Re: About renewable energy

On 25 Apr 2006 08:21:09 -0400, nicksanspam@xxxxxxxxxxxxxxxxx wrote:


Nuclear bigness may be a problem. Too big, like large municipal union
public transit and garbage collection systems with crippling strikes and
automatic pay raises. An over-concentration of economic and political
power, as well as electrical power. Smaller plants might be better-
controlled, politically, with fewer opportunities for bribery and other
skullduggery, eg terrorism. They might even provide district heating :-)

There are several problems involved here. At the core of the matter
is the fact that Rickhover's little submarine reactor design didn't
scale up 10X or more very well. What works well at 50 or 100MW
doesn't work so well at 1200 or more.

Unfortunately Rickhover was able to throw enough temper tantrums that
the government and Westinghouse went along, Shippingport was a PWR and
the rest is history.

There are MUCH better methods of making a few thousand megawatts of
nuclear heat than the light water reactor. Some of those will be
deployed on this next round of nuclear build-out.

As far as business bigness, it has been the small utilities that have
had the most problems. I came out of TVA where despite media hype to
the contrary, we did things mostly right. There were the necessary
resources available for first class training and equipment.

TMI was my first venture outside the big utility biz. Frankly I was
stunned. Met-Ed was a tiny utility - a few hydro plants, a couple of
coal plants. And the nukes. I got the distinct impressing that back
in the 60s someone was thumbing through the latest issue of "Power"
magazine, saw an ad for a nuke plant, dialed 1-800-nukes-r-us and put
one on the company Iridium Amex card :-)

Pre-accident, they relied almost 100% on navy nuke training. No
simulator (they sent operators to B&W's simulator whenever they
could). Little technical depth, as they relied on the constructor/A-E
to build the plant. Little plant-specific training.

In contrast, TVA built its own simulator facility with a simulator for
each of the three brands of reactors. It had its own design
engineering division which designed everything except the actual NSSS
(nuclear steam supply system) We were all trained in-depth and in
many disciplines in-house. I served an engineering apprenticeship AND
trained as a reactor operator - almost 9 years total.

Additionally, TVA would pay for any job-related training. I became a
certified welder and a certified non-destructive testing engineer,
just because I wanted to. TVA still has the reputation as the educator
for the industry. BPS, Ga Power, Duke and other very large utilities
are about the same.

Going on the "outside" was like parachuting from the Concorde and
ending up on a deserted island with nothing but a stick for a tool.
Culture shock en extremis!

One of the major contributing factors to the TMI event was that the
operators were trained as navy nuke operators to never, ever let the
reactor coolant system go solid - that is, no expansion space in the
pressurizer. Taking a large power plant solid is of no consequence.
There is enough elasticity in the miles of piping that no damage is
done when the system is hydraulically locked. But based on this navy
nuke training and a defective pressurizer water level indicator (stuck
pointer), they turned off the emergency core cooling system at the
very moment it was needed the most - when a steam bubble was forming
in the reactor.

Had these pumps been allowed to operate on automatic, the incident
would have ended with a flooded containment sump, a press release,
some bureaucratic finger pointing and not much else.

Having spent probably thousands of hours on full scale power plant
control room simulators and having run the emergency drills many times
that involved letting the primary system go solid while figuring out
just what the hell was going on, when I read the prelim
sequence-of-events report from TMI, I just shook my head and wondered
out loud, "what the hell were those guys thinking?" Flood the system
with cooling water and THEN assess the available info and figure out
what the root problem is. I found out that they were thinking
"submarine reactor".


A friend who taught physics in the 50s built a reactor in a pickle barrel
in a college basement, reminding his students not to carry around more
than one critical mass in their hands. Why do we need such big nukes?

Arguably we don't. Utilities tended to copy practices developed from
coal plants. Fuel is the biggest cost for a dirt burner. Fuel is a
negligible cost for nukes. Fossil plant designers do whatever they
can to eek out fractions of a percent improvements in efficiency.
Efficiency improves faster than cost with scale.

Other factors tend to make the operating experience with huge plants -
fossil or nuke - less than completely satisfactory.

An example. Cumberland City steam plant was for quite some time the
largest coal plant in the world. 14 story boiler, about 3200 psi, 900
deg F steam, more than 1400MWe output per unit. When the two units
were running, they supplied a significant fraction of TVA's entire
load (I think the entire system load back then was on the order of 20
gigawatts and Cumberland City supplied about 3 gigawatts.) The heat
rate (efficiency) was the best of class.

