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USED NUCLEAR FUEL:
Used nuclear fuel contains radio active atomic isotopes (radio isotopes) that form as a result of nuclear fission or of absorption of free neutrons. These radio isotopes spontaneously decay over time. Each radio isotope has a characteristic half life. However, when a radio isotope decays it often becomes another radio isotope. Used nuclear fuel has significant value because it can generally be reprocessed to make new nuclear fuel and/or to yield high value elements.
Nuclear waste contains radio active atomic isotopes (radio isotopes) that form as a result of absorption of free neutrons by materials in or near a nuclear reactor. These radio isotopes spontaneously decay over time. Each radio isotope has a characteristic half life. However, when a radio isotope decays it often becomes another radio isotope. Nuclear waste has little or no economic value because it generally cannot be reprocessed to make anything else of significant value.
Nuclear fuel and waste disposal is influenced by irrational politics. Nowhere is that irrationality more evident than in the Green Party of Canada (GPC), as demonstrated by the following video.
The GPC falsely claims that Canadian energy needs can be met purely with renewable energy, whereas the supply of renewable energy is clearly insufficient in the winter. The GPC claims that nuclear waste persists for millions of years but opposes implementation of used nuclear fuel reprocessing which reduces the waste persistence time from about 400,000 years to about 300 years and which increases the effective nuclear fuel reserve by over 100 fold.
NUCLEAR WASTE CATEGORY REVIEW:
Nuclear waste containing radio isotopes with half lives of less than 30 years is referred to by government as Low Level Waste (LLW). Nuclear waste containing radio isotopes with half lives of greater than 30 years is referred to by government as High Level Waste (HLW). A mixture of HLW and LLW is referred to by government as Intermediate Level Waste (ILW). After ILW has been in storage for 300 years the radio toxicity of the remaining LLW component will be very small relative to the radio toxicity of the remaining HLW component. Hence over a few centuries ILW becomes HLW.
PREFERRED NUCLEAR WASTE STORAGE SITE:
Reference: Coupling Repository to Fuel Cycle
The site in Canada that is believed to be most geophysically suitable for accessible long term dry storage of used nuclear fuel and perhaps nuclear waste is the Jersey Emerald mine complex in British Columbia. No matter what else is done with used CANDU fuel and nuclear waste, the public will remain at risk from extreme natural events until the used fuel and nuclear waste is moved to a safer location than at the existing CANDU reactor sites that are seldom at an elevation significantly above a large neighbouring body of water.
In the view of this author the existing political guidelines from both the government of Ontario and the government of Canada relating to used nuclear fuel and nuclear waste transport, processing and disposal are wrong. These guidelines are founded in irrational public fears and in a political planning horizon that does not extend beyond the next election. In the view of this author it is a huge mistake to let short term political considerations take precedence over scientific fact, good engineering, energy efficiency and public safety.
NWMO USED NUCLEAR FUEL DISPOSAL CONCEPT:
There are several competing used nuclear fuel disposal concepts. The concept presently advocated by the Nuclear Waste Management Organization (NWMO) and Ontario Power Generation (OPG) is to place all used nuclear fuel and nuclear waste in inaccessible Deep Geologic Repositorys (DGRs) which are located in limestone far below the local water table within a "receptive community". That concept requires ensuring that the HLW remains isolated from ground water and the biosphere for as much as 3,000,000 years. The practical difficulties of ensuring reliable dry isolation that lasts 600X the life of the ancient Egyptian Pyramids should not be under estimated.
Such storage appears to be possible in very thick salt deposits, but anything so stored soon becomes completely inaccessible for future use.
A fundamental problem with the NWMO/OPG methodology is that it does not permit fuel recycling. The NWMO/OPG concept is to dig a deep hole in limestone, dump the waste down the hole, backfill with limestone and then hope that there is negligible radioisotope transport out of this deep underground dump for the next four hundred thousand years. The NWMO/OPG concept relies on the collapse of the limestone under gravitational stress to seal the dump. I am not arguing that the NWMO methodology will not work for a few dumps. However, after a few hundred years the province will be littered with such toxic waste dumps. It is like having a few hundred nuclear reactors operating without maintenance. Sooner or later one of them will fail. If such a failure occurs there is almost nothing practical that can be done to mitigate the situation.
The NWMO/OPG methodology makes assumptions about the subsurface geology that may or may not be true. For example at Bruce there are less than a dozen documented drill cores. As we saw at the Niagara Tunnel and the Seymour Tunnel, assumptions based on limited core drilling are often wrong with short term construction cost consequences in the extra $1 billion / incident range.
The NWMO is so divorced from practical mining and tunneling reality that I frankly see no solution other than to completely wind up the NWMO and start again with new professional personnel who have practical Canadian deep hard rock mining/tunneling experience. As a minimum the NWMO and OPG should have engaged persons who worked on the Niagara Tunnel in order to bring into the NWMO/OPG planning some sense of practical reality with respect to deep underground water seepage and ventilation requirements.
In the Niagara Tunnel shotcrete was applied to the tunnel walls immediately behind the tunnel boring machine. The shotcrete was followed by an olefin plastic water barrier and then a concrete structural liner. There is currently no provision for these measures in the NWMO/OPG plans for the Bruce DGR. For the Niagara Tunnel OPG employed European engineering consultants who had relevant experience with comparable deep European tunnels.
However, for reasons unknown to me the experience gained by OPG during construction of the Niagara Tunnel was not considered by OPG in planning of the Bruce DGR.
One of the problems that is not adequately appreciated with respect to the proposed Bruce DGR is that the hydraulic pressure head that builds up behind an olefin plastic water barrier is enormous. (680 m head of water at Bruce). A very thick concrete structural liner would be required to prevent that hydraulic pressure head rupturing the liner. Without a liner seepage water has to be constantly pumped out. The cost of that seepage pumping will likely be millions of dollars per year. Ideally in this situation the overhead ground should be dewatered to limit seepage. However, the proximity of the Bruce site to Lake Huron makes such dewatering impossible. Further, adjacent property owners that rely on water wells would vigorously object if the local aquifers were drained.
