Gen IV Nuclear Plants - AIChE Presentation

Subtitle: Gen IV Designs Have Too Many Serious Flaws

This article follows the previous article (see link) with my recollections and comments on the nuclear power presentation at the AIChE dinner meeting on 4-11-2019 in Houston, Texas.

The presenter, Dr. Pavel V. Tsvetkov, seemed quite knowledgeable and sincere in his views.  To his credit, he mentioned a few negative points for nuclear energy in general, and specific points to some of the designs he presented.  He did, however, say some things that were either unrealistic, or entirely too optimistic in my view.   And, that is ok; I believe we need optimists in the world, as long as their views are filtered and judged through a sober process that adequately considers safety, costs, and better alternatives. 

The questions in my previous article remained unanswered for the most part, as they were not asked.  A few others in attendance did ask a similar question on the safety, and spent fuel, and plant size or capacity.  But, nothing on subsidies, capacity factor in operation, construction costs, operating costs, or decommissioning costs. 

A few of the presenter's points made me pause and hope that no one ever, ever builds one of these things.  More on that below. 

In no particular order, then, here are some points I recall that seemed true about nuclear energy's drawbacks. 

- The entire fission nuclear process is carbon-free only in the operating reactor portion.  All the other aspects are performed now, and likely in the future, with a large degree of fossil fuel use.   Those other aspects include, but are probably not limited to, uranium mining, uranium ore processing and concentration, uranium fuel preparation and delivery, constructing a plant, decommissioning a plant, and spent fuel cooling, handling and monitoring. 

- Nuclear reactors have some ways to produce electricity other than boiling water or heating a gas, but the engineering challenges are simply too great to spend time on these.  

-  Nuclear plants can be built to follow the grid load, but the costs are greater.  This is a crucial point, because already high costs are increased even more as the plant reduces output to follow the load.  

Next, here are some points the presenter made that are absolutely false, in my experience. 

- Existing nuclear plants will run for 100 years.   No, they won't.  These plants shut down almost always before the 40th year of operation.  The ones that keep running are crying desperately for more government subsidies because they are losing money. 

-  SMR, or small modular reactors of various designs, will be very low-cost.  He stated they will be built in factories just like cars are built.   That is certainly not going to happen, as the need for electrical plants simply is not on the same scale as automobile sales.   Automobile sales are in the millions of units per year.  Power plant sales are in the few hundreds of plants per year.    No economy of production volume will change those economics.   For example, one can calculate that for a 40 year life, replacing only the natural gas and coal-fired plants in the US requires approximately 60 new plants each year.  If these were small enough, say 50 MWe output as envisioned for small modular reactors, we can increase that to 300 plants per year.   That is nowhere close to the millions per year required to achieve economy of scale through increased production volume.  Instead, the economics work against one, as smaller units cost much more per quantity of output. 

- Molten salt reactors, such as molten fluoride with dissolved thorium or uranium, are intrinsically safe.  No, they are not.  He showed a conceptual flow diagram that made me cringe.  The molten, 900 degree C radioactive bath is pumped from the reactor vessel through a heat exchanger, where a heat transfer fluid is heated.   That heat transfer fluid is then pumped through a second heat exchanger, where water is boiled to make steam for a turbine.  The heat transfer fluid is then pumped back around in a loop to the first heat exchanger.   The cringe-worthy aspect is the fact that heat exchangers eventually leak.  There will be heat exchanger fluid flow either into the radioactive molten salt, or the other way round with the molten salt injected into the heat exchanger fluid.  One picks one, or the other by choice of operating pressures in the heat exchanger.  Either way, that is some serious bad news when (not IF) the leaks occur.    As proof, one need only look at the heat exchanger leaks that occur periodically in the existing nuclear reactor fleet; and note soberly that such a leak was what caused the San Onofre Generating Station (SONGS) to shut down permanently.   That was "only" a radioactive steam leak.  

Another serious drawback is the pumping of that radioactive, molten fluoride salt.   Pumps leak, and having that material leak onto the concrete floor is more than a bit troublesome.  There will also be valves in the lines, and valves also leak.  Who wants radioactive, molten fluoride salt dripping from a valve, making a puddle to step in or over?

- Gen IV nuclear plants can be used to produce fresh water via desalination.   No, they won't.  The economics will not allow such a thing.  Even if desalination is ever necessary, solar thermal plants have a huge economic advantage over the incredibly expensive and dangerous nuclear plants. 

- Molten metal Gen IV nuclear plants will operate at high temperatures, therefore high thermal cycle efficiencies, and will be safe.   No, the same issues exist as described above with pumping molten salts: it is extremely difficult and dangerous to pump hot, molten sodium, and the same for hot, molten lead.   Sodium reacts explosively with contact with humid air, and lead fumes cause all manner of brain damage in humans. 

