Read the text below to answer the questions 11-15.
NASA Researchers Studying Advanced Nuclear
Rocket Technologies
January 9, 2013
By using an innovative test facility at NASA's Marshall
Space Flight Center in Huntsville, Ala., researchers are able to
use non-nuclear materials to simulate nuclear thermal rocket
fuels – ones capable of propelling bold new exploration missions
to the Red Planet and beyond. The Nuclear Cryogenic
Propulsion Stage team is tackling a three-year project to
demonstrate the viability of nuclear propulsion system
technologies. A nuclear rocket engine uses a nuclear reactor to
heat hydrogen to very high temperatures, which expands
through a nozzle to generate thrust. Nuclear rocket engines
generate higher thrust and are more than twice as efficient as
conventional chemical rocket engines.
The team recently used Marshall's Nuclear Thermal
Rocket Element Environmental Simulator, or NTREES, to
perform realistic, non-nuclear testing of various materials for
nuclear thermal rocket fuel elements. In an actual reactor, the
fuel elements would contain uranium, but no radioactive
materials are used during the NTREES tests. Among the fuel
options are a graphite composite and a "cermet" composite – a
blend of ceramics and metals. Both materials were investigated
in previous NASA and U.S. Department of Energy research
efforts.
Nuclear-powered rocket concepts are not new; the United
States conducted studies and significant ground testing from
1955 to 1973 to determine the viability of nuclear propulsion
systems, but ceased testing when plans for a crewed Mars
mission were deferred.
The NTREES facility is designed to test fuel elements and
materials in hot flowing hydrogen, reaching pressures up to
1,000 pounds per square inch and temperatures of nearly 5,000
degrees Fahrenheit – conditions that simulate space-based
nuclear propulsion systems to provide baseline data critical to
the research team.
"This is vital testing, helping us reduce risks and costs
associated with advanced propulsion technologies and ensuring
excellent performance and results as we progress toward further
system development and testing," said Mike Houts, project
manager for nuclear systems at Marshall.
A first-generation nuclear cryogenic propulsion system
could propel human explorers to Mars more efficiently than
conventional spacecraft, reducing crews' exposure to harmful
space radiation and other effects of long-term space missions. It
could also transport heavy cargo and science payloads. Further
development and use of a first-generation nuclear system could
also provide the foundation for developing extremely advanced
propulsion technologies and systems in the future – ones that
could take human crews even farther into the solar system.
Building on previous, successful research and using the
NTREES facility, NASA can safely and thoroughly test simulated
nuclear fuel elements of various sizes, providing important test
data to support the design of a future Nuclear Cryogenic
Propulsion Stage. A nuclear cryogenic upper stage – its liquidhydrogen
propellant chilled to super-cold temperatures for
launch – would be designed to be safe during all mission phases
and would not be started until the spacecraft had reached a safe
orbit and was ready to begin its journey to a distant destination.
Prior to startup in a safe orbit, the nuclear system would be cold,
with no fission products generated from nuclear operations, and
with radiation below significant levels.
"The information we gain using this test facility will permit
engineers to design rugged, efficient fuel elements and nuclear
propulsion systems," said NASA researcher Bill Emrich, who
manages the NTREES facility at Marshall. "It's our hope that it
will enable us to develop a reliable, cost-effective nuclear rocket
engine in the not-too-distant future."
The Nuclear Cryogenic Propulsion Stage project is part of
the Advanced Exploration Systems program, which is managed
by NASA's Human Exploration and Operations Mission
Directorate and includes participation by the U.S. Department of
Energy. The program, which focuses on crew safety and mission
operations in deep space, seeks to pioneer new approaches for
rapidly developing prototype systems, demonstrating key
capabilities and validating operational concepts for future vehicle
development and human missions beyond Earth orbit.
Marshall researchers are partnering on the project with
NASA's Glenn Research Center in Cleveland, Ohio; NASA's
Johnson Space Center in Houston; Idaho National Laboratory in
Idaho Falls; Los Alamos National Laboratory in Los Alamos,
N.M.; and Oak Ridge National Laboratory in Oak Ridge, Tenn.
The Marshall Center leads development of the Space
Launch System for NASA. The Science & Technology Office at
Marshall strives to apply advanced concepts and capabilities to
the research, development and management of a broad
spectrum of NASA programs, projects and activities that fall at
the very intersection of science and exploration, where every
discovery and achievement furthers scientific knowledge and
understanding, and supports the agency's ambitious mission to
expand humanity's reach across the solar system. The NTREES
test facility is just one of numerous cutting-edge space
propulsion and science research facilities housed in the state-ofthe-art
Propulsion Research & Development Laboratory at
Marshall, contributing to development of the Space Launch
System and a variety of other NASA programs and missions.
