Friday, April 12, 2019

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
Climate  and here
Fresh  and here
Free Speech.................... here

Thursday, April 11, 2019

On Generation IV Nuclear Plants

Subtitle: Safer and Cheaper, or Just Make-Work Projects?

Tonight, 4-11-2019, the South Texas Section of AIChE will have the monthly dinner meeting, at which the presentation will discuss the research and status of Generation IV nuclear power plants.  This topic is the result, most likely, of the mis-guided belief by the current Section leadership that man-made climate change requires non-carbon-based electric power generation.  Therefore, they say, more nuclear plants should be built.  And, since no one can deny that the existing crop of nuclear power plants are far too dangerous and far too costly, they see a need for a new generation of nuclear designs.   This article poses a few questions I would ask, given the opportunity, about these planet-saving Gen IV nuclear power plants. 

What is a Gen IV plant?  These are, according to the NRC, nuclear plant designs that do not use light water as a moderator in the reactor.  At present, the existing plants use boiling water, or high pressure water in the reactor core as neutron moderators.  These have been shown to be far too expensive, as stated above.   The Gen IV plants will use various other things, such as graphite spheres in a high-temperature gas reactor (HTGR), molten fluoride salt in the reactor (MSR), or various molten or liquid metals in the reactor (molten lead, molten sodium, e.g.) .  

The questions, for now, include these:  What is the safety for Gen IV?  Will these plants require subsidies?  What is the on-line  capacity factor, or reliability of Gen IV?  What is the cost to construct?  What is the cost to operate?  What is the cost to decommission?  What are the issues with long-term spent fuel?


Will Gen IV reactors be safe, so safe that there is no longer an absolute need for the US government to provide damage payments for a catastrophic nuclear incident?  At present, every reactor enjoys such protection under the Price-Anderson Act.  Insurance companies refuse to insure nuclear plants, above a modest amount that is required by federal law.   Will these plants have materials of construction that operate reliably and safely for decade after decade?  We note that molten fluoride salts had serious metal cracking and embrittlement in earlier tests, are there proven alloys today that provide a safe operating system?


Will Gen IV plants require the numerous subsidies that current generation of light water reactors have?  SLB has articles on the numerous subsidies, such as liability for radiation leaks via the Price-Anderson Act, construction loan guarantees, new reactor direct subsidies for the first 10 years of operation, making lawsuits during construction almost impossible, and others.

Capacity Factor

Will Gen IV reactors run at 90 percent output year after year, for 40 years or more?  Will these exotic materials, molten lead, molten sodium, molten fluoride salts, create operating problems that shut the plant down routinely?  Test reactors over the years have had very serious drawbacks with pumping such materials, to name just one. 

Cost to Construct  

Will Gen IV plants be built at a low cost, so they can actually compete in the electricity market?  We see that pressurized water reactors now have an outrageous cost, of $12 billion for a 1000 MWe output.   How can anyone know what the costs to build will be?  The industry has time after time given low-ball initial costs, then see the actual costs balloon to 3, 4, and 5 times that initial cost.   

Cost to Operate

Will Gen IV plants have a low cost to operate, so that they can actually compete in the market?  We see today that plant after plant in the US cannot compete, even on their cash costs.  Current plants are shutting down, or crying to the government for more and more subsidies to keep the plants operating.   

Cost to Decommission

Will Gen IV plants require billions of dollars, and decades of time to decommission when the plants finally close?  Who provides that money?  Will it be a government subsidy, like the light water reactors now enjoy?

 Long-term Issues with Spent Fuel

Will the Gen IV reactors have spent fuel that must be stored, guarded, and cooled for centuries?  What are those radioactive byproducts, and what are the toxicity issues?  What requirements will be made to ensure many generations are safe from deadly radiation from these plants?

These questions will suffice, for now.   I hope to ask a question or two.

UPDATE:  The meeting concluded, my thoughts and comments are on the next post at this link.  end update 4-12-2019

Roger E. Sowell, Esq.
Houston, Texas
copyright (c) 2019 by Roger Sowell - all rights reserved

Topics and general links:

Nuclear Power
Climate  and here
Fresh  and here
Free Speech.................... here