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Nuclear quiz 2
| Question | Answer |
|---|---|
| Charged particles (such as alpha particles and beta particles) interact with matter primarily in which mechanisms? | Ionization Excitation |
| In soft tissue, the range of alpha particles is on the order of: | Micrometers |
| Alpha particles emitted during nuclear transitions are: | monoenergetic |
| Which of the following statements correctly describe interactions of beta particles with matter? 1 | The lowest energy betas are easily stopped in small amounts of material, while the highest energy betas determine the total shielding thickness needed. |
| Which of the following statements correctly describe interactions of beta particles with matter? 2 | A scattered electron with more than ~1 keV energy can itself cause ionizations and is called a delta ray. / Beta particles are emitted with a continuous spectrum of energies |
| Bremsstrahlung radiation | From Deceleration of energetic electrons in matter |
| Annihilation photons | From positron/electron annihilation (always 0.511 MeV) |
| X-ray | From electron orbital shells of atoms |
| Gamma (γ) ray | From the nucleus |
| Which of the following best describes the energy distribution of positrons emitted in decay? | They have a continuous spectrum of energies ranging from 0 up to the maximum theoretical β energy |
| For -rays, the linear attenuation coefficient () represents: | The rate at which the intensity of radiation decreases per unit thickness of material |
| Photoelectric effect | A photon is completely absorbed, and its energy is transferred to an orbital electron, which is then ejected from the atom. |
| Pair production | The photon disappears, producing an electron–positron pair near the nucleus; this process occurs only when photon energy exceeds 1.02 MeV. |
| Compton effect | The photon transfers part of its energy to an electron and is scattered with reduced energy. |
| Which statement best describes how ionizing radiation can damage DNA? | Damage can occur either directly, when radiation interacts with atoms in the DNA, or indirectly, when radiation interacts with nearby water molecules to produce free radicals that attack the DNA |
| Complete the following unit conversion relationship for the absorbed dose: | 1 Gy = 1J/kg = 100rad |
| Based on the ICRP-recommended radiation weighting factors (WR), which of the following statements best describes their general trend? | WR values are highest for radiations that cause dense ionization, such as alpha particles and fission fragments. |
| Which of the following statements best summarizes the early historical development of radiation discovery and understanding of its biological effects? | Antoine Henri Becquerel discovered spontaneous emission of radiation from uranium, and Marie and Pierre Curie later identified new radioactive elements such as polonium and radium |
| Abosorbed dose | The amount of energy deposited by ionizing radiation per unit mass of material; expressed in grays (Gy). |
| Equivalent does | The absorbed dose adjusted for the biological effectiveness of the radiation type, using radiation weighting factors; expressed in sieverts (Sv). |
| Exposure | A measure of the ionization produced by photons in air; expressed in coulombs per kilogram (C/kg) or roentgens (R). |
| Which statement best describes the historical incident involving the radium dial painters in the early 20th century? | The workers developed radiation-induced bone damage and cancers after ingesting radium-based paint while shaping their brushes with their lips. |
| The LD 50/60 is the lethal dose at which ___% of those exposed to that does will die within ___ days | 50, 60 |
| Which statement best describes what the Linear No-Threshold (LNT) model implies for radiation protection policy? | The risk of harmful effects increases proportionality with dose, even at very low levels |
| Which of the following statements correctly describe how biological or physical factors can influence the dose–response relationship of radiation? 1 | Decreasing the dose rate allows more time for cellular repair, thereby increasing the LD50 and making cells more tolerant to radiation. |
| Which of the following statements correctly describe how biological or physical factors can influence the dose–response relationship of radiation? 2 | The presence of oxygen enhances the biological effect of radiation, making oxygenated cells more radiosensitive than hypoxic cells. |
