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G-Demption technology is a patent pending process of reusing spent nuclear fuel while it is being stored by harvesting the gamma rays produced in the spent nuclear fuel and using them for commercial processes. Spent nuclear fuel (in fuel assembly or fuel rod form) will be placed into a container that maximizes the usable gamma signal that can be recovered while preventing the escape of radioactive elements into the environment. This container is then transported to a separate facility which houses hundreds of other containers that are constantly emitting gamma rays. A hangar system remotely transports boxes of products through the facility and the gamma rays deposit energy inside of the boxes of products which treats the products or renders sterile any deadly micro-organisms.
Conceptual cutaway illustration of spent nuclear fuel rod inside of container. The coolant inside of the container as well as the material that the container is composed of is proprietary information of G-Demption LLC that may become public information at a later date. This also applies to several passive safety systems associated with the facility.
G-Demption technology relies on routine and proven spent nuclear fuel handling methods that are already in use at nuclear power plants today. It also leverages several of the same techniques already in use at Cobalt-60 based gamma ray irradiation facilities. The innovation is that the spent nuclear fuel storage industry and the gamma ray irradiation industry could be combined to safely and economically provide a new source of valuable gamma rays.
Conceptual illustration of medical supplies being sterilized inside of the facility which is storing the spent nuclear fuel rods that are inside of G-Demption containers. The blue glow is meant to illustrate the gamma rays but in real life the containers would not actually look like they are glowing blue. In the same way that you can’t directly see a radio wave you also can’t directly see a gamma ray.
G-Demption technology solves two major problems simultaneously. The first problem is a stagnant global supply of Cobalt-60 [a gamma ray emitting isotope produced mostly in Canadian nuclear reactors and imported into the US]. The limited capacity for production of this isotope constrains the implementation of gamma ray irradiation for medical supply sterilization, food preservation, and other useful processes. Today only 40% of one time use medical supplies are sterilized with Cobalt-60 and the rest are sterilized with Ethylene Oxide gas (a highly toxic and flammable gas). The new, and less expensive, gamma ray resources that G-Demption technology brings to the market would help reduce our reliance on Ethylene Oxide gas to provide the sterile medical supplies that our medical industry has come to rely on.
The second problem G-Demption technology solves is how to store spent nuclear fuel in the absence of a national waste repository like Yucca Mountain and in the context of the politics surrounding interim spent nuclear fuel storage costs. A typical commercial nuclear power plant will spend tens of millions of dollars over its operating lifetime to store spent nuclear fuel on-site after more spent nuclear fuel accumulates on-site than they ever anticipated having to deal with. The politics of interim spent nuclear fuel storage are that commercial utilities (through a tax on nuclear energy) contribute $750 million dollars annually to the Nuclear Waste Fund as established by the 1982 Nuclear Waste Policy Act. This fund now has an unspent balance of $25 billion dollars but the federal government has not effectively used the money to solve the problem that it was supposed to solve. Since the nuclear power plants have already spent a fortune in taxes they believe it is the federal government’s responsibility to use the Nuclear Waste Fund to deal with the problem of their limited spent nuclear fuel storage capacity. The federal government, being in hard financial times right now, does not want to spend the money in the Nuclear Waste Fund for such purposes because they already spent it on other things [see this article in the Huffington Post for more information http://www.huffingtonpost.com/2011/03/30/nuclear-waste-fund-us-24-billion_n_842762.html ]. Like most things the science and engineering associated with spent nuclear fuel storage is not the issue, rather it is the politics that slow progress toward a solution and the politics are largely driven by money in this case. G-Demption technology offers an innovative alternative to get out of the dilemma that both sides (federal and commercial) could stand behind. By generating a revenue stream from selling the gamma rays produced in the spent nuclear fuel it is possible to make more money reusing the spent nuclear fuel with G-Demption technology than it costs to store it which eliminates the crux of the interim nuclear waste storage cost issue.
