ANS CNP cheat sheet

Fission of U-235 by a thermal neutron releases about 200 MeV, roughly 2.5 prompt neutrons, and energy split among fission fragments, neutrons, gamma rays, and neutrinos.

Six-factor formula: k_eff = epsilon * p * f * eta * P_FNL * P_TNL, where epsilon is fast fission factor, p resonance escape probability, f thermal utilization, eta reproduction factor, and the last two are non-leakage terms.

Criticality condition is k_eff = 1; k_eff < 1 is subcritical and k_eff > 1 is supercritical. Reactivity rho = (k_eff - 1)/k_eff, often expressed in pcm (1 pcm = 1e-5).

Prompt neutron lifetime in a thermal reactor is on the order of 1e-4 s, which is why delayed neutrons (about 0.65% of total in U-235) are essential for controllability.

Delayed neutron fraction beta for U-235 is about 0.0065; the reactor is prompt critical when reactivity exceeds beta.

Inhour equation relates stable reactor period T to reactivity through the six delayed neutron groups; for small positive reactivity, T is approximately (l* + sum(beta_i/(lambda_i - 1/T)))/rho.

Four-factor formula for an infinite thermal reactor: k_inf = epsilon * p * f * eta; leakage is added by the non-leakage probabilities from the buckling and migration area.

Xenon-135 has a thermal absorption cross section near 2.6 million barns and produces post-shutdown reactivity transients; samarium-149 is a stable, slow-saturating fission product poison.

Control rods are withdrawn to add positive reactivity; rod worth is greatest where the neutron flux is highest, so differential worth curves peak near the core midplane.

The startup rate (SUR) in decades per minute relates to reactor period by SUR = 26.06 / T, with T in seconds.

A reactor period of 30 s corresponds to about 0.87 decades per minute; operators typically limit positive periods to avoid rapid power escalation.

Axial flux shape is affected by xenon redistribution; flux tilting can occur when local xenon burnout or buildup shifts the power distribution.

The moderator temperature coefficient is typically negative in PWRs because water density decreases with temperature, reducing moderation; void coefficient behavior varies by design.

Boration adds negative reactivity by increasing thermal neutron absorption; dilution adds positive reactivity. Boron letdown and makeup must be controlled by procedure.

Approach to criticality uses the inverse-counts (1/M) plot; a plot trending toward zero at the critical point indicates a valid approach.

Surveillance testing of reactor trip breakers and rod drop times verifies scram capability; rod drop time from full out to dashpot entry is typically under 2 s for PWRs.

Defense in depth uses multiple independent barriers and levels of protection: fuel matrix, cladding, primary pressure boundary, containment, and emergency systems.

The general design criteria in 10 CFR Part 50 Appendix A establish requirements such as single-failure criteria and protection against anticipated operational occurrences.

Design-basis accidents (DBAs) include loss-of-coolant accidents, rod ejection, steam line breaks, and main feedwater line breaks; they bound the safety analysis.

Emergency core cooling system acceptance criteria in 10 CFR 50.46 limit peak cladding temperature to 2200 F and local cladding oxidation to 17% of the initial wall thickness.

Technical specifications define limiting conditions for operation, surveillance requirements, and action statements; exceeding an LCO requires prompt action per the action statement.

The safety limit is the boundary that must not be exceeded to protect the public and fuel; it is more restrictive than the design basis and is enforced by reactor protection setpoints.

10 CFR Part 20 establishes occupational dose limits; 10 CFR Part 50 and Part 100 govern reactor site criteria and radiological emergency planning.

Event reporting under 10 CFR 50.72 and 50.73 requires notification of specified events within 1, 4, or 8 hours depending on severity.

Occupational whole-body dose limit is 5 rem (50 mSv) per year; the lens of the eye limit is 15 rem (150 mSv) per year; extremity and skin limit is 50 rem (500 mSv) per year.

ALARA means keeping doses as low as reasonably achievable, considering social and economic factors; the three protective principles are time, distance, and shielding.

