Spent nuclear fuel

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Spent fuel pool at a nuclear power plant Fuel pool.jpg
Spent fuel pool at a nuclear power plant

Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor (usually at a nuclear power plant). It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor and, depending on its point along the nuclear fuel cycle, it will have different isotopic constituents than when it started. [1]

Contents

Nuclear fuel rods become progressively more radioactive (and less thermally useful) due to neutron activation as they are fissioned, or "burnt", in the reactor. A fresh rod of low enriched uranium pellets (which can be safely handled with gloved hands) will become a highly lethal gamma emitter after 1–2 years of core irradiation, unsafe to approach unless under many feet of water shielding. This makes their invariable accumulation and safe temporary storage in spent fuel pools a prime source of high level radioactive waste and a major ongoing issue for future permanent disposal.

Nature of spent fuel

Nanomaterial properties

In the oxide fuel, intense temperature gradients exist that cause fission products to migrate. The zirconium tends to move to the centre of the fuel pellet where the temperature is highest, while the lower-boiling fission products move to the edge of the pellet. The pellet is likely to contain many small bubble-like pores that form during use; the fission product xenon migrates to these voids. Some of this xenon will then decay to form caesium, hence many of these bubbles contain a large concentration of 135
Cs .

In the case of mixed oxide (MOX) fuel, the xenon tends to diffuse out of the plutonium-rich areas of the fuel, and it is then trapped in the surrounding uranium dioxide. The neodymium tends to not be mobile.

Also metallic particles of an alloy of Mo-Tc-Ru-Pd tend to form in the fuel. Other solids form at the boundary between the uranium dioxide grains, but the majority of the fission products remain in the uranium dioxide as solid solutions. A paper describing a method of making a non-radioactive "uranium active" simulation of spent oxide fuel exists. [2]

Fission products

Spent nuclear fuel contains 3% by mass of 235U and 239Pu (also indirect products in the decay chain); these are considered radioactive waste or may be separated further for various industrial and medical uses. The fission products include every element from zinc through to the lanthanides; much of the fission yield is concentrated in two peaks, one in the second transition row (Zr, Mo, Tc, Ru, Rh, Pd, Ag) and the other later in the periodic table (I, Xe, Cs, Ba, La, Ce, Nd). Many of the fission products are either non-radioactive or only short-lived radioisotopes, but a considerable number are medium to long-lived radioisotopes such as 90Sr, 137Cs, 99Tc and 129I. Research has been conducted by several different countries into segregating the rare isotopes in fission waste including the "fission platinoids" (Ru, Rh, Pd) and silver (Ag) as a way of offsetting the cost of reprocessing; this is not currently being done commercially.

The fission products can modify the thermal properties of the uranium dioxide; the lanthanide oxides tend to lower the thermal conductivity of the fuel, while the metallic nanoparticles slightly increase the thermal conductivity of the fuel. [3]

Table of chemical data

The chemical forms of fission products in uranium dioxide [4]
ElementGasMetalOxideSolid solution
Br Kr Yes---
Rb Yes-Yes-
Sr --YesYes
Y ---Yes
Zr --YesYes
Nb --Yes-
Mo -YesYes-
Tc Ru Rh Pd Ag Cd In Sb -Yes--
Te YesYesYesYes
I Xe Yes---
Cs Yes-Yes-
Ba --YesYes
La Ce Pr Nd Pm Sm Eu ---Yes

Plutonium

Spent nuclear fuel stored underwater and uncapped at the Hanford site in Washington, US Spent nuclear fuel hanford.jpg
Spent nuclear fuel stored underwater and uncapped at the Hanford site in Washington, US

About 1% of the mass is 239Pu and 240Pu resulting from conversion of 238U, which may be considered either as a useful byproduct, or as dangerous and inconvenient waste. One of the main concerns regarding nuclear proliferation is to prevent this plutonium from being used by states, other than those already established as nuclear weapons states, to produce nuclear weapons. If the reactor has been used normally, the plutonium is reactor-grade, not weapons-grade: it contains more than 19% 240Pu and less than 80% 239Pu, which makes it not ideal for making bombs. If the irradiation period has been short then the plutonium is weapons-grade (more than 93%).

Uranium

96% of the mass is the remaining uranium: most of the original 238U and a little 235U. Usually 235U would be less than 0.8% of the mass along with 0.4% 236U.

Reprocessed uranium will contain 236U, which is not found in nature; this is one isotope that can be used as a fingerprint for spent reactor fuel.

