197+ Free PE Nuclear Practice Questions

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Question 1

Score: 0/0

A radionuclide has a half-life of 8 hours. What fraction of the original activity remains after 24 hours?

50%

25%

12.5%

6.25%

to track

2026 Statistics

Key Facts: PE Nuclear Exam

Exam Questions

NCEES

8.5 hrs

Exam Time

NCEES

9.5 hrs

Total Appointment

NCEES

$400

Exam Fee

NCEES

48%

1st-Time Pass Rate

NCEES Jan 2026

Oct 27, 2026

Next Test Date

NCEES

The PE Nuclear exam is an 85-question NCEES CBT with a 9.5-hour appointment, a $400 exam fee, and a single-day annual administration. As of March 12, 2026, NCEES lists the next PE Nuclear test date as October 27, 2026 and reports January 2026 pass rates of 48% for first-time takers and 60% for repeat takers. NCEES opened a PE Nuclear PAKS update study on March 6, 2026, but no new exam blueprint has been published yet; the current public specification remains the version effective October 1, 2021.

Sample PE Nuclear Practice Questions

Try these sample questions to test your PE Nuclear exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 197+ question experience with AI tutoring.

1A radionuclide has a half-life of 8 hours. What fraction of the original activity remains after 24 hours?

A.50%

B.25%

C.12.5%

D.6.25%

Explanation: Twenty-four hours is three half-lives for a nuclide with an 8-hour half-life. After each half-life, the activity is cut in half, so the remaining fraction is (1/2)^3 = 1/8. That corresponds to 12.5% of the starting activity.

2For a roughly 1 MeV gamma ray passing through water or tissue, which interaction mechanism is usually dominant?

A.Photoelectric effect

B.Compton scattering

C.Pair production

D.Coherent scattering

Explanation: At about 1 MeV in low-Z materials such as water and tissue, Compton scattering is typically the dominant photon interaction. The photoelectric effect dominates more strongly at lower energies, while pair production becomes increasingly important only above its threshold of 1.022 MeV and especially at higher energies and higher atomic numbers. That energy-range intuition is central to shielding and dosimetry work.

3A shield adds two half-value layers for a narrow-beam gamma source. Assuming ideal exponential attenuation, what fraction of the original intensity remains?

A.12.5%

B.25%

C.50%

D.75%

Explanation: Each half-value layer reduces intensity by one-half. Two half-value layers therefore reduce the intensity to (1/2)^2 = 1/4 of the original value. That means 25% remains, ignoring buildup and geometry effects.

4Which detector is most appropriate when high-resolution gamma-ray spectroscopy is required?

A.BF3 proportional counter

B.High-purity germanium detector

C.Geiger-Mueller pancake probe

D.Ion chamber survey meter

Explanation: High-purity germanium detectors provide excellent energy resolution and are widely used for gamma spectroscopy and isotopic identification. BF3 detectors are associated with neutron detection, GM probes are useful for contamination surveys but not precision spectroscopy, and ion chambers are better for dose-rate measurement than energy discrimination. Resolution is the key distinction here.

5A worker receives an absorbed dose of 0.20 Gy from alpha radiation. If the radiation weighting factor is 20, what equivalent dose results?

A.0.01 Sv

B.0.20 Sv

C.4.0 Sv

D.20 Sv

Explanation: Equivalent dose is the absorbed dose multiplied by the radiation weighting factor. For alpha radiation, 0.20 Gy x 20 = 4.0 Sv. This reflects the much greater biological effectiveness of alpha particles relative to photons or electrons.

6If a source cannot be removed, which combination of controls best reduces external radiation dose to workers?

A.Increase time near the source, reduce distance, and add shielding

B.Reduce time near the source, increase distance, and add shielding

C.Reduce time near the source, reduce distance, and remove shielding

D.Increase time near the source, increase distance, and remove shielding

Explanation: The classic external-dose reduction methods are time, distance, and shielding. Lowering exposure time, increasing distance, and placing shielding between the source and worker all reduce dose. These principles sit at the core of ALARA implementation.

7What is the decay constant for a radionuclide with a 30-minute half-life?

A.0.3465 min^-1

B.0.1386 min^-1

C.0.0231 min^-1

D.43.3 min^-1

Explanation: The decay constant is lambda = ln(2) / t1/2. Using 30 minutes gives lambda = 0.693 / 30 = 0.0231 min^-1. This relationship links exponential decay directly to half-life and appears frequently in activity calculations.

8A dose rate is 40 mSv/h at 1 meter from a point source. Neglecting attenuation, what is the dose rate at 2 meters?

A.5 mSv/h

B.10 mSv/h

C.20 mSv/h

D.80 mSv/h

Explanation: The inverse-square law says intensity varies as 1/r^2 for a point source in open space. Doubling the distance from 1 meter to 2 meters reduces the dose rate by a factor of four. Therefore, 40 mSv/h becomes 10 mSv/h.

9A shield thickness corresponding to one tenth-value layer is added to a beam. Ignoring buildup, what fraction of the original intensity remains?

A.1%

B.10%

C.25%

D.50%

Explanation: A tenth-value layer reduces intensity to one-tenth of its previous value. That means 10% of the incoming intensity remains after one TVL. TVLs are convenient for rough shielding estimates when large attenuation factors are needed.