| Which of the following statements best describes the scientific concern regarding how the Linear No-Threshold (LNT) model is sometimes used? | Most regulatory bodies use the LNT model to establish prudent dose limits, but using it to make scientific predictions about cancer deaths from very small doses is an improper extrapolation beyond observed data |
| Which of the following statements best summarizes the current scientific consensus and major competing hypotheses regarding the biological effects of low doses of radiation? | The National Academy of Sciences BEIR Committee concludes that the most prudent model remains the Linear No-Threshold (LNT) model, which assumes risk increases linearly with dose and has no safe threshold |
| Arrange the following cell types in order from most sensitive to least sensitive to radiation | a. Most sensitive b. Lymphocytes and blood forming cells c. Reproductive and gastrointestinal Cells d. Nerve and muscle cells e. Least sensitive |
| Two types of cells are exposed to the same radiation dose: Cell Type A: Rapidly dividing with high oxygen supply Cell Type B: Slowly dividing with low oxygen supply Which statement best explains the expected difference in radiation response? | Cell Type A will be more sensitive due to its active division and oxygen-rich environment |
| Which of the following statements correctly describe the concepts of Relative Biological Effectiveness (RBE) and radiation weighting factors (wᵣ)? 1 | RBE compares the doses of different types of radiation needed to produce the same biological effect in a given experiment. RBE values depend on experimental conditions such as cell type, dose rate, and the biological endpoint studied. |
| Which of the following statements correctly describe the concepts of Relative Biological Effectiveness (RBE) and radiation weighting factors (wᵣ)? 2 | High Linear Energy Transfer radiation generally has a higher RBE than low LET radiation, although this relationship is not strictly linear. Radiation weighting factors (wᵣ) are simplified operational values derived from conservative RBE estimates for |
| According to the Law of Bergonie and Tribondeau, which type of cells are generally the most radiosensitive? | Rapidly dividing, unspecialized cells with a long dividing future |
| Which of the following statements correctly distinguishes deterministic (nonstochastic) effects from stochastic effects of radiation exposure? | Deterministic effects occur only when a threshold dose is exceeded, and their severity increases with dose, while stochastic effects have no threshold, and their probability—not severity—increases with dose. |
| No immediate observable effects | < 50 mGy (<5 rad) |
| Nausea, fatigue, vomiting likely | 500 mGy - 1.5 Gy (50 - 150 rad) |
| Severe blood changes; possible death within weeks | 1.5 - 11 Gy (150 - 1100 rad) |
| Central nervous system failure; death certain | > 20 Gy (> 2000 rad) |
| LD 50/60 for human with minimal care | 3 - 4 Gy (300 - 400 rad) |
| Which of the following most closely represents the pressure and outlet temperature conditions of a Pressurized Water Reactor (PWR)? | 15 MPa and 320 °C |
| Read 1 | In a PWR, power is primarily controlled using control rods for immediate reactivity changes and boric acid for slow reactivity compensation. |
| Read 2 | In a BWR, reactor power can be adjusted not only by moving control rods, but also by changing the coolant flow rate which alters the moderator density and therefore the fission rate. |
| Designed for intermediate-pressure emergencies, injecting water from the refueling water storage tank (RWST) during small-to-intermediate breaks. | Intermediate Pressure Injection System |
| Operates during large-break loss-of-coolant accidents when system pressure is very low, including long-term recirculation cooling through the containment sump | Low Pressure Injection System (Residual Heat Removal) |
| Injects borated water at high pressure during small-break or steam-line rupture accidents when system pressure remains relatively high. | High Pressure Injection System |
| Provides automatic flow of borated water without electrical power when system pressure drops rapidly, using pressurized nitrogen to drive injection | Cold Leg Accumulators |
| After a PWR has been shut down, which of the following statements correctly describe how decay heat is removed from the reactor core? 1 | The auxiliary feedwater system supplies water from the condensate storage tank to the steam generators to remove decay heat. Even after shutdown, fission product decay continues to generate enough heat to damage fuel if not removed. |