If using a thorium fuel to produce fissile 233U, the SNF (Spent Nuclear Fuel) will have 233U, with a half-life of 159,200 years (unless this uranium is removed from the spent fuel by a chemical process). The presence of 233U will affect the long-term radioactive decay of the spent fuel. If compared with MOX fuel, the activity around one million years in the cycles with thorium will be higher due to the presence of the not fully decayed 233U.

For natural uranium fuel, fissile component starts at 0.7% 235U concentration in natural uranium. At discharge, total fissile component is still 0.5% (0.2% 235U, 0.3% fissile 239Pu, 241Pu). Fuel is discharged not because fissile material is fully used-up, but because the neutron-absorbing fission products have built up and the fuel becomes significantly less able to sustain a nuclear reaction.

Some natural uranium fuels use chemically active cladding, such as Magnox, and need to be reprocessed because long-term storage and disposal is difficult. [5]

Minor actinides

Spent reactor fuel contains traces of the minor actinides. These are actinides other than uranium and plutonium and include neptunium, americium and curium. The amount formed depends greatly upon the nature of the fuel used and the conditions under which it was used. For instance, the use of MOX fuel (239Pu in a 238U matrix) is likely to lead to the production of more 241Am and heavier nuclides than a uranium/thorium based fuel (233U in a 232Th matrix).

For highly enriched fuels used in marine reactors and research reactors, the isotope inventory will vary based on in-core fuel management and reactor operating conditions.

Spent fuel decay heat

Decay heat as fraction of full power for a reactor SCRAMed from full power at time 0, using two different correlations Decay heat illustration.PNG
Decay heat as fraction of full power for a reactor SCRAMed from full power at time 0, using two different correlations

When a nuclear reactor has been shut down and the nuclear fission chain reaction has ceased, a significant amount of heat will still be produced in the fuel due to the beta decay of fission products. For this reason, at the moment of reactor shutdown, decay heat will be about 7% of the previous core power if the reactor has had a long and steady power history. About 1 hour after shutdown, the decay heat will be about 1.5% of the previous core power. After a day, the decay heat falls to 0.4%, and after a week it will be 0.2%. The decay heat production rate will continue to slowly decrease over time.

Spent fuel that has been removed from a reactor is ordinarily stored in a water-filled spent fuel pool for a year or more (in some sites 10 to 20 years) in order to cool it and provide shielding from its radioactivity. Practical spent fuel pool designs generally do not rely on passive cooling but rather require that the water be actively pumped through heat exchangers. If there is a prolonged interruption of active cooling due to emergency situations, the water in the spent fuel pools may therefore boil off, possibly resulting in radioactive elements being released into the atmosphere. [6]

Fuel composition and long term radioactivity

Activity of U-233 for three fuel types. In the case of MOX, the U-233 increases for the first 650,000 years as it is produced by decay of Np-237 that was created in the reactor by absorption of neutrons by U-235. Activityofuranium233.jpg
Activity of U-233 for three fuel types. In the case of MOX, the U-233 increases for the first 650,000 years as it is produced by decay of Np-237 that was created in the reactor by absorption of neutrons by U-235.
Total activity for three fuel types. In region 1 we have radiation from short-lived nuclides, and in region 2 from Sr-90 and Cs-137. On the far right we see the decay of Np-237 and U-233. Activitytotal1.svg
Total activity for three fuel types. In region 1 we have radiation from short-lived nuclides, and in region 2 from Sr-90 and Cs-137. On the far right we see the decay of Np-237 and U-233.

The use of different fuels in nuclear reactors results in different SNF composition, with varying activity curves.

Long-lived radioactive waste from the back end of the fuel cycle is especially relevant when designing a complete waste management plan for SNF. When looking at long-term radioactive decay, the actinides in the SNF have a significant influence due to their characteristically long half-lives. Depending on what a nuclear reactor is fueled with, the actinide composition in the SNF will be different.

