And what standards should we apply for incidents such as Flixborough, Seveso, Bhopal, Minimata, and a few items that, like these, trip off the tongue? No reason to invoke Boston molasses furore or a few of the NH4NO3 blasts in the last century or so? Or aircraft mortalities? Or smoking? Would you care to compare body (sorry, shred) counts? Or long-term morbidity? Or community pollution or degradation?
Or would you care to calculate a titre for standards that seem to be appropriate and enforceable in each category?
Not that I mean to nag of course, but need I say more about why I think that your protestations might strike some parties as unpersuasive?
Or why I disagree with PeterDonis when he says in part: "...there seems to be little point in arguing about it since we simply have different standards of risk for this particular case". When selectivity of standards are irrational, it strikes me as altogether rational, even responsible, to dispute them rather than capitulate to selective arguments and leave uncommitted parties prey to the hysterical subjunctive.
Engineering needs more responsible standards than that.

 

[anorlunda]

When selectivity of standards are irrational, it strikes me as altogether rational, even responsible, to dispute them rather than capitulate to selective arguments and leave uncommitted parties prey to the hysterical subjunctive.

Engineers tend to be left brain thinkers. I imagine that almost every engineer anywhere anytime would sympathize with that sentiment. But alas, it can never happen.

• Suppose we made a completely objective safety priority list, with ranking based on lives saved per dollar spent. It would be likely that the top ranked things would be mundane (like non-skid strips in bathtubs that cost only pennies), while emotional hazards (like drunk driving) might rank only in the thousands. My personal favorite (a permanent national 55 mph speed limit) would actually save money so it could conceivably rank #1 even if people hate it. The public would laugh off such as list as being absurd and stupid.
• Even completely irrational fears are real, and such fear causes actual suffering. It is called the nocebo effect (the flip side of placebo). We can explain patiently why they are baseless, but we can't dismiss or ignore them. More important, politicians can gain votes by pandering fearful voters and TV producers can gain fame and fortune pandering fearful viewers. Objectivity in public affairs has always been, and will continue to be a loosing tactic.

Engineers will never be put in charge of national priorities precisely because they are objective.

 

[Jon Richfield]

Engineers tend to be left brain thinkers. I imagine that almost every engineer anywhere anytime would sympathize with that sentiment. But alas, it can never happen.
...
...
Engineers will never be put in charge of national priorities precisely because they are objective.

I sympathise with your remarks, but we still have to raise our voices as persuasively as we can.
For one thing if we do not we can't in good conscience jerk when things go wrong.
Secondly we need to give rational people material to work on.
Thirdly we need to offer alerts and education to the next generations.
There are more of course, but those will do to go on with...

 

[mheslep]

GNF2 is the latest 10x10 BWR fuel design in reload quantities.

That last reference indicates only that GNF2 will be used with ESBWRs as you indicate. Are their any advantages over the older fuel designs, such as improved heat transfer which would yield higher power density? Less fission product leakage, or perhaps greater safety in case of accident?

Edit - Found what i was looking for,page 26 (slide 52) from the 2008 brief.

 

[Astronuc]

That last reference indicates only that GNF2 will be used with ESBWRs as you indicate. Are their any advantages over the older fuel designs, such as improved heat transfer which would yield higher power density? Less fission product leakage, or perhaps greater safety in case of accident?

Edit - Found what i was looking for,page 26 (slide 52) from the 2008 brief.

The reference design for ESBWR was GE14e, an earlier 10x10 fuel design. GNF2 has been steadily replacing GE14 since about 2007. Now GNF has adapted the GNF2 design to ESBWR (GNF2e), which is shorter length fuel assembly (reduced active fuel length) for a reduced pressure drop to take advantage of natural circulation.

A number of BWRs have taken advantage of GE14 and GNF2 to realize power uprates, which pushed the average power up by 10 to 20%.

