Achal H P

Interested in Fluid Fuel Reactors.

[achalhp]

The rift.

Alvin Weinberg (the inventor of the Light Water Reactors) was not fully convinced about the safety of Light Water Reactors. In his biography "The first nuclear era" he concedes, 

"had safety been the primary design criterion, I  suspect we might have hit upon what we now all inherently safe reactors at the beginning of the first nuclear era, rather than 50 years later at the beginning of the second nuclear era."

Alvin Weinerg advocated for the inherently safe reactors, the safety of which primarily depended on the laws of physics. The engineered redundant systems & safety culture were an additional layer to this inherent safety.

This fact is also highlighted by prominent energy policy analyst, Vacalav Smil. Smil in his "Energy at the Crossroads" writes about the dire need of the newer nuclear technology.

"Although the Western PWRs with their containment vessels and tighter operating procedures could not experience such a massive release of radiation as did the unshielded Soviet reactor that accident only reinforced the widely shared public perception of all nuclear power being inherently unsafe."

"Inherent safety" and "safety culture"; NOT "Inherent safety" v/s "safety culture"

The Nuclear industry completely neglects Weinberg, with Rickover himself calling the non-PWR, inherently-safe nuclear technology as "Paper Reactors"; and, due to the lack of support from the industry, these "Paper reactors" did not come out of "paper", to become practical.

On the other hand, I have seen a French documentary which represents Rickvoer as a bureaucrat-clown. The documentary advocates nuclear innovation, highlighting the Thorium-Molten-Salt-Reactors. Nuclear innovation proponents ignore the unrivaled safety record of the US nuclear navy, which was possible with good safety culture.

These great ideas should be equally honored and must not be treated as opposing views.

Can both the sides meet?

I need to know why the nuclear industry do not consider the views of Alvin Weinberg on nuclear safety? Had nuclear industry considered the views of both these great personalities: Weinberg and Rickover, we would have definitely living in a different world. Nuclear power would have grown to its full potential just like semiconductors/computers. Are we going to finally resolve the nuclear safety “rift”?

References:

“First Nuclear Era” by Alvin Weinberg.

“Energy at the Crossroads” by Vacalav Smil.

"Paper Reactors" http://ecolo.org/documents/documents_in_english/Rickover.pdf

Thorium, la face gâchée du nucléaire: www.arte.tv/guide/en/050775-000-A/thorium-the-far-side-of-nuclear-power

[achalhp]

Drowning forests for Pumped Storage is outrageous.

My country (India) aims at adding 175 GW capacity of dilute-intermittent-location specific “renewable energy technologies”. When we have planned such large amounts of variable power generation, we need at least 10's of GW's of storage. What storage technologies can scale up to 10's of GW's?

Other than pumped hydro there are no proven storage solution that can scale up. Therefore, India has plans for these GW-sized pumped storage.

These pumped storage plans are highly publicized by the greens. But, many of these pumped hydro projects are located in hilly regions and these regions hosts what is left of the endangered western ghats and Himalayan forests. Renewable energy systems themselves take large amount of land area, and for the sake of balancing and storage, destroying what is left of our precious forests in is outrageous.

It would be really great if we backup/balance those intermittent renewables with stable, dispatchable, low carbon, power generation sources like ingeniously designed PHWR's or Thorium Molten salt reactors. Nuclear power do not require forest land and water resources, or farm land. These advanced reactors are safe to be located near cities, which again saves clearing forest land for transmissions.

Thorium do not require extra mining, it is a leftover of the rare earth's extraction which are used to make wind turbines. Food for thought: How can so called “renewable energy technologies” be “renewable” when they require much more land, material, human and energy resources that nuclear power to generate a kWh of power and when they last only for 20 years compared to 40-60 year lifespan of nuclear power?

[achalhp]

Before the World War 2, a radioactive toothpaste which was sold under brand "Doramad" in Gremany. "Your teeth will shine with radioactive brilliance" it advertised. It was very popular, and was considered tonic because it had thorium added to it and radioactivity was considered beneficial.

Image 1 from http://www.orau.org/ptp/collection/quackcures/toothpaste.htm H/T @thenuclearblog

Image 2 from : http://kcd-elements.tumblr.com/image/26179564691 @kcd-elements

[achalhp]

Energy poverty and the "Energy Access" Irony

In India many know what it really means to get access to clean water, clean cooking, sanitation and a little lighting during the evening. These basic needs are taken for granted by developed countries. Does access to "modern energy" mean access to 60W of electricity for 5 hours a day per person? which is exactly what the IEA says, 250KWh/year for a family or 100KWh per Person per Year.

