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This presentation is intended for engineering audiences.

By Charles Rhodes, P.Eng., Ph.D.


Hello. In this approximately half hour presention we will discuss the intersection of climate change, renewable energy and sustainable nuclear power.

- 30% increase in the concentration of CO2 in Earth's atmosphere
- similar increase in dissolved CO2 mass in oceans
- increase in dry land surface temperature
- snow and ice melting which decreases Earth's solar reflectivity
- more solar heat absorption
- floating ice melting which further decreases solar reflectivity
- ongoing net heat absorption by oceans @ 3.5 W / m^2
- increase in ocean surface temperature

1) Presently the world consumes about 100,000,000 barrels of petroleum per day and comparable amounts of coal and natural gas. Almost all of this fossil hydro-carbon mass eventually oxidizes to form CO2, soot and H2O.

2) Since WWII Earth's atmospheric CO2 concentration has increased by about 30%. During the same period the oceans have absorbed an approximately equal mass of CO2 via conversion of insoluble CaCO3 (limestone) into water soluble Ca(HCO3)2. This chemical change (ocean acidification) threatens marine life which relies on CaCO3 insolubility for its bone and shell structures.

3) The increase in atmospheric CO2 concentration reduces Earth infrared (IR) emission into space in certain frequency bands. This reduced IR emission causes an increase in Earth's dry land surface temperature.

4) The increase in Earth dry land surface temperature reduces seasonal snow and ice cover, which reduces Earth's average solar reflectivity (planetary albedo).

5) The combination of reduced IR emission and increased solar energy absorption causes ongoing net heat absorption by the oceans, presently at a rate of about 3.5 W / m^2.

- polar ice melting
- rise in dry land temperature, reduced rainfall
- insect damage and forest fires
- violent tropical storms
- ongoing ocean thermal expansion
- ongoing sea level rise
- insured fire and hurricane damages in USA > $200 billion / year
- uncontrolled human migration

6) That net heat adsorption is:
- increasing ocean surface temperature
- causing ocean thermal expansion
- accelerating polar ice melting
- causing a rise in sea level

7) Increases in both dry land and ocean surface temperatures have led to extensive forest damage by insects and wild fire control problems on the west coast of North America and have triggered violent hurricanes on the eastern and southern coasts of the USA. These ongoing problems are presently costing the US public more than $200 billion / year just in insured property damage. Taxpayer borne costs are additional. These costs are rapidly rising.

8) There is non-linearity in the equations which govern the rates of radiant energy absorption and emission by planet Earth. Over geologic times this non-linearity caused planet Earth to have alternating prolonged states of global glaciation and global high temperature.

9) Today the effects of excess CO2 are triggering a transition from a climatic cool period to a climatic hot period. This state transition is known as thermal runaway. It is mathematically analogous to a bi-stable circuit in a computer that switches from a"0" state to "1" state. This transition will trigger a major rise in sea level, an increase in violent storm activity, a rise in human migration from equatorial to more temperate countries and an extinction of most large land animal life forms.

10) To halt thermal runaway it is necessary to leave fossil hydro-carbons in the ground and to supply consumers with energy and power from non-fossil sources.

11) Absent abundant hydrocarbons the efficient way to transmit energy over significant distances is via electricity. Less efficient alternatives are to transmit piped electrolytic hydrogen or ammonia.

12) Today elected persons are making governmental policy decisions about fossil fuel pipelines and public purchase of non-fossil energy and power. Unfortunately generally these persons have little understanding of the underlying physics and give more weight to popular opinion than to the advice of professional engineers. Frequently irrational public fears and near term profit issues in the fossil fuel sector over ride claimed fossil CO2 emission reduction policies.

13) Many governments have promoted of solar and wind electricity generation. However, from the perspective of reliable public electricity supply solar and wind electricity generation:
- are poorly distributed,
- are seasonal,
- are intermittent,
- are not statistically random,
- do not provide rotating inertia for grid voltage and frequency stability
- cannot be used for grid black start.

14) Solar and wind energy generation simply cannot not meet the seasonal energy supply requirements in higher latitude countries such as Canada where reliable winter heating system functionality is paramount.

15) The long winter periods of high thermal load in combination with both low wind and low sun cannot be economically bridged with any form of energy storage.

16) In temperate regions, that do not have the high mountains necessary for forming very large hydraulic energy storage reservoirs, there is also no economic means of seasonal electrical energy storage.

17) To fill in the local energy supply gaps with renewable energy it is necessary to transmit electricity right across the continent. That transmission is prohibitively expensive.

18) Experience has shown that due to lack of energy storage intermittent solar and wind generation can only economically displace about 40% of the fossil fuel otherwise required for electricity generation.

19) The fundamental constraint is that within a radius of about 1000 km wind and solar energy generation are highly co-related, not statistically random. When there is low wind and low sun in one place there is usually low wind and low sun almost everywhere within an economic transmission radius.

