Being a slow day, I thought I'd pass along a short story which
happened in my early days, when I was a engineering student. I suspect
many woodworkers on this NG may have similar backgrounds. Our class
was allowed to visit the Bergen Generating Station in the NJ
medowlands.

We were shown around the facility and then treated to a chalk talk
about the ME aspects of of the boiler and steam turbines we saw. The
power station at that time could be fired by steam coal or natural
gas. Our lecturer explained that the thermal efficiency of the plant
could be calculated by dividing the temperature of the cold body by
that of the hot body.

Thus the efficiency was controlled by the temperature of the cooling
water in Overpeck Creek which cooled the condensers and the maximum
steam temperature which the turbine fan blades could withstand on a
sustained basis.

We were told the plant ran at the highest possible thermal efficiency
and that your reputation as a future engineer would be made if you
could improve it one tenth of one per cent.

Pushing the envelope of technology is not easy!

Joe G

On Jun 7, 2:01*pm, GROVER wrote:
Being a slow day, I thought I'd pass along a short story which
happened in my early days, when I was a engineering student. I suspect
many woodworkers on this NG may have *similar backgrounds. Our class
was allowed to visit the Bergen Generating Station in the NJ
medowlands.

We were shown around the facility and then treated to a chalk talk
about the ME aspects of of the boiler and steam turbines we saw. The
power station at that time could be fired by steam coal or natural
gas. Our lecturer explained that the thermal efficiency of the plant
could be calculated *by dividing the temperature of the cold body by
that of the hot body.

Thus the efficiency was controlled by the temperature of the cooling
water in Overpeck Creek which cooled the condensers and the maximum
steam temperature which the turbine fan blades could withstand on a
sustained basis.

We were told the plant ran at the highest possible thermal efficiency
and that your reputation as a future engineer would be made if you
could improve it one tenth of one per cent.

Pushing the envelope of technology is not easy!

Joe G

They have tried justabout everything. The big ****er is the latent
heat of water. They have tried other fluids, but that created a whole
new set of problems, like corrosiveness. They have tried super-
critical systems, but the plumbing had to be sooo huge as to be cost
prohibitive, like a steam line with 12" ID and 36" OD, just think of
the flanges.

Better look for cheap heat. Like a CANDU.

Robatoy wrote:
....

... They have tried super-
critical systems, but the plumbing had to be sooo huge as to be cost
prohibitive, like a steam line with 12" ID and 36" OD, just think of
the flanges.

....

That's not so...there are some 600 supercritical plants in operation
dating to as early as the 60's. TVA's Bull Run went on line in 1967 and
routinely has had one of the best if not leading heat rate and
availability in the US since, winning the annual efficiency rating
fairly frequently until some of the newer units came on line. It's
still routinely in the top five.

Bull Run generates more than six billion kilowatt-hours of
electricity a year, enough to supply about 430,000 homes. It has been ranked the
most-efficient coal-fired plant in the nation 13 times and is
consistently in the top five each year. In 2005, the plant achieved its
best summer reliability ever, and in November of that year it set a
plant record for continuous operation when it ran nonstop for 189 days
with no unscheduled outages for maintenance or repairs.

I don't know the actual steam line dimensions, but while it is very
thick-wall as compared to normal Sch 40/60/80 indeed, I'm pretty sure
12" walls are extreme (and 12" ID is way too small, I think they're more
like 30" ID).

I looked in my old B&W _Steam_ book; they don't have any typical
supercritical plant steam line dimensions unfortunately, but state that
the Barberton fabrication facility could manufacture up to 8" wall
thickness. There are almost no flanges in a supercritical facility;
it's virtually all welded (for obvious reasons). I'll ask one of my old
buddies what is a typical steam line dimension. (BTW, at least in the
olden days, thick-wall pipe of these dimensions was made by boring solid
material; I presume probably still is).

I'm not up to date on current statistics; quite a number of the recent
and current boilers being built in China are supercritical units so
they're certainly not out of style.