An example of this effect is the use of nuclear fuels with thorium. Th-232 is a fertile material that can undergo a neutron capture reaction and two beta minus decays, resulting in the production of fissile U-233. Its radioactive decay will strongly influence the long-term activity curve of the SNF around a million years. A comparison of the activity associated to U-233 for three different SNF types can be seen in the figure on the top right. The burnt fuels are Thorium with Reactor-Grade Plutonium (RGPu), Thorium with Weapons-Grade Plutonium (WGPu) and Mixed Oxide fuel (MOX, no thorium). For RGPu and WGPu, the initial amount of U-233 and its decay around a million years can be seen. This has an effect in the total activity curve of the three fuel types. The initial absence of U-233 and its daughter products in the MOX fuel results in a lower activity in region 3 of the figure on the bottom right, whereas for RGPu and WGPu the curve is maintained higher due to the presence of U-233 that has not fully decayed. Nuclear reprocessing can remove the actinides from the spent fuel so they can be used or destroyed (see Long-lived fission product#Actinides).

Spent fuel corrosion

Noble metal nanoparticles and hydrogen

According to the work of corrosion electrochemist David W. Shoesmith, [7] [8] the nanoparticles of Mo-Tc-Ru-Pd have a strong effect on the corrosion of uranium dioxide fuel. For instance his work suggests that when hydrogen (H2) concentration is high (due to the anaerobic corrosion of the steel waste can), the oxidation of hydrogen at the nanoparticles will exert a protective effect on the uranium dioxide. This effect can be thought of as an example of protection by a sacrificial anode, where instead of a metal anode reacting and dissolving it is the hydrogen gas that is consumed.

Storage, treatment, and disposal

Spent fuel pool at TEPCO's Fukushima Daiichi Nuclear Power Plant on 27 November 2013 Spent Fuel Pool (02813601).jpg
Spent fuel pool at TEPCO's Fukushima Daiichi Nuclear Power Plant on 27 November 2013

Spent nuclear fuel is stored either in spent fuel pools (SFPs) or in dry casks. In the United States, SFPs and casks containing spent fuel are located either directly on nuclear power plant sites or on Independent Spent Fuel Storage Installations (ISFSIs). ISFSIs can be adjacent to a nuclear power plant site, or may reside away-from-reactor (AFR ISFSI). The vast majority of ISFSIs store spent fuel in dry casks. The Morris Operation is currently the only ISFSI with a spent fuel pool in the United States.

Nuclear reprocessing can separate spent fuel into various combinations of reprocessed uranium, plutonium, minor actinides, fission products, remnants of zirconium or steel cladding, activation products, and the reagents or solidifiers introduced in the reprocessing itself. If these constituent portions of spent fuel were reused, and additional wastes that may come as a byproduct of reprocessing are limited, reprocessing could ultimately reduce the volume of waste that needs to be disposed.

Alternatively, the intact spent nuclear fuel can be directly disposed of as high-level radioactive waste. The United States has planned disposal in deep geological formations, such as the Yucca Mountain nuclear waste repository, where it has to be shielded and packaged to prevent its migration to humans' immediate environment for thousands of years. [1] [9] On March 5, 2009, however, Energy Secretary Steven Chu told a Senate hearing that "the Yucca Mountain site no longer was viewed as an option for storing reactor waste." [10]

Geological disposal has been approved in Finland, using the KBS-3 process. [11]

In Switzerland, the Federal Council approved in 2008, the plan for the deep geological repository for radioactive waste. [12]

Remediation

Algae has shown selectivity for strontium in studies, where most plants used in bioremediation have not shown selectivity between calcium and strontium, often becoming saturated with calcium, which is present in greater quantities in nuclear waste. Strontium-90 is a radioactive byproduct produced by nuclear reactors used in nuclear power. It is a component of nuclear waste and spent nuclear fuel. The half life is long, around 30 years, and is classified as high-level waste. [13]

Researchers have looked at the bioaccumulation of strontium by Scenedesmus spinosus (algae) in simulated wastewater. The study claims a highly selective biosorption capacity for strontium of S. spinosus, suggesting that it may be appropriate for use of nuclear wastewater. [14] A study of the pond alga Closterium moniliferum using non-radioactive strontium found that varying the ratio of barium to strontium in water improved strontium selectivity. [13]

Risks

Spent nuclear fuel stays a radiation hazard for extended periods of time with half-lifes as high as 24,000 years. For example 10 years after removal from a reactor, the surface dose rate for a typical spent fuel assembly still exceeds 10,000 rem/hour—far greater than the fatal whole-body dose for humans of about 500 rem received all at once. [15]

There is debate over whether spent fuel stored in a pool is susceptible to incidents such as earthquakes [16] or terrorist attacks [17] that could potentially result in a release of radiation. [18]

In the rare occurrence of a fuel failure during normal operation, the primary coolant can enter the element. Visual techniques are normally used for the postirradiation inspection of fuel bundles. [19]