60W/person is only enough for a ultra efficient small light and a small fan. What about clean water and sanitation? Who will pump clean water and who will manage the sewage?

The Energy and Investment needed to provide “Energy Access”

IEA says "energy access" includes clean cooking fuels, "textile and other industries" & other public services. but, who will account for the energy involved in manufacturing of these efficient lights, stoves and solar panels with backup batteries? http://www.worldenergyoutlook.org/resources/energydevelopment/definingandmodellingenergyaccess/

By contrast Average American Household uses 10,932 KWh of Electricity per year, https://www.eia.gov/tools/faqs/faq.cfm?id=97&t=3

More information:

Making Energy Access Meaningful: http://issues.org/29-4/making-energy-access-meaningful/

More than a Light-bulb video: https://youtu.be/nufhHX1UABU

[achalhp]

Role of Innovation to solve Energy Poverty

Solving the problem of climate change, simultaneously providing access to modern energy is a huge global challenge.

The role of Innovation:

The present clean energy technologies are not economical and not reliable without costly energy storage. Without fruitful results, the motivation for continuous investment will vanish. Continuous investment is necessary to fulfill the goals of ambitious initiatives like Sustainable Energy for All, Power Africa etc.

[Maintaining Renewables needs a lot of money Eg.: Giving solar panels for poor, which can last 10 years along with a costly battery which can last only for 2-4 years. This is not very useful in the long term, it is only useful to take pictures & show them as achievement]

Centralized or decentralized?

There is a ever-going debate on different approaches by which we provide energy access. Watch the recent one: https://www.youtube.com/watch?v=_b93Kbsv1WU

But, whatever solution we choose to do, it should compete for investment, or else governments in developing countries will continue to invest in the only effective path they know, the cheap fossil fuels. The best example to this is the recent expansion(or call explosion!) of coal in India. The green-solutions should be economical and be more effective in-order to compete in open market with fossil fuels.

Innovation can help both developing and developed nations to reach climate goals:

Deployment of massive amount of renewable technologies within the developed countries will not help developing countries. One might argue that leaning and volume production may reduce the price by some amount, but it will not solve the intermittency and reliability problems of the renewables. Solar has to get a magnitude cheaper in-order to compete against coal: http://www.vox.com/2016/4/18/11415510/solar-power-costs-innovation Similar case for wind: https://www.researchgate.net/publication/269026923_Why_Wind_is_not_Coal_On_the_Economics_of_Electricity

More:

http://www.nearzero.org/reports/global-innovation

https://www.gatesnotes.com/Energy/Energy-Innovation

http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1576699

[achalhp]

The proper way to make solar

PV solar and Li batteries are not the perfect utility scale solution. It is only good for residential use in remote places for lighting.

Concentrating solar with molten-salt thermal storage is the way to go. But as Stewart Brand says, it should be done in mineral desserts like That desert not on green deserts where little grass and bush grow. (Northern Karnataka, Gujarat, Madhya Pradesh etc.)

Even high power density concentrating solar uses lot of materials, but solar thermal will use commonly used material in large quantities not use exotic materials.

Also, we need to include the cost of transmissions from solar-rich north-west parts(Thar desert) of India to the demand centers mostly located in central(Delhi) and southern parts(Mumbai) of India. I do not recommend the solar thermal as a good solution, because it is not worth its cost. Concentrating solar power is better than wind and PV-solar. One should note that we cannot completely depend on solar, we may have to rely on backup generation for a month during monsoons where cloud cover will drastically reduce the solar power generation.(Even Rajasthan will get little rain during monsoons)

Reference, Sustainable Energy without the hot air, David Mackay: Chapter 25: A technology that adds up

[achalhp]

Molten Salt Reactors are the Safest.

When it comes to the inherent safety MSR's beats out every other reactor types.

MSR’s rely on Deterministic safety systems or inherent safety; One system which works perfect at mode of failure (any scenario). Other types of reactors rely on Probabilistic safety or redundant safety systems (or engineered safety) to prevent accidents like meltdowns.

The inherent safety of MSR’s can make MSR’s cheaper than any other existing power sources. Inherent safety makes design of the safety systems simple and economical.

Inherent safety characteristics:

Atmospheric pressure (NO Spills!):

The Molten Salt in the reactor is like the liquid/water in a swimming pool, it is at the same pressure as its surroundings. There will be no pressure gradient under which “spill” of the Molten Salt can take place. (The reactor vessel and the heat exchangers will not be working at high pressures like the Light Water Reactors.) 