- Gen IV reactors will be ideal for supplying process heat in refineries and petrochemical plants, also chemical plants.   No, they won't.  The inherent dangers in such process plants simply will not be improved by the presence of a nuclear plant, whether for electricity or process heat production.  Instead, having a nuclear plant on the premises will make emergency responses much, much more hazardous.   Unfortunately, refineries and other process plants sometimes have operating upsets, fires, and explosions that require emergency response personnel to enter and handle the problems.   Who wants to speculate on the incredible situation where the plant is on fire, but the nuclear plant is so close to the fire that a radiation release is not only possible, but very likely.   No, thanks.  


There may be more issues to write about and discuss, but here ends the article for today. 

Roger E. Sowell, Esq.

Houston, Texas

copyright (c) 2019 by Roger Sowell - all rights reserved

Topics and general links:

Nuclear Power Plants.......here

Climate Change................here  and here

Fresh Water......................here

Engineering......................here  and here

Free Speech.................... here

Renewable Energy...........here  

Time-Shifting Building Cooling

Subtitle:  How To Cut Power Bills and Still Cool The Building

It has long been known that one can save on the power bill by using cheap power at night to chill water, or freeze the water into ice, then using the cold created thereby the next day to provide air conditioning.  University of Southern California, USC, has done this for some years.  Today, an article is published showing how Goldman Sachs is doing the same for its large skyscraper in Wall Street.  see link  

The beauty of the system is it can also be a way to cut power prices even more - especially when very expensive power prices exist due to brand-new nuclear power plants.  Instead of using electricity at night, one would purchase natural gas to run thermal chillers, store the chilled water or ice, then run only low-powered fans and pumps to chill the building the next day.   Customers in Georgia and South Carolina will soon be looking into this with great interest as the very, very expensive new nuclear plants are built on their grids. 

Removing a large load from the grid - especially at night - forces nuclear plants to reduce rate at night.  The utility then must request a rate increase to pay for the nuclear plant, since fewer kWh are produced.  This makes it even more attractive for its customers to either stop buying power, generate their own power, or as this article shows, purchase cheap natural gas at night in order to not run expensive air conditioners the next day.  

As shown earlier in The Truth About Nuclear Power, part 7, as nuclear power percentage increases on a grid, more and more customers will opt out of the grid by reducing their purchases, self-generating, or by other means.  see link  

Roger E. Sowell, Esq. 
Marina del Rey, California

Copyright (c) 2014 by Roger Sowell -- All rights reserved

The Truth About Wind Energy - Part One

Subtitle:  Wind Energy for Long Term Power

Following the success of a 30-article series on The Truth About Nuclear Power  see link, this article begins a similar series on Truth About Wind Energy, TAWE.    Arguments rage about wind power, with detractors making wild claims about high electric power costs, grid instabilities, unfair subsidies from government, death to flying birds and mammals, unsightly turbines blighting views, and others.   Supporters show that wind has enormous potential to replace almost every other form of grid power, that grids operate stably and will be even better in the future, subsidies are found in other forms of power generation - especially nuclear power, there is an urgency to develop renewable power and global warming has nothing to do with it, and many other points that favor wind power. 

This series of articles, planned to be approximately one dozen, takes the many arguments and looks at each one factually, with sound engineering, economics, legal aspects, and policy objectives.

This first article is a work in-progress, and will likely be modified from time to time.   As with TANP articles, each article in the series will be linked at the bottom as it is published.

A first effort at topics for TAWE include:  Is wind economic? Costs to install wind turbines? Annual output, capacity factor? What about subsidies? Technology types for turbines? Onshore vs Offshore potential? Impact on existing grids? Backup power supplies required? Experience shows us what?    Emissions from backup plants?   Impact on birds, bats? Safety – is anyone injured? Brief history of wind power? Longterm outlook for energy supplies?  Time-shifting energy via storage and discharge?   A concluding chapter. 

Update: 8/4/2014 - Is wind economic?

The calculation for wind energy economics is very simple, in that the cost/benefit analysis is fairly easy to perform.  As with most cost/benefit analyses, we begin with the benefits.  It makes no sense to calculate the costs of a system if there are no benefits, so we must determine first if there are any benefits. 

Benefits are found from average output in kW multiplied by average hours per year of generation, multiplied by the average price per kWh for power sales.  

1)  $ = kW x hrs/y x $/kWh

Power from wind is given by the equation (2)

2)  kW = 1/2 / 1000 x Eff x density x Area x Velocity ^3

Where W = Watts power produced
Eff   =  percent of available wind energy extracted by the turbine
density = air density, a constant usually at 1.225 kg/cubic meter
Area = swept area of the wind turbine blades, square meters
Velocity = wind speed in meters per second

For a sample calculation, 
Eff = 0.4
Area = 5,026 sq meters (from a rotor 80 meters diameter)
Velocity = 16 meters per second (equivalent to 36 miles per hour)

Then kW = 0.5 /1000 x 0.4 x 1.225 x 5,026 x 16 ^3 
kW = 5,044

For a location where wind blows an average of 7 hours per day, then hours per year is 

3) hrs/y = 7 x 365  = 2555

If the average sales price is $0.075 per kWh, then

$ benefits per year = 5,044 x 2,555 x 0.075  = $967,000 (rounded to thousands)


We can then proceed to the cost side of the analysis, having established that a 5 MW wind turbine at that location would produce revenue of almost $1,000,000 per year. 


