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34-410: Watts Bar may refer to: Watts Bar Nuclear Plant Watts Bar Dam Watts Bar Steam Plant Watts Bar Lake [REDACTED] Topics referred to by the same term This disambiguation page lists articles about distinct geographical locations with the same name. If an internal link led you here, you may wish to change the link to point directly to

68-489: A lathe to "single-point" the threads or by rolling the threads in the solution treated condition (for hardenable alloys) using a screw machine . Inconel 718 can also be roll-threaded after full aging by using induction heat to 700 °C (1,290 °F) without increasing the grain size. Holes with internal threads are made by threadmilling. Internal threads can also be formed using a sinker electrical discharge machining (EDM). Welding of some Inconel alloys (especially

102-412: A heat exposure of 850 °C (1,560 °F), and continues to grow after 72 hours of exposure. The most prevalent hardening mechanisms for Inconel alloys are precipitate strengthening and solid solution strengthening . In Inconel alloys, one of the two often dominates. For alloys like Inconel 718, precipitate strengthening is the main strengthening mechanism. The majority of strengthening comes from

136-512: A radius of 10 miles (16 km), concerned primarily with exposure to, and inhalation of, airborne radioactive contamination , and an ingestion pathway zone of about 50 miles (80 km), concerned primarily with ingestion of food and liquid contaminated by radioactivity. The 2010 U.S. population within 10 miles (16 km) of Watts Bar was 18,452, an increase of 4.1 percent in a decade, according to an analysis of U.S. Census data for msnbc.com. The 2010 U.S. population within 50 miles (80 km)

170-601: A result of thermally induced crystal vacancies (see Arrhenius equation ). Inconel's high temperature strength is developed by solid solution strengthening or precipitation strengthening , depending on the alloy. In age-hardening or precipitation-strengthening varieties, small amounts of niobium combine with nickel to form the intermetallic compound Ni 3 Nb or gamma double prime (γ″). Gamma prime forms small cubic crystals that inhibit slip and creep effectively at elevated temperatures. The formation of gamma-prime crystals increases over time, especially after three hours of

204-580: A total of $ 4.7 billion bringing the total costs of the two unit plant to more than $ 12 billion. It will likely be the last Generation II reactor to be completed in the US. TVA declared construction substantially complete in August 2015 and requested that NRC staff proceed with the final licensing review; on October 22, the NRC approved a 40-year operating license for Unit 2, marking the formal end of construction and allowing for

238-535: A winter net dependable generating capacity of 1,167 megawatts. Unit 2 has a capacity of 1,165 megawatts. Unit 2 was the first of three new power reactors to enter service in the 21st century in the United States, followed by Vogtle Electric Generating Plant Units 3 and 4. Construction on Unit 1 began on 23 January 1973 and suffered from many delays. After construction was halted on both units in 1985, construction resumed on Unit 1 in 1992. Criticality

272-431: Is a difficult metal to shape and to machine using traditional cold forming techniques due to rapid work hardening . After the first machining pass, work hardening tends to plastically deform either the workpiece or the tool on subsequent passes. For this reason, age-hardened Inconels such as 718 are typically machined using an aggressive but slow cut with a hard tool, minimizing the number of passes required. Alternatively,

306-481: Is also used in the turbo system of the 3rd generation Mazda RX7 , and the exhaust systems of high powered Wankel engine and Norton motorcycles where exhaust temperatures reach more than 1,000 °C (1,830 °F). Inconel is increasingly used in the boilers of waste incinerators . The Joint European Torus and DIII-D tokamaks' vacuum vessels are made of Inconel. Inconel 718 is commonly used for cryogenic storage tanks, downhole shafts, wellhead parts, and in

340-443: Is coherent and has an FCC structure, like the γ matrix; The γ' phase is much less prevalent than γ″. The volume fraction of the γ″ and γ' phases are approximately 15% and 4% after precipitation, respectively. Because of the coherency between the γ matrix and the γ' and γ″ precipitates, strain fields exist that obstruct the motion of dislocations. The prevalence of carbides with MX(Nb, Ti)(C, N) compositions also helps to strengthen

374-512: Is common in gas turbine blades, seals, and combustors, as well as turbocharger rotors and seals, electric submersible well pump motor shafts, high temperature fasteners, chemical processing and pressure vessels , heat exchanger tubing, steam generators and core components in nuclear pressurized water reactors , natural gas processing with contaminants such as H 2 S and CO 2 , firearm sound suppressor blast baffles, and Formula One , NASCAR , NHRA , and APR, LLC exhaust systems. It