Available in: http://www.nasa.gov
Read the following sentence taken from the text. “Nuclear rocket engines generate higher thrust and are more than twice as efficient as conventional chemical rocket engines.” It is correct to affirm that the adjectives in bold and underlined are, respectively,
Read the text below to answer questions 16-20.
Background
The Naval Nuclear Propulsion Program (NNPP) started in
1948. Since that time, the NNPP has provided safe and effective
propulsion systems to power submarines, surface combatants,
and aircraft carriers. Today, nuclear propulsion enables virtually
undetectable US Navy submarines, including the sea-based leg
of the strategic triad, and provides essentially inexhaustible
propulsion power independent of forward logistical support to
both our submarines and aircraft carriers. Over forty percent of
the Navy's major combatant ships are nuclear-powered, and
because of their demonstrated safety and reliability, these ships
have access to seaports throughout the world. The NNPP has
consistently sought the best way to affordably meet Navy
requirements by evaluating, developing, and delivering a variety
of reactor types, fuel systems, and structural materials. The
Program has investigated many different fuel systems and
reactor design features, and has designed, built, and operated
over thirty different reactor designs in over twenty plant types to
employ the most promising of these developments in practical
applications. Improvements in naval reactor design have allowed
increased power and energy to keep pace with the operational
requirements of the modern nuclear fleet, while maintaining a
conservative design approach that ensures reliability and safety
to the crew, the public, and the environment. As just one
example of the progress that has been made, the earliest
reactor core designs in the NAUTILUS required refueling after
about two years while modern reactor cores can last the life of a
submarine, or over thirty years without refueling. These
improvements have been the result of prudent, conservative
engineering, backed by analysis, testing, and prototyping. The
NNPP was also a pioneer in developing basic technologies and
transferring technology to the civilian nuclear electric power
industry. For example, the Program demonstrated the feasibility
of commercial nuclear power generation in this country by
designing, constructing and operating the Shipping port Atomic
Power Station in Pennsylvania and showing the feasibility of a
thorium-based breeder reactor.
In: Report on Low Enriched Uranium for Naval Reactor Cores. Page 1.
Report to Congress, January 2014.
Office of Naval Reactors. US Dept. of Energy. DC 2058
http://fissilematerials.org/library/doe14.pdf
Read the passage taken of the text below.
“The Naval Nuclear Propulsion Program (NNPP) started in
1948.Since that time, the NNPP has provided safe and
effective propulsion systems to power submarines, surface
combatants, and aircraft carriers. Today, nuclear propulsion
enables virtually undetectable US Navy submarines, including
the sea-based leg of the strategic triad, and provides essentially
inexhaustible propulsion power independent of forward
logistical support to both our submarines and aircraft carriers."
Choose the alternative in which the words can properly
substitute the ones in bold and underlined, respectively.
Read the text below to answer the questions 11-15.
NASA Researchers Studying Advanced Nuclear
Rocket Technologies
January 9, 2013
By using an innovative test facility at NASA's Marshall
Space Flight Center in Huntsville, Ala., researchers are able to
use non-nuclear materials to simulate nuclear thermal rocket
fuels – ones capable of propelling bold new exploration missions
to the Red Planet and beyond. The Nuclear Cryogenic
Propulsion Stage team is tackling a three-year project to
demonstrate the viability of nuclear propulsion system
technologies. A nuclear rocket engine uses a nuclear reactor to
heat hydrogen to very high temperatures, which expands
through a nozzle to generate thrust. Nuclear rocket engines
generate higher thrust and are more than twice as efficient as
conventional chemical rocket engines.
The team recently used Marshall's Nuclear Thermal
Rocket Element Environmental Simulator, or NTREES, to
perform realistic, non-nuclear testing of various materials for
nuclear thermal rocket fuel elements. In an actual reactor, the
fuel elements would contain uranium, but no radioactive
materials are used during the NTREES tests. Among the fuel
options are a graphite composite and a "cermet" composite – a
blend of ceramics and metals. Both materials were investigated
in previous NASA and U.S. Department of Energy research
efforts.
Nuclear-powered rocket concepts are not new; the United
States conducted studies and significant ground testing from
1955 to 1973 to determine the viability of nuclear propulsion
systems, but ceased testing when plans for a crewed Mars
mission were deferred.