Meltdowns NEVER happen in a MSR.

The "freeze plug" is the prominent safety feature which is unique to MSR's.

The "freeze plug" is a frozen lump of same salt used in the reactor. It will be cooled by an electric fan. It blocks the pipe which connects reactor vessel and the dump tanks. When there is an electrical failure, the frozen salt melts without cooling, the salt in the reactor vessel is drained into the dump tanks. Workers have no control over this.

This freeze plug prevents the molten salt damaging the reactor vessel and everything inside the reactor vessel. The dump tanks can be designed such that it can be cooled by passive natural convection process.

In any kind of extreme disaster reactor vessel will remain intact (in solid state!).

Reaction Control,

In MSR's the fuel will be dissolved in the molten salt. This mixture has negative temperature coefficient for reactivity. Meaning, when the temperature increases, the reactivity decreases. One of the reason for this is the thermal expansion of salt with the increase in temperature.

The temperature will be maintained at desirable values due to this property. In theory this feature makes controlling reactor easier and safer.

Proliferation safety.

MSR's require very less fissile material for starting reactor (to full power criticality). With less fissile inventory the risk of proliferation is reduced. During the operation of LFTR's, they don’t require additional fissile material. LFTR’s are designed to run on fertile material like thorium.

For MSR’s which run on low enriched Uranium or spent Uranium fuel, the fuel salt will be in a denatured state and pose no proliferation risks.

For LFTR’s which run on Thorium in thermal spectrum, the fuel salt will be contaminated by gamma emitter U232 which makes the proliferation process difficult and detectable.

Waste Management:

The volume of waste generated by MSR’s is tiny. The fission products can be removed from the salt medium quickly before it absorbs a neutron and becomes more radioactive. Fuel will be kept long time in the reactor so that all the actinides have sufficient time to undergo fission.

Easier decommissioning and decontamination : This is due to the quantity of materials which are in contact to radiation is less compared to a light water reactor. The bulky fuel assemblies do not exist in MSR’s. The heat exchangers are compact due to low pressure and high temperature of the coolant salt.  

Other radioactive waste/fission fragments will be short lived, LFTR’s which use Thorium fuel cycle produce negligible amount of long lived waste.

[achalhp]

Vortices in machines

Vortices are formed when 2 fluids moving in different velocities interact (OR/AND) a fluid in motion interacts a solid object. Vortices are usually formed due to flow separation and indicate that the flow is turbulent.  

Vortices are visible in various natural phenomenon like tornados, whirlpools, etc. This article focuses on vortices in man-made machines.

Wing tip vortices:

Wingtip vortices form on airplanes due to the finite length of their wings. In general, lift on the wings results from low-pressure, high-velocity air moving over the top of the wing and high-pressure, low-velocity air moving below the wing. Near the wingtips, the high-pressure air is able to slip around the edge to the top of the wing, generating a vortex that then trails behind the airplane.

Over time, these counter-rotating vortices will sink downward and break up due to viscosity and instabilities induced by their proximity.

Vortices are BAD,

These vortices are associated both with the production of lift on the wing and with unavoidable induced drag

They can be hazardous to other (lighter) aircraft. They also contribute to downwash that decreases the effective lift of a wing. The larger an aircraft, the stronger and longer lasting its vortices; this can be a source of danger for smaller aircraft passing through the wake. If a pilot crosses one wingtip vortex and overreacts to compensate, crossing the second counter-rotating vortex can cause even greater damage.

Vortices should not be confused with engine exhaust!

Image: Wing-tip vortices mark the path of Space Shuttle Discovery as she makes her final landing.(her engine is off!)

Though not always visible, these vortices are generated by any lifting body planform and can be a major source of induced drag on the craft. Here the vortices are visible because the low pressure in the core of the vortex caused a local temperature drop below the dew point, thus causing condensation. Such vortices persist for significant lengths of time in the wake of aircraft; they are a major source of wake turbulence, which limits how frequently aircraft can take-off or land on a single runway.

Fan blade vortices in the wind turbine:

Like air plane wings, wind turbine blades generate a vortex in their wake, and the vortices from each blade can interact downstream. These intricate wakes complicate wind turbine placement for wind farms. A turbine located downstream of one of its fellows not only has a decreased power output but also has higher fatigue loads than the upstream neighbor. In other words, the downstream turbine produces less power and will wear out sooner. Researchers visualize, measure, and simulate turbine wakes and their interactions to find ways of maximizing the wind power generated.

