EPRI Reactor Theory Practice Exam

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• What happens to U-235 and Pu-239 during operation?
• What is Pu-239 production and its effect on reactivity in a thermal reactor?
• Transport theory is preferred over diffusion theory in which scenario?
• Which statement best describes the meaning of supercritical, critical, and subcritical states in terms of neutron population?
• How does fuel burnup affect reactor reactivity over long operation?
• Why would the Chernobyl design not have met U.S. licensing design requirements?
• What is the purpose of perturbation theory in reactor physics?
• What is neutron leakage and its effect on reactor criticality?
• The Chernobyl accident involved which event?
• Redundancy in safety systems refers to having
• Which of the following is NOT listed as a fuel failure cause?
• In a BWR, where are moisture separators and steam dryers typically located?
• Beta particle emission can be electron emission (beta minus) or positron emission (beta plus). The daughter products are usually what?
• How do perturbation methods estimate the change in k_eff due to small material property changes?
• Atomic mass unit is defined as?
• Manufacturing defects and design limitations can lead to fuel cladding failure; which example is given?
• What is the extrapolated boundary in diffusion theory and how is the extrapolation length z_e determined?
• If control rods are inserted deeper into the core, what is the expected effect on reactivity?
• What is the effect of neutron leakage on the effective multiplication factor k_eff?
• What is a radioisotope?
• Fuel failures contribute to which of the following as a consequence?
• What is the sign of the moderator temperature coefficient in typical light-water reactors?
• What is the correct form of the basic two-group point-kinetics equations for neutron density n(t) and precursor concentrations C_i?
• Which of the following is a feature in a nuclear power plant that promotes safety?
• In the diffusion equation, what does the term (ν Σ_f φ)/k_eff represent?
• Which description best defines nuclear fission?
• Sub-cooled nucleate boiling regions in a reactor core are described as areas where
• Atomic mass is described as?
• What is a reactor's safety margin and why is it essential?
• Boron dilution in a PWR refers to which situation?
• Proton is defined as?
• The negative fuel temperature coefficient is an example of which type of safety feature?
• Inserting more control rods into the core results in what?
• Which are the three major modes of radioactive decay?
• In PWRs, boron concentration is used as soluble poison; as fuel depletes, what do operators do with boron concentration?
• Which statement about rod worth curves is accurate?
• Why is locating a failed fuel during refueling time-consuming?
• Name three major neutron cross-section categories and what each represents.
• What does Λ denote in the point kinetics equations?
• Which statement best describes the role of steam in driving the turbine in a nuclear plant?
• What does radioactive decay involve?
• Which statement best describes a passive safety system?
• Typically, how many delayed-neutron groups are used in reactor kinetics, and what is the typical total delayed-neutron fraction (β_eff) for thermal reactors?
• Doppler (fuel temperature) coefficient: typical sign in thermal reactors?
• In a Pressurized Water Reactor (PWR), which substance is dissolved in the moderator/coolant to control the neutron population?
• β equals what in the multi-group model?
• In many thermal reactors, approximately how many pcm is defined per dollar (given β_eff ≈ 0.0065)?
• Redundant and diverse systems are used in safety design to enhance safety by
• What are worth curves and how are they used in reactor operation?
• Fuel failure is a breach of what?
• Describe the fission process in general?
• Voids in the coolant primarily concern which reactor type?
• Which events are among the three significant accidents in commercial nuclear power plants?
• In some PWRs, corrosion products deposited on the fuel cladding can cause boric acid and LiOH to accumulate in deposits in regions of sub-cooled nucleate boiling, leading to a shift of core power to other regions. This can cause
• What does C_i denote in the point kinetics equations?
• One pcm corresponds to what relative change in k/k?
• Isotope refers to?
• What is the purpose of including burnable poison in some fuel assemblies after refueling?
• If the isotope decays for another ten years, what fraction remains?
• Coulombic repulsion describes which physical concept?
• What is decay heat in a nuclear reactor context?
• In a PWR, injecting a slug of cold water into the core will have what effect on reactivity?