For an investor, seeking a minimum return on his money of 10 percent before taxes, a simple method of screening a project is to determine the number of years required to payback the investment.   Using 10 year payback period, then the investment can be:

4) Inv = 10 * 1,000,000 = $10,000,000 

A check on the investment per kW of turbine output shows 

5)  $/kW = 10,000,000 / 5,000  = 2,000 (approximately)

This result, $2,000 per kW, compares favorably to that published by California Energy Commission for onshore wind projects with 2009 installation, where the cost was $1,990 per kW.    It should be noted that wind turbine costs have declined considerably since then (only 5 years ago at this writing), with some sources indicating 30 percent decline.   (end update 8/4/14)

The above provides the basic equations for computing wind power output, however, the turbine efficiency and wind speed are critical for individual project performance.   In the US, there are actually few locations, if any, that have wind speed of 16 m/s (36 miles per hour) for 7 hours each day.  Wind speed maps of the US are available; these show a typical range from zero to 10 m/s.   Wind speed is also classified into 7 classes, 1 - 7, with good wind being in class 3 and 4, and excellent wind in class 5.  These classes are for wind speed of 6.4 to 7.5 m/s for class 3 to 4, and from 7.5 to 8.0 m/s for class 5.   In places offshore on both the Pacific and Atlantic coasts, wind averages 9 to 10 m/s.   The great wind corridor from the Canadian border to central Texas, and extending from the Rocky Mountains east approximately 450 miles, has annual average wind speeds of approximately 9 m/s.  

Using a value for class 7 wind, 9 m/s in the above equations, gives 894 kW, a factor of 5.6 times less than 5,044.    

Roger E. Sowell, Esq.

Marina del Rey, California

As always on SLB, comments are welcome however they must be on-topic, non-commercial, and respectful.  All comments are moderated by Roger Sowell.  Comments may not appear right away. 

Copyright 2014, Roger E. Sowell

Kaya Identity and Energy Crisis 1979

Subtitle:  Response to Energy Crisis Catalyzed by Equation

The Kaya Identity, as posted earlier on SLB, is back for another round. see link.   Apparently, even more bloggers are weighing in, with Dr. Roy Spencer posting his take on his blog, and WattsUpWithThat also having more.    Dr. Spencer, for those who may not

Oil Refinery
source: Wikipedia commons

know, is an eminent, well-respected PhD climatologist at University of Alabama - Huntsville.  see link to his blog article on Kaya Identity Crisis.  

In my earlier post, I wrote that the units on both sides do indeed cancel, and in this post I will demonstrate that even when the same variable appears on each side, an equation is quite useful.   The blog-blather seems to be that, if the equation reduces to CO2 = CO2, then it is useless (where CO2 is in tons per year).  

Background

A bit of background, first.  In a somewhat analogous situation to the current climate scare, in which the entire Earth is said by alarmists to overheat because man's activities emit carbon dioxide, CO2, into the atmosphere, we had an actual energy disruption in the early 1980s.  This was no vague, arm-waving exercise by some data-manipulating maniacs, this was hard, cold fact of oil price increase.   I was a small part of that back then.  But, owing to my recent graduation from college and being early in my engineering career, I did not participate in developing our version of the Kaya Identity, nor in policy discussions on which aspects were to be pursued.  I was, however, on the front line for our private-sector company (multiple oil refineries, gas processing plants, an ethylene plant, various petrochemical plants) and obtaining the desired results in the most profitable manner. 

Thirty-five years ago, in 1979, the oil cartel OPEC increased the price of oil dramatically, to $36 per barrel, more than double the price only a few months earlier.   One of the results, in the US, was a government mandate to reduce energy consumption in the process industries, I believe the target was 25 percent.  

The Equations

The equation that (perhaps) was used back then, very similar to the Kaya Identity, was 

 1)    Eg = P x T/P x Ec/T x Eg/Ec

Where 

Eg = Energy, trillion Btu/y, e.g. gross energy consumed

P   = Process plants, a number

T   = Throughput per process plant, tons per year

Ec = Energy consumed in the process plant, trillion Btu/y

Note the similarity to the Kaya Identity, equation 2:

2)  CO2 = P x GDP/P x E/GDP x CO2/E

Each equation 1) and 2) has four terms on the right hand side, the numerator of the fourth term is identical to the left hand side, and all the other units cancel out on the right hand side (P / P, GDP / GDP, E / E all cancel.)

