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61-532: Commissioned in 1968, the Cumberland Fossil Plant contains two identical units, rated at 1.235 GWe gross each, Units 1 and 2 were launched into service in March and November 1973, respectively. In 2004, the two units accounted for almost 12% of TVA's total electricity generation. As of the mid 2010s, however, TVA's Sequoyah Nuclear Plant near Soddy Daisy, Tennessee , with a slightly lower capacity,

122-426: A chemical shim produces small but non-negligible quantities of tritium. Tritium is also produced in heavy water-moderated reactors whenever a deuterium nucleus captures a neutron. This reaction has a small absorption cross section , making heavy water a good neutron moderator , and relatively little tritium is produced. Even so, cleaning tritium from the moderator may be desirable after several years to reduce

183-530: A warhead is continually undergoing radioactive decay, becoming unavailable for fusion. Also, its decay product , helium-3, absorbs neutrons. This can offset or reverse the intended effect of the tritium, which was to generate many free neutrons, if too much helium-3 has accumulated. Therefore, boosted bombs need fresh tritium periodically. The estimated quantity needed is 4 grams (0.14 oz) per warhead. To maintain constant levels of tritium, about 0.20 grams (0.0071 oz) per warhead per year must be supplied to

244-648: A fixed production rate, and losses proportional to the inventory. Tritium for American nuclear weapons was produced in special heavy water reactors at the Savannah River Site until their closures in 1988. With the Strategic Arms Reduction Treaty (START) after the end of the Cold War , the existing supplies were sufficient for the new, smaller number of nuclear weapons for some time. 225 kg (496 lb) of tritium

305-525: A helium-cooled pebble bed, also known as a breeder blanket. High-energy neutrons can also produce tritium from lithium-7 in an endothermic reaction, consuming 2.466 MeV. This was discovered when the 1954 Castle Bravo nuclear test produced an unexpectedly high yield. Prior to this test, it was incorrectly assumed that 3 Li would absorb a neutron to become 3 Li , which would beta-decay to 4 Be , which in turn would decay to two 2 He nuclei on

366-478: A moderator of a natural uranium reactor which needs to keep neutron absorption outside the fuel as low as feasible. Some facilities that remove tritium also remove (or at least reduce the content of) O and O, which can – at least in principle – be used for isotope labeling . India, which also has a large fleet of pressurized heavy water reactors (initially CANDU technology but since indigenized and further developed IPHWR technology), also removes at least some of

427-756: A small political token to the Cherokee in compensation for the dam-flooding and destruction of their historic sites that TVA required to control flooding on the Tennessee River. The NRC defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone of 10 miles (16 km) radius (concerned primarily with exposure to, and inhalation of, airborne radioactive contamination), and an ingestion pathway zone of about 50 miles (80 km) radius (concerned primarily with ingestion of food and liquid contaminated by radioactivity). The 2010 U.S. population within 10 miles (16 km) of Sequoyah

488-686: A smaller containment building . Sequoyah's two units have a winter net dependable capacity of 2,440 megawatts, making Sequoyah the most productive of TVA's three nuclear plants . Sequoyah is the second-most powerful power plant in Tennessee, after the Cumberland Fossil Plant northwest of Nashville, but actually generates more power. Following the restart of Brown's Ferry Unit 1 , that plant became TVAs most productive at 3,440 MW. TVA constructed dry cask storage facilities at Sequoyah and purchased special storage containers for

549-406: A total timeframe much longer than the duration of the explosion. High-energy neutrons irradiating boron-10 , also occasionally produce tritium: A more common result of boron-10 neutron capture is Li and a single alpha particle . Especially in pressurized water reactors which only partially thermalize neutrons, the interaction between relatively fast neutrons and the boric acid added as

610-415: Is 9,650 curies per gram (3.57 × 10   Bq /g). Tritium figures prominently in studies of nuclear fusion due to its favorable reaction cross section and the large amount of energy (17.6 MeV) produced through its reaction with deuterium: All atomic nuclei contain protons as their only charged particles. They therefore repel one another because like charges repel ( Coulomb's law ). However, if