AREVA has introduced an 11x11 fuel design called ATRIUM-11. The 11x11 design has smaller diameter fuel rods in the same assembly envelope, which means the fuel rod diameter is about the same as a 17x17 PWR fuel rod. AREVA's 10x10 design uses a square channel in the interior of the bundle, which is slightly offset from center, since it replaces 3x3 or 9 fuel rod locations, so its a 10x10-9 or 91 fuel rods.

Meanwhile, Westinghouse (ABB) is supplying SVEA-96 (96 fuel rods, in a 4 x 5x5-1 lattice) Optima 2 and soon Optima 3, both 10x10 with a water cross inside.

 

[mheslep]

A number of BWRs have taken advantage of GE14 and GNF2 to realize power uprates, which pushed the average power up by 10 to 20%.

Only by the fuel itself, or would an accompanying upgrade to the turbine typically be required?

 

[Astronuc]

The industry recognizes different degrees, or types, of power uprates.

Measurement uncertainty recapture power uprates are less than 2 percent and are achieved by implementing enhanced techniques for calculating reactor power. This involves the use of state-of-the-art feedwater flow measurement devices to more precisely measure feedwater flow, which is used to calculate reactor power. More precise measurements reduce the degree of uncertainty in the power level, which is used by analysts to predict the ability of the reactor to be safely shutdown under postulated accident conditions.

Stretch power uprates are typically up to 7 percent and are within the design capacity of the plant. The actual value for percentage increase in power a plant can achieve and stay within the stretch power uprate category is plant-specific and depends on the operating margins included in the design of a particular plant. Stretch power uprates usually involve changes to instrumentation setpoints but do not involve major plant modifications.

Extended power uprates are greater than stretch power uprates and have been approved for increases as high as 20 percent. These uprates require significant modifications to major balance-of-plant equipment such as the high pressure turbines, condensate pumps and motors, main generators, and/or transformers.

http://www.nrc.gov/reactors/operating/licensing/power-uprates/type-power.html
A number of plants have done extended power uprates (EPU) up to 20%, which requires plant modifications including the turbine and generator, as well as an increase in thermal rating/duty.

In Germany, some plants were uprated on the balance-of-plant (BOP) side by improvements to the turbines, e.g., improved blade/foil design, which requires the replacement of turbine blades and stators, without an increase in stages, as well as improved seals. So, basically, the turbine-generator is made more efficient. If the thermal output is increased, so as to increase the steam flow, then the number of stages may be increased, and the entire HP (IP) or LP turbine (rotor and stator) may need replacing depending on the magnitude of increase in thermal power. This is where an original designer must provide for a range of performance capability.

The changes to which I was referring in the previous are with respect to the increase in thermal output, which means the fuel design must have sufficient margins to technical and safety limits in order to ensure that the integrity of the plant is not compromised by realizing greater power output. Many of the current LWRs were designed with large margins based on conservative design principles at the time. Now, with modern technology in fuel and BOP, many commercial LWRs can realize significant power capabilities well above the original rated power.

http://www.nrc.gov/reactors/operating/licensing/power-uprates.html

 

[nikkkom]

There are no such areas, "thousands of square kilometers uninhabitable for centuries", not at Chernobyl

Yes, there are thousands of square kilometers around Chernobyl where people did not return. Modulo a few old people who didn't find new places to live the rest of their life. You can grasp at straws and point out that I'm technically wrong ("some people did return, therefore the land is not uninhabitable"), because it's not your country, and not your people who suffered all this economic and psychological devastation. For you, it's a discussion topic on an internet forum, nothing more.

They are my people and my country, though.

 

[nikkkom]

I actually have considerable sympathy with this complex of points of view, but there are differences between on the one hand holding one technology to stricter standards than another, and on the other, forbidding that one on a blanket basis. That amounts to making the standard "no nukes", which is not a rational standard.