The NWMO fails to appreciate that a "receptive community" will not exist without a local source of fresh water such as an aquifer, but anywhere with such an aquifer is poorly suited for long term nuclear waste storage. The NWMO should be looking for "no community" DGR site opportunities where there is not and never will be an overhead aquifer.
The NWMO currently plans to bury untreated HLW in domed end cylindrical copper coated steel containers surrounded by bentonite clay.
There are long term corrosion chemistry issues associated with burial of nuclear waste. Some of these corrosion issues are mentioned in As Nuclear Waste Piles Up Scientists Seek The Best Long-Term Storage Solutions.
ALTERNATIVE USED NUCLEAR FUEL DISPOSAL CONCEPTS:
In my view the present NWMO plan for dealing with high atomic weight high level waste (HLW) is complete foolishness. Using proven technology high atomic weight high level waste HLW can be converted into fuel for liquid sodium cooled fast neutron reactors. Such reactors can fission the HLW atoms so that these atoms become low level waste (LLW) atoms which are relatively simple to deal with from a disposal perspective. Furthermore, fast neutron reactors can multiply by 100 fold the useful energy obtainable per kg of natural uranium as compared to a CANDU reactor.
The existing inventory of HLW could be concentrated on existing reactor sites, interim stored at Jersey Emerald and eventually reprocessed at Chalk River or possibly at Trail, BC which is about 40 km away. Trail has a long history of bulk processing of highly toxic mined materials.
The alternative used nuclear fuel disposal concepts are completely different from the NWMO concept.
1) The Ottensmeyer Plan features the greatest efficiency in use of natural uranium and in elimination of long lived radio isotopes. The electrochemistry used does not produce pure plutonium. Further, the reactors used denature the plutonium by forming Pu-240 which makes the plutonium unsuitable for future weapon use.
2) The Moltex Plan reduces the CANDU fuel recycling complexity at considerable expense in terms of fuel utilization efficiency.
3) The PUREX Plan is presently used by several countries to make nuclear weapons. The PUREX nuclear fuel reprocessing chemistry results in pure plutonium but has the disadvantge of production of large amounts of difficult to manage liquid radioactive waste. It also has the major disadvantage of enabling nuclear weapon proliferation.
Canada has no interest in pursuit of nuclear weapons. For that reason PUREX fuel reprocessing chemistry is not further considered on this web site.
A summary of the Moltex Plan prepared by Darryl Siemer from published literature is:
MOLTEX’s WATTS reprocessing scheme represents another promising way to fuel tomorrow’s reactors with today’s radwastes. CANDU or LWR oxide-based fuel rods would first be declad by blowing hot chlorine gas over them which would convert their metallic zirconium cladding to gaseous ZrCl4. The thus-exposed oxide - mostly UO2 with ~0.3 (CANDU) to 0.6 wt% PuO2 plus misc. FPs, also mostly oxides - fuel pellets would then be dumped into a molten chloride salt electrolyte along with some iron filings. The fuel pellets’ more readily reduced elements including its actinides would then be electroplated out into a low melting (eutectic) molten uranium-iron metallic electrode. When that’s done, that electrode would be flooded with a “clean” NaCl/FeCl2 molten salt. Because metallic plutonium and americium are stronger reducing agents than is uranium, they should be selectively oxidized by that salt stream’s ferrous ion which reaction would convert them to molten salt-soluble chloride salts and the ferrous iron to metallic iron thereby separating the former from the bulk of the molten alloy’s uranium. Sufficient additional ferrous ion would then oxidize/transfer enough of the uranium to the salt phase to generate a fuel salt sufficiently rich in fissile (>10% of the HM, mostly 239Pu and 241Pu) to fuel MOLTEX’s “waste burning” SSR-W.
That’s a very clever scheme but like most of the others I’ve heard about, in practice may not prove to be superior to one utilizing a more conventional PUREX-type cleanup/fissile recovery approach. Only real-world experimentation will tell.
On August 13, 2021 Ian Scott of Moltex indicated that Moltex plans "have evolved quite substantially beyond what we have published". Hence Darryl Siemer's above summary may no longer be accurate.
Used CANDU reactor fuel is converted into FNR fuel by:
a) Selective separation of uranium, zirconium and cesium with the aid of a uranium oxide recrystalization cascade;
b) Electrolytic separation of uranium and Pu/U alloy from chloride salts containing the fission products;
c) Casting new FNR core and blanket fuel rods;
d) Send fission product salts to 300 year dry storage.
The purpose of an accessible radio isotope storage facility is five fold.
1) To provide structural protection for engineered radio isotope containers placed within the facility for at least 10 half lives of the stored radio isotopes;
2) To provide ongoing physical access to the engineered containers for inspection, material recycling, and container monitoring/repair/replacement.
3) To provide natural gravity water drainage so that the containers remain dry and are never subject to a large external hydraulic pressure head;
4) To provide natural ventilation for heat and water vapor removal.
5) To provide safe default long term radio isotope storage in the event of a future society collapse.
In an acxcesible radio isotope storage facility the primary barrier to radio isotope transport is the engineered container, not the surrounding rock. About 5000 years ago the ancient Egyptians put mummies in limestone coffins and stored these coffins in pyramids under reasonably dry conditions. These mummies are on exhibition in museums today. It is my belief that we can greatly improve on the ancient Egyptian storage technology using the materials stainless steel, porcelain and a suitably chosen liquid/wax dielectric.
In my view these objectives can be met within the crack free granite core of a selected substantial mountain. The advantages of this alternate concept are:
1) Ongoing radio isotope accessibility for recycling and storage system repair;
2) Capacity to recycle both storage space and storage containers for relatively short lived isotopes such as fission products;
3) Long term certainty that stored radio isotopes will not escape into the environment.
If one assumes, as does the NWMO, that the storage site must be within a "receptive community" then the NWMO methodology may seem to have a lower first cost.
