Carolinas-Virginia Tube Reactor
Encyclopedia
Carolinas-Virginia Tube Reactor (CVTR) was an experimental pressurized tube heavy water
nuclear power reactor at Parr, South Carolina
in Fairfield County. It was built and operated by the Carolinas Virginia Nuclear Power Associates.
and cooled pressurized tube reactor
for civilian power. It was the first US heavy water power reactor.
The reactor consisted of 36 vertical U-tube fuel channels in a moderator tank which was 10 feet in diameter and 16 feet tall. Each leg of the U-tube contained one fuel assembly made up of 19 fuel rods. The reactor used enriched uranium
; 12 of the tubes contained fuel enriched to 1.5% U-235 and 24 tubes contained fuel enriched to 2% U-235.
During power operation, heavy water was circulated by primary pumps through the U-tubes containing the fuel assemblies which heated the water. The heated water then flowed through an inverted U-tube steam generator
where the heat was transferred to the secondary side light water which turned to steam
. The steam flowed to an oil-fired superheater
which increased the steam quality before the steam entered the turbine
which spun the electrical generator
. After passing through the steam generator, the primary loop water was pumped back to the reactor by the primary pumps to repeat the cycle. The primary loop heavy water was pressurized to ensure that the heavy water remained liquid and did not flash
to steam at any point in the loop.
The U-shaped pressure tubes containing the fuel were thermally isolated from the hot fuel assembly by two circular thermal baffle tubes around the fuel assembly. This allowed the pressure tubes to operate at low temperatures, essentially that of the moderator tank which was maintained about 155 degrees F and close to atmospheric pressure. The moderator tank contained heavy water which moderated the fission process during operation of the reactor.
The CVTR containment
design was a new concept at the time; the general design later became the prevalent design for pressurized water reactor containments in the United States. Designed by Stone and Webster Engineering, the design was focused on not allowing any leakage of radioactive gases or material following an accident. The containment design featured a flat concrete foundation, cylindrical walls, and a hemispherical dome, all with an airtight 1/2" or 1/4" (depending on location) steel plate welded liner. The containment was constructed of reinforced concrete
. From the basement floor to the interior surface of the top of the dome measured 114’-2”. The vertical walls were 2’-0” thick, the cylindrical structure had an interior diameter of 58’-0”, and the dome had a slightly larger interior radius of 29’-4”.
The reactor and facilities were located at Parr, SC just to the northeast of the existing Parr Reservoir
hydroelectric dam across the Broad River
on a high bluff that overlooks the dam powerhouse.
’s Advisory Committee on Reactor Safeguards in January 1959. Construction started in 1960.
for the first time on March 30, 1963. CVTR operated successfully from 1963 to 1967. It was shut down after the completion of the planned test program.
By the Fall of 2009, demolition was complete and the site returned to greenfield
.
The much larger and currently operational Virgil C. Summer Nuclear Generating Station is located approximately three miles north of the CVTR.
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...
nuclear power reactor at Parr, South Carolina
South Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...
in Fairfield County. It was built and operated by the Carolinas Virginia Nuclear Power Associates.
Purpose
Construction started in 1960. The CVTR was built to test the concept of a heavy water moderatedNeutron moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235....
and cooled pressurized tube reactor
Pressurized water reactor
Pressurized water reactors constitute a large majority of all western nuclear power plants and are one of three types of light water reactor , the other types being boiling water reactors and supercritical water reactors...
for civilian power. It was the first US heavy water power reactor.
Design
Design of the CVTR began around 1955. CVTR had a thermal output of about 65 MW and an electrical output of about 19 MW. Westinghouse Atomic Power Division was responsible for the design of the nuclear systems while Stone and Webster Engineering designed the remainder of the plant.The reactor consisted of 36 vertical U-tube fuel channels in a moderator tank which was 10 feet in diameter and 16 feet tall. Each leg of the U-tube contained one fuel assembly made up of 19 fuel rods. The reactor used enriched uranium
Enriched uranium
Enriched uranium is a kind of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Natural uranium is 99.284% 238U isotope, with 235U only constituting about 0.711% of its weight...
; 12 of the tubes contained fuel enriched to 1.5% U-235 and 24 tubes contained fuel enriched to 2% U-235.
During power operation, heavy water was circulated by primary pumps through the U-tubes containing the fuel assemblies which heated the water. The heated water then flowed through an inverted U-tube steam generator
Steam generator (nuclear power)
Steam generators are heat exchangers used to convert water into steam from heat produced in a nuclear reactor core. They are used in pressurized water reactors between the primary and secondary coolant loops....
where the heat was transferred to the secondary side light water which turned to steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...