However. When one of those units tripped, and they tripped a lot, it
rattled the whole grid. Worse, many times the other unit would suffer
a sympathetic trip. Instantly losing 3 gigawatts really shakes things
up.

Reliability was and is a problem simply because everything has to be
so large. Unit coal trains run through the plant continuously day
and night. Coal cars are emptied by being flipped over, 3 at a time,
every few seconds as the 100 car unit train slowly moves through the
yard. I forget the exact spec but a train car full of coal only lasts
a minute or two.

OTOH, let's look at Widow's Creek plant near Scottsboro, Al. This
plant has 13 units of various sizes, the largest being about 300MWe
and the smallest about 80. (This is from very old memory so don't sue
me if you look it up and the numbers are a little different.) The
plant is ancient in design, some parts over 80 years old.

There is ALWAYS something wrong with one or more units and there is
ALWAYS at least one unit off-line for repairs. BUT! There are also
ALWAYS 8 or 10 or more units running. Always. Despite individual
units being highly unreliable and worn out, the plant as a whole is
one of the most reliable generators in the system.

The industry has realized that the same thing will hold true for
nukes. Rather than 2-3 >1000MWe plants at a site, build a dozen or
more little 100-300MWe plants. Even better, scatter them around the
system, locating each close to a load center. One or more units may
be off-line for maintenance at any given time but something less than
100% output is always there.

Equally important, when a unit trips, it doesn't destabilize the
system. This is very important.

I was in the control room at Sequoyah in Chattanooga the day in 1975
when they set the Browns Ferry NP (BFNP) control room on fire with the
candle. TVA built the switchyard at Sequoyah a good ten years ahead
of the plant construction. The yard served as a major transmission
hub, wheeling power from multiple sources.

Both approx 1100MWe units at BFNP tripped within minutes of each
other. The resulting grid disturbance took down both Cumberland City
units (3000MWe) and another smaller plant, I don't remember which. The
operators at Sequoyah and at Central Dispatch in Chickamauga spent
over an hour sh*tting nails trying to keep the entire grid from going
down.

The grid underwent a severe "load slosh" event. Load Slosh is when,
because of the dynamical nature of the grid, loads swing back and
forth across the grid, like water sloshing in a canoe. One sees the
load on a given plant swing wildly from near zero to overload in
seconds.

Think of holding a slinky stretched out and shaking one end. The
disturbance sloshes back and forth. Unlike the Slinky where friction
dampens the oscillations, a power grid can easily go divergent and
ultimately go down.

The grid operators had to not only figure out what major loads to shed
but exactly WHEN to shed them to generator a counter-balancing
transient. At the same time, the operators at the power plants had to
ride the throttle and the generator excitation to try to catch and
dampen the slosh.

I've had to address sloshes on the simulator and I can tell you that
there's nothing more stressful. I'd come out drenched in sweat and
totally drained of energy, even though the entire evolution might last
only 20-30 minutes.

With many diverse generating units, this sort of major disturbance or
loss of capacity just isn't possible, except maybe from a major
weather event.

Small units bring additional benefits. Easy to site. Not so much
land needed. Massive amounts of cooling water not needed. None of
the headaches of transporting components too large for the highway or
railroads.

When new nukes are built here, this is the route the industry will go.
The US has lost ALL its heavy nuclear manufacturing base. New plants
will come from overseas. Japan has a nifty little intrinsically safe
100 MWe plant just ready and waiting. This is a standardized design,
a package unit as it were, that will only require heavy safety
analysis scrutiny once. After that they'll be stamped out
cookie-cutter style.

There is a consortium of utilities, A-Es and manufacturers working
through the NRC's new streamlined licensing procedure as a "will it
work" test. Once a standardized design is type-accepted and licensed,
construction should only take 2-3 years for each unit.

I'd love to see units of an appropriate size and number be scattered
around cities everywhere so that they could supply district heat/steam
in addition to electricity. It seems kinda dumb to turn heat into
electricity, only to turn it back into heat again by the end-user.
Especially low grade comfort heat.

PS: Is it true that it costs more energy to mine and refine uranium than
the net energy gain from burning it in a US nuclear plant? Is the US nuke
industry merely a way to provide less expensive nuclear weapons?

