Melania Trump Club

Melania Trump Club
Melania Trump Club

Friday, April 29, 2011

PlayStation Networking

(States Twitter)-PlayStation Network, often abbreviated as PSN, is an online multiplayer gaming and digital media delivery service provided/run by Sony Computer Entertainment for use with the PlayStation 3 and PlayStation Portable video game consoles. As of April, 2011, there are 77 million registered PlayStation Network accounts. Since April 20, 2011, the PlayStation Network has been offline due to a "compromise of personal information as a result of an illegal intrusion.
History

In 2006, Sony announced an online network for the PlayStation 3 system at the 2006 PlayStation Business Briefing meeting in Tokyo, tentatively named "PlayStation Network Platform". Sony also confirmed that the service will always be connected,free, and include multiplayer support. The full list of features available at launch was announced at their TGS 2006 press conference. When the network launched, the registration interface could only be accessed through the PS3 or PSP system interfaces. This has been changed since to allow users to sign up from the PlayStation Network website.
At the Tokyo Game Show on September 21, 2006, it was revealed that users will be able to download some of the PlayStation and PSP titles from the PlayStation Network for about US$5–$15, starting with those with the smallest game data.
On May 8, 2007 Sony Computer Entertainment announced PlayStation Network Cards, a form of electronic money that can be used with the Store. PlayStation Network Tickets, available in units of 1,000, 3,000, 5,000, and 10,000 yen, can be purchased at convenience stores throughout Japan.Each ticket contains a 12 character alphanumeric code which can be input on the PlayStation Network to place credits in the virtual wallet. The tickets are available through electronic kiosks at 26,000 convenience stores, including Lawsons, Family Mart, Daily Yamazaki, Ministop and Sunkus. They are also available at 26,000 post office ATMs, although registration is required first at a special mobile website.

April 2011 outage
The PlayStation Network April 2011 outage, which began on April 20, 2011 and affected 77 million registered accounts, is the longest amount of time the PSN has been offline since its inception in 2006. Sony acknowledged that the outage prevented users from having the "ability to enjoy the services provided by PlayStation Network and Qriocity including online gaming and online access to music, movies, sports and TV shows.
While remaining offline, the PlayStation 3 was unable to play certain Capcom titles that were downloaded from the PlayStation Store. Streaming video providers Hulu, Vudu and Netflix are noted to be inaccessible displaying the same maintenance message. The maintenance message on Netflix can be bypassed, however, and the service can be used (two failed attempts to sign into PSN will allow access to the service).
User registration

Registration is performed via the PlayStation 3 console, a PlayStation Portable or a PC. Two types of accounts can be created; Master accounts and Sub accounts. Master accounts allow full access to all settings, including parental control, but the Master must be over the age of 18 to create an account. Sub accounts can subsequently be created with desired restrictions set by the master account hold
Since Master/Sub accounts are not linked to the PlayStation 3 serial number, which allows users to buy and sell used consoles, they can be used with different consoles as a guest user; therefore a single console can have multiple Master accounts. Although unregistered users can access and browse the PlayStation Store, registration is required to purchase items. Once purchased, items can be downloaded from the PlayStation Store to up to five consoles, however, if the owner account is deleted from a console, the content becomes invalid and is locked.
PlayStation Network launched in November 2006 to coincide with the launch of the PlayStation 3 console in North America and Japan. Due to the delay of the European launch to March 2007, Sony allowed residents of Europe to pre-register their PlayStation Network via PC in order to reserve their favored PSN ID, allowing them to quickly retrieve their details on the day of release.

Angus T. Jones

Angus Turner Jones (born October 8, 1993) is an American actor. He is best known for his role as Jake Harper in the CBS sitcom Two and a Half Men (2003–present).
Notable events

On June 7, 2008, Jones joined stars such as Dakota Fanning, Cuba Gooding Jr., Val Kilmer, and former Bringing Down the House co-star Kimberly J. Brown, to lend their support to the First Star Organization to help abused and neglected children.
On August 26, 2008, Jones joined stars such as Madeline Zima, Thom Barry and Brandon Barash at the annual "Rock 'N Roll Fantasy Camp."
On October 4, 2008, Jones was among many stars, including Miranda Cosgrove, Meaghan Jette Martin, Ray Liotta, Selena Gomez, and Shailene Woodley to attend the Variety's Power of Youth benefit for St. Jude Children's Research Hospital in Memphis, Tennessee.
In October 2009, his Two and a Half Men co-star Jon Cryer presented Jones with the award for the Rising Star of 2009 at the Big Brothers Big Sisters Rising Star Gala.
Filmography

Year Title Role Notes
1999 Simpatico Five-Year-Old
2001 See Spot Run James
Dinner with Friends Sammy TV movie
ER Sean Gattney Episode: "Quo Vadis?"
2002 The Rookie Hunter Morris
Bringing Down the House Georgie Sanderson
2003 Audrey's Rain Tye Powell TV movie
George of the Jungle 2 George of the Jungle Jr.
2003–present Two and a Half Men Jake Harper Lead role
2005 The Christmas Blessing Charlie Bennett TV movie
2010 Hannah Montana Forever T.J. Guest star
Career

Aside from Two and a Half Men, Jones has also had supporting roles in the films See Spot Run, The Rookie, Bringing Down the House, George of the Jungle 2, and The Christmas Blessing.
Jones signed a contract guaranteeing him $7.8 million over 2 seasons (26 episodes), plus a $500,000 signing bonus. This amounts to $300,000 per episode of Two and a Half Men, making him the highest paid child star on television.

Ryan Mallett

(States Twitter)-Ryan Mallett (born June 5, 1988), nicknamed "Big Tex", is an American football quarterback for the New England Patriots of the National Football League, taken in the third round of the 2011 NFL Draft. He played college football for the Arkansas Razorbacks. Mallett spent his freshman year at the University of Michigan.
2010
It was announced on February 17 that Mallett had suffered a left foot injury in a change of direction conditioning drill. The junior had successful surgery later that day, and a planned second surgery was announced on June 9.Mallett missed the Razorback spring game and spring drills, but he did not miss fall camp. During the off season, Mallett was named one of college football's most irreplaceable players by ESPN.com, and he appeared on College Football Live.At the SEC's 2010 Media Days conference, Mallett became the first Arkansas quarterback to be named preseason first-team All-SEC by the SEC coaches. He has been listed as the frontrunner for the Davey O'Brien Award by The Sporting News and a potential Heisman Trophy candidate. He was also named a preseason All-SEC quarterback and preseason All-American quarterback by numerous organizations.
Mallett's performance in 2009 has led to higher expectations in 2010. The junior has stated that he wishes to change the mindset of Arkansas fans into that of a winning program. The confident Mallett has been quoted saying, "I'm looking for 14," when asked about how many wins the 2010 Razorbacks can achieve.
On September 4, 2010, Mallet completed 21-of-24 passes (87.5%), setting an Arkansas school record for completion percentage in a game. The completion percentage also ranks second all-time in SEC football history. Mallett contributed 301 passing yards, as well, with a total of 8 receivers recording catches. Arkansas defeated Tennessee Tech in the game 44-3.
Mallett finished seventh in voting for the 2010 Heisman Trophy award.
On January 6, 2011 Mallett decided to forgo his senior year at Arkansas and declare for the 2011 NFL Draft shortly after Andrew Luck decided to stay for his senior year.
Mallett did say that Luck's decision did not have any impact on him declaring for the Draft.
Collegiate awards
2010 Premier Player of College Football Trophy Winner
2009 and 2010 All-SEC second team by Coaches and AP
Autozone Liberty Bowl Offensive MVP
SEC Offensive Player of the Week (vs. South Carolina & Mississippi State)
High school career