Since the September 11 attacks the Nuclear Regulatory Commission has instituted a series of rules mandating that all fuel pools be impervious to natural disaster and terrorist attack. As a result, used fuel pools are encased in a steel liner and thick concrete, and are regularly inspected to ensure resilience to earthquakes, tornadoes, hurricanes, and seiches. [20] [21]

See also

Related Research Articles

<span class="mw-page-title-main">Thorium</span> Chemical element with atomic number 90 (Th)

Thorium is a chemical element. It has the symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive gray when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high melting point. Thorium is an electropositive actinide whose chemistry is dominated by the +4 oxidation state; it is quite reactive and can ignite in air when finely divided.

<span class="mw-page-title-main">Radioactive waste</span> Unusable radioactive materials

Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, nuclear decommissioning, rare-earth mining, and nuclear weapons reprocessing. The storage and disposal of radioactive waste is regulated by government agencies in order to protect human health and the environment.

<span class="mw-page-title-main">Nuclear fuel cycle</span> Process of manufacturing and consuming nuclear fuel

The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. It consists of steps in the front end, which are the preparation of the fuel, steps in the service period in which the fuel is used during reactor operation, and steps in the back end, which are necessary to safely manage, contain, and either reprocess or dispose of spent nuclear fuel. If spent fuel is not reprocessed, the fuel cycle is referred to as an open fuel cycle ; if the spent fuel is reprocessed, it is referred to as a closed fuel cycle.

<span class="mw-page-title-main">Nuclear reprocessing</span> Chemical operations that separate fissile material from spent fuel to be recycled as new fuel

Nuclear reprocessing is the chemical separation of fission products and actinides from spent nuclear fuel. Originally, reprocessing was used solely to extract plutonium for producing nuclear weapons. With commercialization of nuclear power, the reprocessed plutonium was recycled back into MOX nuclear fuel for thermal reactors. The reprocessed uranium, also known as the spent fuel material, can in principle also be re-used as fuel, but that is only economical when uranium supply is low and prices are high. Nuclear reprocessing may extend beyond fuel and include the reprocessing of other nuclear reactor material, such as Zircaloy cladding.

Mixed oxide fuel, commonly referred to as MOX fuel, is nuclear fuel that contains more than one oxide of fissile material, usually consisting of plutonium blended with natural uranium, reprocessed uranium, or depleted uranium. MOX fuel is an alternative to the low-enriched uranium fuel used in the light-water reactors that predominate nuclear power generation.

<span class="mw-page-title-main">Breeder reactor</span> Nuclear reactor generating more fissile material than it consumes

A breeder reactor is a nuclear reactor that generates more fissile material than it consumes. These reactors can be fueled with more-commonly available isotopes of uranium and thorium, such as uranium-238 and thorium-232, as opposed to the rare uranium-235 which is used in conventional reactors. These materials are called fertile materials since they can be bred into fuel by these breeder reactors.

<span class="mw-page-title-main">Uranium-238</span> Isotope of uranium

Uranium-238 is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239. 238U cannot support a chain reaction because inelastic scattering reduces neutron energy below the range where fast fission of one or more next-generation nuclei is probable. Doppler broadening of 238U's neutron absorption resonances, increasing absorption as fuel temperature increases, is also an essential negative feedback mechanism for reactor control.

<span class="mw-page-title-main">Integral fast reactor</span> Nuclear reactor design

The integral fast reactor (IFR), originally the advancedliquid-metal reactor (ALMR), is a design for a nuclear reactor using fast neutrons and no neutron moderator. IFRs can breed more fuel and are distinguished by a nuclear fuel cycle that uses reprocessing via electrorefining at the reactor site.

<span class="mw-page-title-main">Uranium-234</span> Isotope of uranium

Uranium-234 is an isotope of uranium. In natural uranium and in uranium ore, 234U occurs as an indirect decay product of uranium-238, but it makes up only 0.0055% of the raw uranium because its half-life of just 245,500 years is only about 1/18,000 as long as that of 238U. Thus the ratio of 234
U to 238
U in a natural sample is equivalent to the ratio of their half-lives. The primary path of production of 234U via nuclear decay is as follows: uranium-238 nuclei emit an alpha particle to become thorium-234. Next, with a short half-life, 234Th nuclei emit a beta particle to become protactinium-234 (234Pa), or more likely a nuclear isomer denoted 234mPa. Finally, 234Pa or 234mPa nuclei emit another beta particle to become 234U nuclei.