Smoke released from the end of a test blade shows the helical pattern of a tip vortex from a horizontal-axis wind turbine. (US National Renewable Energy Laboratory testing)

Vortices in a propeller:

Cavitation occurs in moving liquids when the local pressure—in this case, at the tip of the propeller—drops below the vapor pressure. The fast-moving fluid transitions to a gas phase, creating a tip vortex of water vapor even though the propeller is completely submerged.

How to get rid of vortices?

Even though vortices look beautiful, they just indicate the aerodynamic inefficiency.

While the vortices in the nature cannot be controlled (as of now, and they are growing strong day by day due to global warming), vortices formed in machines can be controlled by simple modifications in the design (and operation) of the machines…..see my doodle……

The next generation wind turbine by Altaeros Energies.

Useful Vortices?

Induced Vortices: Ever look out an airplane’s window and wondered why a row of little fins runs along the upper side of the wing? These vortex generators help prevent a wing from stalling at high angle of attack by keeping flow attached to the surface. Airflow over the vanes creates a tip vortex that transports the higher-momentum fluid from the freestream closer to the wing’s surface, increasing the momentum in the boundary layer. As a result of this momentum exchange, the boundary layer remains attached over a greater chordwise distance. This also increases the effectiveness of trailing-edge control surfaces, like ailerons, on the wing.

In the natural world, Geese use the vortices to their advantage when flying in a V-formation, this reduces fatigue when they migrate. Some snakes use it to glide. As usual nature is the best engineer!

Vortices in the 4th state of matter!‏​

The main challenge from the beginning of magnetic fusion research has been confining the plasma long enough to keep it hot. 

Small reactors loose heat quickly and scaling up the reactor will be costly! Therefore it is very important that we accurately predict the rate of heat transport across the confining magnetic field lines to the wall of the tokamak. This is the forefront of the ongoing fusion research. If scientists can predict the temperature at the reactor's edge, they will be able to easily predict the core temperature.

This is not a easy task. The blame goes to "Plasma turbulence" or simply call it "PLASMA VORTICES"

Turbulence in magnetized plasmas has small eddy motions, not only in the plasma "fluid" itself, but also in the electric and magnetic fields. Understanding turbulent plasma transport in tokamaks is critical to designing a full-scale commercial reactor in the future.​

Image: Plasma Vortices are formed in the Tokamak devices used for nuclear fusion (or creating a star on earth!)

Images and info from the blogs: @fuckyeahfluiddynamics and others.

[achalhp]

Spills kill birds.

The picture shows death of birds caused by our energy sources. 

Out of all the sources nuclear makes least damage for the amount of power it produces. It has 1,000,000 times more power density and hence 1,000,000 times less damaging!

https://www.pinterest.com/achalhp/spill-kill-the-birds/

[achalhp]

The next generation wind is out there and it is awesome!

Welcome to Buoyant Airborne Turbines or simply floating wind turbines. These wind turbines require less materials to build and can be deployed anywhere at any time.

These wind turbines are designed to catch high altitude winds. Wind is more stable at high altitude so lesser will be the intermittency, hence can produce more power (more Kilo-Watt-Hours or more capacity factor). Ducted blades have can catch more wind, minimizing losses from blade tip vortices. Also, these wind turbines do not obstruct the birds, because it is out of reach and it is visible.

Altaeros energies a MIT startup is a leader making these floating wind turbines. IRONY: I see none of the wind advocates make it their cover image and give it some publicity!

I found an application for these wind turbines. (I know that new hybrid transmission lines with wind turbines attached can be built, but these wind turbines can be attached to existing transmission lines!)

Floating Wind turbines on existing high voltage transmission towers!

[achalhp]

For a nuclear reactor, water is unsuitable to be used as a coolant.

Pressurised Water Reactors, In order to use water we have to pressurize it 150-160 times the atmospheric pressure! And we need to have multiple coolant pumps, having multiple redundancies to help water to get to the reactor core and maintain its temperature. While shutting down, we should maintain pressure and keep pumps running till the reactor cools down completely. This is the reason behind multiple redundant backup systems to keep the pumps running and to maintaining the high pressure. The safety promise is “Even if reactor core melts there wont be an explosion and leakage of radioactive materials”

Molten Salt Reactors, The fuel is already in molten state. The “Freeze Plug” when melted drains all the fuel to another tank designed to dissipate heat quickly. (Fluids can transfer large amounts of heat quickly to the coolants and can be cooled by natural convection alone.) The safety promise is “Meltdown will never happen”

In his blog about Fukushima accident, Adam Curtis writes about inherent safety flaws of Boiling water reactors, ...and in 1971 the Atomic Energy Commission did a series of tests of Emergency Core Cooling systems. Accidents were simulated. In each case the emergency systems worked - but the water failed to fill the core. Often being forced out under pressure. As one of the AEC scientists says: "We discovered that our theoretical calculations didn't have a strong correlation with reality. But we just couldn't admit to the public that all these safety systems we told you about might not do any good" 

[achalhp]

Molten Salt Reactors

Meltdowns = Goals!