Therefore, if the Kaya Identity naysayers are correct, then equation 1) should also be useless.  After all, in equation 1), the cancelled units on the right hand side are (P / P, T / T, and Ec / Ec), leaving Eg = Eg  

Yet, equation 1) was indeed useful.   

The Usefulness

To accomplish the energy reduction, which at the time was deemed not only necessary but crucial to US economic survival, there were quite a number of things that could be done.   Each will be discussed in turn. 

First, variable P, the number of plants, could be reduced by 25 percent.  That single act would have reduced gross energy.  That path was indeed partly pursued, as a number of inefficient, smaller plants were shut down.  The result was not 25 percent reduction, though, in Eg. 

Second, the throughput per plant, T/P, could be reduced by 25 percent.  That also, alone, would have reduced Eg.  However, the US needed the products from those plants.  Instead, throughput per plant was increased, to make up for the plants previously shutdown.  It is true that a recession also occurred, so overall demand was somewhat less than it had been previously.  This was especially true in some industries, such as oil refining.  Drivers suddenly found ways to cut their gasoline consumption, by driving less or carpooling, for example.    It was found that Eg was reduced, also because the remaining plants were somewhat more efficient in energy use per ton of throughput.  

Third, the energy consumed per ton of throughput at each plant could be reduced.  This is the third term in equation 1), Ec/T.   This area generated the most interest and activity among the process engineers, our supervisors and managers, the group of which I was a part.   As good process engineers, we developed more than 40 different items, or process changes, that could be implemented with a reduced energy consumption.  I won't detail the entire list here, but will provide a few as examples.   

A brief note about how Ec differs from Eg in the above equation 1).  Ec is the energy consumed in the process, not including certain inefficiencies or wasted energy such as the hot gas exiting the smokestack on a fired heater.    Examples of Ec include electrical power required to run motors, steam required to run steam turbines, heat absorbed in the reboiler of a distillation column, etc.   In contrast, Eg includes all the inefficiencies, such as the gross fuel burned in a boiler, which includes the heat loss out the smokestack.  

Examples of process changes that can (and do) reduce Ec, energy consumed, included but were not limited to:

a)  replacing steam turbines with electric motors as drivers on pumps and compressors, and gas-driven compressors with electric motor-drives. 

b)  installing new heat exchangers with increased surface area to increase the inlet temperature of streams heated in a fired heater. 

c)  installing different catalysts that operate at a lower temperature, thus requiring a lower temperature exiting a fired heater

d)  installing different catalysts that provide better yields, thus requiring less feed to a process to obtain the same output

e)  installing improved process units that consume less energy intrinsically (e.g. low-pressure catalytic reforming in oil refineries, compared to high-pressure units)

f)  improve process control to reduce reflux and reboil on distillation columns where over-reboiling was the normal practice

g) add more trays to distillation columns, to reduce reflux and reboil requirements, similarly, more efficient packing could be installed in packed columns

h)  use waste process heat (e.g. medium temperature streams) to preheat boiler feedwater, or generate low-pressure steam

i)  recover more steam condensate and return it to the boiler 

j)  install better insulation, also electric heat tracing instead of steam heat tracing

k) install bottoms-to-feed heat exchangers on distillation columns

l)  run process unit intermediate streams hot from upstream to downstream units

m) purchase less energy-intensive feed, e.g. light crude oil instead of heavier crude oil

n)  reduce waste and consequent reprocessing of off-spec product

o)  install variable-speed motors on large motors

p)  install cogeneration utilities, especially combined cycle gas turbine plants.

There are many, many more items on the list of process changes that reduce Ec.    We evaluated them all, and implemented those that met our criteria for return on investment.  

Fourth and finally, the gross energy per unit of energy consumed could be reduced, Eg/Ec.   This involved increasing the efficiency of fired heaters, among other things.   For example, a furnace that operated initially at 85 percent efficiency and consumed 300 million Btu per hour (a common, ordinary furnace in a refinery), wasted fifteen percent or 45 million Btu per hour out the smokestack as hot flue gases.   By careful engineering, the furnace could be improved to 90 or perhaps 92 percent efficiency, corresponding to approximately 280 million Btu per hour of fuel consumed.  The savings was 300 minus 280, or 20 million Btu per hour.    This was approximately 7 percent savings.    The same could be done in a boiler, and other furnaces across the refinery or chemical plant.  

Details of all these process improvements are not given here, but will be familiar to the process engineers.  Many of us lived this, we designed the improvements, supervised the installation, started up the new systems, and documented the energy reductions.  

All in, the process industries exceeded the target, as I recall we accomplished approximately 27 percent reduction.    

The equation 1) , which does reduce in mathematical terms to Eg = Eg, after cancelling out the various terms on the right hand side, was quite useful.  We made use of each and every term, to a greater or lesser extent.  