If on the other hand one assumes that the storage site is an existing depleted hardrock mine far from any significant community, then the alternate methodology is both much less expensive and has many practical advantages. One of these advantages is certainty about the underground geology. As compared to about a dozen documented drill cores at Bruce, Sultan Minerals has about 6000 documented drill cores relating to the depleted Jersey Emerald mine complex and the immediately surrounding area.
OTTENSMEYER PLAN CONCEPT:
The alternative concept for storage and disposal of nuclear waste is known as the Ottensmeyer Plan. The Ottensmeyer Plan involves radio isotope recycling and complete energy extraction from nuclear fuel rather than long term storage of highly radio active material.
The key to understanding the Ottensmeyer Plan is understanding that spent CANDU fuel still contains over 99% of its original nuclear potential energy. The fuel is considered "spent" because it contains low atomic weight high neutron cross section fission products. These high neutron cross section atoms shut down a nuclear reactor. If the LLW fission products are selectively removed and are replaced with HLW material the fuel can be recycled. The recycled fuel contains plutonium-239 in place of uranium-235. To maintain the Pu-239 inventory the fuel must be used in a liquid metal or liquid salt cooled fast neutron reactor instead of in a water cooled reactor. Of the available coolants sodium has the combined advantages of low density, low melting point, low cost and excellent steel compatibility.
The Ottensmeyer Plan involves selective extraction of uranium oxide from spent CANDU reactor fuel followed by separation of the remaining nuclear waste into its low atomic weight (LLW) and high atomic weight (HLW) components.
The selectively removed uranium oxide, which constitutes over 90% of the spent CANDU fuel mass, and which may contain a very small fraction of actinide and U-232 impurities, is stored for future use as fast neutron reactor blanket rod material.
Containers of LLW should be kept in isolated dry storage for 300 years to allow the LLW to naturally decay into stable isotopes. The HLW should be used to form core fuel rods for use in fast neutron reactors.
In one fuel cycle a fast neutron reactor fissions 10% to 20% of its original core fuel weight into LLW. This newly formed LLW is selectively extracted from the used core rod material and is placed in containers for 300 year dry storage. The extracted weight of LLW is replaced by an equal weight of new HLW drawn from inventory and the resulting mixture is again used as core fuel rod material in a fast neutron reactor.
The cycle of LLW extraction, replacement of extracted LLW weight by an equal weight of new HLW/uranium oxide and reuse as fuel in a fast neutron reactor is repeated over and over again to gradually consume the entire HLW/uranium oxide inventory.
The atomic weight based separation process used to extract LLW from HLW is imperfect. A small fraction of low atomic weight long lived isotopes such as C-14, Cl-36, Ca-41 and Ni-59 will remain in the stored LLW. After a container of LLW has been stored for 300 years the radio activity of the container is dominated by a few long lived isotopes. The container is scanned with a gamma ray spectrometer. Based on the recorded gamma ray spectrum chemical treatments are used to selectively extract the long lived isotopes from the decayed LLW. These long lived isotopes are then consigned to very long term storage.
A second neutron irradiation stage of processing is effective at suppressing the longer lived fission products Tc-99, Sn-126, Se-79, Zr-93, Cs-135, Pd-107 and I-129. After a second 300 year storage cycle the container contents are again scanned with a gamma ray spectrometer and again any remaining long lived isotopes can be selectively extracted.
When the radio activity of a container of processed waste is less than the radio activity of an identical container of natural uranium, the container contents can be safely removed and recycled. The decayed LLW primarily consists of rare earths that have high commercial value. The released DGR storage space and the released storage containers are then available for reuse.
OTTENSMEYER PLAN IMPLEMENTATION:
The Ottensmeyer Plan uses technologies that have proven performance in long term preservation and water exclusion. The Ottensmeyer Plan takes into consideration practical aspects of petrochemicals, hard rock mining and sulfur induced corrosion.
In the Ottensmeyer Plan water exclusion problems are avoided by storing the radioactive material for several centuries in engineered containers. These containers are located within an accessible naturally dry (gravity drained) Deep Geologic Repository (DGR) that is at least 300 m above the local water table and by keeping the DGR at atmospheric pressure. Resistance to DGR damage by glaciation and other events is ensured by forming the DGR inside the high density granite core of a mountain that provides over 400 m of overhead rock above the DGR. There is no attempt to find a "receptive community" because at geologically suitable DGR sites there is insufficient fresh water to support a community. In the Ottensmeyer Plan the DGR location is determined primarily by favorable geophysical criteria, not by political criteria.
In the Ottensmeyer Plan double wall storage containers (outer wall porcelain, inner wall stainless steel, liquid/wax dielectric between the inner and outer walls) are used to store the radioactive material while it is in the DGR. While in the DGR the physical integrity of each nuclear waste storage container is constantly remotely monitored by sensing the container dielectric level and dielectric loss tangent.
LONG TERM SAFETY CERTAINTY:
The primary advantage of the Jersey-Emerald mine facility in British Columbia over other large depleted mines in Canada for spent fuel storage and radioactive waste disposal is very long term certainty of naturally nearly dry conditions spanning numerous ice ages. These nearly dry conditions are key to prevention of contact of the stored radioactive waste with ground water. This author is not aware of any other large existing Canadian mine with comparable natural protection that provides comparable long term certainty regarding separation of toxic radioactive materials from ground water. The simple reality is that the hard rock mountains in Ontario are simply not high enough to provide comparable protection from long term changes in the level of the local water table.
The ongoing failure of mankind to adequately address the problem of fossil carbon CO2 emissions has already initiated a process that will over the coming centuries almost certainly lead to an 80 m increase in sea level due to melting of polar icecaps and thermal expansion of the oceans. Glacial pressure could easily reduce the storage site elevation by more than another 100 m, the height of the Niagara escarpment. If we accept the NWMO recommendation of requiring 400 m to 500 m of top cover, we are looking for a large naturally dry existing hardrock mine half way up a solid granite mountain with a present height of over 1000 m above the surrounding water table. The simple reality is that there are few sufficiently high mountains in Ontario and there is no existing major hardrock mine in Ontario that meets these specifications.