As an aside, an unfortunate disadvantage of nuclear units of all types
(other than the oddballs that did not prove out like the HTGR or
liquid-Na) are limited as compared to fossil owing to the limitation of
core power density required to prevent either DNBR (PWRs) and/or
centerline fuel melt (both) of the fuel. This limits them to lesser
thermal efficiency than fossil units. One reason for the B&W OTSG was
its ability to have 30-40F of superheat that compensated somewhat (as
compared to conventional SG's). I'd have to look up CANDU but I don't
think it's power density rates any higher than that of conventional
LWRs; it's advantage is low-enrichment cost and the continuous refueling
facility.

So, the supercritical boiler is alive and well... (At least outside
the US where progress hasn't had the plug pulled, anyway....)

--

Lew Hodgett wrote:
....

Both are less than 20%.
....

Large fossil-fired generation is in the 35-36%; Bull Run mentioned
earlier is about 38%; new super-criticals are up to at least pushing the
40% mark if none have yet broken it.

--

On Jun 7, 3:49*pm, dpb wrote:
*I'd have to look up CANDU but I don't
think it's power density rates any higher than that of conventional
LWRs; it's advantage is low-enrichment cost and the continuous refueling
facility.

CANDU's are fuelled on the fly, but initial capital cost is very high.
Ontario Power Generation is now considering a LWR.
A lot of people I know/knew has worked or now works for OPG. Their
scrapping the SuperCritical plans had everything to do with the cost
of plumbing. None of those to be found in this network. Mind you,
those studies were done in the 30's. 12" walled pipe? Prolly not. But
thick and expensive nonetheless.

So, the supercritical boiler is alive and well... *(At least outside
the US where progress hasn't had the plug pulled, anyway....)

Our biggest generators are 850's and that's already a bit of a pain in
the ass when taking spinning reserve into account. Everybody was
always happy to see Big Alice come on line....not.

Speaking spinning reserve... I always thought that super tankers
should have at least 30% of empty tanks on board... a set of big
transfer pumps and presto... spring a leak, dump the leaking tank into
an empty one.

Robatoy wrote:
On Jun 7, 3:49 pm, dpb wrote:
I'd have to look up CANDU but I don't
think its power density rates any higher than that of conventional
LWRs; its advantage is low-enrichment cost and the continuous refueling
facility.

CANDU's are fuelled on the fly, but initial capital cost is very high.
Ontario Power Generation is now considering a LWR.

Probably the wiser choice...(says an old PWR guy... )...

I'd think the $/MWe would quite possibly be higher for CANDU given layout.

A lot of people I know/knew has worked or now works for OPG. Their
scrapping the SuperCritical plans had everything to do with the cost
of plumbing. None of those to be found in this network. Mind you,
those studies were done in the 30's. 12" walled pipe? Prolly not. But
thick and expensive nonetheless.

Ages and ages ago had number of acquaintances at Chalk River but nobody
at OPG.

With current technology the overall plant is often actually
cheaper/smaller owing to the reduction elsewhere in fuel handling
equipment sizing, pulverizer size/numbers, ash handling, etc., etc.,
etc. despite the complications required for the supercritical working fluid.

There's no reason one couldn't build smaller supercritical units for
smaller grids that I can see...it's just that the current market is
primarily overseas at the moment although B&W has a couple of current
projects in that size range (altho I think they're both at least
two-unit stations).

So, the supercritical boiler is alive and well... (At least outside
the US where progress hasn't had the plug pulled, anyway....)

Our biggest generators are 850's and that's already a bit of a pain in
the ass when taking spinning reserve into account. Everybody was
always happy to see Big Alice come on line....not.

When I was doing coal analyzers and SaskPower was one customer, there
was a new B&W-supplied unit finishing up just east of Weyburn (this
15(?) years ago or maybe longer now...my where does time go? ). I
don't recall particulars on it other than another mine-mouth plant but
it was pretty large (at least that of Poplar River and Koronach and
probably larger) iirc. Not sure of cycle constants for it.

Speaking spinning reserve... I always thought that super tankers
should have at least 30% of empty tanks on board... a set of big
transfer pumps and presto... spring a leak, dump the leaking tank into
an empty one.

Interesting thought, but how often is there/has there been a significant
tanker leak that wasn't associated w/ serious trouble rather than just a
single/simple tank leak? Seems to me my recollection is they're
generally in extreme circumstances (albeit sometimes of own making a la
Exxon Valdez). Maybe not; just a conception, not data/researched...