Perhaps those who stoutly insist that the Kaya Identity is useless because it, too, reduces to CO2 = CO2, are unaware of the energy crisis of 1979 and the subsequent events in the US.  Perhaps knowing this now, they will pause and reconsider.    One can ask any of us who were engineers at the time, between about 1980 and 1985.   We lived it.  

Roger E. Sowell, Esq.

Marina del Rey, California

Coal Unmined - Cost Prohibitive

Subtitle: The coal is there but is mining it profitable?

From an article in the Sydney Morning Herald,  ". . .according to a new report by the Institute for Energy Economics and Financial Analysis, sinking coal prices and high development costs would make the [Galilee Basin, Queensland] project prohibitively expensive to supply India’s growing demand for electricity.

“The key point is that retail electricity prices in India are considerably lower than the level required for the profitable generation of imported coal-fired power, particularly when that coal is sourced from isolated deposits with none of the required infrastructure in the middle of Queensland. . .” "

In addition, infrastructure must be built, adding to the project cost:  "[the project requires]  massive infrastructure investment including rail lines and port facilities in environmentally sensitive areas close to the Great Barrier Reef near Townsville and Mackay."

see link

As seen earlier on SLB, see link, the world will soon run out of coal.  Even if coal deposits are already identified, economics will dictate whether the coal is actually mined, transported, and burned in a power plant for electricity.   The above indicates this coal may not be economic at this time.  However, the Indian companies that own the coal lease claim to be pressing forward on the project. 

From the Indian government perspective, economics may not matter.  India is quickly exhausting its domestic coal reserves and has little choice but to import coal to keep the power plants running.  A conference at UCLA discussed the India energy outlook, concluding that domestic coal reserves will be exhausted in less than 20 years (by 2030).  India is desperate for electricity, with approximately one-third of the population having none. 

Roger E. Sowell, Esq.
Marina del Rey, California

Exelon Nuclear Plants Fail to Win Bid to Sell Power

Subtitle:  Unable to Compete, Nuclear Seeks Subsidies from Uncle Sam

From The Chicago Tribune, three nuclear power plants that cannot compete in selling power to the market have the powerful Speaker of the House in the Illinois state legislature stand up for them, seeking yet another bail-out from the federal government.   As stated earlier on SLB, nuclear plants in the US cannot compete against natural gas and wind energy.  see link

"Three nuclear plants owned by Chicago-based Exelon Corp. failed to secure contracts to provide power to the electrical grid at an annual auction held last week.

Exelon’s Byron and Quad Cities plants in Illinois were priced out of the auction by competing power providers, the company said Tuesday, placing the future of those assets in question. Its Oyster Creek plant in New Jersey, which is slated to close in 2019, also didn’t clear the auction. . . . But [Illinois] House Speaker Michael Madigan [D - IL] wants to help keep those plants open. They are among the top employers in the towns and counties in which they operate. A resolution sponsored by Madigan was introduced to the House last Friday urging the U.S. Environmental Protection Agency, the Federal Energy Regulatory Commission and the electric grid operators, to adopt policies that are "friendly" to nuclear power. Translation: enact a new rule to curb carbon emissions, which would be a boon to Exelon because its nuclear plants do not release greenhouse gases."

The company also decries the loss of jobs from shutting down the nuclear plants.  It seems (in their view) there would be no jobs created by the companies that step up to build competitive power plants, whether natural gas-fired or renewable.

For perspective, California recently closed the San Onofre Nuclear Generating Station, with two reactors.  Hundreds of jobs were lost.   But, more jobs are created by those who build more power plants to replace the unsafe nuclear power.  

Finally, Exelon argued that nuclear power plants are reliable and provide power even during the recent cold winter.  That may be true, but one wonders exactly how utilities managed to provide reliable power in the almost 100 years (1880-1960) before those oh-so-reliable nuclear plants were on the grids.  Even today, how does a northern state without any nuclear plants provide reliable power in the winter, e.g. Wyoming, Montana, Idaho, North Dakota, and South Dakota?     The desperation is indeed apparent, based on the "we are reliable" argument. 

For more on nuclear power's inability to compete, see this link.

For more on nuclear power enjoying multiple subsidies, see this link. 

Roger E. Sowell, Esq.

Marina del Rey, California

Four by Sixteen Rule for Heat Exchangers

Subtitle: Easy Estimation for Heat Exchanger Area

An earlier post (see link) discussed a quick but accurate way to mentally determine process pipe size.  I was asked if there is a similar technique for sizing a process heat exchanger?  It turns out, Yes, there is.  This post describes the technique. 

Estimating Exchanger Size

The design of heat exchangers is quite complex, but a few quick and easy decisions can make the design process suitable for initial design, costing, and economic evaluation.  A practicing process engineer frequently needs to assess the process for the benefits and costs of installing a new heat exchanger.  This is true for oil refineries, petrochemical plants, chemical plants, water treatment, and other processes where fluids must be heated or cooled.   The good engineer will not waste time and computing resources doing a detailed heat exchanger evaluation for each potential application, but can speed things along by a quick but accurate estimation procedure.  