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408-422: Is irradiated. During the times the reactor does this, it must be fuelled with "unobligated" uranium , (uranium that is not legally or contractually restricted to peaceful use only, as most commercial reactor uranium is). Technology and equipment as well as the fuel used to produce it must be of U.S. origin. The NRC defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with

442-492: The Nuclear Regulatory Commission (NRC) issued 9 orders to improve safety at domestic plants. Two changes applied to Watts Bar Unit 2 and required design modifications: "Mitigation Strategies Order" and "Spent Fuel Pool Instrumentation Order". In February 2012, TVA said the design modifications to Watts Bar 2 were partially responsible for the project running over budget and behind schedule. The second unit costs

476-531: The Tennessee Valley Authority (TVA) Board approved completion of Unit 2 on August 1, and construction resumed on October 15. The project was expected to cost $ 2.5 billion and employ around 2,300 contractor workers. Once finished, it was expected to employ 250 people in permanent jobs. The final cost of the plant is estimated at $ 6.1 billion. A year after the 2011 Tōhoku earthquake and tsunami and subsequent Fukushima Daiichi nuclear disaster ,

510-527: The Inconel trademark were acquired in 1998 by Special Metals Corporation . Inconel alloys vary widely in their compositions, but all are predominantly nickel, with chromium as the second element. When heated, Inconel forms a thick and stable passivating oxide layer protecting the surface from further attack. Inconel retains strength over a wide temperature range, attractive for high-temperature applications where aluminium and steel would succumb to creep as

544-477: The Laves phase can exhaust the matrix of these elements, ultimately making precipitate and solid-solution strengthening more difficult. For alloys like Inconel 625, solid-solution hardening is the main strengthening mechanism. Elements like Mo are important in this process. Nb and Ta can also contribute to solid solution strengthening to a lesser extent. In solid solution strengthening, Mo atoms are substituted into

578-475: The Watts Bar 2 was the first United States reactor to enter commercial operation since 1996. Due to failures in its condenser, TVA took it offline on March 23, 2017. The condenser, which was installed during the original construction phase of the plant in the 1970s, suffered a structural failure in one of its sections. On August 1, 2017, the unit was restarted after four months of repairs to the condenser. In 2022,

612-466: The Watts Bar reactor. TVA began irradiating tritium-producing rods at Unit 1 in the fall of 2003. TVA removed these rods from the reactor in the spring of 2005. DOE successfully shipped them to its tritium extraction facility at Savannah River Site in South Carolina . DOE reimburses TVA for the cost of providing the irradiation services and also pays TVA a fee for each tritium-producing rod that

646-596: The aerospace industry -- where it has become a prime candidate material for constructing heat resistant turbines. Rolled Inconel was frequently used as the recording medium by engraving in black box recorders on aircraft. Alternatives to the use of Inconel in chemical applications such as scrubbers, columns, reactors, and pipes are Hastelloy , perfluoroalkoxy (PFA) lined carbon steel or fiber reinforced plastic . Alloys of Inconel include: In age hardening or precipitation strengthening varieties, alloying additions of aluminum and titanium combine with nickel to form

680-419: The earthquake, but personnel would conduct further inspections as a precaution. Inconel Inconel is a nickel - chromium -based superalloy often utilized in extreme environments where components are subjected to high temperature, pressure or mechanical loads . Inconel alloys are oxidation - and corrosion -resistant. When heated, Inconel forms a thick, stable, passivating oxide layer protecting

714-446: The four original steam generator units installed in the 1970s on unit 2 were replaced with units made from Inconel 690 which is more resistant to stress corrosion cracking and expected to last the life of the plant. Replacing the units involved cutting two large holes in the containment building . Because of radioactive contamination the old units will be kept until the plant is decommissioned. The NRC operating license for Watts Bar

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748-432: The gamma prime precipitation hardened family; e.g., Waspaloy and X-750) can be difficult due to cracking and microstructural segregation of alloying elements in the heat-affected zone . However, several alloys such as 625 and 718 have been designed to overcome these problems. The most common welding methods are gas tungsten arc welding and electron-beam welding . Inconel is often encountered in extreme environments. It

782-518: The installation of nuclear fuel and subsequent testing. On December 15, 2015, TVA announced that the reactor was fully loaded with fuel and ready for criticality and power ascension tests. In March 2016, the NRC described the project as a "chilled work environment," where employees are reluctant to raise safety concerns for fear of retribution. On May 23, 2016, initial criticality was achieved. Commercial operation began in October 2016. On October 19, 2016