Siting of spent nuclear fuel storage facilities also becomes easier since G-Demption technology provides several good paying jobs to a host community. Other spent nuclear fuel storage facilities only provide a few security guard jobs to a host community and job creation comes primarily from manufacturing that occurs far away from the host community. G-Demption technology will create similar manufacturing and construction jobs but will also require several on site permanent jobs associated with the operation of the sterilization facility. G-Demption technology directly benefits the host community and makes residents more likely to welcome the facility and its associated tax revenues.
The largest application of G-Demption’s technology is using gamma rays to sterilize one-time use medical supplies. However, there are many other commercial applications.
Gamma rays are commonly used to alter the physical properties of polymers, which allows plastic to be utilized in more diverse ways. For example, varying the dose of gamma rays on polyvinyl chloride (PVC) allows material scientists to fine tune the softening point, abrasion resistance, and flammability of the plastic; it can then be used for a specific engineering purpose. Polymers treated with gamma rays have found widespread use in the automobile industry, as well as other industries which demand high performance materials.
The application of gamma rays in agricultural products is an enormous market that is currently constrained by a lack of affordable gamma ray sources. The enhanced supply of gamma rays that G-Demption technology makes possible could lead to a substantially higher level of food safety both in the US and abroad. Gamma rays can be used to safely inactivate harmful micro-organisms in spices, herbs, and dietary supplements without affecting the quality of the products. The Centers for Disease Control and Prevention has reported that the salmonella found in poultry products, fruits, vegetables, and undercooked meats causes nearly one million cases of food poisoning each year; resulting in approximately 20,000 hospitalizations and 400 annual deaths in the US alone. Even more alarming, salmonella and other bacteria responsible for causing food-borne illnesses are becoming resistant to antibiotic treatments. Luckily, they are still susceptible to gamma rays.
Irradiating food with gamma rays also extends their shelf life, which means less wasted food from spoilage and sprouting along with the ability to stockpile more food for extended periods of time. These safe stockpiles of food could be incorporated into natural disaster and national emergency relief plans.
Food irradiation has also been used to provide mold and insect control as a more environmentally friendly alternative to pesticides and chemical fumigation. This is especially true with parasite and insect control in international trade markets where strict quarantines to prevent the spread of invasive species are implemented.
It may surprise you to hear that even the jewelry industry employs gamma ray irradiation technologies. Several different types of quartz, topaz, tourmaline, zircon, and diamonds change color when exposed to gamma rays. Consumers are willing to pay higher prices for these new, unique colors. The American Gem Trade Association estimates that six tons of topaz stones alone are irradiated annually to make their appearance more alluring to potential customers.
Cobalt-60 currently provides the main source of gamma rays used in the irradiation industry. However, Cobalt-60 is in increasingly short supply compared to the demand for it. Nearly 80% of the Cobalt-60 produced gamma ray market is tied up in sterilizing medical supplies. Syringes, disposable gloves, surgical dressings, bandages, plastic forceps, catheters, and even replacement hip joints are all used extensively in the modern medical industry and require sterilization.
It is also becoming increasingly common to see cosmetics and toiletries that could be contaminated with microbial bacteria being sterilized with gamma rays.
In medical supply sterilization and food irradiation, gamma rays neutralize harmful organisms by preventing cell division. The ionizing effects of the radiation cause breakdowns and rearrangements of the helix of DNA, which prevents the harmful micro-organisms from reproducing. Different micro-organisms have different amounts of DNA and different DNA repair mechanisms, meaning varying amounts of gamma rays are required depending on the micro-organism being neutralized.
Gamma rays effect polymers by making their chains shorter and inducing cross-linking between thepolymer chains. Essentially, the gamma rays break down bonds in the material which results in the molecular structures and material properties of the plastics changing in predictable and controllable ways.