671-468: Is a gas at standard temperature and pressure . Combined with oxygen , it forms tritiated water ( H 2 O ). Compared to hydrogen in its natural composition on Earth, tritium has a higher melting point (20.62 K vs. 13.99 K), a higher boiling point (25.04 K vs. 20.27 K), a higher critical temperature (40.59 K vs. 32.94 K) and a higher critical pressure (1.8317 MPa vs. 1.2858 MPa). Tritium's specific activity

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732-469: Is about 0.19 millibarn and that of oxygen-17 ( O) is about 240 millibarns. While O is by far the most common isotope of oxygen in both natural oxygen and heavy water; depending on the method of isotope separation , heavy water may be slightly richer in O and O . Due to both neutron capture and (n, α ) reactions (the latter of which produce C , an undesirable long-lived beta emitter, from O) they are net "neutron consumers" and are thus undesirable in

793-404: Is an important component in nuclear weapons; it is used to enhance the efficiency and yield of fission bombs and the fission stages of hydrogen bombs in a process known as " boosting " as well as in external neutron initiators for such weapons. These are devices incorporated in nuclear weapons which produce a pulse of neutrons when the bomb is detonated to initiate the fission reaction in

854-399: Is another isotope of hydrogen, which occurs naturally with an abundance of 0.015%. Their experiment could not isolate tritium, which was first accomplished in 1939 by Luis Alvarez and Robert Cornog , who also realized tritium's radioactivity. Willard Libby recognized in 1954 that tritium could be used for radiometric dating of water and wine . The half life of tritium is listed by

915-484: Is based on outdated dose calculation standards of National Bureau of Standards Handbook 69 circa 1963. Four millirem per year is about 1.3% of the natural background radiation (~3 mSv). For comparison, the banana equivalent dose (BED) is set at 0.1 μSv, so the statutory limit in the US is set at 400 BED. Updated dose calculation standards based on International Commission on Radiological Protection Report 30 and used in

976-473: Is dumped into Cumberland River water. On January 10, 2023, TVA announced plans to retire the first unit by the end of 2026 and the second by the end of 2028. The plant is tentatively planned to be replaced with a 1,450 MW combined-cycle natural gas generation plant, which has drawn criticism from environmental groups. To reduce sulfur dioxide (SO 2 ) emissions, both units at Cumberland use wet limestone scrubbers . To reduce nitrogen oxides (NO x ),

1037-550: Is no practical separation technology on an industrial scale. Accordingly, a controlled environmental release is said to be the best way to treat low-tritium-concentration water." After a public information campaign sponsored by the Japanese government, the gradual release into the sea of the tritiated water began on 24 August 2023 and is the first of four releases through March 2024. The entire process will take "decades" to complete. China reacted with protest. The IAEA has endorsed

1098-505: Is owned and operated by the Tennessee Valley Authority (TVA). The plant has two Westinghouse pressurized water reactors . Sequoyah units 1 & 2, as well as their sister plant at Watts Bar , both have ice condenser containment systems. In case of a large loss-of-coolant accident , steam generated by the leak is directed toward borated ice which helps condense the steam creating a lower pressure, allowing for

1159-531: Is used in a medical and scientific setting as a radioactive tracer . Tritium is also used as a nuclear fusion fuel, along with more abundant deuterium , in tokamak reactors and in hydrogen bombs . Tritium has also been used commercially in Betavoltaic devices such as NanoTritium batteries . Tritium was first detected in 1934 by Ernest Rutherford , Mark Oliphant and Paul Harteck after bombarding deuterium with deuterons (deuterium nuclei). Deuterium

1220-421: Is used in self-powered lighting devices called betalights , which are used for night illumination of firearm sights, watches, exit signs , map lights, navigational compasses (such as current-use M-1950 U.S. military compasses ), knives and a variety of other devices. As of 2000 , commercial demand for tritium is 400 grams (0.88 lb) per year and the cost is $ 30,000 per gram ($ 850,000/oz) or more. Tritium