This procedure begins with a "Four" and a "Sixteen", just as the pipe-sizing method does.  In this case, the "Four" is a four-foot diameter shell for a shell-and-tube heat exchanger.   The "Sixteen" is for two elements: the tubes are sixteen feet long, and there are 1600 tubes in the tube bundle.  (The area is actually 5,027 square feet).  

This configuration, 1600 tubes of length 16 feet, for 3/4 inch OD tubes on triangular pitch with 1/4 inch spacing, provides a heat exchange area of almost exactly 5,000 square feet.  The tubes will fit nicely inside a 4-foot diameter shell, with about 23 percent unused area in the tubesheet. 

Knowing that 5,000 square feet is an exchanger 4 feet diameter and 16 feet long, one can use the process calculations to determine the required surface area.  Then, almost the same rules of pipes and sizing apply to heat exchangers.   There are a few caveats.  If one has, for example, a required area of 2,500 square feet, or half of the 5,000 in the base case, one can determine the shell size as 4 divided by 1.4, or approximately the square root of 2. Working this backwards, what number can be multiplied by 1.4 to yield 4?  The answer is just slightly less than 3, as 3 times 1.4 is 4.2.   We can use 34 inches, slightly less than 36 inches, and a quick check shows that 1.4 x 34 is 47.6, close enough to 48 inches.   The 2,500 square foot area can be obtained in a 34 inch shell with 16 foot tubes. 

But, what if the required area is greater than 5,000 square feet?  Perhaps 7,500 square feet is required.  Then, a caveat applies.  Heat exchangers, in general, are less costly with long tubes and small-diameter shells.  However, longer tubes require that the velocity in each tube is rather high, and pressure drop is also higher compared to shorter tubes.   If we maintain the 16 foot tube length, the shell diameter is then 4 times 1.22, or 4.88 feet or 58 inches (the 58.6 actual value is rounded down to 58).  It might be better to maintain the 4 foot shell, and use 24 foot tubes in this case.   How do we know that 24 foot tubes will work?  Because, the required area is 50 percent greater (7500 / 5000 is 1.5), and 1.5 times 16 feet long tubes is 24 feet long. 

Some caveats: this technique is for shell and tube exchangers, using English units of inches, feet, and square feet.  It does not work well for other designs, although a clever engineer can probably develop similar quick estimating procedures.   Also, for highly viscous fluids, shorter tubes are desirable to minimize pressure drop.   There are also various tube inserts to increase turbulence in low-velocity but shorter tubes. 

In hopes that this article helps the various process engineers, in whose shoes I also once walked. 

Roger E. Sowell, Esq.
Marina del Rey, California

The Truth About Nuclear Power - Part 14

Subtitle: A Few More Reasons Nuclear Cannot Compete

This article discusses a few economic issues including project cancellations due to unfavorable economics, the desperation of reactor vendors, nuclear advocates tout low operating costs and ignore capital costs, nuclear utilities never ask for a rate decrease when building a new nuclear plant, and high nuclear costs are buried in a large customer base.    Future articles will discuss nuclear safety, research into new forms of nuclear power, and the driving force behind countries that choose nuclear power in spite of its numerous and serious disadvantages. 

Previously, the articles on The Truth About Nuclear Power emphasized the economic aspect by showing that (one) modern nuclear power plants are uneconomic to operate compared to natural gas and wind energy, (two) they produce preposterous pricing if they are the sole power source for a grid, (three) they cost far too much to construct, (four) use far more water for cooling, 4 times as much, than better alternatives, (five) nuclear fuel makes them difficult to shut down and requires very costly safeguards, (six) they are built to huge scale of 1,000 to 1,600 MWe or greater to attempt to reduce costs via economy of scale, (seven) an all-nuclear grid will lose customers to self-generation, (eight) smaller and modular nuclear plants have no benefits due to reverse economy of scale, (nine) large-scale plants have very long construction schedules even without lawsuits that delay construction, (ten) nuclear plants do not reach 50 or 60 years life because they require costly upgrades after 20 to 30 years that do not always perform as designed, (eleven) France has 85 percent of its electricity produced via nuclear power but it is subsidized, is still almost twice as expensive as prices in the US, and is only viable due to exporting power at night rather than throttling back the plants during low demand, (twelve) nuclear plants cannot provide cheap power on small islands, and (thirteen) US nuclear plants are heavily subsidized but still cannot compete.  Links to previous articles are found at the conclusion of this article.  