The NTREES facility is designed to test fuel elements and
materials in hot flowing hydrogen, reaching pressures up to
1,000 pounds per square inch and temperatures of nearly 5,000
degrees Fahrenheit – conditions that simulate space-based
nuclear propulsion systems to provide baseline data critical to
the research team.
"This is vital testing, helping us reduce risks and costs
associated with advanced propulsion technologies and ensuring
excellent performance and results as we progress toward further
system development and testing," said Mike Houts, project
manager for nuclear systems at Marshall.
A first-generation nuclear cryogenic propulsion system
could propel human explorers to Mars more efficiently than
conventional spacecraft, reducing crews' exposure to harmful
space radiation and other effects of long-term space missions. It
could also transport heavy cargo and science payloads. Further
development and use of a first-generation nuclear system could
also provide the foundation for developing extremely advanced
propulsion technologies and systems in the future – ones that
could take human crews even farther into the solar system.
Building on previous, successful research and using the
NTREES facility, NASA can safely and thoroughly test simulated
nuclear fuel elements of various sizes, providing important test
data to support the design of a future Nuclear Cryogenic
Propulsion Stage. A nuclear cryogenic upper stage – its liquidhydrogen
propellant chilled to super-cold temperatures for
launch – would be designed to be safe during all mission phases
and would not be started until the spacecraft had reached a safe
orbit and was ready to begin its journey to a distant destination.
Prior to startup in a safe orbit, the nuclear system would be cold,
with no fission products generated from nuclear operations, and
with radiation below significant levels.
"The information we gain using this test facility will permit
engineers to design rugged, efficient fuel elements and nuclear
propulsion systems," said NASA researcher Bill Emrich, who
manages the NTREES facility at Marshall. "It's our hope that it
will enable us to develop a reliable, cost-effective nuclear rocket
engine in the not-too-distant future."
The Nuclear Cryogenic Propulsion Stage project is part of
the Advanced Exploration Systems program, which is managed
by NASA's Human Exploration and Operations Mission
Directorate and includes participation by the U.S. Department of
Energy. The program, which focuses on crew safety and mission
operations in deep space, seeks to pioneer new approaches for
rapidly developing prototype systems, demonstrating key
capabilities and validating operational concepts for future vehicle
development and human missions beyond Earth orbit.
Marshall researchers are partnering on the project with
NASA's Glenn Research Center in Cleveland, Ohio; NASA's
Johnson Space Center in Houston; Idaho National Laboratory in
Idaho Falls; Los Alamos National Laboratory in Los Alamos,
N.M.; and Oak Ridge National Laboratory in Oak Ridge, Tenn.
The Marshall Center leads development of the Space
Launch System for NASA. The Science & Technology Office at
Marshall strives to apply advanced concepts and capabilities to
the research, development and management of a broad
spectrum of NASA programs, projects and activities that fall at
the very intersection of science and exploration, where every
discovery and achievement furthers scientific knowledge and
understanding, and supports the agency's ambitious mission to
expand humanity's reach across the solar system. The NTREES
test facility is just one of numerous cutting-edge space
propulsion and science research facilities housed in the state-ofthe-art
Propulsion Research & Development Laboratory at
Marshall, contributing to development of the Space Launch
System and a variety of other NASA programs and missions.
Available in: http://www.nasa.gov
Consider the verb tense in the following sentence taken from the text. “Nuclear-powered rocket concepts are not new.” Choose the alternative in which the extract is in the same verb tense as the one above.
Read the text below to answer questions 16-20.
Background
The Naval Nuclear Propulsion Program (NNPP) started in
1948. Since that time, the NNPP has provided safe and effective
propulsion systems to power submarines, surface combatants,
and aircraft carriers. Today, nuclear propulsion enables virtually
undetectable US Navy submarines, including the sea-based leg
of the strategic triad, and provides essentially inexhaustible
propulsion power independent of forward logistical support to
both our submarines and aircraft carriers. Over forty percent of
the Navy's major combatant ships are nuclear-powered, and
because of their demonstrated safety and reliability, these ships
have access to seaports throughout the world. The NNPP has
consistently sought the best way to affordably meet Navy
requirements by evaluating, developing, and delivering a variety
of reactor types, fuel systems, and structural materials. The
Program has investigated many different fuel systems and
reactor design features, and has designed, built, and operated
over thirty different reactor designs in over twenty plant types to
employ the most promising of these developments in practical
applications. Improvements in naval reactor design have allowed
increased power and energy to keep pace with the operational
requirements of the modern nuclear fleet, while maintaining a
conservative design approach that ensures reliability and safety
to the crew, the public, and the environment. As just one
example of the progress that has been made, the earliest
reactor core designs in the NAUTILUS required refueling after
about two years while modern reactor cores can last the life of a
submarine, or over thirty years without refueling. These
improvements have been the result of prudent, conservative
engineering, backed by analysis, testing, and prototyping. The
NNPP was also a pioneer in developing basic technologies and
transferring technology to the civilian nuclear electric power
industry. For example, the Program demonstrated the feasibility
of commercial nuclear power generation in this country by
designing, constructing and operating the Shipping port Atomic
Power Station in Pennsylvania and showing the feasibility of a
thorium-based breeder reactor.