--

Robatoy wrote:
....

One big difference in pollutants is to burn that ' clean coal' those
adverts on US TV talk about. *smirk*
Seriously, one plant I worked at had a pile of 'summer coal' for those
hazy days.

That used to be quite common; not so much any longer w/ restricted
limits altho may be some places that still have to. Detroit Edison
Monroe plant did so routinely; we had online sulfur meter there to
monitor in real time.

One major advantage in going to the super-critical cycle; it could
reduce coal consumption 20% or even more depending on the age/efficiency
of generation it replaced.

Over the last 30 years or so, SO2 and NOx reduction through scrubbing
and selective catalytic reduction technologies has made significant
differences in those smog/acid rain contributors. Fabric filters and
improvements in electrostatic precipitators have reduced particulate
emissions and more recently, technologies such as wet electrostatic
precipitators and sorbent injection are capable of further reductions
including fine particulates. Commercially available mercury control,
for both eastern and western coals are being deployed in the US now.

Eventual C sequestration is undoubtedly on the horizon.

That said, nukes have major advantages in regard to operating emissions
but the closure of the backend of the fuel cycle is still an impediment
in the US owing to lack of political resolve primarily.

....

One of OPG's stations had a blend B&W and CE boilers. Circ pumps and
tangential fires made the CE's my favourites. Those were only 500'MW
single shaft two-pole, the B&W were tandems. Big wheels on the LP
side. None were over 30% efficient.

Bull Run is CE tangential-fired. I, too, like the tangential furnace
despite being a B&W retiree (altho I was NPGD, not FPGD; I only drifted
into the fossil side years later in the consulting gig).

--

Doug Houseman wrote:
In article ,
....

Common steam plants in use today, built years ago - are in the 40-42
percent thermal efficiency range. Newer prototype plants have hit over
60 percent. I doubt the prototypes will ever be built full scale with
that level of efficiency.
....

Who are those? Gas combined-cycle turbines, maybe?

Sure not coal-fired; current super-critical units are just now at around
the 42% numbers...

--

On Jun 7, 9:56*pm, dpb wrote:
Doug Houseman wrote:
In article ,

...

Common steam plants in use today, built years ago - are in the 40-42
percent thermal efficiency range. Newer prototype plants have hit over
60 percent. I doubt the prototypes will ever be built full scale with
that level of efficiency.

...

Who are those? *Gas combined-cycle turbines, maybe?

Sure not coal-fired; current super-critical units are just now at around
the 42% numbers...

--

NG fired cogen turbines are kinda cool. Quick start for peak load, but
time will tell about their reliability.
Dunno what they're running in terms of efficiency, but they are
building them all over.

Robatoy wrote:
On Jun 7, 9:56 pm, dpb wrote:
Doug Houseman wrote:
In article ,
...

Common steam plants in use today, built years ago - are in the 40-42
percent thermal efficiency range. Newer prototype plants have hit over
60 percent. I doubt the prototypes will ever be built full scale with
that level of efficiency.
...

Who are those? Gas combined-cycle turbines, maybe?

Sure not coal-fired; current super-critical units are just now at around
the 42% numbers...

--

NG fired cogen turbines are kinda cool. Quick start for peak load, but
time will tell about their reliability.
Dunno what they're running in terms of efficiency, but they are
building them all over.

Except for the use of prodigious amounts of NG that's far more suited to
other uses than central-station generation.

--

In article ,
dpb wrote:

Doug Houseman wrote:
In article ,
...

Common steam plants in use today, built years ago - are in the 40-42
percent thermal efficiency range. Newer prototype plants have hit over
60 percent. I doubt the prototypes will ever be built full scale with
that level of efficiency.
...

Who are those? Gas combined-cycle turbines, maybe?

Sure not coal-fired; current super-critical units are just now at around
the 42% numbers...

--

53 to 54 percent at perfect load for combined cycle now. 42 percent for
coal fired steam plants, again at perfect loading. None of these plants
get to stay at perfect loading very much of the time, but they try.