• The workforce and its corrective action program constitute the first line of defense against accidents. Which statement describes this?
• What is the diffusion length L_d and how is it defined in terms of D and Σ_a?
• Negative moderator temperature feedback implies reactivity changes in what way?
• Why can't BWRs use dissolved boron to control reactivity?
• What does the spectral effect necessitate in cross section data representation?
• Which statement best describes reactivity control in US light-water reactors?
• How does decay heat change with time after shutdown?
• What is a rod worth calibration method used in practice?
• Which shielding is typically used to reduce exposure to gamma radiation?
• Explain the concept of adjoint flux in reactor theory.
• λ_i represents what in the multi-group kinetics model?
• Mass-energy equivalence in fission relates to?
• What does temperature affect in reactor reactivity?
• Energy release in fission is due to what?
• Chemistry-induced fuel failures are caused by which factor?
• What is the primary means of preventing a rod ejection accident?
• What design feature reduces the risk of control rod release mechanism failures?
• A reactivity control accident is defined as?
• What is the role of recirculation flow control in BWRs?
• What is the effect of xenon-135 on reactor reactivity and how does it arise?
• Which statement describes the Bohr model?
• Which statement describes a strongly negative temperature coefficient?
• Which device in a nuclear power plant is described as having rotating blades turned by a fluid?
• Explain why a strongly negative temperature coefficient aids reactor shutdown.
• What is a coolant in a nuclear reactor?
• Rod ejection accident mitigation is achieved by which design feature?
• In a PWR, where are the moisture separators located?
• Which statement best describes xenon-135 poisoning?
• Gamma ray emission is one of the three major decay modes. How are gamma rays characterized?
• Define the effective multiplication factor k_eff and state what k_eff = 1, k_eff > 1, and k_eff < 1 imply for reactor operation.
• At Three Mile Island, was there a release of radiation to the environment?
• Which expression correctly defines the diffusion coefficient D in terms of the transport cross-section Σ_tr?
• What is the purpose of the corrective action program in a nuclear plant?
• What does the effective delayed neutron fraction β_eff represent in reactor kinetics?
• In a BWR, reactor power is controlled by what mechanisms?
• What is the effect of withdrawing control rods in a reactor?
• What is a criticality search?
• In diffusion theory, when is it not a good approximation?
• Alpha particle emission is typically associated with heavy nuclei. What is a key shielding characteristic of alpha particles?
• After fission, what do the fission fragments emit before decaying?
• Cracking of cladding can result from
• Which statement correctly contrasts the design of PWRs and BWRs?
• Explain the concept of burnup and fuel depletion in a reactor.
• Which of the following represents the steady-state diffusion equation for a homogeneous, one-speed reactor with a source term S, including the fission production term?
• What are typical fission product poisons that accumulate during operation?
• What caused the Fukushima accident to lose cooling capability?
• Negative reactivity addition means which?
• Neutron is defined as?
• Why is adequate cooling required for the first days after shutdown?
• Which statement best describes a Boiling Water Reactor (BWR)?
• What are Light Water Reactors?
• What is the shutdown margin and why is it required?
• Pellet-clad interaction (PCI) occurs under what condition?
• How does k_eff differ from k_infty, and why does leakage matter in finite reactors?
• What is half-life?
• Which neutron cross-section represents capture without fission?
• What characterizes a Pressurized Water Reactor?
• In a Pressurized Water Reactor, what happens to the heated water after leaving the core?
• Which statement accurately describes shielding for the two reactor types?
• Atomic number is?
• What is the main assumption behind diffusion approximations?
• If the effective multiplication factor k_eff is greater than 1, the reactor is in which state?
• Fission fragments are what type of nuclei?
• Which term describes the center of an atom containing most of its mass and consisting of neutrons and protons?
• In spectral effects, what aspects are affected by the energy dependence of cross sections and neutron spectra?
• Radioactivity is defined as unstable nuclei naturally releasing energy by means of decay. Which term describes this phenomenon?
• Which scenario constitutes a core reload error during refueling?