Cancellations Due To Economics

Several planned projects were cancelled due to unfavorable economics, including the South Texas Nuclear Project expansion.  That project was to double the existing plant output by installing two more reactors.  A Japanese firm made several cost estimates to the prospective owners, with each estimate higher than the last.  At $17 billion, the vendor admitted they had not provided the final figure.  The project collapsed.  The cities of Austin, and San Antonio were approached as potential owners and customers, however Austin (wisely) said an emphatic NO.  San Antonio signed on for a while, but finally said No also after no final project cost was to be had from the vendor.  

Desperate Reactor Vendors

Reactor vendors are desperate to sell plants and subsidize new plants in UK, Turkey, and India, perhaps also in China.  This was mentioned briefly in Part 11, which discusses the French nuclear industry.  A French firm contracted with India to provide a multiple-reactor power complex, but had to agree to only 10 cents per kWh as the sales price (they asked for 16 cents) and had to sweeten the deal by financing the construction at only 4.8 percent interest over 25 years.  

[Update - 6/24/2014: Russia's Rusatom also is desperate to sell nuclear plants and signed a sweetheart deal with Hungary to finance two new reactors - 80 percent of the construction cost at approximately 4 percent interest over 21 years, beginning after plant startup.  "Hungary will be required to repay its debt in euros -- at variable rates of 3.95-4.95 percent interest -- over a term of 21 years, starting after the new blocks are commissioned."  see link  --- end update]

Bait and Switch

Nuclear proponents emphasize low operating costs but ignore high capital costs.  This is like buying a new car that gets 1,000 miles per gallon.  Sure, the operating costs would be fifteen gallons of fuel per year, or roughly $60 in the US at current prices.   That is the price of one tank-full for most modern cars.  But, the car payments would be ten times what a normal car would cost.  Instead of $500 per month, the bank will charge $5,000 each month.   Few consumers would choose such a car because they simply cannot afford to pay $5,000 per month for a car.   Yet, this is exactly what nuclear proponents are advocating for their nuclear power plants.  Even the older, paid-for plants cannot compete in today's and the foreseeable future's market on low operating costs.  

Never a Rate Decrease

To the best of my knowledge, no utility has ever asked for a rate decrease to build a nuclear plant.   If nuclear power could really be produced for 2 or 3 cents per kWh, one would expect that the customers would see their power bills decrease when the nuclear plants are built.  Instead, high power prices are disguised by burying them in a huge customer base.  Perhaps that is the reason that, again to my knowledge, nuclear plants are not merchant plants but are owned by the utilities themselves.  A merchant plant would need to sell its power on a contract to the utility.  That contract would necessarily have the price much higher to recover the capital costs and the operating costs. 

Conclusion

The articles thus far have provided at least 20 reasons why nuclear power plants are uneconomic and therefore should not be built nor operated.   The main issue is the use of nuclear fuel pellets to provide heat for the water to boil to steam.  All else follows from that.  The plants are huge to obtain economy of scale, they are more costly to increase safety, they have larger equipment and pipes because more steam flow is required for the same output of electricity, prices must be much higher but are disguised or buried among a huge customer base, they use too much water for cooling, and even France has multiple problems even after massive subsidies for decades, plus many, many other reasons described in the first 13 articles.  

Previous articles in the Truth About Nuclear Power series are found at the following links.  Additional articles will be linked as they are published. 