J. Clarke wrote:
.....

Coal still emits massive quantities of CO2, and the idea of burning it
then somehow "sequestering the carbon" is whackadoodle. ...

Oh, I agree wholeheartedly it's a seemingly asinine thing to do, but w/
current politics in charge it appears it will be either that or...well,
just what, specifically??? There doesn't appear to be a substitute of
the magnitude required in the short term to simply quit.

--

Doug Houseman wrote:
In article ,
dpb wrote:

Doug Houseman wrote:
In article ,
...

Common steam plants in use today, built years ago - are in the 40-42
percent thermal efficiency range. Newer prototype plants have hit over
60 percent. I doubt the prototypes will ever be built full scale with
that level of efficiency.
...

Who are those? Gas combined-cycle turbines, maybe?

Sure not coal-fired; current super-critical units are just now at around
the 42% numbers...

--

53 to 54 percent at perfect load for combined cycle now. 42 percent for
coal fired steam plants, again at perfect loading. None of these plants
get to stay at perfect loading very much of the time, but they try.

Well, the 42% of a current supercritical boiler isn't what I'd have
interpreted as "common and built years ago"...is about right for last 10
years or so, agreed.

The only real hassle w/ the combined cycle is that it's a misuse of NG
for baseload generation imo. Good choice for load following, etc., ...

--

On 6/8/2010 12:56 PM, dpb wrote:
J. Clarke wrote:
....

Coal still emits massive quantities of CO2, and the idea of burning it
then somehow "sequestering the carbon" is whackadoodle. ...

Oh, I agree wholeheartedly it's a seemingly asinine thing to do, but w/
current politics in charge it appears it will be either that or...well,
just what, specifically??? There doesn't appear to be a substitute of
the magnitude required in the short term to simply quit.

When enough people figure out that the choices are to pay ludicrous
electric rates, freeze to death in the dark, or build nukes, the
greenies will be told to go pound sand.

J. Clarke wrote:
....
When enough people figure out that the choices are to pay ludicrous
electric rates, freeze to death in the dark, or build nukes, the
greenies will be told to go pound sand.

I used to think so; any more I'm not so sure it'll just not be roll-over
time...

I've said numerous times that as the current spate of applications for
new units comes up for licensing hearings we'll learn real soon now how
serious the C-sequestration people are for actually accomplishing
something as opposed to simply being obstructionists. I have my opinion
what we'll see of them; hopefully to be shown it's wrong...

--

On Tue, 08 Jun 2010 11:56:45 -0500, dpb wrote:

J. Clarke wrote:
....

Coal still emits massive quantities of CO2, and the idea of burning it
then somehow "sequestering the carbon" is whackadoodle. ...

Oh, I agree wholeheartedly it's a seemingly asinine thing to do, but w/
current politics in charge it appears it will be either that or...well,
just what, specifically??? There doesn't appear to be a substitute of
the magnitude required in the short term to simply quit.

Some seqestering is being used to increase production of oil fields.

Mark

Markem wrote:
On Tue, 08 Jun 2010 11:56:45 -0500, dpb wrote:

J. Clarke wrote:
....

Coal still emits massive quantities of CO2, and the idea of burning it
then somehow "sequestering the carbon" is whackadoodle. ...
Oh, I agree wholeheartedly it's a seemingly asinine thing to do, but w/
current politics in charge it appears it will be either that or...well,
just what, specifically??? There doesn't appear to be a substitute of
the magnitude required in the short term to simply quit.

Some seqestering is being used to increase production of oil fields.

Yes, there are some byproduct uses but I think will remain quite small
volumes relative to the product stream (product being a waste in this case).

I guess one could clean it up and use it for carbonation, too...

--

On Wed, 09 Jun 2010 15:09:13 -0500, dpb wrote:

Markem wrote:
On Tue, 08 Jun 2010 11:56:45 -0500, dpb wrote:

J. Clarke wrote:
....

Coal still emits massive quantities of CO2, and the idea of burning it
then somehow "sequestering the carbon" is whackadoodle. ...
Oh, I agree wholeheartedly it's a seemingly asinine thing to do, but w/
current politics in charge it appears it will be either that or...well,
just what, specifically??? There doesn't appear to be a substitute of
the magnitude required in the short term to simply quit.

