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Neutron activation is a process where materials become radioactive due to exposure to neutron radiation.
Answer: True
Neutron activation is defined as the process by which materials become radioactive after capturing free neutrons, leading to the formation of unstable, excited nuclei.
After capturing a neutron, an excited atomic nucleus exclusively emits gamma rays as it decays.
Answer: False
Upon neutron capture, an excited atomic nucleus can decay by emitting not only gamma rays but also various particles such as beta particles, alpha particles, fission products, and sometimes additional neutrons.
Neutron activation is unique because it is the only common method to make a stable material intrinsically radioactive through nuclear transformation.
Answer: True
Neutron activation is distinguished by its ability to induce intrinsic radioactivity in a stable material, meaning the material itself undergoes a nuclear transformation rather than merely being contaminated.
Only man-made materials can be activated by neutron capture; naturally occurring substances like air and water are immune.
Answer: False
Naturally occurring materials, including air, water, and soil, can all be activated to some extent by neutron capture, leading to the production of neutron-rich radioisotopes.
Nuclear fission can occur after neutron capture, and if energy is required for this process, it is supplied by the kinetic energy of the incoming neutron.
Answer: True
Neutron capture can indeed induce nuclear fission, and any energy deficit required for this process is compensated by the kinetic energy of the incident neutron.
Significant neutron activation only occurs during specific, short-lived events or in active nuclear environments.
Answer: True
Substantial neutron activation requires specific conditions, such as the intense neutron fluxes found during nuclear weapon explosions, within active nuclear reactors, or in spallation neutron sources.
What is the fundamental process by which neutron activation causes materials to become radioactive?
Answer: Atomic nuclei capture free neutrons, become heavier, and enter excited states.
Neutron activation fundamentally involves atomic nuclei capturing free neutrons, which increases their mass and places them in an excited, unstable state, leading to radioactive decay.
Which of the following is NOT typically emitted when an excited nucleus decays after capturing a neutron?
Answer: X-rays
When an excited nucleus decays after neutron capture, it typically emits gamma rays, beta particles, alpha particles, or fission products. X-rays are generally not a primary emission product of nuclear decay.
What makes neutron activation a unique method for inducing radioactivity in stable materials?
Answer: It causes the material itself to undergo a nuclear transformation.
Neutron activation is unique because it intrinsically transforms the stable material into a radioactive one through nuclear changes, rather than merely surface contamination or chemical reactions.
Which statement accurately describes the activatability of naturally occurring materials by neutron capture?
Answer: All naturally occurring materials, including air, water, and soil, can be activated to some degree.
All naturally occurring materials, such as air, water, and soil, are susceptible to neutron activation to varying extents, leading to the formation of neutron-rich radioisotopes.
How can neutron capture lead to nuclear fission, and what provides the necessary energy if the fission requires it?
Answer: Neutron capture can cause fission, with the kinetic energy of the incoming neutron supplying any required energy.
Neutron capture can induce nuclear fission, and if the fission process is endothermic, the kinetic energy of the incoming neutron provides the necessary energy.
Under what circumstances are neutrons available in sufficient quantities to cause significant activation?
Answer: Only during the microseconds of a nuclear weapon's explosion, within an active nuclear reactor, or in a spallation neutron source.
Significant neutron activation occurs only in environments with high neutron fluxes, such as nuclear weapon detonations, active nuclear reactors, or spallation neutron sources.
Which of the following is listed as a related scientific concept to neutron activation?
Answer: Neutron embrittlement
Neutron embrittlement is a related scientific concept to neutron activation, both involving the interaction of neutrons with materials and their resulting effects.
Atoms that require the capture of more than one neutron are generally easier to activate due to increased probability.
Answer: False
Atoms requiring multiple neutron captures are more difficult to activate because the probability of such events is significantly lower than that of a single neutron capture.
Water is relatively difficult to activate because its hydrogen component requires a double neutron capture to become tritium.
Answer: True
The hydrogen component of water necessitates a double neutron capture to form tritium, and its oxygen component requires three captures to become unstable oxygen-19, making water relatively resistant to activation.
Sodium chloride is relatively easy to activate because both sodium and chlorine atoms can become unstable with a single neutron capture.
Answer: True
Sodium chloride is readily activated because both its sodium and chlorine atoms can achieve an unstable state through the capture of just a single neutron.
Cobalt-60 is produced when stable cobalt-59 captures a neutron, transforming it into the radioactive isotope.
Answer: True
Cobalt-60 is formed in nuclear reactors when the naturally abundant stable isotope cobalt-59 captures a neutron, undergoing a nuclear transformation.