Date: June 4, 2021
Charles Rhodes, P.Eng;,
Xylene Power Ltd.
Micro Fusion International Ltd.
This document is a response to an invitation from the NWMO to comment on the NWMO plan for disposal of nuclear fuel waste. This document identifies major problems with the present NWMO plan, solutions to these problems and possible future new problems related to extraction of high value elements from the fission product waste stream.
The NWMO's present used nuclear fuel disposal plan, to which it has adhered since about 2005, rests on a series of implicit assumptions, some of which are inappropriate or not true. These assumptions are:
a) After a period in dry storage on CANDU reactor sites, custody of the nuclear waste will be transferred to the NWMO.
b) The form of the waste will be unmodified used CANDU fuel bundles;
c) The NWMO will transport the waste to a disposal site yet to be determined;
d) The NWMO will package the waste in copper coated steel containers;
e) The NWMO will place these containers in limestone vaults about 600 m below grade, far below the local water table.
f) The NWMO will surround each container with bentonite clay;
f) When the vault is full the NWMO will back fill the access shaft(s) leading to the vault.
g) Some time after the access shaft(s) are back filled water seepage into the vault will raise the hydraulic pressure at the containers to about 60 atmospheres or about 6 MPa. Reliably withstanding this pressure requires containers fabricated from relatively expensive schedule 160 thick wall steel pipe with near hemisphere end caps.
h) After many decades in storage this type of container will fail. Practical experience with buried pressure pipe with galvanic protection indicates that after a period ranging from 60 years to perhaps several hundred years the container's end cap welds will develop cracks that will ultimately lead to container failure. This author believes that the underlying failure mechanism is long term metal phase change at the weld. For example if the weld material spontaneously changes from a BCC to FCC crystal lattice enormous internal stresses develop within the weld material.
i) The NWMO is counting on the bentonite clay and long term settlement of the surrounding limestone to keep water soluble radio isotope ions within the immediate vicinity of the containers for at least one million years into the future.
j) Economic recovery of the container contents from this form of storage is not seriously contemplated.
Today, for the following reasons, the present NWMO plan is not viable:
a) The amount of fissile fuel required to sustainably displace fossil fuels is several orders of magnitude greater than the amount of fissile fuel consumption originally contemplated by the NWMO; It is not economic to keep burying large amounts of U-238.
b) The increase in fissile fuel requirement can only be sustainably met by breeding U-238 into Pu-239 and Pu-240 and by breeding Th-232 into U-233.
c) Efficient harvesting of the Pu-239, Pu-240 and U-233 requires used nuclear fuel recycling;
d) The fuel recycling process replaces U, Pu and the transuranium actinides previously in the waste stream by fission products;
e) The form in which nuclear waste will likely be transferred to the custody of the NWMO will not be used CANDU fuel bundles. Instead the waste will be a stream of fission products rejected during the reprocessing of CANDU fuel into FNR fuel or a waste stream produced by selective extraction of high value elements from the fission products;
f) Today there are various fuel reprocessing schemes which involve interim fission product storage periods ranging from a few years to centuries. The issues of who owns what, who has custody of what and who is responsible for what before, during and after such storage periods are currently unresolved;
g) For reasons further detailed herein owners of real property anywhere near the geologic storage vaults contemplated by the NWMO will do everything possible to prevent execution of the present NWMO plan;
h) For reasons further detailed herein the chemical industry will do all necessary to prevent execution of the present NWMO plan;
i) There are three fundamental problems that precipitate opposition to the NWMO's present plan:
i) The present NWMO plan involves long term storage of toxic substances below the water table which emit ionizing radiation;
ii) The waste storage containers and vaults contemplated by the NWMO are inaccessible for ongoing inspection, content reprocessing or long term maintenance;
iii) The fission products contain several extremely high value elements such as Pt and Ir for which there are no substitutes. If the NWMO management insists on burying fission products without selective removal of these high value elements the chemical industry will do all necessary to put the NWMO out of business.
LAND OWNER OPPOSITION:
Due in part to unsubstantiated public fear of ionizing radiation the NWMO plan creates safety uncertainty in the minds of potential purchasers of properties located anywhere near the contemplated NWMO geologic storage site. Irrational public fear of ionizing radiation that has been promoted by both fossil fuel interests and big pharma for more than 60 years. This public fear will significantly lower property values within as much as a 15 km radius of any contemplated NWMO waste storage site that is below the local water table. As a consequence owners of property anywhere near the contemplated NWMO waste storage site will use every possible legal means to oppose implementation of the present NWMO plan.
CHEMICAL INDUSTRY OPPOSITION:
The radio toxicity of the fission products initially rapidly declines until after about 300 years in storage the radio toxicity of the fission products nearly plateaus at a level comparable to the radio toxicity of natural uranium. The initial rapid decline in radio toxicity makes it advantageous to leave the fission products in isolated dry storage for at least a few decades to simplify subsequent fission product chemical processing. However, the immense monetary value of certain fission products, particularly Pt and Ir, means that no matter what NWMO management decides, industry will do all necessary to gain access to the fission products for selective removal of these high value elements. If at a small marginal extra cost industry can also recover other financially less valuable elements such as gold, osmium and certain rare earths it will do so.
It is important for the NWMO management to grasp that there is no substitute for platinum as a chemical catalyst and there is no substitute for iridium for use in manufacture of semiconductor products. The monetary value of these rare materials will almost certainly determine fission product disposal policy.