Inverse square law: dose rate from a point source varies as 1/r^2, so doubling distance reduces dose rate by a factor of four.

Half-value layer (HVL) is the thickness of material that reduces gamma intensity by half; intensity I = I0 * (1/2)^(x/HVL).

Annual public dose limit is 100 mrem (1 mSv) from licensed facilities; the dose constraint for a single source is typically a small fraction of this.

Derived air concentration (DAC) and annual limit on intake (ALI) are used to control internal exposure; DAC is the concentration in air that would give an ALI over a working year.

Committed effective dose equivalent (CEDE) accounts for internal uptake over 50 years; tritium and iodine-131 are common internal dose contributors in nuclear facilities.

Personnel dosimetry uses TLDs, OSLs, or film badges; dosimeters are worn at the collar or torso and must be processed and records maintained per 10 CFR Part 20.

The front end of the fuel cycle includes uranium mining, conversion to UF6, enrichment, and fuel fabrication; the back end includes storage, reprocessing, and disposal.

Enrichment increases the U-235 fraction; natural uranium is about 0.711% U-235, and typical power reactor fuel is enriched to 3-5% U-235.

Spent fuel is highly radioactive and thermally hot; it is stored in pools for cooling and shielding before dry cask storage or disposal.

High-level waste includes spent fuel and reprocessing raffinate; low-level waste includes contaminated tools, clothing, and resins; transuranic waste is defined by activity above 100 nCi/g of alpha-emitting transuranics with half-life over 20 years.

The once-through cycle treats spent fuel as waste; a closed cycle reprocesses fuel to recover uranium and plutonium, reducing waste volume but raising proliferation concerns.

Waste classification and disposal requirements are in 10 CFR Part 61 for low-level waste and 10 CFR Part 60/63 for high-level waste geologic disposal.

Decay heat from spent fuel decreases over time; after about 5 years, heat output drops enough that forced cooling requirements can be reduced for some storage designs.

Waste package acceptance criteria and transportation are governed by 10 CFR Part 71 and DOT regulations; Type B casks are designed for severe accident conditions.

Physical protection of nuclear facilities is governed by 10 CFR Part 73; it requires a security plan, access controls, and protection against design-basis threats.

The IAEA safeguards system uses nuclear material accountancy, containment and surveillance, and inspections to verify that material is not diverted.

The Nuclear Non-Proliferation Treaty (NPT) requires non-nuclear-weapon states to accept IAEA safeguards on all nuclear material; the Additional Protocol strengthens verification.

Material control and accounting (MC&A) uses item and bulk measurement, material balances, and anomaly investigation to detect diversion.

Category I special nuclear material (Pu and U-235 above specified quantities) requires the highest physical protection; Category II and III have progressively lower requirements.

Two-person rule and access authorization programs are required for access to vital areas; background checks and fitness-for-duty programs support insider threat mitigation.

Security event reporting and drills are required; the design-basis threat defines the adversary capabilities against which the facility must be protected.

Cyber security for nuclear facilities is addressed under 10 CFR 73.54, requiring protection of digital computer and communication systems from cyber attacks.

Engineers must hold public safety paramount; when safety and production conflict, safety governs and the conflict must be escalated through the chain of command.

The duty to report safety concerns includes internal reporting and, where required, reporting to regulators; retaliation for good-faith reporting is prohibited.

Falsification of records, test results, or operator logs is a serious violation that can lead to license action and criminal liability under 18 U.S.C. 1001.

Operators must follow the plant technical specifications and procedures; deviations require documented justification and approval, not informal shortcuts.

Conflicts of interest must be disclosed; engineers should avoid accepting gifts or favors that could influence technical judgment.

Professional competence requires maintaining qualifications, completing required training, and self-assessing before performing safety-related tasks.

Whistleblower protections exist under federal law and 10 CFR 50.7; discrimination against employees for raising safety concerns is prohibited.

Ethical decision-making in nuclear settings uses stepwise reasoning: identify the issue, gather facts, evaluate options against codes and regulations, decide, and document.