• Which isotopes are the primary concerns due to high neutron absorption cross sections?
• If an isotope has a half-life of ten years and is allowed to decay for ten years, what fraction remains?
• Debris-induced clad failure is commonly caused by what scenario?
• Which component provides rapid shutdown capability in a reactor?
• For small ρ, what is the simple expression for the reactor period P in terms of Λ and ρ?
• Which statement best describes the diffusion-adjoint eigenvalue problem used in reactor theory?
• What is iodine-135 and its relation to xenon poisoning?
• How is the total cross-section Σ_t defined in the framework described?
• What best describes the function of control rods in a reactor?
• Void coefficient: what is it and why is it important in BWRs?
• If the multiplication factor k is less than 1, what must be applied to bring the reactor to criticality?
• What is the nucleus of an atom?
• What is defined as radiation in the nuclear context?
• What happens to the reactor period as reactivity ρ approaches β_eff?
• Intrinsic vs extrinsic feedback: which statement is correct?
• Reactivity is defined as the change in neutron multiplication in a reactor. What does a multiplication factor k = 1 indicate?
• How many neutrons are typically released during fission?
• What is the concept of control rod worth and how is it measured?
• Which statement best characterizes a heat exchanger in a nuclear plant?
• Regarding steam production, which statement is true?
• What is the neutron current J and how is it related to the neutron flux φ in diffusion theory?
• What is the role of spectral effects in reactor physics?
• How is β_eff defined in the multi-group kinetics model?
• Power-induced failures include which mechanism?
• What is the function of a pressurizer in a PWR primary system?
• What systems are used to remove decay heat in a nuclear plant?
• How does Pu-239 production occur in a reactor, and what is its effect on reactivity?
• What is the effect of increasing the macroscopic absorption cross section Σ_a on the diffusion length L_d?
• What term describes a feedback mechanism that increases reactor reactivity?
• Explain what a safety factor margin is in nuclear design.
• In fission, the released neutrons and energy come from what phenomenon?
• In a BWR, where does boiling primarily occur?
• What is the transport cross-section Σ_tr and how is it defined in terms of Σ_t, Σ_s, and μ̄?
• Diverse safety systems are defined as systems that
• In Boiling Water Reactors, how does increasing steam voids affect reactivity?
• What best defines the nuclear force?
• In perturbation calculations, which fluxes are typically used to compute Δk_eff?
• What is neutron diffusion theory, and when is it a good approximation?
• Positive reactivity addition means which of the following?
• In a PWR, reactor power is controlled primarily by what?
• What is the Reactor Core?
• Inherent safety features are features incorporated into the design and are a result of basic physics, such as the
• What does the term one-speed mean in reactor diffusion theory?
• Describe the role of delayed neutron precursors in reactor control.
• In diffusion theory, what does the condition φ = 0 at the extrapolated boundary enforce?
• What is a moderator in a nuclear reactor?
• An example of an active safety system is
• What is a delayed neutron and why are they important for reactor control?
• In neutron diffusion theory, solving for the neutron flux φ as the eigenfunction of the diffusion operator with eigenvalue 1/k_eff corresponds to which equation?
• Define reactivity ρ and its typical units.
• Identify the factors contributing to the TMI accident beyond the cooling malfunction.
• What does a condenser do in a power plant?
• Fission product poisons affect reactivity by doing what?
• How does a nuclear power plant generate electricity?
• Define the macroscopic cross sections Σ_a and Σ_f.
• Which of the following is listed as a type of reactivity control accident?
• The Three Mile Island accident was primarily caused by what?
• What is the spectral effect in cross sections and why is it important?
• What is the purpose of neutron detector calibration in reactor operation?
• In point kinetics, what best describes β_eff and its role?
• Electron is defined as?
• Which condition is NOT a scenario where diffusion approximation may be inadequate?
• Which statement best describes control rod release mechanisms?
• In a PWR, reactor coolant temperature is controlled by what?
• What is the primary coolant in a PWR?
• Which statement correctly describes gamma decay?