During the period 2008 to 2012 senior parties in the Canadian mining industry, who had extensive experience with management and storage of high toxicity mine waste, proposed to the NWMO a much more viable nuclear waste storage plan. At the time the NWMO rejected the mining industry proposal without serious consideration. At the time the mining industry proposal was backed by $100 million dollars in private sector financing plus a lot of work to assemble the necessary property and mineral rights. Today that mining industry plan is still almost certainly the most physically viable method for nuclear waste disposal in Canada. However, due to foolish past behavior by the NWMO the cost of implementation of the mining industry proposal has likely increased by about an order of magnitude from less than $100 million to the order of $1 billion.
i) The mining industry proposal involved storage of nuclear materials in containers placed in existing permanently accessible gravity drained high density granite vaults which are located high above the local water table. The vaults were formed during the period 1940 to 1970 (during WWII and the subsequent cold war). These vaults are sufficiently robust to withstand a direct strike by a nuclear bomb. Due to favorable nearby geology there is opportunity for substantially further increasing the available vault space.
ii) The cost of vault space enlargement would be partially offset by the value of molybdenum ore removed.
iii) The fission product storage containers would be permanently accessible to enable periodic examination, maintenance and future material reprocessing . Storage of the containers at atmospheric pressure far above the local water table means that, unlike the original NWMO plan the containers do not need to withstand a large external hydraulic pressure. Storage of the containers in a naturally dry environment means that they will be much more resistant to long term external corrosion than containers stored below the water table. The vaults are naturally ventilated, can be gravity drained and are sufficiently robust to protect the containers against future glaciation.
iv) The containers would be fitted with pressure relief devices to prevent long term internal pressure accumulation. It is contemplated that the containers would have an inner stainless steel wall and an outer porcelain wall with the two walls separated by a heavy oil (bitumen) dielectric. Bitumen containment successfully preserved dinosaur remains for 76 million years.
v) Good porcelain (as distinct from cheap porcelain bathroom fixtures) is a man made material rarely found in nature. It does not absorb water. Some museums contain good porcelain containers that are more than 3000 years old with no significant signs of deterioration or wear.
DEPLOYMENT OF ADVANCED POWER REACTORS:
In order to mitigate climate change caused by the increasing accumulation of CO2 in Earth's atmosphere and oceans it is necessary to widely deploy nuclear power reactors that are fueled by the abundant isotopes U-238 and Th-232 instead of by the much rarer isotope U-235.
These advanced power reactors obtain fissile isotopes by transmuting fertile U-238 into fissile Pu-239 and Pu-240 and by transmuting fertile Th-232 into fissile U-233. The fissile fuel production process requires intermediate fuel reprocessing.
These advanced power reactors are not figments of the imagination. Large liquid sodium cooled power reactors have been operating in Russia for more than 30 years. Since about 2010 China has had a team of more than 600 engineers working on advanced power reactor development. China expects to have two more large liquid sodium cooled power reactors operating in 2023.
CANDU FUEL REPROCESSING:
CANDU used fuel reprocessing to make Fast Neutron Reactor (FNR) fuel typically involves four major steps.
1) Selective UO2 extraction. This step removes about 90% of the UO2 and also extracts Ar, Kr, Xe, Cs, Zr and Np.
2) Material reduction. This step converts metal oxides into metals;
3) Electrolytic separation. This step extracts U, U + Pt alloy and any remaining Zr leaving behind the fission products embedded in a chloride salt;
4) Fuel fabrication. This step combines extracted U, Np and Zr to form FNR blanket fuel and combines U, Np, Pu and Zr to form FNR core fuel.
The CNSC will likely regulate matters relating to the inert gases Ar, Kr and Xe. The NWMO will have to deal with storage of Cs. Cs-137 has a half life of 30 years. It needs to be stored for 300 to 600 years so that it naturally decays into stable Ba-137.
The NWMO will also have to deal with the fission products embedded in chloride salt.
The fission product storage issues will likely be complicated by selective extraction of high value elements which extraction processes may introduce additional waste streams.
FISSION PRODUCT ISSUES:
a) Electricity generation utilities which presently own and store used CANDU fuel bundles are realizing that these used fuel bundles still contain about 99X the energy that was released in the CANDU reactor. This energy can be harvested by an appropriate use of Fast Neutron Reactors (FNRs) and fuel recycling.
b) After fuel recycling the form of the waste is not CANDU fuel bundles. The form of the waste is a combination of inert gases, cesium, and solid fission products embedded in a chloride salt.
c) Release of the inert gases will likely be regulated by the CNSC.
d) The uranium and trans-uranium actinides are consumed by fission.
e) Initially the waste form is solid fission products embedded in a chloride salt. However, after some period in storage the fission product waste form will become more complex due to subsequent processes used to selectively remove high value elements such as Pt and Ir which have unique properties.
f) Currently the monetary value if these elements is about $10,000 / troy ounce. The fraction of these high value elements in the fission product stream is sufficient to ensure that they will be selectively extracted, regardless of the cost and complexity of the extraction process or its impact on nuclear waste disposal. The NWMO will simply have to adapt itself to this situation.
g) The fission products also contain a group of elements known as rare earths. These elements are used in modern electrical and electronic systems and have critical defense applications. To the extent that these rare earth elements can be economically recovered during the high value element recovery work, then that rare earth element recovery will also likely occur.
h) There are various nuclear fuel recycling processes. The process that Canada will most likely adopt is the Ottensmeyer Plan. As compared to other PUREX like processes the Ottensmeyer plan offers high resistance to nuclear weapon proliferation and has no waste streams other than inert gases and dry fission products.
i) The solid fission products contain both shorter lived isotopes such as Sr-90 which has a half life of about 27.7 years and long lived isotopes such as I-129 which has a half life of 1.7 X 10^7 years.
j) Ideally the fission products should be dry stored for about 300 years to allow the shorter lived isotopes to naturally decay before further fission product chemical processing;
k) Subsequent recovery of the high value elements and possible recovery of some rare earths will likely involve aqueous processing, which will likely create more challenging waste streams than previously contemplated by the NWMO.
l) Thus the NWMO faces a potentially complex issue. Following the mining industry proposal is relatively simple and straight forward. The material in interim storage consists of dry fission products embedded in dry chloride salt. The contemplated storage containers are dry and the contemplated storage vaults are dry.
m) However, dealing with aqueous radioactive waste resulting from selective extraction of high value elements from fission products introduces significant new waste disposal complexities. This author recommends that the NWMO consult with Dr. Darryl Siemer, a retired senior scientist and waste disposal expert from the Idaho National Laboratory, for guidance on the issue of disposal of fission products contained in aqueous solutions.