Mallett graduated from Texas High School in Texarkana, Texas, and was ranked as the #2 quarterback and #4 overall player in the nation by Rivals.com. He was also the Gatorade Player of the Year in Texas in 2006. Mallett participated in the U.S. Army All-American Bowl in 2007 and won the Glenn Davis Army Award as the best player on the West team.
College career
Mallett made his first appearance at Michigan in the second game of the 2007 season against Oregon. He entered the game for the injured Chad Henne in the third quarter and completed 6 of 17 passes for 49 yards and one interception. Mallett started the next week against Notre Dame and led the Wolverines to a 38-0 victory by throwing 3 touchdown passes, going 7/15 (46.7%) for 90 yards. Mallett started his first Big Ten conference game against Penn State the following week. He went 16/29 (55.2%) with 170 yards and one interception. He also scored on a 10-yard rush in the first quarter. Henne returned to start the Wolverines' next three games. In those games, Mallett had limited playing time completing .
Departure from Michigan
Mallett's departure from Michigan was widely expected after new head coach Rich Rodriguez was hired to replace retiring coach Lloyd Carr. Rodriguez overhauled Michigan's offense and installed a "spread" option offensive scheme, which did not fit Mallett's skills as a drop-back, pocket quarterback.
On January 14, 2008, Mallett made his move back to his home state official and enrolled at the University of Arkansas, where he redshirted the 2008 season due to the NCAA transfer policies. Mallett quarterbacked the Arkansas scout team in practice that season.
Arkansas
2009
In 2009 as a redshirt sophomore, Mallett began his career as an Arkansas Razorback, under the direction of head coach Bobby Petrino. Prior to the 2009 season, Mallett was named by ESPN's Bruce Feldman as one of college football's top 10 newcomers of the year, citing his arm strength as a major determining factor. In subsequent interviews, when Mallett was questioned about how far he could throw the football, he said farther than 80 yards.
On March 1, 2009, he was arrested on charges of public intoxication. He pled guilty to the misdemeanor charge on April 3, 2009 and paid $155 in court costs, fines, and fees. Mallett was also punished by Coach Petrino with early wake up calls, extra running, and early curfews.
Mallett earned the starting job in the Razorbacks' first game against Missouri State, going 17-of-22 for 309 yards and a touchdown. Two weeks later, Mallett passed for 408 yards and five touchdowns against Georgia in a losing effort. The passing yardage and touchdowns were single game school records. Ryan would throw for more than 250 yards in three of Arkansas' next five games, with nine touchdowns against three interceptions. Impressive victories over Texas A&M and Auburn were coupled with tough losses to Alabama and Ole Miss, and a loss vs. Florida. After a dismal 3-4 start, Mallett led Arkansas to three consecutive victories over Eastern Michigan (14-of-16 for 248 yards and three touchdowns), South Carolina (23-of-27 for 329 yards and one rushing touchdown), and Troy (23-of-30 for 405 yards, five touchdowns and one interception). Over those three games, he completed 83.1 % of his passes, and had a quarterback rating of 165.05, which was third-best in the nation. The victory over Troy pushed Arkansas' record to 6-4 and secured the Hogs' bowl eligibility, with games against Mississippi State and LSU remaining. Mallett went on to throw for 313 yards and matched his career high of five touchdown passes in a 42-21 victory over Mississippi State. The following week, he threw for 227 yards and a touchdown in a 33-30 overtime loss to LSU in Baton Rouge. Ryan was named to the All-SEC 2nd Team squad by the coaches and the AP for his performance during the season, behind Florida QB Tim Tebow despite superior passing statistics. The Razorbacks finished the 2009 season with an 8-5 record and won the 2010 Liberty Bowl against East Carolina University, 20-17 in OT. Mallett was named the bowl game's Offensive MVP.

Fossa (animal)

(States Twitter)-Fossa, is a cat-like, carnivorous mammal that is endemic to Madagascar. It is a member of the Eupleridae, a family of carnivorans closely related to the mongoose family (Herpestidae). Its classification has been controversial because its physical traits resemble those of cats, yet other traits suggest a close relationship with viverrids (most civets and their relatives). Its classification, along with that of the other Malagasy carnivores, influenced hypotheses about how many times mammalian carnivores have colonized the island. With genetic studies demonstrating that the fossa and all other Malagasy carnivores are most closely related to each other (forming a clade, recognized as the family Eupleridae), carnivorans are now thought to have colonized the island once around 18 to 20 million years ago.
The fossa is the largest mammalian carnivore on the island of Madagascar and has been compared to a small cougar. Adults have a head-body length of 70–80 cm (28–31 in) and weigh between 5.5–8.6 kg (12–19 lb), with the males larger than the females. It has semi-retractable claws and flexible ankles that allow it to climb up and down trees head-first, and also support jumping from tree to tree. The fossa is unique within its family for the shape of its genitalia, which share traits with those of cats and hyenas.
The species is widespread, although population densities are usually low. It is found solely in forested habitat, and actively hunts both by day and night. Over 50% of its diet consists of lemurs, the endemic primates found on the island; tenrecs, rodents, lizards, birds, and other animals are also documented as prey. Mating usually occurs in trees on horizontal limbs and can last for several hours. Litters range from one to six pups, which are born blind and toothless (altricial). Infants wean after 4.5 months and are independent after a year. Sexual maturity occurs around three to four years of age, and life expectancy in captivity is 20 years. The fossa is listed as "Vulnerable" by the International Union for Conservation of Nature (IUCN). It is generally feared by the Malagasy people and is often protected by their taboo, known as fady. The greatest threat to the species is habitat destruction.
Taxonomy

The fossa was formally described in 1833 by Edward Turner Bennett. The genus name Cryptoprocta refers to how the animal's anus is hidden by its anal pouch, from the Ancient Greek words crypto- "hidden", and procta "anus". The species name ferox is the Latin adjective "fierce" or "wild." Its common name is Malagasy and can be spelled fossa or fosa. The common name is the same as the generic name of the Malagasy civet (Fossa fossana), but they are different species. Because of shared physical traits with civets, mongooses, and cats (Felidae), its classification has been controversial. Bennett originally placed the fossa as a type of civet in the family Viverridae, a classification that long remained popular among taxonomists. Its compact braincase, large eye sockets, retractable claws, and specialized carnivorous dentition have also led some taxonomists to associate it with the felids. In 1939, William King Gregory and Milo Hellman placed the fossa in its own subfamily within Felidae, the Cryptoproctinae. George Gaylord Simpson placed it back in Viverridae in 1945, still within its own subfamily, yet conceded it had many cat-like characteristics.
Human interactions