Cobalt-60 has a half-life of approximately 10 years and is primarily used as a source of alpha radiation.
Answer: False
Cobalt-60 has a half-life of approximately 5.27 years and is primarily utilized as a source of gamma radiation, particularly in radiotherapy, not alpha radiation.
Chromium-51 forms in chrome steel when chromium-50 is exposed to reactor neutron flux.
Answer: True
Chromium-51 is produced in chrome steel when its chromium-50 component undergoes neutron activation within a reactor's neutron flux.
When aluminum captures a neutron, it generates radioactive sodium-24, which has a half-life of 15 hours.
Answer: True
Neutron capture by aluminum leads to the formation of radioactive sodium-24, an isotope with a half-life of 15 hours.
Why are some atoms more difficult to activate through neutron capture?
Answer: They require the capture of more than one neutron to become unstable.
The difficulty in activating certain atoms stems from the requirement for multiple neutron captures to achieve an unstable state, a process with a significantly lower probability than single capture events.
What makes water relatively difficult to activate by neutron capture?
Answer: Its hydrogen component requires a double neutron capture to become tritium.
Water's resistance to neutron activation is largely due to its hydrogen component needing a double neutron capture to form tritium, and its oxygen component requiring three captures for oxygen-19.
Which common material is described as relatively easy to activate due to single neutron capture susceptibility?
Answer: Sodium chloride
Sodium chloride is considered easy to activate because both its sodium and chlorine atoms can readily become unstable through a single neutron capture.
What is the nuclear reaction for the production of cobalt-60 in a nuclear reactor?
Answer: Co-59 + n → Co-60
Cobalt-60 is produced in a nuclear reactor when stable cobalt-59 captures a neutron, transforming it into the radioactive isotope cobalt-60.
What is the approximate half-life of cobalt-60, and what is its primary application?
Answer: 5.27 years; used as a source of gamma radiation in radiotherapy.
Cobalt-60 has a half-life of approximately 5.27 years and is widely used as a source of gamma radiation, particularly in medical radiotherapy.
Which isotope is formed by neutron activation in chrome steel containing chromium-50?
Answer: Chromium-51
When chrome steel containing chromium-50 is exposed to reactor neutron flux, chromium-51 is formed through neutron activation.
When aluminum captures a neutron, which radioactive isotope is generated, and what is its half-life?
Answer: Sodium-24; 15 hours
Neutron capture by aluminum results in the generation of radioactive sodium-24, an isotope with a half-life of 15 hours.
The Operation Crossroads atomic test series in 1946 provided theoretical insights into material activation but no practical experience.
Answer: False
The Operation Crossroads atomic tests in 1946 provided practical experience and empirical evidence regarding the varying degrees to which different materials could be activated by neutrons.
When lithium-7 is bombarded with fast neutrons, it undergoes a fusion reaction to form a heavier element.
Answer: False
When bombarded with fast neutrons, lithium-7 undergoes a fission reaction, splitting into lighter elements like helium-4 and tritium, rather than a fusion reaction to form a heavier element.
The Castle Bravo accident's unexpectedly high yield was partly due to the high probability of lithium-7 fission upon neutron capture.
Answer: True
The unforeseen high yield of the Castle Bravo thermonuclear test was significantly influenced by the unexpectedly high probability of lithium-7 undergoing fission upon neutron capture.
Nuclear fallout from atomic weapons is primarily caused by unspent fissile material, not neutron activation.
Answer: False
A significant portion of nuclear fallout from high-altitude atomic weapon bursts is attributed to the neutron activation of the metallic bomb casing, which is subsequently vaporized.
When neutrons irradiate soil near the Earth's surface during a nuclear burst, the soil elements undergo neutron activation, contributing to fallout.
Answer: True
During a nuclear burst at or near the Earth's surface, neutrons irradiate and activate the chemical elements within the dispersed soil, thereby contributing to nuclear fallout.
Sulfur, tantalum, and gold have been used as test targets to determine the yield of nuclear weapons through their neutron activation products.
Answer: True
Elements such as sulfur, tantalum, and gold have been historically employed as test targets to quantify the yield of nuclear weapons by analyzing the specific neutron activation products generated.
What was the unexpected nuclear process that significantly contributed to the Castle Bravo accident's higher-than-expected yield?
Answer: The fission of lithium-7 into helium-4 and tritium.
The unexpectedly high yield of the Castle Bravo accident was largely due to the fission of lithium-7 into helium-4 and tritium upon neutron capture, a process with a higher probability than anticipated.