Some seqestering is being used to increase production of oil fields.

Yes, there are some byproduct uses but I think will remain quite small
volumes relative to the product stream (product being a waste in this case).

I guess one could clean it up and use it for carbonation, too...

Make dry ice.......

Mark

Robatoy wrote:
....

...They have tried super-
critical systems, but the plumbing had to be sooo huge as to be cost
prohibitive, like a steam line with 12" ID and 36" OD, ...

I never did find the eng'g drawings online for Bull Run and my TN
buddies are busy and I told 'em to not waste their time if didn't either
know it or have it directly at hand...

So, I did a very rudimentary minimum wall thickness calculation for
seamless tubing based on the ASME B31.1 criterion based on allowable
stress and got a number otoo 4" for 30" nominal diameter, 3500 psi
working pressure w/ steel derated to 12000 psi for temperature. I don't
think that's _way_ out of line, but it's certainly not a design
calculation.

Higher tensile strength values would reduce that at about an 80%
proportionally to the ratio of strengths. I didn'tfind the applicable
ASME table for temperature factors online and it's one I don't have at
hand (I'm a nuc-e, not mech, ... need cross-sections? I got those or
shielding data or ... ) so reduced another 20% based on a
subcritical system calculation. OTOH, one might reasonably expect
better alloys which would be higher at temperature, to compensate. So,
as is it's a guesstimate. Better data would be nice but only tables
and/or piping calculators I found were all for purchase, none were
online modules like the sagulator the likes of which I was hoping I
might find...

--

On 6/11/2010 2:17 PM, dpb wrote:

which would be higher at temperature, to compensate. So, as is it's a
guesstimate. Better data would be nice but only tables and/or piping
calculators I found were all for purchase, none were online modules like
the sagulator the likes of which I was hoping I might find...

Don't know if it applies here, but Engineer's Edge has become a routine
stop for me as a free resource:

http://www.engineersedge.com/

--
www.e-woodshop.net
Last update: 4/15/2010
KarlC@ (the obvious)

Swingman wrote:
On 6/11/2010 2:17 PM, dpb wrote:

which would be higher at temperature, to compensate. So, as is it's a
guesstimate. Better data would be nice but only tables and/or piping
calculators I found were all for purchase, none were online modules like
the sagulator the likes of which I was hoping I might find...

Don't know if it applies here, but Engineer's Edge has become a routine
stop for me as a free resource:

http://www.engineersedge.com/

Thanks...I had seen it before but it didn't come up in my searches this
time. Looking, I found a pressure vessel calculator that gives somewhat
higher values at similar conditions but it has no references to the
basis for the computation, unfortunately, so I can't tell what's causing
them. Clearly it's not the same as B31.1 but doesn't reference either a
Standard nor the criterion behind it so can't tell.

Unfortunately, they don't have a link to the pertinent ASME Standard,
either...so, useful site for much but didn't help me out on this
particular sidelight trivia quest...it got me to wondering in that I
really don't know what the dimensions actually are, myself. I've got
the TVA design book for a couple of the older plants we did some
technology demonstration projects at but they're not of any help for the
supercritical units, unfortunately.

--

"Gerald Ross" wrote in message
...
Lew Hodgett wrote:

Might be nice if they could be switched to fans to suck the smog out of
California.

I think there was a Beverly Hillbilliees episode that dealt with that
very proposition wherein investors approached Jed with the idea of drilling
a large shaft/tunnel through one of the mountains above L.A. to include
giant fans that would suck the smog out of the L.A. basin. Having advised
Jed they had investment commitments for all the major components save the
tunnel Jed asked, "Well, who gets the shaft?"

Dave in Texas

Robatoy wrote:
On Jul 27, 11:20 am, dpb wrote:
I keep trying to reconcile the what we know about nuclear powered
satellites and the size of the behemoths we seem bent on building on
the ground. Even the small units that power subs and aircraft
carriers. Why do these power plants always have to be so big and
unwieldy? I don't want to go as far as suggesting 'Neighbourhood Black
Power Boxes' but....(I understand there would be security issues but
that is not why the big nukes are as big as they are.)

nuke plants are large because of the generation size, and containment
(accidents).

subs don't have 'large' plants because they skip a lot of the safety and
containment bits. if they get a meltdown, it just goes out the bottom of the
hull.

chaniarts wrote:
....

subs don't have 'large' plants because they skip a lot of the safety and
containment bits. if they get a meltdown, it just goes out the bottom of the
hull.

