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There Is No Nuclear Waste Problem

An issue which has been raised so often that it has become synonymous with nuclear power is that of nuclear waste and the storage of it. Through decades of clamoring by anti-nuclear groups and individuals there is no doubt in the mind of the average person that the issue of many tons of highly dangerous, highly radioactive nuclear waste is both real and the primary reason to switch to so-called renewable technologies such as solar and wind power. Due to the strong anti-nuclear lobby and public mood also due to the nuclear threat of the Cold War precious little effort has been made to examine in how far this nuclear waste issue is real or imaginary.

The premise of the suggested nuclear waste issue is that nuclear reactors will always produce large amounts of highly-radioactive materials which will have to be stored for thousands of years, forming a lethal risk to current and future generations. Hereby we have a few items of importance: that nuclear reactors produce large amounts of highly-radioactive material, that this will have to be stored as waste, and that this forms a major risk to humanity.

Starting with the first item, less than a minute of research will show that current commercial reactors use only about 0.65% of the energy contained in the uranium as it is mined, and less than 5% of the enriched uranium fuel.[1] The major alternative reactor design, so-called breeder reactors [2] which due its neutron economy are capable of generating more fissile material (fuel) than it consumes. This includes the actinides, the transuranic elements which are highly radioactive due to their unstable nature. A breeder reactor in combination with a reprocessing step for removing neutron-absorbing fission products (low-radioactive elements) can use virtually all of the energy contained in the uranium fuel, reducing the fuel requirements by about two orders of magnitude (90+% versus <5% efficiency).

With a breeder reactor design such as the Integral Fast Reactor [3] (cancelled in 1994 by the US Congress despite working as expected) or its successors Sodium-Cooled Fast Reactor (SFR) [4] and S-PRISM [5], so-called Generation IV reactors, the only waste would be long-lived fission products (LLFP) [6], which have half-lives on the order of 200,000 to millions of years and sometimes have such low radioactivity that these elements can still be found in nature dating back to the formation of the universe. Only seven of these are relevant due to having relatively short half-lives:

  • Technetium-99
  • Tin-126
  • Selenium-79
  • Zirconium-93
  • Caesium-135
  • Palladium-107
  • Iodine-129

None of these seven isotopes form a risk to biological life. Technetium-99 [7] as the most short-lived of these is commonly injected into humans in the form of Tc-99m, an isomeric form of Tc-99, for medical testing where it transitions back into the Tc-99 form inside the human body and is deemed virtually harmless due to the half-life of 211,000 years.

If we start building Generation IV reactors such as the ones listed above now, we can use existing ‘waste’ from Gen-II and III reactors in them, while adding small amounts of fresh uranium fuel from time to time. In combination with uranium mining from seawater we would have virtually infinite amounts of energy, with no dangerous waste to store. This takes care of the second point, and the third point.

When talking about radiation hazards, one would be wise to consider natural sources of radiation, such as granite [8]. Many types of granite contain significant amounts of uranium and thorium, which decay into radioactive radon gas, which is the number two cause of lung cancer in the USA after smoking. A building with for example a basement on granite bedrock is likely to collect this gas, resulting in significant cancer risk for its inhabitants. While deemed harmless by most, granite and other types of rock apparently are a far great radiation risk than that imagined for the waste output of nuclear reactors.

Maya

[1] https://en.wikipedia.org/wiki/Integral_Fast_Reactor#Advantages
[2] https://en.wikipedia.org/wiki/Breeder_reactor
[3] https://en.wikipedia.org/wiki/Integral_Fast_Reactor
[4] https://en.wikipedia.org/wiki/Sodium-Cooled_Fast_Reactor
[5] https://en.wikipedia.org/wiki/S-PRISM
[6] https://en.wikipedia.org/wiki/Long-lived_fission_product
[7] https://en.wikipedia.org/wiki/Technetium-99
[8] https://en.wikipedia.org/wiki/Granite#Natural_radiation

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Filed under: Analysis, Nuclear Technology, , , , ,

Importance Of Nuclear Industry In Health And Sciences

In light of the recent controversy surrounding nuclear power plants and the insistence by many that they can be swapped out without any harmful effects for alternative power sources I figured it’d be refreshing to look at a side of nuclear power plants which isn’t part of public knowledge.

There are two groups of useful radioactive compounds for medical and other examinations and research. These fall into the transuranium (transuranic) elements [1] and other isotopes. Transuranium isotopes are generally only produced artificially as they’re heavier than uranium. Beyond trace elements they do not occur naturally. Similarly, the other isotopes are of the highly radioactive type which consequently have very brief half-lives. These isotopes are all derived or obtained from products of a nuclear reactor.