Fission of U-235 by a thermal neutron releases about 200 MeV, roughly 2.5 prompt neutrons, and energy split among fission fragments, neutrons, gamma rays, and neutrinos.

Six-factor formula: k_eff = epsilon * p * f * eta * P_FNL * P_TNL, where epsilon is fast fission factor, p resonance escape probability, f thermal utilization, eta reproduction factor, and the last two are non-leakage terms.

Criticality condition is k_eff = 1; k_eff < 1 is subcritical and k_eff > 1 is supercritical. Reactivity rho = (k_eff - 1)/k_eff, often expressed in pcm (1 pcm = 1e-5).

Prompt neutron lifetime in a thermal reactor is on the order of 1e-4 s, which is why delayed neutrons (about 0.65% of total in U-235) are essential for controllability.

Delayed neutron fraction beta for U-235 is about 0.0065; the reactor is prompt critical when reactivity exceeds beta.

Inhour equation relates stable reactor period T to reactivity through the six delayed neutron groups; for small positive reactivity, T is approximately (l* + sum(beta_i/(lambda_i - 1/T)))/rho.

Four-factor formula for an infinite thermal reactor: k_inf = epsilon * p * f * eta; leakage is added by the non-leakage probabilities from the buckling and migration area.

Xenon-135 has a thermal absorption cross section near 2.6 million barns and produces post-shutdown reactivity transients; samarium-149 is a stable, slow-saturating fission product poison.

Control rods are withdrawn to add positive reactivity; rod worth is greatest where the neutron flux is highest, so differential worth curves peak near the core midplane.

The startup rate (SUR) in decades per minute relates to reactor period by SUR = 26.06 / T, with T in seconds.

A reactor period of 30 s corresponds to about 0.87 decades per minute; operators typically limit positive periods to avoid rapid power escalation.

Axial flux shape is affected by xenon redistribution; flux tilting can occur when local xenon burnout or buildup shifts the power distribution.

The moderator temperature coefficient is typically negative in PWRs because water density decreases with temperature, reducing moderation; void coefficient behavior varies by design.

Boration adds negative reactivity by increasing thermal neutron absorption; dilution adds positive reactivity. Boron letdown and makeup must be controlled by procedure.

Approach to criticality uses the inverse-counts (1/M) plot; a plot trending toward zero at the critical point indicates a valid approach.

Surveillance testing of reactor trip breakers and rod drop times verifies scram capability; rod drop time from full out to dashpot entry is typically under 2 s for PWRs.

Defense in depth uses multiple independent barriers and levels of protection: fuel matrix, cladding, primary pressure boundary, containment, and emergency systems.

The general design criteria in 10 CFR Part 50 Appendix A establish requirements such as single-failure criteria and protection against anticipated operational occurrences.

Design-basis accidents (DBAs) include loss-of-coolant accidents, rod ejection, steam line breaks, and main feedwater line breaks; they bound the safety analysis.

Emergency core cooling system acceptance criteria in 10 CFR 50.46 limit peak cladding temperature to 2200 F and local cladding oxidation to 17% of the initial wall thickness.

Technical specifications define limiting conditions for operation, surveillance requirements, and action statements; exceeding an LCO requires prompt action per the action statement.

The safety limit is the boundary that must not be exceeded to protect the public and fuel; it is more restrictive than the design basis and is enforced by reactor protection setpoints.

10 CFR Part 20 establishes occupational dose limits; 10 CFR Part 50 and Part 100 govern reactor site criteria and radiological emergency planning.

Event reporting under 10 CFR 50.72 and 50.73 requires notification of specified events within 1, 4, or 8 hours depending on severity.

Occupational whole-body dose limit is 5 rem (50 mSv) per year; the lens of the eye limit is 15 rem (150 mSv) per year; extremity and skin limit is 50 rem (500 mSv) per year.

ALARA means keeping doses as low as reasonably achievable, considering social and economic factors; the three protective principles are time, distance, and shielding.