Why that can't possibly be a rational standard? There is something inherent in nuclear power that we *must* have it?
We have standards such as "no gold-plated toilet seats", because gold-plated toilet seats, while possible, are economically idiotic.
We have standards such as "no pouring of mercury salts into rivers", because while it might make some industrial processes cheaper, it would poison many people.

It actually is quite simple in principle to establish standards that would reduce risks to the point that nukes are not the operative concern.

In principle, yes. Is it actually simple *in practice*? We have empirical evidence that it is far from simple - because it is still not done, 50+ years later.

The thousands of square km remark however, leaves me nonplussed. Which thousands of square km would those be? Windscale? TMI? Chernobyl? Fukushima?

Chernobyl exclusion zone is some 2600 km^2. That is only Ukraine's half of it, Belarus in fact got more than half of the fallout, and on their side this land is called "Polesie State Radioecological Reserve", some 2150 km^2 more.

 

[Jon Richfield]

Why that can't possibly be a rational standard? There is something inherent in nuclear power that we *must* have it?

Here we have a technological field which in engineering terms has completely, demonstrably, and demonstrable desirable features, even in comparison to other compatible or rival technologies. Every one of those others has its associated risks, including irreversible waste of resources (over a periods of millions of years or more, such as by burning fossil chemical accumulations for trivial benefit), environmental degradation and human suffering, both in those applying and supporting, and those who use them or are innocent bystanders, some of whose adverse effects exceed avoidable effects in nuclear engineering, and the major examples which amount to driving vandalistically into increasing dependence on limited supplies in the face of increasing demand.
And in the face of all that and much more, each of them, in spite of feasible options for improving our practices, has hardly been alleviated, let alone corrected, and not one has been abandoned.
And yet now you plead in effect that "there is something inherent in nuclear power that we *mustn't* have it"?
That is irrational in engineering terms for a start.
And how many nuclear plants are there around the world at the moment?
And how many of them have caused Windscales, Fukushimas, Chernobyls, or even TMIs? Have nukes rivalled any other energy industry on a similar scale world wide, in casualties?
That too is irrational in engineering terms.
Would you care to pursue the theme of engineering rationality?
Need any help? I am busy, but in a good cause I might extend myself.

We have standards such as "no gold-plated toilet seats", because gold-plated toilet seats, while possible, are economically idiotic.
We have standards such as "no pouring of mercury salts into rivers", because while it might make some industrial processes cheaper, it would poison many people.

Nice parodies, but rotten analogies; they have nothing to do with what anyone was saying. Some of them even are counter-factual in implication, such as the mercury (and Cd while you are at it!) that in the face of the standards did wind up in rivers and even in food etc. You surely can do better than that, can't you? Those wouldn't persuade any competent engineer, and they shouldn't persuade anyone else, though I admit that this latter remark is wistful thinking.

In principle, yes. Is it actually simple *in practice*? We have empirical evidence that it is far from simple - because it is still not done, 50+ years later.

Firstly, the same applies to coal and oil; one could argue the same for mining, travel by air, land, sea, and even space.
Secondly, the argument is specious. As I said above: "And how many nuclear plants are there around the world at the moment?
And how many of them have caused..." bla bla bla...?
If empirical evidence is what you demand, then that too is empirical evidence. Furthermore in every case that I listed, the untoward effects resulted from gross abuse of standards. If it is rational to continue with the practices that caused disasters in other industries when standards were abused, then why is it <ahem!> rational to demand that we abandon nukes because problems arose where rotten practice and rotten engineering caused problems?

Any more questions about engineering rationality?

Chernobyl exclusion zone is some 2600 km^2. That is only Ukraine's half of it, Belarus in fact got more than half of the fallout, and on their side this land is called "Polesie State Radioecological Reserve", some 2150 km^2 more.

Now why, I wonder, would they call it something like "Radioecological Reserve"...? Someone's sense of humour?
And in fact, where did I read that Ukraine was refusing to make their exclusion zone available for a similar reserve?
In any case, those "exclusion zones" are largely precautionary, as the plant, animal and human incursions demonstrate. There are plenty of nonradioactive regions around the planet, heavily populated, with far worse health records.
So let us not exclude everything too glibly.