<span class="mw-page-title-main">Nuclear fuel</span> Material fuelling nuclear reactors

Nuclear fuel is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission. Nuclear fuel has the highest energy density of all practical fuel sources. The processes involved in mining, refining, purifying, using, and disposing of nuclear fuel are collectively known as the nuclear fuel cycle.

Uranium-233 is a fissile isotope of uranium that is bred from thorium-232 as part of the thorium fuel cycle. Uranium-233 was investigated for use in nuclear weapons and as a reactor fuel. It has been used successfully in experimental nuclear reactors and has been proposed for much wider use as a nuclear fuel. It has a half-life of 160,000 years.

<span class="mw-page-title-main">Plutonium-239</span> Isotope of plutonium

Plutonium-239 is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 is also used for that purpose. Plutonium-239 is also one of the three main isotopes demonstrated usable as fuel in thermal spectrum nuclear reactors, along with uranium-235 and uranium-233. Plutonium-239 has a half-life of 24,110 years.

Uranium (92U) is a naturally occurring radioactive element (radioelement) with no stable isotopes. It has two primordial isotopes, uranium-238 and uranium-235, that have long half-lives and are found in appreciable quantity in Earth's crust. The decay product uranium-234 is also found. Other isotopes such as uranium-233 have been produced in breeder reactors. In addition to isotopes found in nature or nuclear reactors, many isotopes with far shorter half-lives have been produced, ranging from 214U to 242U. The standard atomic weight of natural uranium is 238.02891(3).

Plutonium (94Pu) is an artificial element, except for trace quantities resulting from neutron capture by uranium, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. It was synthesized long before being found in nature, the first isotope synthesized being plutonium-238 in 1940. Twenty plutonium radioisotopes have been characterized. The most stable are plutonium-244 with a half-life of 80.8 million years; plutonium-242 with a half-life of 373,300 years; and plutonium-239 with a half-life of 24,110 years; and plutonium-240 with a half-life of 6,560 years. This element also has eight meta states; all have half-lives of less than one second.

<span class="mw-page-title-main">Thorium fuel cycle</span> Nuclear fuel cycle

The thorium fuel cycle is a nuclear fuel cycle that uses an isotope of thorium, 232
Th
, as the fertile material. In the reactor, 232
Th
 is transmuted into the fissile artificial uranium isotope 233
U
 which is the nuclear fuel. Unlike natural uranium, natural thorium contains only trace amounts of fissile material, which are insufficient to initiate a nuclear chain reaction. Additional fissile material or another neutron source is necessary to initiate the fuel cycle. In a thorium-fuelled reactor, 232
Th
 absorbs neutrons to produce 233
U
. This parallels the process in uranium breeder reactors whereby fertile 238
U
 absorbs neutrons to form fissile 239
Pu
. Depending on the design of the reactor and fuel cycle, the generated 233
U
 either fissions in situ or is chemically separated from the used nuclear fuel and formed into new nuclear fuel.

Uranium-236 (236U) is an isotope of uranium that is neither fissile with thermal neutrons, nor very good fertile material, but is generally considered a nuisance and long-lived radioactive waste. It is found in spent nuclear fuel and in the reprocessed uranium made from spent nuclear fuel.

In nuclear power technology, burnup is a measure of how much energy is extracted from a primary nuclear fuel source. It is measured as the fraction of fuel atoms that underwent fission in %FIMA or %FIFA as well as, preferably, the actual energy released per mass of initial fuel in gigawatt-days/metric ton of heavy metal (GWd/tHM), or similar units.

Long-lived fission products (LLFPs) are radioactive materials with a long half-life produced by nuclear fission of uranium and plutonium. Because of their persistent radiotoxicity, it is necessary to isolate them from humans and the biosphere and to confine them in nuclear waste repositories for geological periods of time. The focus of this article is radioisotopes (radionuclides) generated by fission reactors.

Hybrid nuclear fusion–fission is a proposed means of generating power by use of a combination of nuclear fusion and fission processes.

<span class="mw-page-title-main">Nuclear transmutation</span> Conversion of an atom from one element to another

Nuclear transmutation is the conversion of one chemical element or an isotope into another chemical element. Nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus of an atom is changed.