The fossa has been assessed as "Vulnerable" by the IUCN Red List since 2008, as its population size has probably declined by at least 30% over the last 21 years; previous assessments have included "Endangered" (2000) and "Insufficiently Known" (1988, 1990, 1994) The species is dependent on forest and thus threatened by the widespread destruction of Madagascar's native forest, but is also able to persist in disturbed areas. A suite of microsatellite markers (short segments of DNA that have a repeated sequence) have been developed to help aid in studies of genetic health and population dynamics of both captive and wild fossas.Several pathogens have been isolated from the fossa, some of which, such as anthrax and canine distemper, are thought to have been transmitted by feral dogs or cats.
Description

The fossa appears as a diminutive form of a large felid, such as a cougar, but with a slender body and muscular limbs,and a tail nearly as long as the rest of the body. It has a mongoose-like head, relatively longer than that of a cat, although with a muzzle that is broad and short, and with large but rounded ears. It has medium brown eyes set relatively wide apart with pupils that contract to slits. Like many carnivorans that hunt at night, its eyes reflect light; the reflected light is orange in hue. Its head-body length is 70–80 cm (28–31 in) and its tail is 65–70 cm (26–28 in) long. There is some sexual dimorphism, with adult males (weighing 6.2–8.6 kg; 14–19 lb) being larger than females (5.5–6.8 kg; 12–15 lb). Smaller individuals are typically found north and east on Madagascar, while larger ones to the south and west. Unusually large individuals weighing up to 20 kg (44 lb) have been reported, but there is some doubt as to the reliability of the measurements. The fossa can smell, hear, and see well. It is a robust animal and illnesses are rare in captive fossas.
Habitat and distribution

The fossa has the most widespread geographical range of the Malagasy carnivores, and is generally found in low numbers throughout the island in remaining tracts of forest, preferring pristine undisturbed forest habitat. It is also encountered in some degraded forests, but in lower numbers. Although the fossa is found in all known forest habitats throughout Madagascar, including the western, dry deciduous forests, the eastern rainforests, and the southern spiny forests, it is seen more frequently in humid than in dry forests. This may be because the reduced canopy in dry forests provides less shade, and also because the fossa seems to travel more easily in humid forests. It is absent from areas with the heaviest habitat disturbance and, like most of Madagascar's fauna, from the central high plateau of the country.
The fossa has been found across several different elevational gradients in undisturbed portions of protected areas throughout Madagascar. In the Réserve Naturelle Intégrale d'Andringitra, evidence of the fossa has been reported at four different sites ranging from 810 to 1,625 m (2,660 to 5,331 ft). Its highest known occurrence was reported at 2,000 m (6,600 ft); its presence high on the Andringitra Massif was subsequently confirmed in 1996. Similarly, evidence has been reported of the fossa at the elevational extremes of 440 m (1,440 ft) and 1,875 m (6,152 ft) in the Andohahela National Park. The presence of the fossa at these locations indicates its ability to adapt to various elevations, consistent with its reported distribution in all Madagascar forest types.

Nuclear power plant

(States Twitter)-Nuclear power plant (NPP) is a thermal power station in which the heat source is one or more nuclear reactors.
Nuclear power plants are base load stations, which work best when the power output is constant (although boiling water reactors can come down to half power at night).

The conversion to electrical energy takes place indirectly, as in conventional thermal power plants: The heat is produced by fission in a nuclear reactor (in a coal power plant it would correspond to the boiler) and given to a heat transfer fluid - usually water (for a standard type light water reactor). Directly or indirectly water vapor-steam is produced. The pressurized steam is then usually fed to a multi-stage steam turbine. Steam turbines in Western nuclear power plants are among the largest steam turbines ever. After the steam turbine has expanded and partially condensed the steam, the remaining vapor is condensed in a condenser. The condenser is a heat exchanger which is connected to secondary side such as a river or a cooling tower. The water then pumped back into the nuclear reactor and the cycle begins again. The water-steam cycle corresponds to the Rankine cycle.
Nuclear reactors
See also: Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. The most common use of nuclear reactors is for the generation of electric energy and for the propulsion of ships.
The nuclear reactor is the heart of the plant. In its central part, the reactor core's heat is generated by controlled nuclear fission. With this heat, a coolant is heated as it is pumped through the reactor and thereby removes the energy from the reactor. Heat from nuclear fission is used to raise steam, which runs through turbines, which in turn powers either ship's propellers or electrical generators.
Since nuclear fission is creates radioactivity, the reactor core is surrounded by a protective shield. This containment absorbed radiation and prevent radioactive material released into the environment. In addition, many reactors are equipped with a dome of concrete to protect the reactor against external impacts.
In nuclear power plants, different types of reactor, different nuclear fuels, differing cooling circuits and moderators are sometimes used.
Steam turbine
The object of the steam turbine is to convert the heat contained in steam into rotational energy. To the turbine shaft, the shaft of the generator is coupled. In nuclear power plants are mostly Saturated steam turbine Application. The turbine has a high-pressure part, and usually two or three low pressure stages. Due to the high moisture vapor after the high pressure part of the steam is dried before entering the low pressure part of means of steam heating and high-speed deposition. At the end of the last blade row of the low pressure part of the steam has a moisture content of about 15%. The expansion into the wet steam region leads to a high working efficiency, but with the disadvantages associated with wet steam.
If the generator to hand over by a disturbance generated electrical energy can, he takes little analogy to mechanical energy. In response to this Load drop would be the Speed the turbine to increase the allowable operating limit by the threat of self-destruction too high Centrifugal. To avoid this process, are close to the turbine inlet valves in the steam pipe installed. If this quick-closing valves activated, they direct the steam bypassing the turbine directly into the Capacitor. In parallel, the reactor is shut down because of the full reactor power capacitor can absorb only a limited time.
The engine house with the steam turbine is usually structurally separated from the main reactor building. It is oriented to fly from the destruction of a turbine in operation as no debris in the direction of the reactor.
In the case of a pressurized water reactor, the steam turbine hermetically separated from the nuclear system. To detect a leak in the steam generator and thus the passage of radioactive water at an early stage is the outlet steam of the steam generator mounted an activity meter. In contrast, boiling water reactors and the steam turbine with radioactive water applied and therefore part of the control area of ​​the nuclear power plant.
Generator
The generator converts kinetic energy supplied by the turbine into electrical energy. Low-pole AC synchronous generators of high rated power are used. The Olkiluoto nuclear power plant was the largest synchronous generator (as of 2010) made. It has a rated power 1992 MW.
Main coolant pump (PWR) and forced circulation pump (BWR)
The reactor coolant pump in the case of the DWR has the task to circulate the coolant between the reactor and steam generators. In western nuclear power plants, the nuclear reactor is fed with four redundant pumps (loops), each separated by Redundancy structurally accommodated in the reactor building. The design of the pump corresponds to a Centrifugal with a one-piece forged body. The throughput is up to 10,000 l / s at a pressure of 175 bar and a maximum allowable temperature of 350 ° C. The increase in pressure through the main coolant pump when DWR indicates pressure loss in the reactor, steam generators and piping system. Even after the failure of the main coolant pumps (RESA is the result of) the circulation and thus the heat dissipation is by so-called Natural circulation guaranteed.
In the case of boiling water reactor are the reactor pressure vessel forced circulation pumps to avoid core wings attached to their interpretation is approximately equal to those in a PWR. You are responsible for the safety of the plant is not absolutely necessary.
Besides these main coolant pump of a nuclear power plant has usually still have several emergency supplies at different pressure levels, the case of disturbances (see Design basis accident) Maintain the cooling of the reactor core.
Safety valves
The pressure in the reactor pressure vessel at an incident, to limit upward, two independent safety valves are available. The pressure relief prevents bursting of pipes or reactor. The valves are in their capacity designed so that they can derive all of the supplied flow rates with little increase in pressure. In the case of the BWR, the steam is directed into the condensate chamber and condenses there. The chambers are on heat exchanger connected to the intermediate cooling circuit.
Should not close the safety valves, are very close again safety shut any, should, if necessary, prevent coolant accident. The non-closing of a safety valve led to a serious accident at Three Mile Island.
History