 

[nikkkom]

Here we have a technological field which in engineering terms has completely, demonstrably, and demonstrable desirable features, even in comparison to other compatible or rival technologies.

Is nuclear power cheaper than other power sources? No.
Will its potential fuel reserves last for millions of years? No, uranium resources are limited. (Solar power's energy source is good for next ~4 billion years).
It produces no waste? No. (Solar doesn't. Even old panels are fully recyclable).
Is it safe from causing very costly accidents? Demonstrably, no. (Solar is safe).

So, what are those desirable features? Power density? Yep, cool. If you build a spacecraft for a trip to Jupiter, it is very important. Is it *that* important in terrestrial power plant?

And yet now you plead in effect that "there is something inherent in nuclear power that we *mustn't* have it"?
That is irrational in engineering terms for a start.

Wrong. It's a completely valid question whether some technology is good enough to be used, or not. Or even bad enough to be abandoned or banned. Many technologies, while having some benefits, nevertheless were abandoned. Say, radium glowing paint. Lead additives to petrol. Chlorofluorocarbons. Etc etc etc...

 

[mheslep]

They are my people and my country, though.

Yes, the Chernobyl accident was tragic. Please recognize there have been, and will be, industrial accidents in other countries, not just yours, but that does not give us all leave to exaggerate their impact, which ironically would worsen the psychological damage you mention. There are for instance, coal emissions that result inhttp://www.catf.us/resources/publications/files/The_Toll_from_Coal.pdf, every year.

 

[mheslep]

In any case, those "exclusion zones" are largely precautionary, as the plant, animal and human incursions demonstrate. There are plenty of nonradioactive regions around the planet, heavily populated, with far worse health records.

Not just occasional human incursions. After the infamous disaster with unit 4 in 1986, staff reported to work every day for years at Chernobyl station to operate the reactors (1, 2, and 3) that did not fail, the last of these operating until 2000.
http://www.world-nuclear-news.org/RS-Chernobyl-1-3-enter-decommissioning-phase-13041501.html

 

[mheslep]

Is nuclear power cheaper than other power sources? No.

Depends where it is built

...The report includes two nuclear data points for China, with overnight costs of USD 1 807/kWe and USD 2 615/kWe; LCOES are USD 26/MWh and USD 31/MWh at a 3% discount rate, USD 37/MWh and USD 48/MWh at 7% and USD 49/MWh and USD 64/MWh at 10%.

Chinese nuclear is three times cheaper than gas, two times cheaper than coal. I suspect only hydro is cheaper in China among reliable power sources.

https://www.iea.org/Textbase/npsum/ElecCost2015SUM.pdf

 

[jim hardy]

What should we use for perspective in such discussions?

Ten billion humans on the planet seems aberrant to me and if we don't do something about population growth we'll soon enough pave the whole place and have nowhere left to grow food.
Not to mention putting all that carbon back into the atmosphere as we burn fuel and make concrete(by cooking the CO2 out of limestone).

http://www.geocraft.com/WVFossils/Carboniferous_climate.html

Global Temperature and Atmospheric CO2 over Geologic Time

Late Carboniferous to Early Permian time (315 mya -- 270 mya) is the only time period in the last 600 million years when both atmospheric CO2 and temperatures were as low as they are today (Quaternary Period ).

I see Nuclear as mankind's hundred year bridge from carbon fuel to fusion.
We have to learn to do all things well - maybe it'll teach us that too.

To me it's that simple.

old jim

 

[Jon Richfield]

Is nuclear power cheaper than other power sources? No.
Will its potential fuel reserves last for millions of years? No, uranium resources are limited. (Solar power's energy source is good for next ~4 billion years).
It produces no waste? No. (Solar doesn't. Even old panels are fully recyclable).
Is it safe from causing very costly accidents? Demonstrably, no. (Solar is safe).