Inverse square law: dose rate from a point source varies as 1/r^2, so doubling distance reduces dose rate by a factor of four.

Half-value layer (HVL) is the thickness of material that reduces gamma intensity by half; intensity I = I0 * (1/2)^(x/HVL).

Annual public dose limit is 100 mrem (1 mSv) from licensed facilities; the dose constraint for a single source is typically a small fraction of this.

Derived air concentration (DAC) and annual limit on intake (ALI) are used to control internal exposure; DAC is the concentration in air that would give an ALI over a working year.

Committed effective dose equivalent (CEDE) accounts for internal uptake over 50 years; tritium and iodine-131 are common internal dose contributors in nuclear facilities.

Personnel dosimetry uses TLDs, OSLs, or film badges; dosimeters are worn at the collar or torso and must be processed and records maintained per 10 CFR Part 20.

The front end of the fuel cycle includes uranium mining, conversion to UF6, enrichment, and fuel fabrication; the back end includes storage, reprocessing, and disposal.

Enrichment increases the U-235 fraction; natural uranium is about 0.711% U-235, and typical power reactor fuel is enriched to 3-5% U-235.

Spent fuel is highly radioactive and thermally hot; it is stored in pools for cooling and shielding before dry cask storage or disposal.

High-level waste includes spent fuel and reprocessing raffinate; low-level waste includes contaminated tools, clothing, and resins; transuranic waste is defined by activity above 100 nCi/g of alpha-emitting transuranics with half-life over 20 years.

The once-through cycle treats spent fuel as waste; a closed cycle reprocesses fuel to recover uranium and plutonium, reducing waste volume but raising proliferation concerns.

Waste classification and disposal requirements are in 10 CFR Part 61 for low-level waste and 10 CFR Part 60/63 for high-level waste geologic disposal.

Decay heat from spent fuel decreases over time; after about 5 years, heat output drops enough that forced cooling requirements can be reduced for some storage designs.

Waste package acceptance criteria and transportation are governed by 10 CFR Part 71 and DOT regulations; Type B casks are designed for severe accident conditions.

Physical protection of nuclear facilities is governed by 10 CFR Part 73; it requires a security plan, access controls, and protection against design-basis threats.

The IAEA safeguards system uses nuclear material accountancy, containment and surveillance, and inspections to verify that material is not diverted.

The Nuclear Non-Proliferation Treaty (NPT) requires non-nuclear-weapon states to accept IAEA safeguards on all nuclear material; the Additional Protocol strengthens verification.

Material control and accounting (MC&A) uses item and bulk measurement, material balances, and anomaly investigation to detect diversion.

Category I special nuclear material (Pu and U-235 above specified quantities) requires the highest physical protection; Category II and III have progressively lower requirements.

Two-person rule and access authorization programs are required for access to vital areas; background checks and fitness-for-duty programs support insider threat mitigation.

Security event reporting and drills are required; the design-basis threat defines the adversary capabilities against which the facility must be protected.

Cyber security for nuclear facilities is addressed under 10 CFR 73.54, requiring protection of digital computer and communication systems from cyber attacks.

Engineers must hold public safety paramount; when safety and production conflict, safety governs and the conflict must be escalated through the chain of command.

The duty to report safety concerns includes internal reporting and, where required, reporting to regulators; retaliation for good-faith reporting is prohibited.

Falsification of records, test results, or operator logs is a serious violation that can lead to license action and criminal liability under 18 U.S.C. 1001.

Operators must follow the plant technical specifications and procedures; deviations require documented justification and approval, not informal shortcuts.

Conflicts of interest must be disclosed; engineers should avoid accepting gifts or favors that could influence technical judgment.

Professional competence requires maintaining qualifications, completing required training, and self-assessing before performing safety-related tasks.

Whistleblower protections exist under federal law and 10 CFR 50.7; discrimination against employees for raising safety concerns is prohibited.

Ethical decision-making in nuclear settings uses stepwise reasoning: identify the issue, gather facts, evaluate options against codes and regulations, decide, and document.