References

  1. 1 2 Large, John H: Radioactive Decay Characteristics of Irradiated Nuclear Fuels, January 2006.[ clarification needed ]
  2. ↑ Lucuta, P.G.; Verrall, R.A.; Matzke, Hj.; Palmer, B.J. (January 1991). "Microstructural features of SIMFUEL – Simulated high-burnup UO2-based nuclear fuel". Journal of Nuclear Materials. 178 (1): 48–60. doi: 10.1016/0022-3115(91)90455-G .
  3. ↑ Dong-Joo Kim, Jae-Ho Yang, Jong-Hun Kim, Young-Woo Rhee, Ki-Won Kang, Keon-Sik Kim and Kun-Woo Song, Thermochimica Acta, 2007, 455, 123–128.
  4. ↑ "Solution of Fission Products in UO2" (PDF). Archived from the original (PDF) on 2008-09-10. Retrieved 2008-05-18.
  5. ↑ "RWMAC's Advice to Ministers on the Radioactive Waste Implications of Reprocessing". Radioactive Waste Management Advisory Committee (RWMAC). 3 November 2002. Archived from the original on 29 August 2008. Retrieved 2008-05-18.
  6. ↑ "Nuclear Crisis in Japan FAQs". Union of Concerned Scientists. Archived from the original on 2011-04-20. Retrieved 2011-04-19.
  7. ↑ "David W. Shoesmith". University of Western Ontario . Retrieved 2008-05-18.
  8. ↑ "Electrochemistry and corrosion studies at Western". Shoesmith research group, University of Western Ontario. Retrieved 2008-05-18.
  9. ↑ Testimony of Robert Meyers Principal deputy Assistant Administrator for the Office of Air and Radiation U.S. Environmental Protection Agency before the subcommittee on Energy and Air Quality Committee on Energy and Commerce U. S. House of Representatives, July 15, 2008
  10. ↑ Hebert, H. Josef. "Nuclear waste won't be going to Nevada's Yucca Mountain, Obama official says". Chicago Tribune. Archived from the original on 2011-03-24.
  11. ↑ Ialenti, Vincent (October 2017). "Death and succession among Finland's nuclear waste experts". Physics Today. 70 (10): 48–53. Bibcode:2017PhT....70j..48I. doi: 10.1063/PT.3.3728 .
  12. ↑ SFOE, Swiss Federal Office of Energy. "Sectoral Plan for Deep Geological Repositories". www.bfe.admin.ch. Retrieved 2020-10-19.
  13. 1 2 Potera, Carol (2011). "HAZARDOUS WASTE: Pond Algae Sequester Strontium-90". Environ Health Perspect. 119 (6): A244. doi: 10.1289/ehp.119-a244 . PMC   3114833 . PMID   21628117.
  14. ↑ Liu, Mingxue; Dong, Faqin; Kang, Wu; Sun, Shiyong; Wei, Hongfu; Zhang, Wei; Nie, Xiaoqin; Guo, Yuting; Huang, Ting; Liu, Yuanyuan (2014). "Biosorption of Strontium from Simulated Nuclear Wastewater by Scenedesmus spinosus under Culture Conditions: Adsorption and Bioaccumulation Processes and Models". Int J Environ Res Public Health. 11 (6): 6099–6118. doi: 10.3390/ijerph110606099 . PMC   4078568 . PMID   24919131.
  15. ↑ "Backgrounder on Radioactive Waste". www.nrc.gov. U.S. Nuclear Regulatory Commission (NRC). 2021-06-23. Retrieved 2021-05-10.
  16. ↑ Parenti, Christian (March 15, 2011). "Fukushima's Spent Fuel Rods Pose Grave Danger". The Nation.
  17. ↑ "Are Nuclear Spent Fuel Pools Secure?". Council on Foreign Relations. June 7, 2003. Archived from the original on 2011-04-12. Retrieved 2011-04-05.
  18. ↑ Benjamin, Mark (March 23, 2011). "How Safe Is Nuclear-Fuel Storage in the U.S.?". Time Magazine. Archived from the original on March 25, 2011.
  19. ↑ Huang, W. H.; Krause, T. W.; Lewis, B. J. (10 April 2017). "Laboratory Tests of an Ultrasonic Inspection Technique to Identify Defective CANDU Fuel Elements". Nuclear Technology. 176 (3): 452–461. doi:10.13182/NT11-A13320.
  20. ↑ "Fact Sheet on Storage of Spent Nuclear Fuel". Archived from the original on 2014-10-27. Retrieved 2017-06-25.
  21. ↑ "Nuclear Waste Disposal". Archived from the original on 2012-07-06. Retrieved 2012-06-05.
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