20) Due to natural isotope abundances the only technology that can sustainably and economically fully displace fossil fuels for power production is liquid metal cooled Fast Neutron Reactors (FNRs). Other nuclear technologies are unsuitable because they require an ongoing supply of the relatively rare fissionable isotope U-235. Natural ore bodies containing U-235 will soon be depleted. However, there are sufficient reserves of U-238 and Th-232 to meet mankind's primary energy requirements using FNRs for several thousnd years. Hence new nuclear power reactors should be FNRs that use U-238 as the primary fuel. In the future, when rapid deployment of FNRs is no longer a major issue, Th-232 could be used to supplement of U-238 and U-233 could be used to supplement Pu-239.

21) FNR technology was developed and operationally proven in the USA over a more than 30 year period ending in 1994, at tremendous cost to US taxpayers. However, after 30 years of operational success this technology was defunded in 1994 by former US president Bill Clinton who claimed that it was "unnecessary". The Russians and the Chinese did not share his opinion and today are seizing the world power reactor market. While the US remained focused on continued use of fossil fuels the Russians gained a 30 year and a more than 100 fold capacity lead in FNRs.

22) FNRs can sustainably provide reliable power when consumers need it for milenia into the future. However, nuclear matters are quite technical and are poorly understood by the public. In North America the fossil fuel industry has protected its market share by intervening politically to prevent deployment of fast neutron reactors. Environmental activists who know little about nuclear physics have further confused the issues.

23) An advantage of FNRs is that their primary fuels are existing spent reactor fuel and abundant natural isotopes. Another advantage of FNRs is their ability convert existing long lived radio toxic spent water moderated reactor fuel into short lived fission products having half lives of less than 30 years. These fission products naturally decay to less than the radio toxicity of natural uranium in about 300 years. The process of fission product extraction reduces the waste fraction by about 100 fold. Chemical separation after the 300 year decay period results in another greater than ten fold radioactive waste mass reduction.

24) Engineering suitable porcelain-metal containers and obtaining suitable sites for 300 year isolated safe storage of a few hundred tonnes of fission products is relatively simple.



25) A FNR consists of a fissile core (shown in red) surrounded by a fertile fuel blanket (shown in pink), and fuel tube plenums (shown in orange) all of which are immersed in a pool of liquid sodium (shown in yellow). There is no water or other low atomic weight moderator. Due to its relatively high thermal coefficient of expansion the liquid sodium naturally circulates past the hot vertical fuel tubes and efficiently conveys heat to the intermediate heat exchange tubes (shown in green).

26) The neutron kinetic energy in a FNR is typically 2 MeV as compared to less than 1 eV in a water moderated reactor.

27) The FNR operating temperature is regulated by thermal expansion of both the fuel and coolant. If the temperature rises above its setpoint the nuclear chain reaction stops. If the temperature falls below the setpoint the chain reaction restarts. The temperature setpoint is a function of the fuel geometry.

28) During FNR operation the high atomic weight core fuel gradually fissions liberating energy, surplus neutrons and low atomic weight fission products. The blanket fuel absorbs the surplus neutrons emitted by the fissioning core fuel. These neutrons transmute the fertile U-238 blanket fuel atoms into fissile Pu-239 and Pu-240 atoms.

29) A liquid sodium guard band around the fuel assembly prevents neutrons damaging the sodium pool structure and the intermediate heat exchange bundles. This guard band enormously extends the working life of a FNR's sodium pool.


30) The blanket fuel material is periodically removed and reprocessed to concentrate the contained Pu-239 which is then used to make new core fuel. The weight of material removed from the blanket is replaced by an equal weight of new U-238 blanket fuel.

31) The core fuel material is periodically removed and is reprocessed to extract fission products. The weight of material removed from the core is replaced by an equal weight of new core fuel.

32) Zirconium is selectively extracted from the fission products and is used to maintain the required U-Pu-Zr alloy constituant ratios in the core and blanket fuels.

33) The remaining fission products, which have short half lives, are packaged in porcelain-metal containers which are then placed in isolated storage.

34) During 300 years in isolated storage natural radioactive decay reduces the radio toxicity of the fission products to less than the radio toxicity of natural uranium.

35) Pool type FNRs operate at atmospheric pressure and can be safely used in higher elevation urban areas to provide both electricity and district heating. Atmospheric pressure pool type reactors have been safely used on univerity campuses for many years.

36) An advantage of a pool type FNR is that within the reactor enclosure there is no high pressure water or steam that can either blow up or chemically combine with a high temperature metal to release explosive hydrogen gas.

37) FNRs can be designed so that all essential cooling is by natural circulation so that there are few valid concerns related to maintaining cooling after a reactor shutdown. These reactors are both walk away safe and suitable for unmanned automous operation.