1281-477: The National Institute of Standards and Technology as 4,500 ± 8 days ( 12.32 ± 0.02 years ) – an annualized rate of approximately 5.5% per year. Tritium decays into helium-3 by beta-minus decay as shown in this nuclear equation: releasing 18.6  keV of energy in the process. The electron 's kinetic energy varies, with an average of 5.7 keV, while the remaining energy is carried off by

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1342-602: The Darlington Tritium Recovery Facility (DTRF) attached to the 3,512 MW electric Darlington Nuclear Generating Station in Ontario. The total production at DTRF between 1989 and 2011 was 42.5 kilograms (94 lb) – with an activity of 409 megacuries (15,100 PBq): an average of about 2 kilograms (4.4 lb) per year. Deuterium's absorption cross section for thermal neutrons is about 0.52 millibarn , whereas that of oxygen-16 ( O)

1403-586: The NRC Regulation 10CFR20 results in a dose of 0.9 millirem (9 μSv) per year at 740 Bq/L (20 nCi/L). Tritiation of drug candidates allows detailed analysis of their absorption and metabolism . Tritium has also been used for biological radiometric assays, in a process akin to radiocarbon dating . For example, [ H] retinyl acetate was traced through the bodies of rats. The beta particles from small amounts of tritium cause chemicals called phosphors to glow. This radioluminescence

1464-536: The Tritiated Water Task Force released a report on the status of tritium in tritiated water at Fukushima Daiichi nuclear plant , as part of considering options for final disposal of the stored contaminated cooling water. This identified that the March 2016 holding of tritium on-site was 760  TBq (equivalent to 2.1 g of tritium or 14 mL of pure tritiated water) in a total of 860,000 m of stored water. This report also identified

1525-471: The U.S. Environmental Protection Agency , self-illuminating exit signs improperly disposed in municipal landfills have been found to contaminate waterways. The legal limits for tritium in drinking water vary widely from country to country. Some figures are given below: The American limit results in a dose of 4.0  millirems (or 40 micro sieverts in SI units ) per year per EPA regulation 40CFR141, and

1586-1007: The US. In one case, leaking water contained 7.5 microcuries (280 kBq) of tritium per liter, which is 375 times the current EPA limit for drinking water, and 28 times the World Health Organization 's recommended limit. This is equivalent to 0.777 nanograms per litre (5.45 × 10  gr/imp gal) or roughly 0.8 parts per trillion . The US Nuclear Regulatory Commission states that in normal operation in 2003, 56 pressurized water reactors released 40,600 curies (1,500,000 GBq) of tritium (maximum: 2,080 Ci (77,000 GBq); minimum: 0.1 Ci (3.7 GBq); average: 725 Ci (26,800 GBq)) and 24 boiling water reactors released 665 Ci (24.6 TBq) (maximum: 174 Ci (6,400 GBq); minimum: 0 Ci; average: 27.7 Ci (1,020 GBq)), in liquid effluents. 40,600 Ci (1,500,000 GBq) of tritium weigh about 4.207 grams (0.1484 oz). According to

1647-513: The atoms have a high enough temperature and pressure (for example, in the core of the Sun), then their random motions can overcome such repulsion, and they can come close enough for the strong nuclear force to take effect, fusing them into heavier atoms. A tritium nucleus (triton), containing one proton and two neutrons, has the same charge as any hydrogen nucleus, and it experiences the same electrostatic repulsion when close to another nucleus. However,

1708-472: The common isotope hydrogen-1 ( protium ) contains one proton and no neutrons, and that of non-radioactive hydrogen-2 ( deuterium ) contains one proton and one neutron. Tritium is the heaviest particle-bound isotope of hydrogen. It is one of the few nuclides with a distinct name. The use of the name hydrogen-3, though more systematic, is much less common. Naturally occurring tritium is extremely rare on Earth. The atmosphere has only trace amounts, formed by

1769-409: The decay (along with that of rhenium-187 ) useful for absolute neutrino mass measurements in the laboratory. The low energy of tritium's radiation makes it difficult to detect tritium-labeled compounds except by using liquid scintillation counting . Tritium is most often produced in nuclear reactors by neutron activation of lithium-6 . The release and diffusion of tritium and helium produced by