| After a PWR has been shut down, which of the following statements correctly describe how decay heat is removed from the reactor core? 2 | If the main condenser is no good, the steam can be released to the atmosphere through atmo. relief valve Once decay heat becomes low, the residual heat remove system continue cooldown by xfer heat to the comp. cooling water and service water system |
| Which of the following statements correctly describe the Reactor Core Isolation Cooling (RCIC) system in a BWR? 1 | The RCIC system provides makeup water to the reactor vessel for core cooling when the main steam lines are isolated and the normal feedwater supply is unavailable. |
| Which of the following statements correctly describe the Reactor Core Isolation Cooling (RCIC) system in a BWR? 2 | The primary water source for the RCIC system is the condensate storage tank, with an alternate source from the suppression pool. |
| Which of the following statements correctly describe the Reactor Core Isolation Cooling (RCIC) system in a BWR? 3 | The RCIC system is designed to provide a flow rate equal to the steaming rate 15 minutes after shutdown at design maximum decay heat conditions. |
| Which of the following statements correctly describe the Reactor Core Isolation Cooling (RCIC) system in a BWR? 4 | The RCIC system’s pump is driven by a turbine, which uses steam from the main steam lines as its energy source. |
| Which of the following statements correctly describes how steam is produced in a Boiling Water Reactor (BWR)? | Steam is produced directly inside the reactor vessel and flows to the turbine. |
| Which of the following statements correctly describe the Emergency Core Cooling Systems (ECCS) in a BWR | The ECCS includes two high-pressure systems and two low-pressure systems) to limit fuel cladding damage during a LOCA. The High Pressure Coolant Injection (HPCI) system is designed to operate while the reactor remains at high pressure. |
| BWR | Has a single cicuit configuration, control rods inserted from below, steam generated directly inside the reactor vessel |
| PWR | Uses boric acid dissolved in coolant for reactivity control, requires separate steam generators, primary circuit isolated from turbine, preventing radioactivity transfer |
| What is the main purpose of the containment in light-water reactors? | To provide mechanical protection, prevent leakage of dangerous substances, and act as radiation shielding. |
| In a BWR, which of the following statements best describes the role of the Residual Heat Removal (RHR) system during shutdown conditions? | It removes decay heat by circulating water from the reactor recirculation loop through a heat exchanger and back to the reactor once pressure drops to about 50 psig. |
| One loop cycle(direct cycle): | Boiling water reactor |
| Two loop cycle(indirect cycle): | Pressurized water reactor, high temperature gas cooled reactor, pressurized heavy water reactor |
| 3 loop (indirect with intermediate heat exchanger): | Liquid metal fast breeder reactor |
| For a PWR, which of the following statements correctly describe the functions or behavior of the Reactor Coolant System (Primary System) and its components? 1 | The Reactor Coolant Pump provides forced coolant flow that is necessary for heat removal when the reactor is at power. b. The primary function of the Reactor Coolant System is to transfer heat from the fuel to the steam generators. |
| For a PWR, which of the following statements correctly describe the functions or behavior of the Reactor Coolant System (Primary System) and its components? 1 | The pressurizer maintains system pressure using electrical heaters, spray, and relief valves |
| In a two-loop indirect steam cycle (such as in a PWR), heat is transferred through several components from the reactor to the final heat sink. Sort the following components in the correct order of heat transfer, starting from the reactor core | a. Heat generation b. Reactor core c. Steam generator d. Steam line e. Turbine generator f. Condenser g. Condenser cooling water h. Final heat sink |
| Encapsulation | Serves as the second barrier, holding fission products that escape from the fuel. |
| Reactor vessel and primary-coolant loop | Provides the third barrier, maintaining system integrity to prevent leakage from the reactor core region |
| Containment structures | Represents the final line of defense, preventing the release of radioactivity to the environment. |
| Fuel particles | Forms the first barrier, designed for a high degree of fission product retention within the fuel itself. |
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