No Goalpost = No meltdowns!

[achalhp]

The need for innovation in Energy storage technologies.

Intermittency is the inherent nature of renewable energy technology which are being deployed now. The power supply form the renewables won’t vary according to the demand. As more renewables are added to grid there will be large gaps between supply and demand. These gaps are unavoidable, there are three solutions for this problem,

Energy storage.

“Super-Grids” spanning entire continents.

Curtailment and Backup gas fired power plants (Least preferred option)

The first two options are not economical and must be done together to get the effect of the third least preferred solution. Storage technologies can thus prevent the “Curtailment” of renewables when the production is in excess of the demand.

Pumped storage:

As we see pumped storage is the only available now, for large scale energy storage. Robert Fares in his blog explains the efficiency improvements in the pumped storage technologies, a modern pumped storage can attain a round-trip about 80% efficiency. The major concern for the pumped storage technology is the deployment, it has large land foot print and water is precious.

A recent study by Eric Hittinger of the Rochester Institute of Technology and Inês Azevedo of Carnegie Mellon University predicts that large scale energy storage (used in today’s energy mix) increases the net emissions of greenhouse gasses. Although energy storage is a solution for the intermittency of renewables, storage is not fundamentally a “green” technology, leading to reductions in emissions, says the study.

Chemical storage:

Chemical storage is another option and don’t require large area of land and precious resources like water. As we see the chemical storage is not economical for large scale usage, even for a large building, diesel generators are economical alternatives than chemical storage. (My office building uses them and also diesel is subsidized in India ;)

Innovations should be made to make chemical storage an economical alternative for medium scale deployment (large office and apartment buildings). Cheap batteries will help the office buildings to deploy rooftop solar panels as well.

There are few ongoing research in this field, Stanford researchers are working on aluminum ion batteries which can charge very fast. Battery-grid integration software is being developed by Growing Energy Labs and Younicos. There is lot of progress in automobile energy storage technologies as well, the energy from braking is used back when accelerating. This is similar to low demand and peak demand!

Curtailment:

When the installed capacity of intermittent renewable energy systems in the grid increases, there will be instances when there will be excess supply of power than the grid demands. Under this circumstances the excess electricity is just not added to grid, this is called “Curtailment”. This prevents overloading of the grid. 

[achalhp]

How energy budget put for innovation can help?

Take the classic example, America(USA). America has a robust innovation infrastructure for energy. The consistent investment in the energy R&D has made America to be global leader in the Energy.

Take the example of Fracking (Hydraulic Fracturing). No other country does the hydraulic fracturing in a scale that America does. The technology of unconventional drilling or fracking is a possible due to the decades of R&D efforts of America’s Department Of Energy labs. Fracking technology has saved a lot for American Economy after the financial recession and America is largest producer of natural gas now. In the future, Natural gas will help America to completely move away from the dirty coal power plants.

America was a pioneer in Nuclear Power Technologies due to the R&D efforts done in DOE labs. Even now American manufacturers are leading suppliers of 3rd generation nuclear power plants. America was a leader for promising 4th generation nuclear technologies. But due to withdrawing funds from successful Fast Breeder project, now Russia is the only operator of commercial Fast breeder Reactors. America made progress on the innovative Molten Salt reactors which have great safety features and deliver heat at high temperature (gives high thermal efficiency), but the lead may go to China in the future.

​Hope every nation give a large share of their energy budget for innovation.

[achalhp]

(via Kurzgestagt)

"Engineering: The art of organizing and directing men, and of materials of nature for the benefit of human race."

[achalhp]

Our Future with MSR:  Molten Salt Reactors open up numerous possibilities for a safe, clean, and prosperous future for all. Created by The Anthropocene Institute Kaitlin Wilkinson

[achalhp]

Fusion is the need of the day. Now we use fission and make sure that fusion experiments will get cheap and clean source of power.