. The steam flowed to an oil-fired superheater
Superheater
A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired...
which increased the steam quality before the steam entered the turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
which spun the electrical generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
. After passing through the steam generator, the primary loop water was pumped back to the reactor by the primary pumps to repeat the cycle. The primary loop heavy water was pressurized to ensure that the heavy water remained liquid and did not flash
Flash evaporation
Flash evaporation is the partial vapor that occurs when a saturated liquid stream undergoes a reduction in pressure by passing through a throttling valve or other throttling device. This process is one of the simplest unit operations...
to steam at any point in the loop.
The U-shaped pressure tubes containing the fuel were thermally isolated from the hot fuel assembly by two circular thermal baffle tubes around the fuel assembly. This allowed the pressure tubes to operate at low temperatures, essentially that of the moderator tank which was maintained about 155 degrees F and close to atmospheric pressure. The moderator tank contained heavy water which moderated the fission process during operation of the reactor.
The CVTR containment
Containment
Containment was a United States policy using military, economic, and diplomatic strategies to stall the spread of communism, enhance America’s security and influence abroad, and prevent a "domino effect". A component of the Cold War, this policy was a response to a series of moves by the Soviet...
design was a new concept at the time; the general design later became the prevalent design for pressurized water reactor containments in the United States. Designed by Stone and Webster Engineering, the design was focused on not allowing any leakage of radioactive gases or material following an accident. The containment design featured a flat concrete foundation, cylindrical walls, and a hemispherical dome, all with an airtight 1/2" or 1/4" (depending on location) steel plate welded liner. The containment was constructed of reinforced concrete
Reinforced concrete
Reinforced concrete is concrete in which reinforcement bars , reinforcement grids, plates or fibers have been incorporated to strengthen the concrete in tension. It was invented by French gardener Joseph Monier in 1849 and patented in 1867. The term Ferro Concrete refers only to concrete that is...
. From the basement floor to the interior surface of the top of the dome measured 114’-2”. The vertical walls were 2’-0” thick, the cylindrical structure had an interior diameter of 58’-0”, and the dome had a slightly larger interior radius of 29’-4”.
The reactor and facilities were located at Parr, SC just to the northeast of the existing Parr Reservoir
Parr Reservoir
Parr Reservoir is an impoundment of the Broad River in Peak, South Carolina. It is the last dam on the Broad River before the river reaches Columbia, South Carolina and the Columbia Canal. The lake is mainly used as a holding pond of sorts, as the water is pulled in and out and used to cool the...
hydroelectric dam across the Broad River
Broad River (Carolinas)
The Broad River is a principal tributary of the Congaree River, about 150 miles long, in western North Carolina and northern South Carolina in the United States. Via the Congaree, it is part of the watershed of the Santee River, which flows to the Atlantic Ocean...
on a high bluff that overlooks the dam powerhouse.
Construction
The site for the CVTR was approved by the Atomic Energy CommissionUnited States Atomic Energy Commission
The United States Atomic Energy Commission was an agency of the United States government established after World War II by Congress to foster and control the peace time development of atomic science and technology. President Harry S...
’s Advisory Committee on Reactor Safeguards in January 1959. Construction started in 1960.
Operation
The reactor went criticalCritical mass
A critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The critical mass of a fissionable material depends upon its nuclear properties A critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The...
for the first time on March 30, 1963. CVTR operated successfully from 1963 to 1967. It was shut down after the completion of the planned test program.
Test facility use
Following decommissioning of the CVTR, the facility was used for conducting large scale tests to provide experimental information on the response of containment structures to severe events. In the late 1960s, three tests were conducted in which large volumes of steam from the nearby coal-fired power plant was suddenly released into the CVTR Containment and the response of the plant measured. The results of these experiments were later used for the development and validation of computer model codes.Decommissioning
The CVTR has been decommissioned and its license was withdrawn. No fuel remains onsite.By the Fall of 2009, demolition was complete and the site returned to greenfield
Greenfield status
Greenfield status is a term used to describe an end point wherein a parcel of land that had been in industrial use is, in principle, restored to the conditions existing before the construction of the plant...
.
The much larger and currently operational Virgil C. Summer Nuclear Generating Station is located approximately three miles north of the CVTR.
External references
- Heavy Water Reactors: Status and Projected Development, IAEA Technical Report No. 407 CVTR is described on pp. 52 – 55.
- Decommissioning Nuclear Power Plants