1830-513: The enactment of the Partial Nuclear Test Ban Treaty proved to be unexpectedly useful to oceanographers. The high levels of tritium oxide introduced into upper layers of the oceans have been used in the years since then to measure the rate of mixing of the upper layers of the oceans with their lower levels. Since tritium is a low energy beta (β) emitter , it is not dangerous externally (its β particles cannot penetrate

1891-451: The environment. The biological half-life of tritiated water in the human body, which is a measure of body water turn-over, varies with the season. Studies on the biological half-life of occupational radiation workers for free water tritium in a coastal region of Karnataka , India, show that the biological half-life in winter is twice that of the summer. If tritium exposure is suspected or known, drinking uncontaminated water will help replace

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1952-443: The fission fuel depletes and also explodes outward, it falls below the density needed to stay critical by itself, but the fusion neutrons make the fission process progress faster and continue longer than it would without boosting. Increased yield comes overwhelmingly from the increased fission. The energy from the fusion itself is much smaller because the amount of fusion fuel is much smaller. Effects of boosting include: The tritium in

2013-672: The fission of lithium can take place within ceramics known as breeder ceramics . Production of tritium from lithium-6 in such breeder ceramics is possible with neutrons of any energy, though the cross section is higher when the incident neutrons have lower energy, reaching more than 900 barns for thermal neutrons . This is an exothermic reaction, yielding 4.8  MeV . In comparison, fusion of deuterium with tritium releases about 17.6 MeV. For applications in proposed fusion energy reactors, such as ITER , pebbles consisting of lithium bearing ceramics including Li 2 TiO 3 and Li 4 SiO 4 , are being developed for tritium breeding within

2074-431: The fissionable core (pit) of the bomb, after it is compressed to a critical mass by explosives. Actuated by an ultrafast switch like a krytron , a small particle accelerator drives ions of tritium and deuterium to energies above the 15  keV or so needed for deuterium-tritium fusion and directs them into a metal target where the tritium and deuterium are adsorbed as hydrides . High-energy fusion neutrons from

2135-442: The interaction of its gases with cosmic rays . It can be produced artificially by irradiation of lithium or lithium-bearing ceramic pebbles in a nuclear reactor and is a low-abundance byproduct in normal operations of nuclear reactors. Tritium is used as the energy source in radioluminescent lights for watches, night sights for firearms, numerous instruments and tools, and novelty items such as self-illuminating key chains. It

2196-420: The metabolism of OBT is less understood than that of H HO. Tritium can incorporate to RNA and DNA molecules within organisms which can lead to somatic and genetic impacts. These can emerge in later generations. H HO has a short biological half-life in the human body of 7 to 14 days, which both reduces the total effects of single-incident ingestion and precludes long-term bioaccumulation of H HO from

2257-407: The most important reaction for natural production, a fast neutron (which must have energy greater than 4.0  MeV ) interacts with atmospheric nitrogen : Worldwide, the production of tritium from natural sources is 148 peta becquerels per year. The global equilibrium inventory of tritium created by natural sources remains approximately constant at 2,590 petabecquerels. This is due to

2318-409: The nearly undetectable electron antineutrino . Beta particles from tritium can penetrate only about 6.0 millimetres (0.24 in) of air, and they are incapable of passing through the dead outermost layer of human skin. Because of their low energy compared to other beta particles, the amount of bremsstrahlung generated is also lower. The unusually low energy released in the tritium beta decay makes

2379-401: The neutrons in the triton increase the attractive strong nuclear force when close enough to another nucleus. As a result, tritium can fuse more easily with other light atoms, than ordinary hydrogen can. The same is true, albeit to a lesser extent, of deuterium. This is why brown dwarfs ("failed" stars ) cannot fuse normal hydrogen, but they do fuse a small minority of deuterium nuclei. Like

2440-498: The operation of nuclear reactors , especially in the reprocessing of nuclear fuel and storage of spent nuclear fuel . The production of tritium is not a goal, but a side-effect. It is discharged to the atmosphere in small quantities by some nuclear power plants. Voloxidation is an optional additional step in nuclear reprocessing that removes volatile fission products (such as all isotopes of hydrogen) before an aqueous process begins. This would in principle enable economic recovery of