In gemstones, gamma rays cause the migration of electrons which changes the charge and orientation of atoms in the crystal lattice. These factors affect how the gemstone absorbs light, and leads to the deep colors observed post-irradiation. Due to mineral impurities in the stones and the statistical nature of the atomic interactions themselves, it is impossible to accurately predict the exact color changes that will occur in the gemstones. This means only a fraction of irradiated gemstones will ultimately be what jewelers and consumers are looking to purchase.
The most common concerns associated with food irradiation are how it affects the nutrients in the products and how safe it is to human health. The nutrients are largely unaffected in most cases, especially when compared to how other food preparation methods destroy nutrients. It is a fact of life that the act of cooking food destroys some nutrients in the food. Cooking foods with a stovetop, oven, grill, or microwave denatures the protein and other nutrients. The same thing happens when freezing, boiling, or steaming foods. Relative to other means of food preparation, food irradiation processes do not significantly affect the food’s nutritional value for most types of food (there are some exceptions where taste is affected). In fact, by eliminating the need for other preservatives (such as excessive salts, artificial colors, and preserving chemicals – some of which are known carcinogens), food irradiation is often viewed as a safer, healthier alternative to traditional food preservation methods and is often prescribed to patients in hospitals that are particularly susceptible to infections or foodborne illnesses.
Countless studies on the effects of food irradiation have been conducted by the United States Department of Agriculture and the World Health Organization. The overwhelming consensus has been that the process is safe to human and environmental health. Public opinion polls show that a majority of people trust the results of these studies and are accepting of the technology. The only reason this lifesaving technology hasn’t been more widely implemented is because the supply of gamma rays is too low, which makes the process prohibitively expensive. But now, with the widespread use of G-Demption’s technology, the world’s supply of gamma rays could easily be tripled and these lifesaving gamma ray irradiation processes could be more widely implemented.
Roughly once every two years a one gigawatt electric nuclear power plant discharges approximately 60 PWR fuel assemblies or 250 BWR fuel assemblies, depending on whether the nuclear power plant uses a Pressurized Water Reactor (PWR) or a Boiling Water Reactor (BWR). Each fuel assembly is a collection of individual fuel rods; meaning that with either the PWR or BWR, approximately 15,000 spent nuclear fuel rods are created each time the reactor has to refuel. G-Demption technology can be used to safely encapsulate BWR assemblies, PWR assemblies, or individual spent nuclear fuel rods.
Once the spent nuclear fuel is discharged from the reactor it is placed into a pool of water to remove any thermal heat still being generated within the spent nuclear fuel. After one year of cooling the thermal heat generated by each spent nuclear fuel rod is only about 40 watts – less than half the heat produced by a light bulb. Plus, the heat is spread out over the full 12 foot length of the spent nuclear fuel rod. Therefore, after one year, the spent nuclear fuel can safely be placed inside of a G-Demption container, with the remaining 40 watts of heat easily being dealt with by passive heat removal systems.
The amount of gamma rays that can be harvested through G-Demption technology for commercial applications depends on which type of spent nuclear fuel is being used. PWR assemblies are typically composed of a 17×17 grid of fuel rods. This means the gamma rays produced from fuel rods in the center of the assembly will deposit their energy into the surrounding fuel rods, instead of usefully depositing their energy into the commercial products attempting to be sterilized. This same phenomenon happens to a lesser extent in BWR fuel assemblies, which are typically arranged in either an 8×8 or 10×10 grid. The amount of harvestable gamma rays is maximized when the fuel rods are taken out of their assemblies and stored individually inside of G-Demption containers. However, by encapsulating the entire assembly it is possible to store more spent nuclear fuel inside of a smaller area. Since G-Demption, LLC has the potential to create a revenue stream both from the sale of gamma rays and the fees charged to store spent nuclear fuel, it may actually be more economically rewarding to maximize the amount of spent nuclear fuel storage rather than the amount of gamma rays that can be harvested.