In: Report on Low Enriched Uranium for Naval Reactor Cores. Page 1.
Report to Congress, January 2014.
Office of Naval Reactors. US Dept. of Energy. DC 2058
http://fissilematerials.org/library/doe14.pdf
According to the text, the Naval Nuclear Propulsion Program – NNPP I.investigates more efficient fuels and reactors for the Navy. II.is concerned about how to spend the financial resources received. III.has also contributed with the civilian power industry. The correct assertion(s) is(are)
Read the text below to answer the questions 11-15.
NASA Researchers Studying Advanced Nuclear
Rocket Technologies
January 9, 2013
By using an innovative test facility at NASA's Marshall
Space Flight Center in Huntsville, Ala., researchers are able to
use non-nuclear materials to simulate nuclear thermal rocket
fuels – ones capable of propelling bold new exploration missions
to the Red Planet and beyond. The Nuclear Cryogenic
Propulsion Stage team is tackling a three-year project to
demonstrate the viability of nuclear propulsion system
technologies. A nuclear rocket engine uses a nuclear reactor to
heat hydrogen to very high temperatures, which expands
through a nozzle to generate thrust. Nuclear rocket engines
generate higher thrust and are more than twice as efficient as
conventional chemical rocket engines.
The team recently used Marshall's Nuclear Thermal
Rocket Element Environmental Simulator, or NTREES, to
perform realistic, non-nuclear testing of various materials for
nuclear thermal rocket fuel elements. In an actual reactor, the
fuel elements would contain uranium, but no radioactive
materials are used during the NTREES tests. Among the fuel
options are a graphite composite and a “cermet" composite – a
blend of ceramics and metals. Both materials were investigated
in previous NASA and U.S. Department of Energy research
efforts.
Nuclear-powered rocket concepts are not new; the United
States conducted studies and significant ground testing from
1955 to 1973 to determine the viability of nuclear propulsion
systems, but ceased testing when plans for a crewed Mars
mission were deferred.
The NTREES facility is designed to test fuel elements and
materials in hot flowing hydrogen, reaching pressures up to
1,000 pounds per square inch and temperatures of nearly 5,000
degrees Fahrenheit – conditions that simulate space-based
nuclear propulsion systems to provide baseline data critical to
the research team.
“This is vital testing, helping us reduce risks and costs
associated with advanced propulsion technologies and ensuring
excellent performance and results as we progress toward further
system development and testing," said Mike Houts, project
manager for nuclear systems at Marshall.
A first-generation nuclear cryogenic propulsion system
could propel human explorers to Mars more efficiently than
conventional spacecraft, reducing crews' exposure to harmful
space radiation and other effects of long-term space missions. It
could also transport heavy cargo and science payloads. Further
development and use of a first-generation nuclear system could
also provide the foundation for developing extremely advanced
propulsion technologies and systems in the future – ones that
could take human crews even farther into the solar system.
Building on previous, successful research and using the
NTREES facility, NASA can safely and thoroughly test simulated
nuclear fuel elements of various sizes, providing important test
data to support the design of a future Nuclear Cryogenic
Propulsion Stage. A nuclear cryogenic upper stage – its liquidhydrogen
propellant chilled to super-cold temperatures for
launch – would be designed to be safe during all mission phases
and would not be started until the spacecraft had reached a safe
orbit and was ready to begin its journey to a distant destination.
Prior to startup in a safe orbit, the nuclear system would be cold,
with no fission products generated from nuclear operations, and
with radiation below significant levels.
“The information we gain using this test facility will permit
engineers to design rugged, efficient fuel elements and nuclear
propulsion systems," said NASA researcher Bill Emrich, who
manages the NTREES facility at Marshall. “It's our hope that it
will enable us to develop a reliable, cost-effective nuclear rocket
engine in the not-too-distant future."