STORAGE VAULT ISSUES:
The NWMO's present concept of burying long lived high level nuclear waste and then forgetting about it is simply not acceptable to rural Canadians who rely on individual water wells. Rural Canadians, especially aboriginal people, have experienced the practical limitations of democratically elected governments. These governments have a very poor history with respect to regulating and enforcing potable water quality. There have been numerous instances in Canada where governmental regulatory failure has led to polluted water which has caused loss of property value, prolonged boil water advisories,sickness and death. In Ontario one needs look no further than the Grassy Narrows Indian reserve or Walkerton to find parties who have experienced and are still experiencing long term sickness and death from water pollution from inadequately regulated commercial/industrial activities. The legal situation is little different in other provinces. Generally the monetary value of a rural property is completely dependent upon a potential purchaser having absolute certainty that that the ground water is potable and will remain that way as long as the purchaser or his/her successors wish to own the property. To such land owners any hint of a nuclear waste facility containing inaccessible toxic radioactive waste below the water table is totally unacceptable. No promise by government, corporations or other bodies relating to water quality and potability is sufficient or is legally enforceable. Such promises have been repeatedly broken. There are legislative and legal loopholes for perpetrators to escape responsibility. For example, at the Bruce Nuclear Power Plant there is a large below grade tritium plume for which OPG has refused to compensate nearby property owners. It does not mater whether or not there is a real health risk. As soon as there is a perception of a possible health issue affected property values fall.
Thus the first lesson for the NWMO is that it will meet consistent community opposition until it adopts storage vaults that are naturally dry, are high above the surrounding water table and are formed in high density stable water tight granite so as to be permanently accessible while providing an easily testable secondary barrier.
There is a geologic argument for permanent storage of nuclear waste in certain salt formations such as exist in New Mexico. However, the present priority use for such formations in Canada is seasonal natural gas storage.
The NWMO must abandon its past policy of being guided by short term political considerations and instead be guided by the physics of long term safe radioisotope storage, the need for accessibility for fission product reprocessing and by the reality that people have no trust in government with respect to rural fresh water quality.
The Canadian mining industry has known since about 2006 that geologically the best location in Canada for long term permanently accessible storage of radio isotope filled containers is the depleted Jersey Emerald mine complex in southern British Columbia and the related adjacent high elevation high density rock formations in Iron Mountain.
The nuclear waste storage containers must be sized to fit into the Jersey Emerald truck tunnels, vaults, and drifts that are generally a minimum of 12 feet high.
The NWMO will simply have to face the reality that to acquire the Jersey Emerald mine complex and the surrounding property the NWMO must deal with the current land owners, current mineral rights owners, the relevant indigenous population and the government of British Columbia. An important aspect of these dealings will be provision of education and long term employment for the local indigenous population. These dealings would have been relatively easy circa 2012 when the land, mineral rights and relevant parties were assembled for sale, but today there will almost certainly be substantial additional costs due to property and mineral rights acquisition by Chinese investors and due to expiration of property and mineral rights purchase options. The NWMO has only itself to blame for this course of events.
The features of the Jersey Emerald location are summarized at Jersey Emerald
THE NECESSITY FOR REPROCESSING OF USED NUCLEAR FUEL:
The present NWMO plan implicitly assumes that at the time of disposal the waste is in the form of used CANDU fuel bundles. However, that assumption would be enormously wasteful of the potential energy contained in used CANDU fuel, which energy is about 99X the energy harvested to date by the fleet of CANDU reactors.
The present NWMO policies do not take into consideration energy and climate related physical constraints which are set out at:
CO2, ENERGY AND POWER REALITIES
Sustainable Nuclear Power
and limitations on wind and solar electricity generation which are set out at Electricity Contents
1) The atmospheric CO2 concentration has continued to monotonically increase and its rate of increase is reasonably projected to at least double over the next three decades. Absent a global nuclear war or a global pandemic with a very high mortality the presently projected increases in atmospheric and ocean CO2 concentration are almost certain to occur. There is no physical process other than widespread implementation of nuclear power that can significantly mitigate the CO2 problem. Elected governments in Canada and its provinces have had three decades in which to take prudent action on CO2 emission mitigation but have failed to act.
2) Various countries and states have attempted to substitute wind and solar power for energy derived from fossil fuels. However, no electricity grid has been able to obtain more than about 25% of its average power requirement from unconstrained wind and solar energy. The physical reasons for this limit lie within advanced electrical power engineering and are generally not understood by either politicians or the general public. This 25% limit results from a combination of consumption pattern, generation pattern, energy storage, energy transmission and grid stability constraints.
3) If mankind is to mitigate CO2 related climate change there must be widespread application of nuclear power to displace at least 70% of the fossil fuels otherwise required for electricity generation, transportation and heating applications.
4) As a consequence of the increasing atmospheric CO2 concentration the average wet bulb temperature in tropical countries is rising. This rise in average wet bulb temperature is driving both human migration and an unprecedented demand for electricity for air conditioning and water desalination. Absent nuclear power, that electricity will be generated by combustion of coal.
5) Three major Asian countries, Russia, China and India have recognized this problem and are are addressing it by large scale nuclear power construction programs. Collectively at present they have about fifty large (> 1 GWe) fission power reactor projects at various stages of implementation. China is reasonably projecting completing eight ~ 1 GWe projects per year between now and 2025 at which point it will have more nuclear power capacity than the USA. It is reasonable to project that during the period 2026 to 2030 China will likely complete about 12 ~ 1 GWe nuclear projects per year.
6) Canada has adopted a fossil carbon tax that by 2030 will likely make energy from new nuclear power capacity cost competitive with energy from combustion of natural gas.