10A detector records 10,000 counts in a fixed interval. Assuming Poisson statistics, what is the approximate relative standard deviation?

A.10%

B.5%

C.1%

D.0.1%

Explanation: For counting statistics, the standard deviation is approximately the square root of the counts. With 10,000 counts, sigma is about 100, so the relative standard deviation is 100 / 10,000 = 1%. This simple square-root rule is fundamental for counting uncertainty.

About the PE Nuclear Exam

The NCEES PE Nuclear exam is a once-yearly computer-based licensure exam for engineers practicing in reactor systems, radiological engineering, fuel-cycle work, reactor physics, and nuclear safety analysis. The blueprint emphasizes reactor physics and criticality safety plus radiological analysis, and candidates should expect a mix of conceptual, analytical, and calculation-driven questions using both SI and U.S. Customary units with only the NCEES electronic reference materials provided on-screen.

Questions

85 scored questions

Time Limit

8.5 hours of exam time (9.5-hour appointment)

Passing Score

NCEES does not publish a fixed passing score

Exam Fee

$400 (NCEES (Pearson VUE))

PE Nuclear Exam Content Outline

21%-32% (18-27 questions)

Radiological Analysis and Consequences

Radiation principles, interaction with matter, shielding, dose and dosimetry, detector behavior, bioeffects, ALARA, and emergency/public protection.

11%-16% (9-14 questions)

Nuclear Fuel Cycle

Front-end fuel-cycle analysis, enrichment, materials accountability, transport packaging, spent fuel storage and disposal, and fuel/cladding performance.

15%-24% (13-20 questions)

Nuclear Systems and Components

Reactor concepts, NSSS and power-conversion systems, ECCS and containment, I&C, software QA and cyber security, reliability, and plant performance.

22%-34% (19-29 questions)

Reactor Physics and Criticality Safety

Cross sections, neutron transport and diffusion, multiplication, reactivity control, kinetics, xenon and samarium behavior, steady-state analysis, and criticality safety.

13%-20% (11-17 questions)

Safety Analysis

Design-basis accidents, thermal-hydraulic and fuel-performance limits, LOCA and non-LOCA transients, PRA, severe accident phenomena, and licensing/regulatory compliance.

How to Pass the PE Nuclear Exam

What You Need to Know

Passing score: NCEES does not publish a fixed passing score
Exam length: 85 questions
Time limit: 8.5 hours of exam time (9.5-hour appointment)
Exam fee: $400

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

PE Nuclear Study Tips from Top Performers

1Weight your prep toward reactor physics and radiological analysis because those two domains dominate the blueprint.

2Practice with only the NCEES electronic handbook and listed standards so your lookup speed is realistic.

3Refresh both SI and U.S. Customary unit conversions because the official specification says the exam uses both systems.

4Drill shielding, inverse-square, attenuation, and detector-statistics questions until setup becomes automatic.

5Rebuild core neutronics skills around cross sections, multiplication, reactivity, kinetics, xenon effects, and criticality controls.

6Study how plant systems interact rather than memorizing isolated components; many questions hinge on integrated behavior and feedback.

7Do mixed problem sets that force you to switch between physics, systems, safety, and regulatory reasoning under time pressure.

8Review why design-basis assumptions, setpoints, uncertainties, and acceptance criteria matter, not just the formulas behind them.

9Use pass-rate data as a reminder that this is a small-volume, technically deep exam where breadth and precision both matter.

10Reserve your seat early after board approval because PE Nuclear is administered as a single-day testing event.

Frequently Asked Questions

How many questions are on the PE Nuclear exam?

NCEES lists 85 questions on the PE Nuclear exam. The exam includes multiple-choice items as well as alternative item types, and candidates work all questions during a 9.5-hour appointment.

How long is the PE Nuclear exam?

NCEES gives candidates a 9.5-hour appointment for PE Nuclear. That appointment includes tutorial and break time, with 8.5 hours of actual exam time available for solving problems.

Which PE Nuclear domains matter most?

Reactor Physics and Criticality Safety carries the largest official range at 19-29 questions, followed by Radiological Analysis and Consequences at 18-27 questions. Nuclear Systems and Components is the next largest section, while Nuclear Fuel Cycle and Safety Analysis are smaller but still material enough to require deliberate study.

Does NCEES publish the PE Nuclear passing score?

No. NCEES states that exam results are based on the total number of correct answers, converted to a scaled score that accounts for minor form difficulty differences, and compared to a minimum ability level set through psychometric methods. Results are reported only as pass or fail.

What references are available during the exam?

NCEES provides an electronic reference handbook and the specified codes and standards listed in the official PE Nuclear specifications. Personal reference materials are not allowed in the exam room, so efficient PDF search and familiarity with the official references are part of test-day readiness.

Were there any 2026 changes to the PE Nuclear exam?

As of March 12, 2026, NCEES has not published a new PE Nuclear blueprint or new effective specification. The notable 2026 update is that NCEES opened a PE Nuclear Professional Activities and Knowledge Study on March 6, 2026, which signals future blueprint review but does not change the current public exam specification.