2501-476: The other isotopes of hydrogen , tritium is difficult to confine. Rubber, plastic, and some kinds of steel are all somewhat permeable. This has raised concerns that if tritium were used in large quantities, in particular for fusion reactors , it might contribute to radioactive contamination , though its short half-life should prevent significant long-term accumulation in the atmosphere. The high levels of atmospheric nuclear weapons testing that took place prior to

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2562-448: The pit. Before detonation, a few grams of tritium–deuterium gas are injected into the hollow " pit " of fissile material. The early stages of the fission chain reaction supply enough heat and compression to start deuterium–tritium fusion; then both fission and fusion proceed in parallel, the fission assisting the fusion by continuing heating and compression, and the fusion assisting the fission with highly energetic (14.1- MeV ) neutrons. As

2623-510: The plan. The water released is diluted to reduce the tritium concentration to less than 1500 Bq/L, far below the limit recommended in drinking water by the WHO. Tritium's decay product helium-3 has a very large cross section (5330 barns) for reacting with thermal neutrons , expelling a proton; hence, it is rapidly converted back to tritium in nuclear reactors . Tritium occurs naturally due to cosmic rays interacting with atmospheric gases. In

2684-470: The produced tritium but even if the tritium is only disposed and not used, it has the potential to reduce tritium contamination in the water used, reducing radioactivity released when the water is discharged since tritiated water cannot be removed from "ordinary" water except by isotope separation. Given the specific activity of tritium at 9,650 curies per gram (357 TBq/g), one TBq is equivalent to roughly 2.8 milligrams (0.043 gr). In June 2016

2745-572: The purpose of storing spent nuclear fuel . The storage facilities have been approved by the NRC. Construction began on Sequoyah on May 27, 1970. Unit 1 was licensed by the NRC on September 17, 1980, and commercial operation began on July 1, 1981. Unit 2 was licensed on September 15, 1981, and began operation on June 1, 1982. Sequoyah was the first new nuclear plant licensed after the Three Mile Island accident . On August 22, 1985, Sequoyah

2806-634: The reactors of the commercial Watts Bar Nuclear Plant from 2003 to 2005 followed by extraction of tritium from the rods at the Tritium Extraction Facility at the Savannah River Site beginning in November 2006. Tritium leakage from the rods during reactor operations limits the number that can be used in any reactor without exceeding the maximum allowed tritium levels in the coolant. Tritium has an atomic mass of 3.016 049 28   Da . Diatomic tritium ( T 2 or H 2 )

2867-417: The reducing concentration of tritium in the water extracted from the buildings etc. for storage, seeing a factor of ten decrease over the five years considered (2011–2016), 3.3 MBq/L to 0.3 MBq/L (after correction for the 5% annual decay of tritium). According to a report by an expert panel considering the best approach to dealing with this issue, " Tritium could be separated theoretically , but there

2928-400: The resulting fusion radiate in all directions. Some of these strike plutonium or uranium nuclei in the primary's pit, initiating a nuclear chain reaction . The quantity of neutrons produced is large in absolute numbers, allowing the pit to quickly achieve neutron levels that would otherwise need many more generations of chain reaction, though still small compared to the total number of nuclei in

2989-407: The risk of its escaping to the environment. Ontario Power Generation 's "Tritium Removal Facility" is capable of processing up to 2,500 tonnes (2,500 long tons; 2,800 short tons) of heavy water a year, and it separates out about 2.5 kg (5.5 lb) of tritium, making it available for other uses. CANDU reactors typically produce 130 grams (4.6 oz) of tritium per year, which is recovered at

3050-442: The skin), but it can be a radiation hazard if inhaled, ingested via food or water, or absorbed through the skin. Organisms can take up H HO, as they would H 2 O. Plants convert H HO into organically bound tritium (OBT), and are consumed by animals. H HO is retained in humans for around 12 days, with a small portion of it remaining in the body. Tritium can be passed along the food chain as one organism feeds on another, though