38) Liquid sodium cooled FNRs must be sited at elevations sufficiently above the levels of rivers and major water bodies to ensure that they will never be subject to flooding.

39) FNRs discharge heat via air cooling and district heating/cooling systems rather than by direct ocean or lake water cooling. This cooling methodology minimizes environmental impact and allows FNRs to be sited at higher elevations away from rivers and large water bodies.

40) On loss of control power FNRs default to cold shutdown.

41) In external appearance a FNR enclosure is architecturally comparable to a recreation center containing an Olympic diving pool.

42) Existing public policies relating to reactor siting, spent fuel transport, closed cycle fuel reprocessing and radio isotope storage are based on fear rather than science. We need fact based public policies and safety regulations to properly deploy FNRs.

43) A key issue relating to large scale FNR deployment is conservation of existing inventories of U-235 and Pu-239 to make core start fuel for FNRs. All politically driven actions to consume, bury or otherwise render inaccessible inventories of Pu-239 and spent water moderated power reactor fuel should be stopped.

44) A non-fossil electricity system may use batteries or other forms of energy storage for load following, which is instant by instant adjustment of total electricity generation to match total electricity consumption. However, at times when the energy storage is close to being either fully discharged or fully charged, the energy storage can no longer perform that important load following role.

45) An advantage of FNRs over many other reactor types is that they can load follow. Due to reduced return on invested capital load following is usually not the most economic way to apply FNRs but the FNR load following capability may be essential for providing grid stability at times when energy storage can not.

46) Nuclear reactors require take-or-pay power purchase agreements.

47) Due to seasonality and high cost of energy storage wind and solar electricity generation cannot completely displace fossil fuel electricity generation. A practical solution to mitigate this problem is to sell uninterruptible and interruptible electricity at different rates.

48) Uninterruptible electricity is higher price electricity that is always instantaneously available to the consumer.

49) The supply of power at the instant when customers demand it is much more complex and expensive than simply capturing renewable energy when nature provides it. The equipment and processes that can physically store and then transmit solar and wind energy are inefficient and usually increase the blended cost per unit of supplied energy by 5 to 10 fold.

50) The cost of providing uninterruptible non-fossil power is proportional to the capital cost of reliable generation and is almost independent of the actual amount of energy supplied. Hence the price of uninterruptible non-fossil electricity should be proportional to the consumer's measured monthly peak demand in kW.

51) Interruptible electricity is lower price electricity that may not be available at times of prolonged low solar and wind generation or at times of high non-interruptible load. Interruptible electricity is sold at a price per kWh.

52) The major long term markets for interruptible electricity are displacement of higher cost hydro-carbon fuels in hybrid energy systems and production of electrolytic hydrogen.

53) Electrolytic hydrogen will be required for making synthetic high energy density liquid fuels, for realizing high temperatures in industrial processes and for meeting the peak winter space heating load.

54) With an appropriate electricity rate structure uninterruptible and interruptible electricity can both be delivered by the same distribution system and registered by the same smart electricity meter. However, the electricity utility must broadcast a signal to the consumer indicating the times when the consumer may exceed his normal peak demand setpoint without financial penalty, thus allowing the consumer access to additional low cost energy when it is available. At all other times the consumer is billed for peak demand.

i) High purity sodium supply (~5000 tonnes / reactor);
ii) Production of high purity ferrochrome tubing (0.5 inch OD,
12% Cr, low Ni, low C, about 2500 km / 1000 MWt reactor);
iii) On-site uranium oxide extraction from existing thermal reactor
spent fuel inventories via two step recrystalization;
  iv) Reduction of spent fuel oxide concentrates into metals;
v) High temperature electrolytic separation of fission products
from the high atomic weight elements (U, Pu);
vi) Zirconium extraction from the fission
products using a dry chloride process;
vii) Production of porcelain-metal containers for
300 year storage of fission products;
viii) Production of synthetic liquid fuels from electrolytic
hydrogen, biomass and nuclear reactor waste heat.


a) Climate change is real and it already threatens
the financial solvency of governments;
b) Non-fossil uninterruptible electricity must be
supplied by Fast Neutron Reactors; (FNRs)
c) Uninterruptible electricity must be sold based on
a price per kW of peak demand;
d) Interruptible electricity, such as from solar and
wind generation, should be sold based on a price per kWh;
d) FNRs feature 100X present reactor fuel efficiency,
1000X less long lived spent fuel waste
and load following capability;
e) A major application of interruptible electricity will be
production of hydrogen which provides inherent energy storage;
f) There will be new opportunites for chemical engineers in the
emerging advanced nuclear power and synthetic fuel sectors;
g) Existing inventories of the fissile fuels U-235 and Pu-239
should be conserved to allow rapid deployment of FNRs.


Thank you for your attention.

This web page last updated February 18, 2019.

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