Electricity was generated for the first time by a nuclear reactor on December 20, 1951 at the EBR-I experimental station near Arco, Idaho in the United States. On June 27, 1954, the world's first nuclear power plant to generate electricity for a power grid started operations at Obninsk, USSR . The world's first commercial scale power station, Calder Hall in England opened in October 17, 1956.
For more history, see nuclear reactor and nuclear power.
For information on the Chernobyl accident which only had a partial containment structure, see that subject and RBMK and nuclear power.

Nuclear reactor technology

(States Twitter)-Nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. The most common use of nuclear reactors is for the generation of electric energy and for the propulsion of ships. Heat from nuclear fission is used to raise steam, which runs through turbines, which in turn powers either ship's propellors or electrical generators. A few reactors manufacture isotopes for medical and industrial use, and some reactors are only operated for research.
Early reactors

The neutron was discovered in 1932. The concept of a nuclear chain reaction brought about by nuclear reactions mediated by neutrons, was first realized shortly thereafter, by Hungarian scientist Leó Szilárd, in 1933. He filed a patent for his idea of a simple nuclear reactor the following year while working at the Admiralty in London. However, Szilárd's idea did not incorporate the idea of nuclear fission as a neutron source, since that process was not yet discovered. Szilárd's ideas for nuclear reactors using neutron-mediated nuclear chain reactions in light elements, proved unworkable.
Inspiration for a new type of reactor using uranium came from the discovery by Lise Meitner, Fritz Strassman and Otto Hahn in 1938 that bombardment of uranium with neutrons (provided by an alpha-on-beryllium fusion reaction, a "neutron howitzer") produced a barium residue, which they reasoned was created by the fissioning of the uranium nuclei. Subsequent studies in early 1939 (one of them by Szilárd and Fermi) revealed that several neutrons were also released during the fissioning, making available the opportunity for the nuclear chain reaction that Szilárd had envisioned six years previously.
On August 2, 1939 Albert Einstein signed a letter to President Franklin D. Roosevelt (written by Szilard) suggesting that the discovery of uranium's fission could lead to the development of "extremely powerful bombs of a new type", giving impetus to the study of reactors and fission. Szilárd and Einstein knew each other well and had worked together years previously, but Einstein had never thought about this possibility for nuclear energy until Szilard reported it to him, at the beginning of his quest to produce the Einstein-Szilard letter to alert the U.S. government.
Shortly after, Hitler's Germany invaded Poland in 1939, starting World War II in Europe. The U.S. was not yet officially at war, but in October, when the Einstein-Szilard letter was delivered to Roosevelt, he commented that the purpose of doing the research was to make sure "the Nazis don't blow us up." The U.S. nuclear project followed, although with some delay as there remained skepticism (some of it from Fermi) and also little action from the small number of officials in the government who were initially charged with moving the project forward.
The following year the U.S. Government received the Frisch–Peierls memorandum from the UK, which stated that the amount of uranium needed for a chain reaction was far lower then had previously been thought. The memorandum was a product of the MAUD Committee, which was working on the UK atomic bomb project, known as Tube Alloys, later to be subsumed within the Manhattan Project.
Eventually, the first artificial nuclear reactor, Chicago Pile-1, was constructed at the University of Chicago, by a team led by Enrico Fermi, in late 1942. By this time, the program had been pressured for a year by U.S. entry into the war. The Chicago Pile achieved criticality on December 2, 1942 at 3:25 PM. The reactor support structure was made of wood, which supported a pile (hence the name) of graphite blocks, embedded in which was natural uranium-oxide 'pseudospheres' or 'briquettes'.
Soon after the Chicago Pile, the U.S. military developed a number of nuclear reactors for the Manhattan Project starting in 1943. The primary purpose for the largest reactors (located at the Hanford Site in Washington state), was the mass production of plutonium for nuclear weapons. Fermi and Szilard applied for a patent on reactors on 19 December 1944. Its issuance was delayed for 10 years because of wartime secrecy.
"World's first nuclear power plant" is the claim made by signs at the site of the EBR-I, which is now a museum near Arco, Idaho. This experimental LMFBR operated by the U.S. Atomic Energy Commission produced 0.8 kW in a test on December 20, 1951 and 100 kW (electrical) the following day, having a design output of 200 kW (electrical).
Besides the military uses of nuclear reactors, there were political reasons to pursue civilian use of atomic energy. U.S. President Dwight Eisenhower made his famous Atoms for Peace speech to the UN General Assembly on December 8, 1953. This diplomacy led to the dissemination of reactor technology to U.S. institutions and worldwide.
The first nuclear power plant built for civil purposes was the AM-1 Obninsk Nuclear Power Plant, launched on June 27, 1954 in the Soviet Union. It produced around 5 MW (electrical).
After World War II, the U.S. military sought other uses for nuclear reactor technology. Research by the Army and the Air Force never came to fruition; however, the U.S. Navy succeeded when they steamed the USS Nautilus (SSN-571) on nuclear power January 17, 1955.
The first commercial nuclear power station, Calder Hall in Sellafield, England was opened in 1956 with an initial capacity of 50 MW (later 200 MW).
The first portable nuclear reactor "Alco PM-2A" used to generate electrical power (2 MW) for Camp Century from 1960.
Components

The control room of NC State's Pulstar Nuclear Reactor.
The key components common to most types of nuclear power plants are:
Nuclear fuel
Nuclear reactor core
Neutron moderator
Neutron poison
Coolant (often the Neutron Moderator and the Coolant are the same, usually both purified water)
Control rods
Reactor vessel
Boiler feedwater pump
Steam generators (not in BWRs)
Steam turbine
Electrical generator
Condenser
Cooling tower (not always required)
Radwaste System (a section of the plant handling radioactive waste)
Refueling Floor
Spent fuel pool
Nuclear safety systems
Reactor Protective System (RPS)
Emergency Diesel Generators
Emergency Core Cooling Systems (ECCS)
Standby Liquid Control System (emergency boron injection, in BWRs only)
Essential service water system (ESWS)
Containment building
Control room
Emergency Operations Facility
Nuclear training facility (usually contains a Control Room simulator)