7) The fundamental issue that needs to be recognized by the NWMO is that going forward there is no alternative to large scale use of nuclear power. This issue is being driven by planetary physics and no policy change by the Canadian government or wishful thinking by the NWMO management or others will change the physical reality.
8) Any sustainable nuclear power program will require nuclear fuel recycling and hence reprocessing of used nuclear fuel. Thus all of the NWMO work to date which assumed burial of CANDU fuel bundles without any fuel reprocessing has been a waste of time and money. This author and others advised the NWMO of this reality in 2012 but the NWMO ignored that advice.
1) The NWMO should not be worrying about disposal of used CANDU fuel. Instead the NWMO should be concentrating on long term disposal of long lived low commercial value radio isotopes that will result from large scale implementation of nuclear power and related fuel reprocessing.
2) The long lived radio isotopes needing disposal fall into several categories.
3) One of the significant fission product groups is inert gases. Argon, krypton and xenon, being inert gases at room temperature, are expensive to store in isolation for long periods of time. The practical disposal method is a combination of on-site cryogenic storage and gradual controlled release to the atmosphere. The xenon has no long lived isotopes. The isotopes of concern are:
|Kr-81||2.1 X 10^5 years|
It may be practical to store Kr-85 for a century to allow it to naturally decay,
but there is no practical alternative other than to gradually release the other isotopes to the atmosphere after some period in storage. This is an issue for which the NWMO should take responsibility in terms of communication to the public. The bottom line is that there is no practical alternative.
4) These inert gases are captured during the process used to extract nearly pure uranium oxide from used CANDU fuel.
5) It is reasonable to project that within this century the world wide fission power requirement will rise to about 33,000 GWt (10,000 GWe) . Thus the NWNO should focus on development of a policy for safe management of these inert gas radio isotopes that lends itself to world wide adoption.
6) Another group of isotopes that the NWMO should focus on are the long lived low atomic weight isotopes that have no commercial value. These include C-14, Cl-36, Ca-41 and Ni-59. These isotopes arise in nuclear reactors that are designed for minimum initial cost rather than for minimum nuclear waste production. Eg: Use of B4C in the neutron flux to reduce reactor physical size will produce C-14; Even small amounts of Cl-35 in molten salt reactors, resulting from imperfect isotope separation of Cl-35 and Cl-37, will produce Cl-36;
Concrete containing Ca-40 used for neutron shielding will produce Ca-41;
Metal alloys containing Ni-58 for high temperature strength, if exposed to neutrons, will produce Ni-59;
7) In this author's view the best way of dealing with the long lived low atomic weight isotopes is to not allow them to form in the first place. Formation of these isotopes can be avoided by appropriate reactor design. However, that appropriate design increases the reactor capital cost. This author is of the opinion that Canadian nuclear reactors should be properly designed in the first place, but those who have to deal with economic reactor construction for use in third world countries for displacement of coal do not share this author's opinion. They think that the CO2 situation is so critical that economy in reactor construction is of the highest priority and parties such as the NWMO, that are responsible for nuclear waste management, will just have to adapt to that reality.
8) Perhaps if the NWMO addresses this matter Canada can have a more enlightened reactor design policy. This issue is already important in Canada because Moltex contemplates using a chloride based fuel salt in its molten salt reactor. Moltex will need to separate Cl-35 from Cl-37 but the extent of that separation, unless influenced by the NWMO, will be set by cost and reactor performance rather than by long lived waste production considerations.
9) The trans-uranium actinides and the uranium are not real problems for the NWMO because they will be repeatedly recycled through Fast Neutron Reactors (FNRs) until these atoms fission.
10) The zirconium contained in used CANDU fuel bundles is not a significant near term problem for the NWMO because this zirconium is needed as an alloying element in FNR fuel to prevent formation of a low melting point Pu-Fe eutectic.
11) The fission product Cs is released and captured during the initial CANDU fuel reprocessing step. Cs-137 has a half life of 30 years. If not captured during the first processing step it becomes a major problem during subsequent high temperature electrolytic fuel separation. It will need isolated dry storage for 300 to 600 years to naturally decay into stable Ba-137. This safe handling and storage of radio Cs is an issue upon which the NWMO should focus.
12) During electrolytic fuel separation the remaining fission products accumulate in a molten chloride salt bath. During the first few centuries in storage the radioactivity of these remaining fission products will be dominated by a few isotopes like Sr-90 which has a half life of 27.7 years. However, after about three centuries in storage the fission product radio toxicity becomes dominated by very long lived isotopes such as I-129 which has a half life of 1.7 X 10^7 years.
13) The issue for the NWMO is that it is not economic to place the fission products in long term storage until after the high value elements have been selectively removed.
14) There are no substitutes for the rare high value elements. Recovery of these critical elements from the spectrum of fission products will be economic, almost no matter what the cost. Hence, until after these high value elements are selectively removed the fission products must remain accessible.
15) The fission products include a group of elements known as rare earths. These elements have various applications in modern electronics and magnets. Whether or not it will be economic to separate some or all of the rare earths from reactor fission products is uncertain at this time. However, the possibility should not be discounted.
16) In summary it will be necessary to interim store chloride salt fission products from electrolytic fuel separation in an accessible manner for as much as 300 years. Since chloride salts are highly mobile in water, both the interim and final storage locations should be naturally dry. The storage containers will need to withstand potential internal chloride salt corrosion.
1) China and India lack native uranium resources, so that via various means they are purchasing much of Canada's natural uranium.
2) The extent of the rich Canadian uranium resources is not infinite. China is attempting to purchase all of it at the lowest possible price. However, the price of this uranium is gradually trending upwards.
3) The trend in new reactor design is toward small breeding reactors. These reactors all need concentrated fissile isotopes as start fuel.
4) There are two sources of concentrated fissile isotopes, enrichment of natural uranium and reprocessing of used nuclear fuel.