3111-433: The tritium from the body. Increasing sweating, urination or breathing can help the body expel water and thereby the tritium contained in it. However, care should be taken that neither dehydration nor a depletion of the body's electrolytes results, as the health consequences of those things (particularly in the short term) can be more severe than those of tritium exposure. Tritium has leaked from 48 of 65 nuclear sites in

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3172-556: The tritium produced in the moderator/coolant of its reactors but due to the dual use nature of tritium and the Indian nuclear bomb program, less information about this is publicly available than for Canada. Tritium is an uncommon product of the nuclear fission of uranium-235 , plutonium-239 , and uranium-233 , with a production of about one atom per 10 fissions. The main pathways of tritium production include ternary fission . The release or recovery of tritium needs to be considered in

3233-483: The units use low-NO x burners as well as selective catalytic reduction systems, which were completed in 2004. Sequoyah Nuclear Plant The Sequoyah Nuclear Plant is a nuclear power plant located on 525 acres (212 ha) located 7 miles (11 km) east of Soddy-Daisy, Tennessee , and 20 miles (32 km) north of Chattanooga , abutting Chickamauga Lake on the Tennessee River . The facility

3294-694: Was Cherokee , part of the Overhill Cherokee , reportedly born in Tuskegee , a town at the confluence of the Tellico River and Little Tennessee River , upriver of the nuclear power plant. He is known for creating the Cherokee syllabary circa 1820. Many Cherokee sites were flooded during the TVA construction of Tellico Dam (1967-1979). Naming the site after a local Native American was considered

3355-455: Was 1 in 19,608, according to an NRC study published in August 2010. Tritium Tritium (from Ancient Greek τρίτος (trítos)  'third') or hydrogen-3 (symbol T or H ) is a rare and radioactive isotope of hydrogen with half-life ~12.3 years. The tritium nucleus (t, sometimes called a triton ) contains one proton and two neutrons , whereas the nucleus of

3416-403: Was 99,664, according to 2010 U.S. Census data analyzed for msnbc.com, an increase of 13.8 percent in a decade. The 2010 U.S. population within 50 miles (80 km) was 1,079,868 (increase of 13.8 percent). Cities within 50 miles include Chattanooga (14 miles to city center). The NRC's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Sequoyah

3477-475: Was generating more power. The Cumberland Fossil Plant has two of the tallest chimneys in the world at 1,001 feet (305 m), built in 1970. These chimneys are no longer in use, having been replaced with smaller chimneys connected to the scrubbers . Bituminous coal is delivered by barges along the Cumberland River waterway. The plant consumes about 20,000 tons of coal a day. All of the waste heat

3538-567: Was modified in September 2002 to allow TVA to irradiate tritium -producing burnable absorber rods at Sequoyah for the U.S. Department of Energy . The process of irradiating tritium-producing rods produces tritium, which is used in nuclear weapons and for various forms of research into nuclear fusion for commercial power production. TVA began irradiating tritium-producing rods at its Watts Bar Nuclear Plant in 2003. As of February 2007, TVA had no plans to produce tritium at Sequoyah. Sequoyah

3599-463: Was produced in the United States from 1955 to 1996. Since it continually decays into helium-3, the total amount remaining was about 75 kg (165 lb) at the time of the report, and about 16 kg (35 lb) as of 2023. Tritium production was resumed with irradiation of rods containing lithium (replacing the usual control rods containing boron , cadmium , or hafnium ), at

3660-439: Was shut down due to safety concerns. An independent contractor hired to analyze the safety systems of the plant had found that TVA lacked documentation proving that all of the plant's safety systems would function properly in the event of an emergency. Brown's Ferry, TVA's only other operating nuclear plant at the time, had been shut down in March 1985, due to safety concerns about a fire ten years earlier, and during this time, TVA

3721-419: Was without nuclear power completely. On March 22, 1988, TVA was authorized by the NRC to restart both Sequoyah units. Both reactors returned to service later that year. The operating license of Sequoyah's Unit 1 was originally set to expire in 2020, and Unit 2's operating license in 2021. In 2015, the NRC renewed the operating license for both units for an additional 20 years. TVA's Sequoyah operating license

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