10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
The RRPT exam has 150 questions and runs 4 hours.
These 10 free RRPT questions are organized by exam domain, so you can see how each part of the Registered Radiation Protection Technologist blueprint is tested. Reveal the answer and explanation under each question.
Y-90 is chemically removed from a Sr-90 solution while the Sr-90 remains in the container. Sr-90 has a 28.8-year half-life; its Y-90 daughter has a 64-hour half-life. No material is subsequently added or removed. Which description correctly predicts how the daughter inventory will evolve?
Correct answer: A - Y-90 activity will build toward the Sr-90 activity and then follow the parent's slow decay.
An employee at an NRC-licensed facility declares her pregnancy in writing for the first time. A qualified assessment establishes that occupational dose equivalent to the embryo/fetus was already 5.8 mSv before the declaration. Which restriction does the late-declaration provision of 10 CFR 20.1208 impose for the remainder of the pregnancy?
Correct answer: D - Additional fetal dose must not exceed 0.5 mSv over the remainder of the pregnancy.
Which repair plan gives the lower collective dose when shielding installation and removal are included? Without temporary shielding, two mechanics would each work for 20 minutes at 3 mSv/h. With shielding, both mechanics would still work for 20 minutes, but at 0.6 mSv/h; installing and removing the shield would also expose two technicians for a combined 30 minutes each at 2 mSv/h. Both plans meet individual dose limits and mandatory controls; other risks and costs are comparable.
Correct answer: C - Proceed without temporary shielding: 2.0 person-mSv rather than 2.4 person-mSv.
A small gamma source produces 240 mrem/h at 0.50 m. A worker will remain 1.50 m from the source during a repair. Treat the source as a point source and neglect attenuation and scatter. The worker's total job allocation is 36 mrem; 8 mrem has already been received, and 4 mrem must remain available for exit. How much repair time remains?
Correct answer: A - 54 minutes
An HPGe spectrum collected with a 200 Bq Co-60 standard close to the detector contains peaks at 1173.2, 1332.5, and 2505.7 keV. Increasing the source-to-detector distance makes the 2505.7 keV peak much weaker relative to the two individual peaks. Instrument dead time is below 0.1% in both geometries. What most likely produces the additional peak?
Correct answer: B - Coincident absorption of both cascade photons from a single nuclear decay.
During P-32 solution dispensing, an acrylic shield protects a technologist's torso, but the fingertips approach the vial opening. The chest dosimeter remains low, while a task survey identifies a steep beta-dose gradient at the fingers. What change would make personnel monitoring representative of the exposure?
Correct answer: B - Retain whole-body monitoring and add beta-sensitive extremity dosimetry at the most exposed finger.
For transfer between controlled areas, the approved procedure specifies a 400 cm² wipe and requires removable contamination below 1000 dpm/100 cm². The wipe produces 2400 counts in 4 minutes; a separate background produces 1000 counts in 10 minutes. The overall counting efficiency for the radionuclide and sample geometry is 25%. The procedure calls for area normalization but no wipe-recovery correction. Which result belongs in the removable-contamination record?
Correct answer: B - 500 dpm/100 cm²; below the transfer criterion.
Following an alpha CAM alarm in a room used for long-lived actinides, personnel withdraw as required. A laboratory counter confirms elevated alpha activity on the collected filter. Without cleaning or replacing it, the same filter is recounted over four hours and approaches background. A contemporaneous outdoor-air filter shows a similar decay pattern; instrument checks remain acceptable. Which explanation best fits the evidence?
Correct answer: D - Short-lived natural radon progeny collected on the filters and decaying after sampling.
A worker has uncontrolled bleeding from a deep leg wound after a fall in a radioactive-liquid handling area. Clothing and skin are contaminated. The source has been secured, radiation levels permit responder access, and the medical team is ready. Which action takes priority?
Correct answer: D - Begin hemorrhage control and transfer with contamination-spread precautions.
A tritiated-water workbench is recorded as uncontaminated after a thin-window GM survey reads background. The meter passed its battery check and responded normally to a Sr-90/Y-90 check source. Which follow-up would address the principal weakness in that conclusion?
Correct answer: C - Analyze a fresh wipe by liquid scintillation counting.
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