How does neutron activation contribute to nuclear fallout from atomic weapons?
Answer: It vaporizes the bomb casing, which then becomes radioactive and contributes to fallout.
Neutron activation contributes to nuclear fallout when the metallic casing of an atomic weapon absorbs neutrons during detonation, becomes radioactive, and is subsequently vaporized and dispersed.
What happens when neutrons irradiate soil near the Earth's surface during a nuclear burst?
Answer: The soil elements undergo neutron activation, contributing to nuclear fallout.
When soil near the Earth's surface is irradiated by neutrons during a nuclear burst, its constituent elements undergo neutron activation, thereby becoming radioactive and contributing to nuclear fallout.
Besides aluminum and copper, which other elements have been used as test targets to determine the yield of nuclear weapons through neutron activation?
Answer: Sulfur, tantalum, and gold
In addition to aluminum and copper, sulfur, tantalum, and gold have been employed as test targets to determine the yield of nuclear weapons by analyzing their neutron activation products.
A Geiger counter measuring gamma ray radioactivity from activated aluminum foil can demonstrate nuclear fusion in a fusor device.
Answer: True
Measuring the gamma ray radioactivity from activated aluminum foil with a Geiger counter is an experimental method to confirm that nuclear fusion has occurred within a fusor device, as fusion produces neutrons that activate the foil.
In Inertial Confinement Fusion (ICF), fusion yield is determined by measuring alpha particle emissions from activation targets.
Answer: False
In Inertial Confinement Fusion (ICF), the fusion yield is typically determined by measuring the gamma-ray emissions from neutron activation targets, as neutron production is directly proportional to fusion yield.
Neutron Activation Analysis (NAA) requires extensive sample preparation, including solubilization, before analysis.
Answer: False
A key advantage of Neutron Activation Analysis (NAA) is that it typically requires no sample preparation or solubilization, allowing for the analysis of intact objects.
NAA is considered non-destructive because the induced radioactivity is typically low and short-lived, preserving the object's integrity.
Answer: True
Neutron Activation Analysis (NAA) is regarded as non-destructive because the induced radioactivity is generally low and short-lived, ensuring the preservation of the analyzed object's integrity.
In oil drilling, activated aluminum-28 is used to determine the oil content of underground areas.
Answer: False
In the oil drilling industry, activated aluminum-28 is specifically utilized to determine the clay content of underground formations, not the oil content.
Historians can authenticate atomic artifacts by identifying specific isotopes formed through neutron activation from fission incidents.
Answer: True
By identifying specific isotopes produced via neutron activation from fission events, historians can authenticate atomic artifacts and materials exposed to such neutron fluxes.
Barium-133 is a common isotope found in all trinitite samples, making it an unreliable authentication marker.
Answer: False
Barium-133 is a rare isotope found in trinitite, formed from Baratol in the Trinity device, making its presence a reliable marker for authenticating trinitite samples.
Neutron irradiation of float-zone silicon slices transmutes silicon atoms into phosphorus, creating p-type silicon.
Answer: False
Neutron irradiation of float-zone silicon slices transmutes silicon atoms into phosphorus, which dopes the silicon to create n-type silicon, not p-type.
Silicon-30 captures a neutron to become silicon-31, which then decays into phosphorus-31, doping silicon into n-type material.
Answer: True
The process of neutron transmutation doping involves silicon-30 capturing a neutron to form silicon-31, which subsequently decays into phosphorus-31, thereby creating n-type silicon.
How can neutron activation be used to demonstrate nuclear fusion in a fusor device?
Answer: By using a Geiger counter to measure gamma ray radioactivity from activated aluminum foil.
Nuclear fusion in a fusor device can be demonstrated by detecting gamma ray radioactivity from an activated aluminum foil using a Geiger counter, as fusion produces neutrons that activate the foil.
In the Inertial Confinement Fusion (ICF) approach, how is the fusion yield typically determined using neutron activation?
Answer: By measuring the gamma-ray emissions from neutron activation targets.
In Inertial Confinement Fusion (ICF) experiments, the fusion yield is typically quantified by measuring the gamma-ray emissions from neutron activation targets, as this is directly proportional to neutron production.
What is a key advantage of Neutron Activation Analysis (NAA) for trace element analysis?
Answer: It requires no sample preparation or solubilization, allowing intact objects to be analyzed.
A significant advantage of Neutron Activation Analysis (NAA) is its ability to analyze intact objects without requiring extensive sample preparation or solubilization, making it suitable for valuable or delicate items.