Of the transuranium elements some of the most remarkable are:

  • Californium: high neutron production, extremely useful for treating types of cervical and brain cancers, radiography of aircraft, etc. to detect corrosion, bad welds, trapped moisture, etc. [2]
  • Curium: to produce plutonium for radioisotope thermoelectric generators (RTGs) for spacecraft and cardiac pacemakers, source of alpha-particle X-ray spectrometers as installed on the Sojourner, Mars, Mars 96, Spirit, Athena and Opportunity rovers. [3]
  • Americium: smoke detectors, RTG fuel in spacecraft, source of gamma rays and alpha particles for medical and industrial use. [4]
  • Plutonium: energy source for RTGs. Used in spacecraft and medical pacemakers. [5]

For medical diagnosis, radiation therapy [6], etc. the following isotopes are commonly used:

  • Iodine: I-123 is commonly used for medical imaging of the thyroid gland. I-131 is very effective in direct cancer therapy for thyroid cancers. [7]
  • Gallium: Ga-67 in the body collects at areas of inflammation and rapid cell division (e.g. tumors), useful for diagnosis and detection. Ga-68 is used as radionuclide with PET-CT scans for cancer diagnosis. Ga-71 is used for neutrino detection in physics experiments. [8]
  • Fluorine: F-18 is used in PET imaging for brain glucose metabolism and imaging cancer tumors. F-19 is used in NMR studies of metabolism, protein structures, etc. [9]
  • Indium: I-111 is used in indium leukocyte imaging, for assessment of antibiotic therapies. It is useful for monitoring white blood cells and commonly used in drug development. [10]
  • Xenon: Xe-133 for imaging of the heart, lungs and brain as well as blood flow. Xe-129 as contrast agent in MRIs for studies of soft issues like the lungs including the gas flow inside the lungs. [11]
  • Yttrium: Y-90 is used for the treatment of various cancers including lymphoma, leukemia, ovarian, colorectal, pancreatic and bone cancers in combination with monoclonal antibodies for adhering to cancer cells. Y-90 is also used for needles to sever nerves more precisely than a scalpel would. [12]
  • Technetium: Tc-99m is generated via molybdenum-99 and used extensively as a radioactive tracer. It’s used for detection and diagnosis of many tumors. It’s used in well over 20 million diagnostic procedures every year. [13]

Shortages of these isotopes have occurred already when maintenance of the nuclear reactors NRU and HFR (Canada) in 2007 took longer than expected. The repeated shutdowns over a period of 3 years led to a massive world-wide shortage of molybdenum-99. Replacement reactors for these aging reactors were planned but scrapped due to safety issues. At this point the world’s supply of these isotopes is provided mostly by rapidly aging nuclear reactors in addition to cyclotrons.

Solutions to in particular the molybdenum-99 shortages could be found in using the many nuclear power reactors for isotopes, though this would mean changing the way they are being regulated. No technical limitations exist there. Another option is to use cyclotrons for this, but this is an unproven method. [14]

For transuranium elements shortages shouldn’t be underestimated either. Without plutonium for powering our spacecraft we’d have no RTGs and thus be limited with our space exploration to a range not far beyond the Earth’s distance from the sun. It’d make large Mars rovers impossible. Plutonium RTGs for pacemakers aren’t uncommon either even at this point. The potential of new transuranium elements shouldn’t be underestimated either.

Non-transuranium isotopes used in medical diagnostics are crucial enough that without their wide availability cancer diagnosis and treatment would become difficult to impossible depending on the type of cancer. The presence of nuclear reactors to generate these is paramount.

It should be clear that the impact of the nuclear industry as it has developed over the past decade and into this decade goes far beyond mere generating of electricity. Lives literally depend on it.

Maya

  1. http://en.wikipedia.org/wiki/Transuranium_element
  2. http://en.wikipedia.org/wiki/Californium
  3. http://en.wikipedia.org/wiki/Curium
  4. http://en.wikipedia.org/wiki/Americium
  5. http://en.wikipedia.org/wiki/Plutonium
  6. http://en.wikipedia.org/wiki/Nuclear_medicine
  7. http://en.wikipedia.org/wiki/Iodine
  8. http://en.wikipedia.org/wiki/Gallium
  9. http://en.wikipedia.org/wiki/Fluorine
  10. http://en.wikipedia.org/wiki/Indium
  11. http://en.wikipedia.org/wiki/Xenon
  12. http://en.wikipedia.org/wiki/Yttrium
  13. http://en.wikipedia.org/wiki/Technetium-99m
  14. http://physicsworld.com/cws/article/news/2010/dec/03/medical-isotope-shortages-could-become-commonplace

Filed under: Analysis, General Science, Nuclear Technology, , , , , , , , , ,

Author

Maya Posch: professional software engineer and game developer. Graphics artist and all-around science junky.

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