No, not at all. Mining coal and mining uranium aren't all that much
different, especially now where much coal is washed and otherwise
processed to remove sulfur and heavy metals.

Now consider the respective energy densities. A 1100MWe, 2500MWt
nuclear plant contains a bit over 100 tons of low enriched fuel. This
amount of fuel is good for full power operation for about 4.5 years.
And during that time less than 3% of the uranium is actually
fissioned. By the time the fuel is burned up that much, fission
products that absorb neutrons and interfere with the reaction have
built up enough to make further operation impossible.

When the "spent fuel" is removed from the reactor, 97% of it is still
"un-spent". Re-refine the fuel to remove the fission products and use
it again. Except that since the Carter administration debacle, that
hasn't been happening. "Spent fuel", actually only slightly used
fuel, is stored at each plant with the ultimate stated goal of the
government being to bury the stuff at Yucca Mountain. Insane!!!

To put this in perspective, I have a little plaque that was given to
me by Westinghouse to celebrate the initial criticality of Sequoyah I.
It contains one fuel pellet, a sintered uranium oxide mass about 3/8"
in diameter and maybe 1/2" long. The caption notes that at the 2.5%
burnup level Sequoyah was initially designed for, that pellet makes
the same energy as about 15 coal cars full of coal. There are
hundreds of thousands of these pellets in the core.

Think back to that Cumberland City steam plant. A railroad car full of
coal lasts a few seconds to a minute there. That same car filled with
uranium would fuel a nuclear reactor for the life of the plant and
more.

Fuel cost is a tiny part of the operating cost of a nuclear plant. I
don't recall the exact numbers anymore (I'm sure EPRI or someone
similar will have that on the web) but it seems like it is in the 3-5%
range. That's with virgin, non-recycled fuel and that is NOT using
surplus weapons fuel.

As far as the commercial industry being a shill for the bomb
community, nothing could be further from the true. For political
reasons, the civilian and military nuclear programs have been kept
completely isolated. As of now, nothing from the civilian side
crosses over to the weapons side and vice versa. This may change in
the future if the plans to burn surplus Pu from decommissioned bombs
work out. I certainly hope so since we'll be burning "free" fuel from
both our and the Russian arsenal.

You might recall the debate about weapons tritium production 3-4 years
ago. Since the Savannah River production reactors have been shut
down, there is no source in the US for new tritium, a vital ingredient
in nuclear bombs. Tritium decays away with a 12.28 years but long
before it decays away, helium, one of the decay products, neurotically
contaminates the stuff so that it's worthless as bomb fuel. Therefore
a new supply is constantly needed. For now, so many bombs have been
decommissioned that the contaminated tritium can be purified and
reused but ultimately all that will decay away and new will be
required.

One proposal was for TVA to produce tritium in their power reactors.
All that is required is to load a few "fuel" bundles with Li-6 instead
of Uranium and place them in the core. The Li-6 absorbs a neutron and
becomes H-3. Very simple and completely safe.

Yet it didn't happen, other than a small proof-of-concept. Why?
Because nobody wanted to cross that barrier between weapons and
civilian power. TVA didn't want the stigma of the first use of a
civilian plant to make a weapon fuel. Therefore, though the plans are
still up in the air, it looks like DOE will build an accelerator to
produce H-3. This will be vastly more expensive, of course but that
line will not have been crossed.

Another example of the barrier between civilian and military nuking
was when I calibrated the post-accident radiation monitors for TMI-1.
These monitors were designed to measure the radiation levels involved
in a hypothetical design-basis accident where millions of curies of
fission product would be released inside the containment. An
impossible event, but that never slowed the NRC rule makers.....

Calibrating these monitors meant subjecting them to known, extremely
intense radiation or in the case of noble gas monitors, very high
concentrations of radioactive gas.

There were no civilian facilities designed to handle this kind of
radiation and radioactive materials so I went hunting for a DOE
facility. The hot cell in my previously posted photos was what I came
up with. This was an old plutonium research facility and nuclear
rocket engine assembly facility located on the same site. There had
been no plutonium work on the site for >20 years but some obsolete and
ancient Pu weapon pits were stored in a vault so technically it was
still a weapons site.

The contractor who operated the site was renting it out for all sorts
of civilian uses - radiation sterilization, medical and industrial
isotope source preparation, radiation polymerization research, etc.