The Nuclear Cryogenic Propulsion Stage project is part of
the Advanced Exploration Systems program, which is managed
by NASA's Human Exploration and Operations Mission
Directorate and includes participation by the U.S. Department of
Energy. The program, which focuses on crew safety and mission
operations in deep space, seeks to pioneer new approaches for
rapidly developing prototype systems, demonstrating key
capabilities and validating operational concepts for future vehicle
development and human missions beyond Earth orbit.
Marshall researchers are partnering on the project with
NASA's Glenn Research Center in Cleveland, Ohio; NASA's
Johnson Space Center in Houston; Idaho National Laboratory in
Idaho Falls; Los Alamos National Laboratory in Los Alamos,
N.M.; and Oak Ridge National Laboratory in Oak Ridge, Tenn.
The Marshall Center leads development of the Space
Launch System for NASA. The Science & Technology Office at
Marshall strives to apply advanced concepts and capabilities to
the research, development and management of a broad
spectrum of NASA programs, projects and activities that fall at
the very intersection of science and exploration, where every
discovery and achievement furthers scientific knowledge and
understanding, and supports the agency's ambitious mission to
expand humanity's reach across the solar system. The NTREES
test facility is just one of numerous cutting-edge space
propulsion and science research facilities housed in the state-ofthe-art
Propulsion Research & Development Laboratory at
Marshall, contributing to development of the Space Launch
System and a variety of other NASA programs and missions.
Available in: http://www.nasa.gov
Considering the text, read the statements below. I.Engines powered by expanded hydrogen work better than regular chemical engines. II.A CERMET composite is made of ceramics, metal and graphite. III.The Nuclear Cryogenic Propulsion Stage created the technology that took human crews to Mars. According to the text, the correct assertion(s) is(are)
Read the text below to answer the questions 11-15.
NASA Researchers Studying Advanced Nuclear
Rocket Technologies
January 9, 2013
By using an innovative test facility at NASA's Marshall
Space Flight Center in Huntsville, Ala., researchers are able to
use non-nuclear materials to simulate nuclear thermal rocket
fuels – ones capable of propelling bold new exploration missions
to the Red Planet and beyond. The Nuclear Cryogenic
Propulsion Stage team is tackling a three-year project to
demonstrate the viability of nuclear propulsion system
technologies. A nuclear rocket engine uses a nuclear reactor to
heat hydrogen to very high temperatures, which expands
through a nozzle to generate thrust. Nuclear rocket engines
generate higher thrust and are more than twice as efficient as
conventional chemical rocket engines.
The team recently used Marshall's Nuclear Thermal
Rocket Element Environmental Simulator, or NTREES, to
perform realistic, non-nuclear testing of various materials for
nuclear thermal rocket fuel elements. In an actual reactor, the
fuel elements would contain uranium, but no radioactive
materials are used during the NTREES tests. Among the fuel
options are a graphite composite and a "cermet" composite – a
blend of ceramics and metals. Both materials were investigated
in previous NASA and U.S. Department of Energy research
efforts.
Nuclear-powered rocket concepts are not new; the United
States conducted studies and significant ground testing from
1955 to 1973 to determine the viability of nuclear propulsion
systems, but ceased testing when plans for a crewed Mars
mission were deferred.
The NTREES facility is designed to test fuel elements and
materials in hot flowing hydrogen, reaching pressures up to
1,000 pounds per square inch and temperatures of nearly 5,000
degrees Fahrenheit – conditions that simulate space-based
nuclear propulsion systems to provide baseline data critical to
the research team.
"This is vital testing, helping us reduce risks and costs
associated with advanced propulsion technologies and ensuring
excellent performance and results as we progress toward further
system development and testing," said Mike Houts, project
manager for nuclear systems at Marshall.
A first-generation nuclear cryogenic propulsion system
could propel human explorers to Mars more efficiently than
conventional spacecraft, reducing crews' exposure to harmful
space radiation and other effects of long-term space missions. It
could also transport heavy cargo and science payloads. Further
development and use of a first-generation nuclear system could
also provide the foundation for developing extremely advanced
propulsion technologies and systems in the future – ones that
could take human crews even farther into the solar system.
Building on previous, successful research and using the
NTREES facility, NASA can safely and thoroughly test simulated
nuclear fuel elements of various sizes, providing important test
data to support the design of a future Nuclear Cryogenic
Propulsion Stage. A nuclear cryogenic upper stage – its liquidhydrogen
propellant chilled to super-cold temperatures for
launch – would be designed to be safe during all mission phases
and would not be started until the spacecraft had reached a safe
orbit and was ready to begin its journey to a distant destination.