Just as conventional power stations generate electricity by harnessing the thermal energy released from burning fossil fuels, nuclear reactors convert the thermal energy released from nuclear fission.
Fission
When a large fissile atomic nucleus such as uranium-235 or plutonium-239 absorbs a neutron, it may undergo nuclear fission. The heavy nucleus splits into two or more lighter nuclei, releasing kinetic energy, gamma radiation and free neutrons; collectively known as fission products. A portion of these neutrons may later be absorbed by other fissile atoms and trigger further fission events, which release more neutrons, and so on. This is known as a nuclear chain reaction.
The reaction can be controlled by using neutron poisons, which absorb excess neutrons, and neutron moderators, which reduce the velocity of fast neutrons, thereby turning them into thermal neutrons, which are more likely to be absorbed by other nuclei. Increasing or decreasing the rate of fission has a corresponding effect on the energy output of the reactor.
Commonly used moderators include regular (light) water (75% of the world's reactors), solid graphite (20% of reactors) and heavy water (5% of reactors). Beryllium has also been used in some experimental types, and hydrocarbons have been suggested as another possibility.
Heat generation
The reactor core generates heat in a number of ways:
The kinetic energy of fission products is converted to thermal energy when these nuclei collide with nearby atoms.
Some of the gamma rays produced during fission are absorbed by the reactor, their energy being converted to heat.
Heat produced by the radioactive decay of fission products and materials that have been activated by neutron absorption. This decay heat source will remain for some time even after the reactor is shut down.
A kilogram of uranium-235 (U-235) converted via nuclear processes releases approximately three million times more energy than a kilogram of coal burned conventionally (7.2 × 1013 joules per kilogram of uranium-235 versus 2.4 × 107 joules per kilogram of coal).
Cooling
A nuclear reactor coolant — usually water but sometimes a gas or a liquid metal or molten salt — is circulated past the reactor core to absorb the heat that it generates. The heat is carried away from the reactor and is then used to generate steam. Most reactor systems employ a cooling system that is physically separated from the water that will be boiled to produce pressurized steam for the turbines, like the pressurized water reactor. But in some reactors the water for the steam turbines is boiled directly by the reactor core, for example the boiling water reactor.
Reactivity control
Nuclear reactor control, Passive nuclear safety, Delayed neutron, Iodine pit, SCRAM, and Decay heat
The power output of the reactor is adjusted by controlling how many neutrons are able to create more fissions.
Control rods that are made of a neutron poison are used to absorb neutrons. Absorbing more neutrons in a control rod means that there are fewer neutrons available to cause fission, so pushing the control rod deeper into the reactor will reduce its power output, and extracting the control rod will increase it.
At the first level of control in all nuclear reactors, a process of delayed neutron emission by a number of neutron-rich fission isotopes is an important physical process. These delayed neutrons account for about 0.65% of the total neutrons produced in fission, with the remainder (termed "prompt neutrons") released immediately upon fission. The fission products which produce delayed neutrons have half lives for their decay by neutron emission that range from milliseconds to as long as several minutes. Keeping the reactor in the zone of chain-reactivity where delayed neutrons are necessary to achieve a critical mass state, allows time for mechanical devices or human operators to have time to control a chain reaction in "real time"; otherwise the time between achievement of criticality and nuclear meltdown as a result of an exponential power surge from the normal nuclear chain reaction, would be too short to allow for intervention.
In some reactors, the coolant also acts as a neutron moderator. A moderator increases the power of the reactor by causing the fast neutrons that are released from fission to lose energy and become thermal neutrons. Thermal neutrons are more likely than fast neutrons to cause fission, so more neutron moderation means more power output from the reactors. If the coolant is a moderator, then temperature changes can affect the density of the coolant/moderator and therefore change power output. A higher temperature coolant would be less dense, and therefore a less effective moderator.
In other reactors the coolant acts as a poison by absorbing neutrons in the same way that the control rods do. In these reactors power output can be increased by heating the coolant, which makes it a less dense poison. Nuclear reactors generally have automatic and manual systems to Scram the reactor in an emergency shut down. These systems insert large amounts of poison (often boron in the form of boric acid) into the reactor to shut the fission reaction down if unsafe conditions are detected or anticipated.
Most types of reactors are sensitive to a process variously known as xenon poisoning, or the iodine pit. Xenon-135 is normally produced in the fission process, and acts as a neutron absorbing "neutron poison", which acts to shut the reactor down, but can be controlled in turn within the reactor by keeping neutron and power levels high enough to destroy it as fast as it is produced. The normal fission process also produces iodine-135, which in turn decays with a half life of under seven hours, to new xenon-135. Thus, if the reactor is shut down, iodine-135 in the reactor continues to decay to xenon-135, to the point that the new xenon-135 from this source ("xenon poisoning") makes re-starting the reactor more difficult, for a day or two, than when first shut down (this temporary state is the "iodine pit.") If the reactor has sufficient extra capacity, it can still be re-started before the iodine-135 and xenon-135 decay, but as the extra xenon-135 is "burned off" by transmuting it to xenon-136 (not a neutron poison), within a few hours the reactor may become unstable as a result of such a "xenon burnoff (power) transient," and then rapidly become overheated, unless control rods are reinserted in order to replace the neutron absorption of the lost xenon-135. Failure to properly follow such a procedure, was a key step in the Chernobyl disaster.
Electrical power generation
The energy released in the fission process generates heat, some of which can be converted into usable energy. A common method of harnessing this thermal energy is to use it to boil water to produce pressurized steam which will then drive a steam turbine that generates electricity.
Classification by moderator material
Used by thermal reactors:
Graphite moderated reactors
Water moderated reactors
Heavy water reactors
Light water moderated reactors (LWRs). Light water reactors use ordinary water to moderate and cool the reactors. When at operating temperature, if the temperature of the water increases, its density drops, and fewer neutrons passing through it are slowed enough to trigger further reactions. That negative feedback stabilizes the reaction rate. Graphite and heavy water reactors tend to be more thoroughly thermalised than light water reactors. Due to the extra thermalization, these types can use natural uranium/unenriched fuel.
Light element moderated reactors. These reactors are moderated by lithium or beryllium.
Molten salt reactors (MSRs) are moderated by a light elements such as lithium or beryllium, which are constituents of the coolant/fuel matrix salts LiF and BeF2.
Liquid metal cooled reactors, such as one whose coolant is a mixture of Lead and Bismuth, may use BeO as a moderator.
Organically moderated reactors (OMR) use biphenyl and terphenyl as moderator and coolant.
Classification by coolant
In thermal nuclear reactors (LWRs in specific), the coolant acts as a moderator that must slow down the neutrons before they can be efficiently absorbed by the fuel.
Water cooled reactor. There are 104 operating reactors in the United States. Of these, 69 are pressurized water reactors (PWR), and 35 are boiling water reactors (BWR).
Pressurized water reactor (PWR)
A primary characteristic of PWRs is a pressurizer, a specialized pressure vessel. Most commercial PWRs and naval reactors use pressurizers. During normal operation, a pressurizer is partially filled with water, and a steam bubble is maintained above it by heating the water with submerged heaters. During normal operation, the pressurizer is connected to the primary reactor pressure vessel (RPV) and the pressurizer "bubble" provides an expansion space for changes in water volume in the reactor. This arrangement also provides a means of pressure control for the reactor by increasing or decreasing the steam pressure in the pressurizer using the pressurizer heaters.
Pressurised heavy water reactors are a subset of pressurized water reactors, sharing the use of a pressurized, isolated heat transport loop, but using heavy water as coolant and moderator for the greater neutron economies it offers.
Boiling water reactor (BWR)
BWRs are characterized by boiling water around the fuel rods in the lower portion of a primary reactor pressure vessel. A boiling water reactor uses 235U, enriched as uranium dioxide, as its fuel. The fuel is assembled into rods that are submerged in water and housed in a steel vessel. The nuclear fission causes the water to boil, generating steam. This steam flows through pipes into turbines. The turbines are driven by the steam, and this process generates electricity. During normal operation, pressure is controlled by the amount of steam flowing from the reactor pressure vessel to the turbine.
Pool-type reactor
Liquid metal cooled reactor. Since water is a moderator, it cannot be used as a coolant in a fast reactor. Liquid metal coolants have included sodium, NaK, lead, lead-bismuth eutectic, and in early reactors, mercury.
Sodium-cooled fast reactor
Lead-cooled fast reactor
Gas cooled reactors are cooled by a circulating inert gas, often helium in high-temperature designs, while carbon dioxide has been used in past British and French nuclear power plants. Nitrogen has also been used.[citation needed] Utilization of the heat varies, depending on the reactor. Some reactors run hot enough that the gas can directly power a gas turbine. Older designs usually run the gas through a heat exchanger to make steam for a steam turbine.
Molten Salt Reactors (MSRs) are cooled by circulating a molten salt, typically a eutectic mixture of fluoride salts, such as FLiBe. In a typical MSR, the coolant is also used as a matrix in which the fissile material is dissolved.
Classification by generation
Generation I reactor
Generation II reactor (most current nuclear power plants)
Generation III reactor (evolutionary improvements of existing designs)
Generation IV reactor (technologies still under development)
The "Gen IV"-term was dubbed by the United States Department of Energy (DOE) for developing new plant types in 2000. In 2003, the French Commissariat à l'Énergie Atomique (CEA) was the first to refer to Gen II types in Nucleonics Week; . First mentioning of Gen III was also in 2000 in conjunction with the launch of the Generation IV International Forum (GIF) plans.
Classification by phase of fuel
Solid fueled
Fluid fueled
Aqueous homogeneous reactor
Molten salt reactor
Gas fueled (theoretical)
Classification by use
Electricity
Nuclear power plants
Propulsion, see nuclear propulsion
Nuclear marine propulsion
Various proposed forms of rocket propulsion
Other uses of heat
Desalination
Heat for domestic and industrial heating
Hydrogen production for use in a hydrogen economy
Production reactors for transmutation of elements
Breeder reactors are capable of producing more fissile material than they consume during the fission chain reaction (by converting fertile U-238 to Pu-239, or Th-232 to U-233). Thus, a uranium breeder reactor, once running, can be re-fueled with natural or even depleted uranium, and a thorium breeder reactor can be re-fueled with thorium; however, an initial stock of fissile material is required.
Creating various radioactive isotopes, such as americium for use in smoke detectors, and cobalt-60, molybdenum-99 and others, used for imaging and medical treatment.
Production of materials for nuclear weapons such as weapons-grade plutonium
Providing a source of neutron radiation (for example with the pulsed Godiva device) and positron radiation (e.g. neutron activation analysis and potassium-argon dating
Research reactor: Typically reactors used for research and training, materials testing, or the production of radioisotopes for medicine and industry. These are much smaller than power reactors or those propelling ships, and many are on university campuses. There are about 280 such reactors operating, in 56 countries. Some operate with high-enriched uranium fuel, and international efforts are underway to substitute low-enriched fuel.