816-534: The intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Watts_Bar&oldid=912525585 " Category : Place name disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Watts Bar Nuclear Plant The plant, construction of which began in 1973, has two Westinghouse pressurized water reactor units: Unit 1, completed in 1996, and Unit 2, completed in 2015. Unit 1 has

850-621: The loss of coherency strengthening, making for a weaker material. That being said, in appropriate quantities, the δ phase is responsible for grain boundary pinning and strengthening. Another common phase in Inconel alloys is the Laves intermetallic phase. Its compositions are (Ni, Cr, Fe) x (Nb, Mo, Ti) y and Ni y Nb, it is brittle, and its presence can be detrimental to the mechanical behavior of Inconel alloys. Sites with large amounts of Laves phase are prone to crack propagation because of their higher potential for stress concentration. Additionally, due to its high Nb, Mo, and Ti content,

884-438: The majority of the machining can be performed with the workpiece in a "solutionized" form, with only the final steps being performed after age hardening. However some claim that Inconel can be machined extremely quickly with very fast spindle speeds using a multifluted ceramic tool with small width of cut at high feed rates as this causes localized heating and softening in front of the flute. External threads are machined using

918-452: The material. For precipitate strengthening, elements like niobium, titanium, and tantalum play a crucial role. Because the γ″ phase is metastable, over-aging can result in the transformation of γ″ phase precipitates to delta (δ) phase precipitates, their stable counterparts. The δ phase has an orthorhombic structure, a Ni 3 (Nb, Mo, Ti) composition, and is incoherent. As a result, the transformation of γ″ to δ in Inconel alloys leads to

952-498: The presence of gamma double prime (γ″) precipitates. Inconel alloys have a γ matrix phase with an FCC structure. γ″ precipitates are made of Ni and Nb, specifically with a Ni 3 Nb composition. These precipitates are fine, coherent, disk-shaped, intermetallic particles with a tetragonal structure. Secondary precipitate strengthening comes from gamma prime (γ') precipitates. The γ' phase can appear in multiple compositions such as Ni 3 (Al, Ti). The precipitate phase

986-530: The surface from further attack. Inconel retains strength over a wide temperature range, attractive for high-temperature applications where aluminum and steel would succumb to creep as a result of thermally-induced crystal vacancies. Inconel's high-temperature strength is developed by solid solution strengthening or precipitation hardening , depending on the alloy. Inconel alloys are typically used in high temperature applications. Common trade names for various Inconel alloys include: The Inconel family of alloys

1020-553: The γ matrix of Inconel alloys. Because Mo atoms have a significantly larger radius than those of Ni (209 pm and 163 pm, respectively), the substitution creates strain fields in the crystal lattice, which hinder the motion of dislocations, ultimately strengthening the material. The combination of elemental composition and strengthening mechanisms is why Inconel alloys can maintain their favorable mechanical and physical properties, such as high strength and fatigue resistance, at elevated temperatures, specifically those up to 650°C. Inconel

1054-455: Was 1,186,648, an increase of 12.8 percent since 2000. The NRC's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Watts Bar was 1 in 27,778, according to an NRC study published in August 2010. The 2018 Southern Appalachian earthquake 's epicenter was located two miles east of the facility. The TVA reported that their facilities are designed to withstand seismic events and were not impacted by

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1088-433: Was first achieved on 1 January 1996, and commercial operation began on May 5, 1996. In the early 2000s, the four original steam generator units were replaced with units made from Inconel 690 which is more resistant to stress corrosion cracking . Unit 2 construction started in 1972. Unit 2 was 60% complete when construction on both units was stopped in 1985 due in part to a projected decrease in power demand. In 2007,

1122-567: Was first developed before December 1932, when its trademark was registered by the US company International Nickel Company of Delaware and New York. A significant early use was found in support of the development of the Whittle jet engine, during the 1940s by research teams at Henry Wiggin & Co of Hereford, England a subsidiary of the Mond Nickel Company , which merged with Inco in 1928. The Hereford Works and its properties including

1156-600: Was modified in September ;2002 to allow irradiation of tritium -producing burnable absorber rods at Watts Bar to produce tritium for the U.S. Department of Energy 's (DOE's) National Nuclear Security Administration in order to maintain the viability of America's nuclear weapons . Tritium, the fusion fuel in nuclear weapons , has a half-life of 12.3 years, which means it decays at 5.5% per year and must be renewed. The Watts Bar license amendment permits TVA to irradiate up to approximately 2,000 tritium-producing rods in

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