Prior to startup in a safe orbit, the nuclear system would be cold,
with no fission products generated from nuclear operations, and
with radiation below significant levels.
"The information we gain using this test facility will permit
engineers to design rugged, efficient fuel elements and nuclear
propulsion systems," said NASA researcher Bill Emrich, who
manages the NTREES facility at Marshall. "It's our hope that it
will enable us to develop a reliable, cost-effective nuclear rocket
engine in the not-too-distant future."
The Nuclear Cryogenic Propulsion Stage project is part of
the Advanced Exploration Systems program, which is managed
by NASA's Human Exploration and Operations Mission
Directorate and includes participation by the U.S. Department of
Energy. The program, which focuses on crew safety and mission
operations in deep space, seeks to pioneer new approaches for
rapidly developing prototype systems, demonstrating key
capabilities and validating operational concepts for future vehicle
development and human missions beyond Earth orbit.
Marshall researchers are partnering on the project with
NASA's Glenn Research Center in Cleveland, Ohio; NASA's
Johnson Space Center in Houston; Idaho National Laboratory in
Idaho Falls; Los Alamos National Laboratory in Los Alamos,
N.M.; and Oak Ridge National Laboratory in Oak Ridge, Tenn.
The Marshall Center leads development of the Space
Launch System for NASA. The Science & Technology Office at
Marshall strives to apply advanced concepts and capabilities to
the research, development and management of a broad
spectrum of NASA programs, projects and activities that fall at
the very intersection of science and exploration, where every
discovery and achievement furthers scientific knowledge and
understanding, and supports the agency's ambitious mission to
expand humanity's reach across the solar system. The NTREES
test facility is just one of numerous cutting-edge space
propulsion and science research facilities housed in the state-ofthe-art
Propulsion Research & Development Laboratory at
Marshall, contributing to development of the Space Launch
System and a variety of other NASA programs and missions.
Available in: http://www.nasa.gov
Read the excerpt below taken from the text. “The program, which focuses on crew safety and mission operations in deep space, seeks to pioneer new approaches for rapidly developing prototype systems, demonstrating key capabilities and validating operational concepts for future vehicle development and human missions beyond Earth orbit.” Choose the alternative that presents the words that best substitutes, respectively, the bold and underlined ones in the sentences above.
Read the text below to answer questions 16-20.
Background
The Naval Nuclear Propulsion Program (NNPP) started in
1948. Since that time, the NNPP has provided safe and effective
propulsion systems to power submarines, surface combatants,
and aircraft carriers. Today, nuclear propulsion enables virtually
undetectable US Navy submarines, including the sea-based leg
of the strategic triad, and provides essentially inexhaustible
propulsion power independent of forward logistical support to
both our submarines and aircraft carriers. Over forty percent of
the Navy's major combatant ships are nuclear-powered, and
because of their demonstrated safety and reliability, these ships
have access to seaports throughout the world. The NNPP has
consistently sought the best way to affordably meet Navy
requirements by evaluating, developing, and delivering a variety
of reactor types, fuel systems, and structural materials. The
Program has investigated many different fuel systems and
reactor design features, and has designed, built, and operated
over thirty different reactor designs in over twenty plant types to
employ the most promising of these developments in practical
applications. Improvements in naval reactor design have allowed
increased power and energy to keep pace with the operational
requirements of the modern nuclear fleet, while maintaining a
conservative design approach that ensures reliability and safety
to the crew, the public, and the environment. As just one
example of the progress that has been made, the earliest
reactor core designs in the NAUTILUS required refueling after
about two years while modern reactor cores can last the life of a
submarine, or over thirty years without refueling. These
improvements have been the result of prudent, conservative
engineering, backed by analysis, testing, and prototyping. The
NNPP was also a pioneer in developing basic technologies and
transferring technology to the civilian nuclear electric power
industry. For example, the Program demonstrated the feasibility
of commercial nuclear power generation in this country by
designing, constructing and operating the Shipping port Atomic
Power Station in Pennsylvania and showing the feasibility of a
thorium-based breeder reactor.
In: Report on Low Enriched Uranium for Naval Reactor Cores. Page 1.
Report to Congress, January 2014.
Office of Naval Reactors. US Dept. of Energy. DC 2058
http://fissilematerials.org/library/doe14.pdf
Choose the alternative in which the bold and underlined word has the same grammar function as the one below. “The NNPP has consistently sought the best way to affordably meet Navy requirements by evaluating, developing, and delivering a variety of reactor types, fuel systems, and structural materials.”
Read the text below to answer the questions 11-15.