Not really. The prime reason is they're highly enriched, much higher
power density (and much smaller total power output/reactor) than
commercial power reactors.

They have design bases that are much more stringent in terms of load
swing, maneuvering rates, ability to restart immediately after shutdown,
etc., owing to the demands placed upon them by combat readiness. Hence,
they're much more expensive per MW also.

--

On Jul 27, 1:26*pm, dpb wrote:
chaniarts wrote:

...

subs don't have 'large' plants because they skip a lot of the safety and
containment bits. if they get a meltdown, it just goes out the bottom of the
hull.

Not really. *The prime reason is they're highly enriched, much higher
power density (and much smaller total power output/reactor) than
commercial power reactors.

....and aren't designed to be run by Homer Simpsons. A trade-off
between safety and function.

They have design bases that are much more stringent in terms of load
swing, maneuvering rates, ability to restart immediately after shutdown,
etc., owing to the demands placed upon them by combat readiness. *Hence,
they're much more expensive per MW also.

They are also much smaller (MW) and have much tighter operational
limits. They fail "safe". ...to the bottom of the ocean.

On 7/27/2010 1:00 PM, chaniarts wrote:
Robatoy wrote:
On Jul 27, 11:20 am, wrote:
I keep trying to reconcile the what we know about nuclear powered
satellites and the size of the behemoths we seem bent on building on
the ground. Even the small units that power subs and aircraft
carriers. Why do these power plants always have to be so big and
unwieldy? I don't want to go as far as suggesting 'Neighbourhood Black
Power Boxes' but....(I understand there would be security issues but
that is not why the big nukes are as big as they are.)

nuke plants are large because of the generation size, and containment
(accidents).

subs don't have 'large' plants because they skip a lot of the safety and
containment bits. if they get a meltdown, it just goes out the bottom of the
hull.

There has never been a meltdown on a US warship including several which
were lost at sea with reactors in operation. Avoiding a meltdown is a
matter of dropping the rods and providing sufficient cooling to deal
with the transient, which is difficult with land-based power plants but
not with power plants that have a whole ocean to use as a heat sink.

In any case, the power output of the largest naval reactor in the US
inventory is somewhere around 100 megawatts, 1/10 the output of a
typical base-load electric generating plant, and the ones used in
submarines are much lower capacity.

And this all leaves aside the different compromises that are made in
military vs civilian installations.

dpb wrote:
chaniarts wrote:
...

subs don't have 'large' plants because they skip a lot of the safety
and containment bits. if they get a meltdown, it just goes out the
bottom of the hull.

Not really. The prime reason is they're highly enriched, much higher
power density (and much smaller total power output/reactor) than
commercial power reactors.

they have a multifeet thick concrete containment vessel, like land power
plants, capable of surviving a jetliner hit? that's a good part of the bulk
of land plants, from what i can see from the outside.

They have design bases that are much more stringent in terms of load
swing, maneuvering rates, ability to restart immediately after
shutdown, etc., owing to the demands placed upon them by combat
readiness. Hence, they're much more expensive per MW also.

Robatoy wrote:
....

I keep trying to reconcile the what we know about nuclear powered
satellites and the size of the behemoths we seem bent on building on
the ground. Even the small units that power subs and aircraft
carriers. Why do these power plants always have to be so big and
unwieldy? I don't want to go as far as suggesting 'Neighbourhood Black
Power Boxes' but....(I understand there would be security issues but
that is not why the big nukes are as big as they are.)

Satellites are mostly isotopic (Pu-238) decay heat powered
thermoelectric generators. The US has only had one experimental fission
reactor launched and that was ages ago while the Russians have used
quite a few altho I don't know just how recently.