Part One – Nuclear Power Plants Cannot Compete

Part Two – Preposterous Power Pricing if Nuclear Power Proponents Prevail

Part Three – Nuclear Power Plants Cost Far Too Much to Construct

Part Four – Nuclear Power Plants Use Far More Fresh Water

Part Five – Cannot Simply Turn Off a Nuclear Power Plant

Part Six –  Nuclear Plants are Huge to Reduce Costs

Part Seven -- All Nuclear Grid Will Sell Less Power

Part Eight – No Benefits from Smaller Modular Nuclear Plants

Part Nine -- Nuclear Plants Require Long Construction Schedules

Part Ten -- Nuclear Plants Require Costly Upgrades After 20 to 30 Years

Part Eleven - Following France in Nuclear Is Not The Way To Go

Part Twelve - Nuclear Plants Cannot Provide Cheap Power on Small Islands

Part Thirteen - US Nuclear Plants are Heavily Subsidized

Part 14 - this article 

Part Fifteen - Nuclear Safety Compromised by Bending the Rules

Part Sixteen - Near Misses on Meltdowns Occur Every 3 Weeks

Part Seventeen - Storing Spent Fuel is Hazardous for Short or Long Term

Part Eighteen - Reprocessing Spent Fuel Is Not Safe

Part Nineteen - Nuclear Radiation Injures People and Other Living Things

Part Twenty - Chernobyl Meltdown and Explosion

Part Twenty One - Three Mile Island Unit 2 Meltdown 1979

Part Twenty Two - Fukushima The Disaster That Could Not Happen

Part Twenty Three - San Onofre Shutdown Saga

Part Twenty Four - St. Lucie Ominous Tube Wear

Part Twenty Five - Price-Anderson Act Protects Nuclear Plants Too Much

Part Twenty Six - Evacuation Plans Required at Nuclear Plants

Part Twenty Seven - Power From Nuclear Fusion

Part Twenty Eight - Thorium MSR No Better Than Uranium Process

Part Twenty Nine - High Temperature Gas Reactor Still A Dream

Part Thirty - Conclusion

Roger E. Sowell, Esq.
Marina del Rey, California

The Four By Sixteen Rule for Pipe Flow

Subtitle: Easily Compute Pipe Diameter in your Head

There are dozens, if not hundreds, of quick-and-easy methods to estimate the required size for process and mechanical equipment.  This article addresses a very fast, easy, and accurate method to determine pipe size in a process plant.   The method requires no calculator, no spreadsheet, as it can be done mentally.  It is especially useful for sitting in a meeting and answering a question that may be posed, or quickly verifying a statement made by another in the meeting. 

The method is one I call "Four by Sixteen", or the 4x16 Rule.   I have never seen this anywhere published, but perhaps it is.  

The basic concept for the 4x16 Rule is, at a flowing velocity of 7 feet per second through a pipe of circular cross-section (most pipes), 4,000 gallons per minute will flow through a 16-inch diameter pipe.  A flowing velocity of 7 feet per second is generally considered optimum, or close to optimum for pipe in a process plant where velocity is provided by a pump. (see caveats below)

Engineers can quickly compute that 4,000 gpm in a 16 inch diameter pipe will provide less than 7 feet per second.  The flow is actually 6.38 feet per second.  However, with 16 inch pipe, the outer diameter is 16 inches, and wall thickness is approximately one-quarter inch, leaving an inner diameter of 15.5 inches.   For the 15.5 inch ID, the flowing velocity is 6.8 feet per second, very close to the optimum of 7.  

From this, we can easily determine the pipe size required for other flow rates.  This is based on the property of pipes, that if one doubles the diameter, four times the flow results for the same flowing velocity.  This also works in reverse, if one halves the pipe diameter, only one-fourth the flow results.  Using numbers, an 8 inch pipe is half of the 16 inch, therefore the flow will be one-fourth of 4,000 gpm, or 1,000 gpm.  

What happens if we want to double the flow from above, for example, we want 2,000 gpm?  For this, we use a rough approximation for the square root of 2, that approximation being 1.4.  The pipe size for 2,000 gpm is then the 8 inch pipe times 1.4, or 11.2 inches.  We generally round up to even numbers for pipe sizes, therefore a 12 inch pipe would be selected. 

This works in the upward direction quite easily, too, so that a 32 inch pipe will carry 4 times that of a 16 inch, or 4 times 4,000 gpm or 16,000 gpm.   Or, we can use the 1.4 factor to compute the diameter required for a doubled flow, from 4,000 to 8,000 gpm.  The 16 inch pipe is multiplied by 1.4, resulting in 22.4 inch pipe.  This would be rounded down to 22 because it is so very close to 22 inch and would not be rounded up to 24 inches. 

How does one multiple 1.4 times a number in one's head?   An example shows this:  take the 8 inch pipe from above, then multiply 8 by 0.4 to give 3.2.  Then add 3.2 to 8, to provide 11.2.  

This method is also very useful for validation checks on computer output.  Experience has shown that computers should be trusted only after very thorough and careful validation.  

A few caveats for the 4x16 Rule.  As stated earlier, this is for process plant piping where 7 feet per second is the accepted optimum.  That optimum is for standard pipe, typically made from mild carbon steel and non-corrosive fluids at 500 pounds per square inch pressure, or less.   For substantially different conditions, for example stainless steel piping at much higher pressures, a detailed economic analysis is required to determine the optimum flowing velocity.   

Also, for petroleum pipelines, the flowing velocity is a bit higher, for example the Alaska Pipeline was designed for flow of approximately 10  16 feet per second.  The Alaska Pipeline is a 60-  48-inch pipe with a design flow of 3 million barrels per day.  With the pipe having 60 48 inch OD and half-inch thick walls, as I recall (now verified), the flow is 87,300 gallons per minute at a flowing velocity of 10.2 16 feet per second.  (note: corrections to the TAPS calculations based on a faulty memory, not 60 inch but 48 inch diameter-  RES)

In hopes that this article helps the various process engineers, in whose shoes I also once walked. 

Update: 4/28/2014:  This same procedure works quite well for SI units, also.  The starting point is a 400 mm ID pipe, carrying 16 cubic meters per minute, at a flowing velocity of 2.1 meters per second (same as 7 feet per second).  -- end update --  Roger

Update 2: 5/12/2014 - A similar procedure for heat exchangers is shown -- see link.  -- end update --  Roger

UPDATE: 5-31-2015 - pipeline calculation above is corrected for 48 inch rather than 60 inch diameter -  end update

Roger E. Sowell, Esq.
Marina del Rey, California