NASA Researchers Studying Advanced Nuclear
Rocket Technologies
January 9, 2013
By using an innovative test facility at NASA's Marshall
Space Flight Center in Huntsville, Ala., researchers are able to
use non-nuclear materials to simulate nuclear thermal rocket
fuels – ones capable of propelling bold new exploration missions
to the Red Planet and beyond. The Nuclear Cryogenic
Propulsion Stage team is tackling a three-year project to
demonstrate the viability of nuclear propulsion system
technologies. A nuclear rocket engine uses a nuclear reactor to
heat hydrogen to very high temperatures, which expands
through a nozzle to generate thrust. Nuclear rocket engines
generate higher thrust and are more than twice as efficient as
conventional chemical rocket engines.
The team recently used Marshall's Nuclear Thermal
Rocket Element Environmental Simulator, or NTREES, to
perform realistic, non-nuclear testing of various materials for
nuclear thermal rocket fuel elements. In an actual reactor, the
fuel elements would contain uranium, but no radioactive
materials are used during the NTREES tests. Among the fuel
options are a graphite composite and a "cermet" composite – a
blend of ceramics and metals. Both materials were investigated
in previous NASA and U.S. Department of Energy research
efforts.
Nuclear-powered rocket concepts are not new; the United
States conducted studies and significant ground testing from
1955 to 1973 to determine the viability of nuclear propulsion
systems, but ceased testing when plans for a crewed Mars
mission were deferred.
The NTREES facility is designed to test fuel elements and
materials in hot flowing hydrogen, reaching pressures up to
1,000 pounds per square inch and temperatures of nearly 5,000
degrees Fahrenheit – conditions that simulate space-based
nuclear propulsion systems to provide baseline data critical to
the research team.
"This is vital testing, helping us reduce risks and costs
associated with advanced propulsion technologies and ensuring
excellent performance and results as we progress toward further
system development and testing," said Mike Houts, project
manager for nuclear systems at Marshall.
A first-generation nuclear cryogenic propulsion system
could propel human explorers to Mars more efficiently than
conventional spacecraft, reducing crews' exposure to harmful
space radiation and other effects of long-term space missions. It
could also transport heavy cargo and science payloads. Further
development and use of a first-generation nuclear system could
also provide the foundation for developing extremely advanced
propulsion technologies and systems in the future – ones that
could take human crews even farther into the solar system.
Building on previous, successful research and using the
NTREES facility, NASA can safely and thoroughly test simulated
nuclear fuel elements of various sizes, providing important test
data to support the design of a future Nuclear Cryogenic
Propulsion Stage. A nuclear cryogenic upper stage – its liquidhydrogen
propellant chilled to super-cold temperatures for
launch – would be designed to be safe during all mission phases
and would not be started until the spacecraft had reached a safe
orbit and was ready to begin its journey to a distant destination.
Prior to startup in a safe orbit, the nuclear system would be cold,
with no fission products generated from nuclear operations, and
with radiation below significant levels.
"The information we gain using this test facility will permit
engineers to design rugged, efficient fuel elements and nuclear
propulsion systems," said NASA researcher Bill Emrich, who
manages the NTREES facility at Marshall. "It's our hope that it
will enable us to develop a reliable, cost-effective nuclear rocket
engine in the not-too-distant future."
The Nuclear Cryogenic Propulsion Stage project is part of
the Advanced Exploration Systems program, which is managed
by NASA's Human Exploration and Operations Mission
Directorate and includes participation by the U.S. Department of
Energy. The program, which focuses on crew safety and mission
operations in deep space, seeks to pioneer new approaches for
rapidly developing prototype systems, demonstrating key
capabilities and validating operational concepts for future vehicle
development and human missions beyond Earth orbit.
Marshall researchers are partnering on the project with
NASA's Glenn Research Center in Cleveland, Ohio; NASA's
Johnson Space Center in Houston; Idaho National Laboratory in
Idaho Falls; Los Alamos National Laboratory in Los Alamos,
N.M.; and Oak Ridge National Laboratory in Oak Ridge, Tenn.
The Marshall Center leads development of the Space
Launch System for NASA. The Science & Technology Office at
Marshall strives to apply advanced concepts and capabilities to
the research, development and management of a broad
spectrum of NASA programs, projects and activities that fall at
the very intersection of science and exploration, where every
discovery and achievement furthers scientific knowledge and
understanding, and supports the agency's ambitious mission to
expand humanity's reach across the solar system. The NTREES
test facility is just one of numerous cutting-edge space
propulsion and science research facilities housed in the state-ofthe-art
Propulsion Research & Development Laboratory at
Marshall, contributing to development of the Space Launch
System and a variety of other NASA programs and missions.