Athens, Alabama

(States Twitter)-Athens is a city in Limestone County, Alabama, United States. As of the 2000 census, the population of the city is 18,967. According to the 2009 U.S. Census estimates, the city had a population of 24,234. The city is the county seat of Limestone County and is included in the Huntsville-Decatur Combined Statistical Area.
Demographics
As of the census of 2000, there were 18,967 people, 7,742 households, and 5,140 families residing in the city. The population density was 482.3 people per square mile (186.2/km2). There were 8,449 housing units at an average density of 214.8 per square mile (82.9/km2). The racial makeup of the city was 77.72% White, 18.26% Black or African American, 0.40% Native American, 0.71% Asian, 0.02% Pacific Islander, 1.92% from other races, and 0.97% from two or more races. 4.86% of the population were Hispanic or Latino of any race.
There were 7,742 households out of which 30.5% had children under the age of 18 living with them, 50.0% were married couples living together, 13.0% had a female householder with no husband present, and 33.6% were non-families. 31.0% of all households were made up of individuals and 13.2% had someone living alone who was 65 years of age or older. The average household size was 2.37 and the average family size was 2.97.
In the city the population was spread out with 23.9% under the age of 18, 9.3% from 18 to 24, 28.4% from 25 to 44, 22.5% from 45 to 64, and 15.8% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 89.8 males. For every 100 females age 18 and over, there were 85.5 males.
The median income for a household in the city of Athens was $33,980, and the median income for a family was $44,544. Males had a median income of $37,191 versus $22,748 for females. The per capita income for the city was $19,315. About 13.7% of families and 16.3% of the population were below the poverty line, including 21.2% of those under age 45and 100.8% of those age 65 or over.
Geography

Athens is located at 34°47′23″N 86°58′10″W (34.789602, -86.969424). It is halfway in between Nashville and Birmingham on Interstate 65. Athens shares a city limit boundary with Huntsville.
According to the U.S. Census Bureau, the city has a total area of 39.4 square miles (102.1 km2), of which, 39.3 square miles (101.9 km2) of it is land and 0.1 square miles (0.2 km2) of it (0.23%) is water.

History

Founded in 1818 by John Coffee, Robert Beaty, John D. Carroll, and John Read, Athens is one of the oldest incorporated cities in the State of Alabama, having been incorporated one year prior to the state's admittance to the Union in 1819. Limestone County was also created by an act of the Alabama Territorial Legislature in 1818. The town was first called Athenson, then the name was then shortened to Athens, after the ancient city in Greece. The town's first mayor was Samuel Tanner, and the town just south of Athens was named on his behalf.
The Athens area was the home of William Wyatt Bibb, the first Governor of Alabama, and of its second Governor, his brother Thomas Bibb, who succeeded him in office when he died in a fall from his horse.
In 1822, local residents purchased 5 acres (20,000 m2) of land and built a building to house the Athens Female Academy. The school became affiliated with the Methodist church in 1842, and was eventually renamed Athens Female College. After becoming coeducational in 1932, the school changed its name again to Athens College. After being taken over by the State of Alabama in 1974, the college was converted to a “reverse junior college,” offering the last two years of instruction for graduates of area community colleges. It is today known as Athens State University.
Many homes in the central part of modern Athens date to the antebellum period, and are part of historic preservation districts.
On May 2, 1862, during the Civil War, Athens was seized by Union forces under the command of Col. John Basil Turchin, a Russian émigré. After occupying the town, Turchin assembled his men and told them: "I shut my eyes for two hours. I see nothing." Business were hit first, and anything of value that could be carried away were looted and anything that could not be was simply destroyed. After rampaging through stores the soldiers plundered private homes. A slave girl was raped. The soldiers also attempted to rape a servant girl. The violent behavior of the soldiers caused a pregnant woman to suffer a miscarriage and die. The townpeople estimated the damge to be fifty-five thousand dollars. The resulting pillage and plunder came to be known as the Rape of Athens.