So, what are those desirable features? Power density? Yep, cool. If you build a spacecraft for a trip to Jupiter, it is very important. Is it *that* important in terrestrial power plant?
Wrong. It's a completely valid question whether some technology is good enough to be used, or not. Or even bad enough to be abandoned or banned. Many technologies, while having some benefits, nevertheless were abandoned. Say, radium glowing paint. Lead additives to petrol. Chlorofluorocarbons. Etc etc etc...

Really nikkkom, do yourself justice. I said I was busy. If you do not address the points you are fulminating, not arguing, and certainly not engineering.
And for fulminations I cannot afford the time. I fallout here.

 

[Jon Richfield]

...
I see Nuclear as mankind's hundred year bridge from carbon fuel to fusion.
We have to learn to do all things well - maybe it'll teach us that too.

To me it's that simple.

old jim

Jim, I largely agree, (though nothing is simple! )
but I think that you understate the scope for what it has become fashionable to call renewables.

 

[nikkkom]

Yes, the Chernobyl accident was tragic. Please recognize there have been, and will be, industrial accidents in other countries, not just yours

Note that even after Chernobyl, which impacted me, I did not yet decide that nuclear is hopeless.
It took another nuclear disaster in another country, Japan, for me to finally change my mind. (Well, the last straw was even later - when I saw people from nuclear industry STILL not getting it, even after Fukushima. "Filters on emergency vent lines are not necesssary"?? No, people with the attitudes like that are what is not necessary.)

 

[Jon Richfield]

Note that even after Chernobyl, which impacted me, I did not yet decide that nuclear is hopeless.
It took another nuclear disaster in another country, Japan, for me to finally change my mind. (Well, the last straw was even later - when I saw people from nuclear industry STILL not getting it, even after Fukushima. "Filters on emergency vent lines are not necesssary"?? No, people with the attitudes like that are what is not necessary.)

I suspect that my views on bosses like that are even stronger than yours, and probably have been in place a good deal longer, but I draw a distinction between technology and politics. (Don't bother to tell me that they are inseparable; I agree, but by that criterion there is hardly a technology that we could use at all.) And in dealing with such matters we are not licensed to have last straws or final changes of mind in matters concerning engineering when the underlying technology is sound.

 

[Jon Richfield]

Some of us might be interested in this item in the Lancet Volume 387, No. 10029, p1707–1708, 23 April 2016:

Chernobyl disaster 30 years on: lessons not learned

DOI: http://dx.doi.org/10.1016/S0140-6736%2816%2930304-X

I might have passed it by, but it seemed like a good example of synchronicity, so I thought I would pass it on.
It is not exactly nuclear engineering source material, but it seems to me generally sound, and the core of the message I support strongly.
One thing I will bet on cheerfully is that politicos and management climbers will hate, hate, hate it!

 

[jim hardy]

DOI link gives "error not found" message

Lancet link takes one to a page that wants $31.50 USD

Guess 'll have to wait for the Nova show.

 

[Astronuc]

Some of us might be interested in this item in the Lancet Volume 387, No. 10029, p1707–1708, 23 April 2016:

Chernobyl disaster 30 years on: lessons not learned . . . .

Without a subscription or purchase, one can only read the summary, which doesn't provide much information: "Ahead of the 30 year anniversary on April 26, 2016, Chris McCall spoke to a former plant operator at Chernobyl and to experts about the explosion's long-term health effects."

While it's not nuclear engineering, it is related to health physics or the effects of radiation on persons.

 

[Jon Richfield]

Without a subscription or purchase, one can only read the summary, which doesn't provide much information: "Ahead of the 30 year anniversary on April 26, 2016, Chris McCall spoke to a former plant operator at Chernobyl and to experts about the explosion's long-term health effects."

While it's not nuclear engineering, it is related to health physics or the effects of radiation on persons.