Available in: http://www.nasa.gov
According to the text, one of the NASA’s Marshall Space Flight Center cutting-edge research facility is called
Read the text below to answer questions 16-20.
Background
The Naval Nuclear Propulsion Program (NNPP) started in
1948. Since that time, the NNPP has provided safe and effective
propulsion systems to power submarines, surface combatants,
and aircraft carriers. Today, nuclear propulsion enables virtually
undetectable US Navy submarines, including the sea-based leg
of the strategic triad, and provides essentially inexhaustible
propulsion power independent of forward logistical support to
both our submarines and aircraft carriers. Over forty percent of
the Navy's major combatant ships are nuclear-powered, and
because of their demonstrated safety and reliability, these ships
have access to seaports throughout the world. The NNPP has
consistently sought the best way to affordably meet Navy
requirements by evaluating, developing, and delivering a variety
of reactor types, fuel systems, and structural materials. The
Program has investigated many different fuel systems and
reactor design features, and has designed, built, and operated
over thirty different reactor designs in over twenty plant types to
employ the most promising of these developments in practical
applications. Improvements in naval reactor design have allowed
increased power and energy to keep pace with the operational
requirements of the modern nuclear fleet, while maintaining a
conservative design approach that ensures reliability and safety
to the crew, the public, and the environment. As just one
example of the progress that has been made, the earliest
reactor core designs in the NAUTILUS required refueling after
about two years while modern reactor cores can last the life of a
submarine, or over thirty years without refueling. These
improvements have been the result of prudent, conservative
engineering, backed by analysis, testing, and prototyping. The
NNPP was also a pioneer in developing basic technologies and
transferring technology to the civilian nuclear electric power
industry. For example, the Program demonstrated the feasibility
of commercial nuclear power generation in this country by
designing, constructing and operating the Shipping port Atomic
Power Station in Pennsylvania and showing the feasibility of a
thorium-based breeder reactor.
In: Report on Low Enriched Uranium for Naval Reactor Cores. Page 1.
Report to Congress, January 2014.
Office of Naval Reactors. US Dept. of Energy. DC 2058
http://fissilematerials.org/library/doe14.pdf
Read the excerpt below taken from the text. “[…] because of their demonstrated safety and reliability, these ships have access to seaports throughout the world.” Choose the alternative that presents the words that would better translate, respectively, the ones in bold and underlined.
Read the text below to answer questions 16-20.
Background
The Naval Nuclear Propulsion Program (NNPP) started in
1948. Since that time, the NNPP has provided safe and effective
propulsion systems to power submarines, surface combatants,
and aircraft carriers. Today, nuclear propulsion enables virtually
undetectable US Navy submarines, including the sea-based leg
of the strategic triad, and provides essentially inexhaustible
propulsion power independent of forward logistical support to
both our submarines and aircraft carriers. Over forty percent of
the Navy's major combatant ships are nuclear-powered, and
because of their demonstrated safety and reliability, these ships
have access to seaports throughout the world. The NNPP has
consistently sought the best way to affordably meet Navy
requirements by evaluating, developing, and delivering a variety
of reactor types, fuel systems, and structural materials. The
Program has investigated many different fuel systems and
reactor design features, and has designed, built, and operated
over thirty different reactor designs in over twenty plant types to
employ the most promising of these developments in practical
applications. Improvements in naval reactor design have allowed
increased power and energy to keep pace with the operational
requirements of the modern nuclear fleet, while maintaining a
conservative design approach that ensures reliability and safety
to the crew, the public, and the environment. As just one
example of the progress that has been made, the earliest
reactor core designs in the NAUTILUS required refueling after
about two years while modern reactor cores can last the life of a
submarine, or over thirty years without refueling. These
improvements have been the result of prudent, conservative
engineering, backed by analysis, testing, and prototyping. The
NNPP was also a pioneer in developing basic technologies and
transferring technology to the civilian nuclear electric power
industry. For example, the Program demonstrated the feasibility
of commercial nuclear power generation in this country by
designing, constructing and operating the Shipping port Atomic
Power Station in Pennsylvania and showing the feasibility of a
thorium-based breeder reactor.
In: Report on Low Enriched Uranium for Naval Reactor Cores. Page 1.
Report to Congress, January 2014.
Office of Naval Reactors. US Dept. of Energy. DC 2058
http://fissilematerials.org/library/doe14.pdf
According to the text, choose the alternative that presents how long can modern reactor cores stay without refueling.