Browns Ferry Nuclear Power Plant

(States Twitter)-Browns Ferry Nuclear Plant is located on the Tennessee River near Decatur and Athens, Alabama, on the north side (right bank) of Wheeler Lake. The nuclear power plant is named after a ferry that operated at the site until the middle of the 20th century. The site has three General Electric boiling water reactor (BWR) nuclear generating units and is owned entirely by the Tennessee Valley Authority. Browns Ferry was TVA's first nuclear power plant; its approval occurred on June 17, 1966 and construction began in September 1966. In 1974, the time of its initial operation, it was the largest nuclear plant in the world. It was the first nuclear plant in the world to generate more than 1 gigawatt of power.
In 2006, the Nuclear Regulatory Commission (NRC) renewed the licenses for all three reactors, extending them for an additional twenty years.
Unit One
Unit One is a 1,065 MWe BWR built by General Electric. Construction started on Unit One September 12, 1966[1] and originally came online on December 20, 1973. It is licensed to operate through December 20, 2033. However, Unit One was shut down for a year after a fire in 1975 damaged the unit. The unit was subsequently repaired and operated from 1976 through 1985, when all three Browns Ferry units were shut down for operational and management issues. Units Two and Three were restarted in 1991 and 1995, respectively.
Starting in 2002, TVA undertook an effort to restore Unit One to operational status, spending $1.8 billion to do so. The United States Nuclear Regulatory Commission (NRC) approved the restart of Unit 1 on May 15, 2007 and the reactor was brought up to criticality on May 22 for the first time since March 3, 1985. During initial testing after restart, on May 24, 2007, a leaky hydraulic control pipe in the turbine hall burst, spilling about 600 gallons of non-radioactive fluid, and the newly restarted reactor was temporarily powered down. Reactor power-up and tests resumed on May 27 and the unit started supplying power to the electricity supply grid on June 2, 2007, reaching full power on June 8. The Browns Ferry restart is expected to pay for itself in five years.
Unit One fire
Polyurethane foam used to fill a cable tray penetration at a power plant in Nova Scotia (subsequently removed and replaced with firestop mortar).
The March 22, 1975 fire started when a worker using a candle to search for air leaks accidentally set a temporary cable seal on fire. At Browns Ferry, foamed plastic covered on both sides with two coats of a flame retardant paint was used as a firestop. The fire spread from the temporary seal into the foamed plastic, causing significant damage to the reactor control cabling in the station.
A U.S. Nuclear Regulatory Commission bulletin explained the circumstances of the fire.
The fire started in the cable spreading room at a cable penetration through the wall between the cable spreading room and the reactor building for Unit 1. A slight differential pressure is maintained (by design) across this wall, with the higher pressure being on the cable spreading room side. The penetration seal originally present had been breached to install additional cables required by a design modification. Site personnel were resealing the penetration after cable installation and were checking the airflow through a temporary seal with a candle flame prior to installing the permanent sealing material. The temporary sealing material was highly combustible, and caught fire. Efforts were made by the workers to extinguish the fire at its origin, but they apparently did not recognize that the fire, under the influence of the draft through the penetration, was spreading on the reactor building side of the wall. The extent of the fire in the cable spreading room was limited to a few feet from the penetration; however, the presence of the fire on the other side of the wall from the point of ignition was not recognized until significant damage to cables related to the control of Units 1 and 2 had occurred.
This later resulted in the Nuclear Regulatory Commission making significant additions to the standards for fire protection through the publication of 10CFR50.48 and Appendix R. According to the Nuclear Information and Resource Service, the newly-restarted Unit One does not comply with these standards. Unit Three was not affected by the accident. This event was pivotal not just for firestopping in the nuclear field, but also in commercial and industrial construction. While the nuclear field went to installations of silicone foam, a wider array of firestops became prevalent in non-nuclear construction.
In a 2005 analysis of significant nuclear safety occurrences in the US, the NRC concluded that the fire at Browns Ferry was the most likely (excluding the actual accident at TMI) "precursor" incident to have led to a nuclear accident in the event of a subsequent failure.
Unit Two

Unit Two is a 1,113 MWe BWR built by General Electric which originally came online on August 2, 1974, and is licensed to operate through June 28, 2034. Unit Two generated 8.911261 TW-h of electricity in 2003, achieving a capacity factor of 94.1%.
During a drought in August 2007, Unit Two was shut down for one day because water temperature in the Tennessee River rose too high for the water to be used for cooling and then discharged back into the river.
Beginning in 2005 Unit 2 was loaded with BLEU (Blended Low Enriched Uranium) recovered by the DOE from weapons programs. This fuel contains quantities of U-236 and other contaminants because it was made from reprocessed fuel from weapons program reactors and therefore has slightly different characteristics when used in a reactor as compared to fresh uranium fuel. By making use of this fuel which would otherwise have been disposed of as waste the TVA is saving millions of dollars in fuel costs and accumulating a database of recycled uranium reactions in LWR use.
Unit Three

Unit Three is a 1,113 MWe BWR built by General Electric which originally came online on August 18, 1976, and is licensed to operate through July 2, 2036. Unit Three generated 9.260078 TW·h, achieving a capacity factor of 99%.
Seismic risk

The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Browns Ferry was: Reactor 1: 1 in 270,270; Reactors 2 and 3: 1 in 185,185, according to an NRC study published in August 2010.
Surrounding population

The population within 50 miles (80 km) of Browns Ferry was 977,941, according to 2010 U.S. Census data analyzed for msnbc.com, an increase of 11.0 percent in a decade. The 2010 population within 10 miles (16 km) is 39,930 (increase of 12.3 percent). Cities within 50 miles (80 km) include Huntsville (28 miles to city center).

Tuscaloosa Birmingham tornado

(States Twitter)-A large wedge tornado tracked across Tuscaloosa County, Alabama, including the southern and eastern portions of Tuscaloosa around 5:10 p.m. CDT and continued northeast. Debris from the tornado was reported to be falling from the sky across Birmingham over 20 miles away in Jefferson County. Skycams operated by local Fox affiliate WBRC (channel 6) and ABC affiliate WBMA-LP/WCFT/WJSU (channels 58, 33 and 40; branded as "ABC 33/40") captured video of the tornado as it struck Tuscaloosa. Several stores and restaurants in a business district at the intersection of McFarland Boulevard and 15th Street, near the DCH Regional Medical Center, were destroyed by the tornado; buildings were also reported destroyed on 35th Street, between Interstate 359 and Martin Luther King Jr. Boulevard. As the tornado traveled east to 35th Street and Kauloosa Avenue, the Tuscaloosa Environmental Services and Cintas facilities suffered severe damage. Numerous homes in the Rosedale and Forest Lake neighborhoods, as well as a P&P Grocery store in Rosedale, were devastated. The University of Alabama suspended its operations, cancelled its softball and rowing competitions, cancelled its final exams period, and postponed its commencement until August 6.