Hmmm....this seems to be a fairly good article altho I didn't read it
carefully, skimming looks reasonable---

http://www.eoearth.org/article/Nuclear_reactors_for_space

The primary reason for the size differential is the space reactors are
quite low power devices in terms of central generation requirements
(otoo 2-3 to 100-200 kw instead of 1000 MW). Also they don't require
much in the way of shielding onboard as there is no manned payload.
There's sufficient shielding in a commercial design that one can be in
containment but outside the biological shield area during operation even
though that is a rare event not done in normal operation as there is no
need for access there. We did do incore physics tests using
manually-controlled drives to insert probes in the calibration ports of
the fixed incore SPNDs (Rh-emitter self-powered neutron detectors)
during initial physics testing and follow-up at Oconee I to provide
verification data for the physics models and instrumentation to the NRC
for final approval of the design models back in the mid-70s. It was a
100F+/80%RH hellhole in the bottom of the incore termination tank and
miserable suited up but we did it. The thought that there was
2250psi/650F water just on the other side of a 1/2" diameter tube w/
only an end cap and weld was unnerving to say the least...

And, just like the boiler in a 1000 MWe coal-fired unit isn't all that
large, the reactor vessel containing the reactor core itself is only
roughly 25-ft tall (about twice the height of the fuel) and 12-15 ft in
diameter. All the rest is ancillary equipment. The reason containment
buildings are the size they are is that they must be large enough to
allow for adequate maneuverability of equipment inside and have ample
volume such that the design overpressure of a design LOCA is within the
ability of the containment to withstand. Years ago circle-W designed a
set of reactors w/ ice containment (a huge rack lining the upper reaches
of containment w/ blocks of ice and the ancillary ice-making equipment).
This did allow them to reduce the initial capital cost by making the
containment significantly smaller since the ice-melt during LOCA would
quench the steam, thereby holding down the maximum pressure but these
turned out to be high maintenance items and afaik the concept has been
dropped in current generation designs on the docket for licensing now.

--

Dan Coby wrote:

On 7/27/2010 9:41 PM, Mark & Juanita wrote:
....snip

There is certainly at least one solar panel farm in that area of the
desert. It's between Ontario and Ridgecrest, close to the federal prison
(don't remember what the highway designation is)


You are probably referring the to facility on 395 at Kramer Junction.

http://en.wikipedia.org/wiki/Solar_E...rating_Systems

Yep, that's it.


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There is never a situation where having more rounds is a disadvantage

Rob Leatham

dpb wrote:
....

One problem w/ wind is that even here in SW KS known for being one of
windiest places in the US the wind doesn't blow all the time,
particularly less in Aug and Feb, the two peak months and at night when
lose thermal heating effects that contribute. The Gray County farm has
averaged only about a 40% capacity factor since it went online in 2002
or so based on their reported generation to DOE/EIA that I looked at a
year or so ago. The maximum monthly average was just over 50% for a
couple of months while the two slack months were in the mid-20% range.
That means need 2.5X extra installed capacity to make up the target
generation on average and 5X in weak months. That's a real construction
burden to do more than augment conventional technologies.

Those statistics were for seven years of operation and were quite
consistent from year to year in the monthly peaks and valleys reflecting
climatological trends, not just a one-year aberration.

The data were only available on a monthly generation basis so the
extremes in availability would be greater as looked at shorter time
periods if that level of reporting were available. Last week in the
doldrums SIL came by the wind farm on way here for visit and reported
only 2-3 of the whole installation were turning.

While the fuel is free it isn't always being delivered and is a diffuse
source so takes a lot of infrastructure to concentrate it into useful
form. That translates to $$/kw on grid; I don't think there would be
any significant interest by utilities at all if it weren't for the
various State-legislated mandates for percentages of generation from
green sources passed onto the utilities and the various tax incentives
to subsidize part of the cost.

Whether it will be cost-competitive eventually w/o those is anybody's
guess; certainly C-taxes if introduced will change the playing field
immensely in foreseen and unforeseen ways (and I personally expect more
of the latter than former). Unfortunately, however much scale and
technology improvements benefit the capital cost/installed-MWe, the
fundamental nature of the intermittent fuel supply can't be improved or
eliminated so the required conventional reserve capacity will still be
required which essentially doubles the cost for every MWe that isn't
available or reduces grid reliability if not there.

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