We negotiated the lease and had things ready to go when we presented
the plan to the TMI NRC site inspector for approval. The fecal matter
hit the air mover! This plan, oh my Gawd, had a nuclear power project
being conducted at a WEAPONS facility. Bureaucrats from Harrisburg to
Washington and back spun in place and wrung their hands in despair.
Many trees were killed so that hundreds of memos could flow back and
forth.

Ultimately it was decided that the facility had been out of the bomb
business long enough and sufficient numbers of civilian jobs had been
done there since then that it wasn't actually a weapons facility any
longer. Despite the concentric 10 ft high concertina-topped fences
with continuous armed guard patrolling the space between the fences.
:-) It was funny. I could photograph anything I wanted inside the
facility but I could not photograph the ordinary chain-link fences
around the place!

This "separation of powers" made it difficult to move one's career
back and forth. I managed to work in both communities but that was
only possible because I owned the company and we did very specialized
work with almost no competition.

Beyond the political aspects, the technical requirements for power vs
bomb fuel are vastly different. For safety and ease of control
considerations as well as cost, civilian US reactors are designed to
use very low enriched uranium, typically containing less than 3%
U-235. After we denied Canada entry into the nuclear community after
WWII, they designed their CANDU heavy water power reactors to use
natural uranium. Smart doods, eh? :-)

In contrast, uranium-fueled bombs use highly enriched uranium (HEU).
HEU is generally regarded as anything 90% or more enriched U-235. For
a number of technical reasons, HEU isn't the fuel of choice for
general weapon fuel. Plutonium is. Specifically Pu-239.

Pu is produced in a so-called "production reactor". This is a reactor
specially designed for high efficiency Pu-239 production.

In a neutron flux, natural U-238 absorbs a neutron and becomes Pu-239.
Unfortunately that atom can absorb another neutron and become Pu-240.
Thus, when natural uranium is first placed in a production reactor,
Pu-239 builds up rapidly but less rapidly, so does Pu-240.

Unfortunately Pu-240 spontaneously fissions so rapidly that it is
unfit as a weapon fuel. As the super-critical mass is assembled
during the implosion process, this spontaneous fission causes
premature detonation before the optimum mass is reached. This is
known as a "dud". Therefore weapon-grade Pu-239 has to have a very
low concentration of Pu-240.

This requirement results in a "quick-in, quick-out" reactor design.
Whereas fuel remains in a power reactor for 4.5 or more years, fuel in
a production reactor is in the core only for days. The Handford
production piles were designed so that virgin U-238 slugs could be
pushed in one side while pushing out irradiated slugs on the other,
all while the reactor operated at full power. Initially the heat was
discarded as waste, though eventually they some of the heat to make
electricity. Fueling the reactor was a continuous daily activity,
quite unsuited for power operation.

Here's a good brief summary of the problem.

http://www.ccnr.org/plute.html

I should add that this "bomb from reactor grade plutonium" is yet
another one of those strawmen created by the anti-nukes to spread FUD.
True, DOE did manage to make a bomb explode using "reactor grade
plutonium" but by any measure other than political, it was a dud. It
required a massive amount of Pu and all the expertise the US nuclear
weapons community could muster to design the thing. The actual
fabrication required the highest level hot cells and work facilities
to handle the hugely radioactive spent fuel and then to handle the
thermally and radiologically hot and chemically unstable reactor grade
Pu. After all that work it did little more than go pop. On a nuclear
scale, of course. And had the device not been promptly detonated
after construction, the intense radiation given off by contaminants
and decay products in the Pu would have quickly degraded the implosion
high explosives.

It is almost completely inconceivable that even a non-nuke nation
could muster the resources to do this kind of work and not have their
actions be detected. It is for sure that they'd not have the computer
codes we have to design and simulate the design.

If you want to spend months reading about nuclear stuff on the "other
side", go here:

http://www.sciencemadness.org/lanldocs.html

and

http://www.sciencemadness.org/library/index.html

This is most of the Los Alamos National Lab's unclassified e-library.
At least as it existed before the convulsive knee-jerk reactionary
cowards in Washington made them take down public access in the
post-9/11 hysteria.

Fortunately many folks including myself had archived most or parts of
this library so it was possible to reconstruct most of it.

This is fascinating reading. If you have the bandwidth, I highly
recommend webstripping the LANL papers to your local machine so that
you can read the stuff at your leisure. Lots of leisure :-)

John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain
.

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