Why is Neutron Activation Analysis (NAA) considered a non-destructive analysis method?
Answer: The induced radioactivity is typically low and short-lived, preserving the object's integrity.
Neutron Activation Analysis (NAA) is considered non-destructive because the induced radioactivity is generally low and short-lived, ensuring that the analyzed object's integrity is maintained after the analysis.
In the oil drilling industry, what is activated aluminum-28 specifically used to determine?
Answer: The clay content of underground areas.
Activated aluminum-28 is specifically employed in the oil drilling industry to ascertain the clay content of subterranean regions, as clay is typically an alumino-silicate.
How can historians utilize neutron activation products to authenticate atomic artifacts?
Answer: By identifying specific isotopes formed through activation from fission incidents.
Historians can authenticate atomic artifacts by identifying characteristic isotopes produced through neutron activation resulting from fission incidents, thereby verifying their origin and exposure.
Which specific barium isotope, formed from Baratol, is used to authenticate trinitite samples?
Answer: Barium-133
Barium-133, a rare isotope formed from Baratol in the Trinity device, serves as a specific marker for authenticating trinitite samples.
In semiconductor production, neutron irradiation of float-zone silicon slices transmutes silicon atoms into what element to create n-type silicon?
Answer: Phosphorus
Neutron irradiation of float-zone silicon slices transmutes silicon atoms into phosphorus, which acts as a dopant to create n-type silicon for semiconductor applications.
Describe the nuclear reaction that transmutes silicon-30 into phosphorus-31 during semiconductor production.
Answer: Si-30 + neutron → Si-31 + gamma ray → P-31 + beta ray
The transmutation of silicon-30 to phosphorus-31 involves silicon-30 capturing a neutron to form silicon-31, which then undergoes beta decay to become phosphorus-31, a process used in semiconductor doping.
What is the half-life and decay energy of aluminum-28, used in oil drilling for clay content determination?
Answer: 2.3 minutes; 4.642 MeV
Activated aluminum-28, utilized in oil drilling for clay content analysis, has a short half-life of 2.3 minutes and decays with an energy of 4.642 MeV.
In PWRs and BWRs, oxygen-16 in coolant water is activated by fast neutrons, transmuting into nitrogen-16.
Answer: True
During reactor operation, fast neutrons activate oxygen-16 in the coolant water, leading to an (n,p) reaction that transmutes it into radioactive nitrogen-16.
Nitrogen-16, formed from activated coolant water, has a long half-life of several hours, requiring prolonged shielding.
Answer: False
Nitrogen-16 has a very short half-life of 7.13 seconds, meaning its radiation rapidly diminishes, not requiring prolonged shielding.
Additional biological shielding is necessary around nuclear reactor plants because nitrogen-16 from coolant water activation emits high-energy gamma rays.
Answer: True
The rapid decay of nitrogen-16, produced from activated coolant water, releases high-energy gamma rays, necessitating additional biological shielding around nuclear reactor plants for safety.
Radiation from activated coolant water typically subsides to safe levels within a few hours, allowing for less shielded handling.
Answer: False
Due to the very short half-life of nitrogen-16, radiation from activated coolant water typically subsides to safe levels within one to two minutes, not several hours.
Cyclotron facility concrete foundations can become radioactive, containing long-lived isotopes like manganese-54 and cobalt-60.
Answer: True
Neutron activation in cyclotron facilities can render concrete foundations radioactive, leading to the presence of various long-lived isotopes such as manganese-54 and cobalt-60.
The release limit for facilities with residual radioactivity in concrete from cyclotron activation is 250 mrem per year.
Answer: False
The regulatory release limit for facilities with residual radioactivity in concrete from cyclotron activation is 25 mrem per year, not 250 mrem per year.
Iron-55 is produced when iron-54 captures a neutron, a process that can occur in reinforcement bars within concrete.
Answer: True
Iron-55 is formed through the neutron capture by iron-54, a reaction that can take place in the iron reinforcement bars embedded within concrete structures exposed to neutron flux.
Neutron activation in nuclear reactor cores helps to preserve lining materials, extending their operational lifespan.
Answer: False
Neutron activation within nuclear reactor cores contributes to material erosion and degradation over time, necessitating the periodic disposal of lining materials as radioactive waste, rather than preserving them.
Using low-activation materials for components in high neutron flux environments can reduce radioactive waste.
Answer: True
Employing low-activation materials in components exposed to high neutron fluxes is a strategy to significantly reduce the generation of radioactive waste and material erosion.
Carbon-14 is primarily generated through the activation of atmospheric oxygen-16 by thermal neutrons.