5) For many nations, including Canada, as a matter of national energy security it is essential to build a used nuclear fuel reprocessing capability. The USA has repeatedly demonstrated that it is not a politically reliable source of enriched nuclear fuel for Canadian reactors.
6) Canada has about 60,000 tonnes of used CANDU fuel stored on CANDU reactor sites.
7) This used CANDU fuel contains enough potential energy, if properly exploited, to meet Canada's projected energy needs for as much as 300 years.
8) Optimum exploitation of used CANDU fuel involves four major steps, uranium oxide extraction, reduction, electrolytic fuel component separation and fuel rod formation.
9) The first major step is closed selective extraction of about 90% of the uranium oxide mass. This uranium oxide extraction should be done on existing CANDU reactor sites using a nitric acid cascade as described at
Used Fuel Concentration
This extraction process has been proven at the laboratory level and is currently being scaled up to the 5 tonne per day level. It is contemplated that separate extraction systems would be located at Pickering, Darlington and Bruce.
10) The outputs of each on-site extraction system would be relatively high purity uranium + neptunium oxides, a mix of inert gases including argon, krypton and xenon, cesium and a mixture of uranium, transuranium actinides and fission products. This later mixture would then be transported to Chalk River, where it would be electrolytically separated into the components necessary for making Fast Neutron Reactor (FNR) fuel. The fission products would be rejected and transported to interim storage. Thus it is likely that the NWMO would take custody of the Fission Products either at Chalk River or at the interim storage location. The NWMO would take custody of the cesium either at CANDU reactor sites or at the interim storage location.
11) It is essential to remove the cesium during the first stage of processing. It will otherwise pollute the extracted uranium and if permitted to go forward with the other fission products will cause major problems during subsequent high temperature electrolytic fuel separation.
To understand the aforementioned requirements it is necessary to have a basic understanding of the world climate situation and the world energy situation.
1) The present atmospheric CO2 concentration is about 410 ppmv.
2) The atmospheric CO2 concentration is presently increasing at about 2.5 ppmv / year.
3) Since commencement of precise atmospheric CO2 concentration measurements in 1957 the average temperature in the tropics has risen over 1 degree C and the average temperature in Canada's northern communities has risen over 3 degrees C.
4) One of the consequences of global warming is warming of the ocean surface.
5) In Canada warming of the ocean surface causes melting of ice.
6) In the USA warming of the ocean surface causes increased incidence of violent storms.
7) In tropical countries warming of the ocean surface causes both increased incidence of violent storms and a major reduction in the temperature difference between human body temperature and the average wet bulb temperature.
8) The nominal human body temperature is about 37 degrees C.
9) An average human being metabolizes food and emits about 120 Wt of heat. This heat output doubles or triples under severe physical stress.
10) In warm climates human beings rely on evaporation of perspiration for cooling. Human beings can exist in dry bulb temperatures much higher than body temperature provided that they can continuously evaporate sufficient perspiration.
11) The limiting factor for human existence in the tropics is not the dry bulb temperature, it is the wet bulb temperature. When the wet bulb temperature exceeds 35 degrees C humans soon die.
12) The present world population is about 7.8 billion people.
13) The present thermal power released by combustion of fossil fuels is about 20,520 GWt and is rapidly increasing;
14) Thus the present world average thermal power release due to combustion of fossil fuels is about 2.65 kWt / person;
15) In Canada and the USA the present average thermal power release due to combustion of fossil fuels is about 9 kWt / person.
16) Over the coming few decades the world wide the average thermal power release due to combustion of fossil fuels will likely rise to about 5 kWt / person;
17) The dominant factors driving this projected increase in average per capita thermal power consumption are human migration to more temperate countries with higher per capita energy usage and the rise in average wet bulb temperature in the tropics. The rise in wet bulb temperature drives demand for both tropical air conditioning and water desalination.
18) It is reasonably projected that absent sufficient nuclear power most of the increase in grid supplied electricity will come from combustion of coal.
19) The population of planet Earth is still increasing. As the average standard of living improves the average female fertility rate will decrease, but it is conservative to project a further 25% population increase before that peak population is reached.
20) The combination of the aforementioned mechanisms indicates that by the year 2050 the average ongoing thermal power release by mankind will likely be about 50,000 GWt.
21) Up to about 25% of the required 50,000 GWt can come from wind and solar generation. That fraction of power supplied by wind and solar is capped by electricity grid stability issues that are little understood by the public. These issues are set out at:
22) Up to about 4% of the required 50,000 GWt can come from hydroelectric and geothermal energy sources. However, due to geophysical issues these energy sources are already close to their theoretical maximums.
23) Possibly about 1% of the required 50,000 GWt might be supplied by other potential energy sources such as fusion, tidal action, wave action, etc.
24) Thus about 70% of the required 50,000 GWt or 35,000 GWt must come from fossil and nuclear power sources.
25) However, to mitigate CO2 driven climate change the present fossil fuel dissipation of about 20,000 GWt must be reduced ten fold to less than 2000 GWt. Hence the remaining load that must be met by nuclear power is about 33,000 GWt (10,000 GWe).
26) Currently China is building about 10 GWe of nuclear power capacity per year. During the 1970s the USA built about 10 GWe / year. France achieved a comparable nuclear capacity construction rate. World wide we will need a sustained nuclear power capacity construction rate of about 200 GWe / year for 50 years to meet this target.
27) To the extent that this target is not met much of Earth's present population will die. That is a hard truth that people must face. It is time for NWMO managers to face reality.
28) In tropical countries there has been wide spread use of of solar panels to charge cell phones, to provide evening lighting and to provide basic refrigeration for food preservation. However, powering air conditioning and water desalination requires much more electricity.
29) Under present circumstances most of that extra electricity will be provided by combustion of coal.
30) Combustion of coal results in twice the CO2 emissions as does combustion of natural gas.
31) Thus the challenge is to provide nuclear electricity in the tropics at a cost comparable to coal fired electricity generation.
This web page last updated August 21, 2021
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