The remains of an apartment complex in Tuscaloosa, AL.
Television cameras, including another skycam operated by WBMA-LP/WCFT/WJSU, captured the mile-wide tornado as it moved east-northeast across the western and northern suburbs of Birmingham around 6:00 p.m. CDT. Initial reports indicate significant structural damage and a mile to 1½ mile wide damage path.
Unofficial surveys have categorized the damage from the tornado that hit Tuscaloosa and the northwestern suburbs of Birmingham as EF4 and possibly EF5, among them by Dr. Greg Forbes of The Weather Channel. Forbes, a student of Dr. Ted Fujita and a major contributor to the Enhanced Fujita Scale, did an aerial tour with the NWS office in Birmingham, Alabama. The overall death toll is uncertain, but initial reports from Tuscaloosa and Birmingham indicated at least 36 people were dead and over 600 injured in the Tuscaloosa area and at least 10 people confirmed dead from Concord and Pleasant Grove. The number of fatalities is highly uncertain due to ongoing search and rescue efforts and is subject to revision following surveys on the track of the tornado from the National Weather Service. Confirmed deaths from this cell stand at 45 in Tuscaloosa County and 19 in Jefferson County on April 29. President Barack Obama and First lady Michelle Obama visited Tuscaloosa on April 29, taking a ground tour of some of the affected areas. He was quoted as saying that he has "never seen devastation like this." He stated further that he had already declared a federal state of emergency in Alabama.
[edit]Non-tornadic events

Minor thunderstorms were reported as far north as Northern Ontario on the evening of April 26. Heavy rains and minor flooding were also reported in Northern Ontario from April 26-28. Windstorms were also reported in Southern Ontario which resulted in some injuries, including one death. Strong Thunderstorms and heavy downpours which led to flooding was also reported in multiple areas across Upstate New York with heavy flooding in the Syracuse, New York area. Interstate 81 was briefly shut down downtown at traffic hour and Upstate University Hopspital also closed briefly due to flooding in the lobby.
Aftermath

Alabama Governor Robert J. Bentley declared a state of emergency in the state of Alabama, due to storm damage from severe thunderstorms earlier on April 27, as well as the forthcoming severe weather later that day. In addition, state of emergency declarations were also placed in Arkansas, Kentucky, Mississippi, Missouri, Tennessee and Oklahoma, because of the flooding and tornadoes.Following the tornado outbreak on the evening of April 27, President Barack Obama granted a federal emergency declaration for the state of Alabama, giving federal assistance, including search and rescue assets to the affected region. More than 2,000 National Guard troops have been deployed to Alabama, assisting local and state first responders in search and rescue efforts. It was announced on April 28, 2011 that Obama would be visiting the affected areas of Alabama on the 29th.
Fatalities by state
State Deaths As of local date & time
Alabama 238 29 Apr 2011 2:52pm CDT
Tennessee 34 29 Apr 2011 10:00am CDT
Mississippi 33 28 Apr 2011 7:45pm CDT
Georgia 15 29 Apr 2011
Arkansas 13[62] 28 Apr 2011 8:00pm CDT
Virgini 28 Apr 2011
Kentucky 1 29 Apr 2011
Total 339
*With no confirmed tornadoes in Kentucky for the 27th, it is possible this is a flooding-related death.
Browns Ferry Nuclear Plant
The Chattanooga Times Free Press reported that the Tennessee Valley Authority had lost the ability to transmit power from its Browns Ferry Nuclear Plant. The loss of ability to transmit power from the plant had forced it to perform a cold shutdown while being run with diesel generators. Chief Operating Officer Bill McCollum of TVA stated that it could be weeks before the plant is up and running again. The Nuclear Regulatory Commission stated at a press conference "The plants' conditions are stable and are being placed in a cooled-down condition.

Most significant tornadoes

(States Twitter)-      Vilonia tornado
The first killer tornado of the outbreak was a large EF2 that struck the small town of Vilonia, Arkansas (Faulkner County) around 7:30 pm CDT on April 25. A tornado warning was issued for the town roughly 30 minutes prior to the tornado's arrival and the relatively low loss of life is attributed to this lead time. A tornado emergency was declared at 7:24 pm CDT for Vilonia shortly before the tornado struck. Four people are known to have been killed in the town and many more injured. Numerous structures were also damaged or destroyed. One mobile home was completely destroyed and debris from the home was scattered a significant distance from where it stood. Several other homes were reportedly leveled by the tornado. Within five minutes of the storm, local fire fighters arrived in the town and began search and rescue efforts. Following the tornado, 85 members of the National Guard were deployed to assist in search and rescue, debris clearing, security and traffic control.
Smithville tornado
A violent tornado struck Smithville, Mississippi, at 2:44 p.m. CDT on April 27. The damage path was less than three miles long, but was half a mile wide, and did extreme damage in Smithville. While initial reports indicated more widespread damage, the NWS damage survey reported EF5 damage, with 18 homes, a post office, a police station, and what was listed as the "water system" completely destroyed, with 52 homes and 7 businesses damaged to varying degrees. Dozens of newly constructed two-story, brick homes were leveled and trees were debarked. Five people are reported as missing. Damage assessments have determined that 150 homes, 14 businesses and 2 churches were destroyed by the tornado in Smithville. The homes were well-built, of recent construction, but the storm was violent enough that all appliances and plumbing fixtures in the damage path were "shredded or missing." 14 people were killed, and 40 injured. The tornado has been officially rated as an EF5 tornado with estimated winds of 205 mph; information is still preliminary.
This was the first confirmed EF5 tornado anywhere in the world since the Parkersburg, Iowa, tornado on May 25, 2008.
Rainsville tornado
This storm, preliminarily rated EF4, is likely to have begun in the Lakeview community northeast of Geraldine, Alabama. The tornado then tracked northeastward generally parallel and just east of State Route 75 through Fyffe, Rainsville, and Sylvania killing 30 people. Damage has also been reported farther to the northeast through the Henagar and Ider areas, although these locations have not been surveyed yet.
The tornado touched town in the Lakeview community initially causing structural damage to small buildings and snapping trees. The tornado grew in intensity and the path width increased from around 50 yards to a half a mile as it entered the the Rainsville and Sylvania communities Damage included houses that were completely removed from foundations and debris scattered for about one mile, trees were debarked, and a few mobile homes were completely destroyed with debris strewn for about a mile downstream. In Sylvania, some of these houses completely removed from foundations contained anchor bolts and foundation straps. Further surveys will be conducted along points between Fyffe and Lakeview and eventually beyond Sylvania, where additional damage occurred.