Answer: False
Carbon-14 is most frequently generated by the neutron activation of atmospheric nitrogen-14 by thermal neutrons, not oxygen-16.
Fast Breeder Reactors (FBRs) produce more Carbon-14 than Pressurized Water Reactors (PWRs) due to their higher operating temperatures.
Answer: False
Fast Breeder Reactors (FBRs) produce approximately an order of magnitude less Carbon-14 than Pressurized Water Reactors (PWRs), primarily because FBRs do not use water as a primary coolant, which is a source of C-14 precursors.
In radiation safety, the activation of sodium and phosphorus in the human body can help estimate acute accidental neutron exposure.
Answer: True
The neutron activation of sodium to sodium-24 and phosphorus to phosphorus-32 in the human body provides a valuable immediate indicator for assessing acute accidental neutron exposure.
During normal operation in PWRs and BWRs, what radioactive isotope is formed when fast neutrons activate oxygen-16 in coolant water?
Answer: Nitrogen-16
In pressurized and boiling water reactors, fast neutrons activate oxygen-16 in the coolant water, transmuting it into the radioactive isotope nitrogen-16.
What are the key characteristics of Nitrogen-16, formed from activated coolant water, regarding its half-life and decay emissions?
Answer: Short half-life (7.13 seconds) and emits high-energy beta particles and gamma radiation.
Nitrogen-16, a product of coolant water activation, is characterized by a very short half-life of 7.13 seconds and decays by emitting high-energy beta particles and gamma radiation.
Why is additional biological shielding necessary around nuclear reactor plants due to coolant water activation?
Answer: Because nitrogen-16 decays rapidly, emitting high-energy gamma rays.
Additional biological shielding is essential around nuclear reactor plants because the rapid decay of nitrogen-16, formed from activated coolant water, releases potent high-energy gamma rays that pose a radiation hazard.
How long does it typically take for the radiation from activated coolant water, primarily due to nitrogen-16, to subside to safe levels?
Answer: One to two minutes
Due to the extremely short half-life of nitrogen-16, the radiation levels from activated coolant water typically decrease to safe levels within one to two minutes.
Which of the following is NOT listed as a long-lived radioactive isotope found in cyclotron facility concrete foundations due to neutron activation?
Answer: Uranium-235
Long-lived radioactive isotopes found in cyclotron facility concrete foundations due to neutron activation include manganese-54, iron-55, and cobalt-60, but not uranium-235.
What is the release limit for facilities with residual radioactivity derived from cyclotron activation in concrete?
Answer: 25 mrem per year
The regulatory release limit for facilities containing residual radioactivity in concrete from cyclotron activation is established at 25 mrem per year.
What is the nuclear reaction for the production of iron-55 from the activation of iron in reinforcement bars?
Answer: Fe-54 + n → Fe-55
Iron-55 is produced when iron-54, a stable isotope, captures a neutron, leading to its transformation into the radioactive isotope iron-55.
What is a significant problem caused by neutron activation within the cores of nuclear reactors over time?
Answer: Material erosion and the generation of low-level radioactive waste.
Over time, neutron activation within nuclear reactor cores leads to material erosion and the accumulation of low-level radioactive waste, necessitating periodic disposal.
What approach can significantly reduce the problem of material erosion and radioactive waste caused by neutron activation in high neutron flux environments?
Answer: Choosing suitably low-activation materials.
The selection of low-activation materials for components exposed to high neutron fluxes is a crucial strategy to minimize material erosion and the generation of radioactive waste.
What is the most frequent pathway for Carbon-14 generation through neutron activation?
Answer: Activation of atmospheric nitrogen-14 by thermal neutrons.
The most common pathway for Carbon-14 generation via neutron activation is the interaction of thermal neutrons with atmospheric nitrogen-14.
How do Fast Breeder Reactors (FBRs) compare to Pressurized Water Reactors (PWRs) in terms of Carbon-14 production?
Answer: FBRs produce approximately an order of magnitude less Carbon-14 than PWRs.
Fast Breeder Reactors (FBRs) generate significantly less Carbon-14 compared to Pressurized Water Reactors (PWRs, approximately an order of magnitude less), primarily because FBRs do not use water as a primary coolant, which is a source of C-14 precursors.
In radiation safety, what human body elements are activated by neutrons to provide an immediate estimate of acute accidental neutron exposure?
Answer: Sodium and phosphorus
The neutron activation of sodium to sodium-24 and phosphorus to phosphorus-32 in the human body serves as an immediate dosimeter for acute accidental neutron exposure.