The graph below shows the strength of the usable gamma ray signal from a single discharge of spent nuclear fuel in each of the three possible storage forms that G-Demption technology can accommodate. Shown for comparison is the usable gamma ray signal of a typical three million Curie (3 MCi) Cobalt 60 source (the current standard for large gamma ray irradiation facilities). Note that the gamma ray signal decays with time as the radioisotopes decay into stable elements.
Amount of harvestable gamma rays from one discharge of spent nuclear fuel as stored in various forms with G-Demption technology
The marketplace value of a kilowatt of gamma rays is conservatively taken to be $200,000 per kilowatt; an estimate based on a value of $2.45 per Curie of Cobalt-60 (a Curie is a unit used to measure radioactivity). Since the sterilization industry is a service industry, there is a large markup that this $200,000 per kilowatt estimate is not taking into account. An analogy to this would be taxi drivers; taxi drivers not only charge for the cost of gasoline, but also for their time, insurance, car repairs, etc. Likewise, the gamma ray source is not the only factor an irradiation facility would take into account when charging its customers. Facility maintenance, product dose verification, shipping, the time of the employees operating the facility, etc would all be analogous to the taxi driver’s expenses that are relayed to the customers. This analogy is meant to highlight that $200,000 per kilowatt is a very conservative estimate and the actual generated revenue could be substantially more than $200,000 per kilowatt because supply is low and marketplace demand is high for gamma ray irradiation.
Every two years another shipment of spent nuclear fuel will have to be stored with G-Demption technology, which will increase the revenue stream of the irradiation facility both by adding more gamma rays that can be harvested and by charging a fee to store the spent nuclear fuel. The following graph shows the gamma ray signal inside of a G-Demption irradiation facility containing three discharges of spent nuclear fuel from a single nuclear reactor. At this point 1/3 of the spent nuclear fuel being stored in the facility would be one year old, 1/3 would be three years old, and 1/3 would be five years old. The gamma ray signal produced inside of the facility based on which type of spent nuclear fuel is being stored in the G-Demption containers is shown. The gamma ray signal inside of a typical three million Curie (3 MCi) Cobalt 60 irradiation facility is also shown for comparison.
Total harvestable gamma ray signal inside of a G-Demption irradiation facility that only stores six years worth of spent nuclear fuel at a time that was discharged by a single nuclear reactor
In this implementation of G-Demption technology, only six years worth of spent nuclear fuel from a single nuclear reactor is stored in the irradiation facility and every two years the oldest spent nuclear fuel in the facility is exchanged for a fresh shipment of one year old (freshly cooled) spent nuclear fuel. It is possible to store several decades worth of spent nuclear fuel inside of a G-Demption irradiation facility, making it possible for even greater amounts of gamma rays to be harvested and sold for commercial applications.
Conservative revenue estimate for a G-Demption irradiation facility that only stores six years worth of spent nuclear fuel at a time that was discharged by a single nuclear reactor
The above graph is the same one as shown earlier, but instead of kilowatts the y-axis shows US dollars after assuming a conservative marketplace value of $200,000 per kilowatt. Again this is the annual revenue generated from six years worth of spent nuclear fuel at a single nuclear reactor implementing G-Demption storage technology.
Many commercial nuclear power plant sites have two, sometimes even three, reactors operating in close proximity to one another. If G-Demption technology were utilized at such a location, the available gamma signal would double or triple accordingly – in turn, doubling or tripling the already large revenue stream G-Demption technology can produce.
A ballpark estimate of the throughput for a G-Demption irradiation facility is the ability to process over 220,000 cubic meters of product a year (roughly 66 million pounds per year. Actual throughput will vary based on product dose needs and product density). The greater dose control available to plant operators in comparison to a Cobalt 60 facility results in more efficient use of the gamma rays which increases revenue and plant flexibility. The greater control and ease of operations associated with G-Demption irradiation facilities is a big advantage over the current Cobalt 60 based irradiation facility fleet and has several sterilization industry leaders excited.