ASNT IRRSP cheat sheet

Inverse square law for a point source: I1/I2 = (d2/d1)^2; doubling distance reduces intensity to one-fourth.

Activity units: 1 Ci = 3.7 × 10^10 Bq = 3.7 × 10^10 disintegrations per second; 1 Bq = 1 dps.

Exposure and dose units: 1 R = 2.58 × 10^-4 C/kg in air; 1 Gy = 1 J/kg = 100 rad; 1 Sv = 100 rem.

Photon attenuation: I = I0 e^(-μx); HVL = ln2/μ ≈ 0.693/μ; TVL = ln10/μ ≈ 3.32 HVL.

Photoelectric absorption dominates at low photon energy and high atomic number; Compton scattering dominates at intermediate energies and low atomic number; pair production requires photon energy above 1.022 MeV.

Gamma and X-rays are uncharged electromagnetic radiation; beta particles are charged electrons with a continuous energy spectrum; beta shielding with high-Z material produces bremsstrahlung.

Common industrial gamma sources and half-lives: Ir-192 73.8 days; Co-60 5.27 years; Se-75 about 120 days; Yb-169 about 32 days.

Co-60 emits gamma rays at 1.17 and 1.33 MeV; Ir-192 has principal gamma energies around 0.3 to 0.6 MeV.

NRC occupational limits: total effective dose equivalent 5 rem/year; lens 15 rem/year; skin and extremities 50 rem/year; public 0.1 rem/year.

A declared pregnant worker may not receive more than 0.5 rem total effective dose equivalent to the embryo or fetus during the entire gestation period.

Stochastic effects have no assumed threshold; probability increases with dose and severity is independent of dose. Examples include cancer and heritable effects.

Deterministic effects have a threshold and severity increases with dose. Examples include skin burns, cataracts, and acute radiation syndrome.

Acute radiation syndrome can appear above about 100 rad whole-body acute dose; the LD50/60 is roughly 400 to 450 rad without medical support.

Cells with rapid division are more radiosensitive: bone marrow, gastrointestinal lining, gonads, and lens are relatively sensitive; mature bone and nerve are relatively resistant.

For gamma, X-ray, and beta radiation the radiation weighting factor is 1; for alpha particles it is 20.

For gamma radiation, 1 R exposure is approximately 0.01 Gy (1 rad) in soft tissue; 1 rem = 0.01 Sv.

Lead is effective gamma shielding; plastic or acrylic is preferred for beta shielding to reduce bremsstrahlung.

An energy-compensated ionization chamber survey meter provides accurate gamma dose-rate measurements for boundary and area surveys.

A Geiger-Muller detector is very sensitive for low-level radiation but can saturate in high radiation fields and has energy-dependent response.

TLD, OSL, and film dosimeters measure cumulative dose over a wearing period and are not real-time survey instruments.

A whole-body dosimeter is worn at the torso; a ring dosimeter is worn on the hand when handling sources or equipment.

Survey instruments are calibrated before first use and at intervals not exceeding 6 months, with a daily response check using a check source and battery check.

Dead time causes count-rate underestimation at high radiation levels; detector saturation can produce falsely low or zero readings.

A pancake GM probe or proportional counter is used for removable contamination surveys with slow, close probe movement.

An electronic personal alarm dosimeter provides immediate audible warning when a preset dose or dose rate is exceeded.

A gamma exposure device stores the sealed source in a shielded position; the drive cable and guide tube move the source to the collimator for exposure.

The exposure device must be locked with the source shielded when not in use; the key is controlled by authorized personnel.

A survey after each exposure confirms that the source has returned to the shielded position and that radiation levels are safe.

Source activity decays as A = A0 e^(-λt), where λ = 0.693 divided by the half-life.

Geometric unsharpness is Ug = F × t / d, where F is source size, t is object-to-film distance, and d is source-to-object distance; smaller F and t and larger d reduce Ug.

A collimator restricts the radiation beam to the area of interest, reducing scatter and unnecessary dose to surrounding personnel and areas.

An X-ray tube produces radiation only when energized; key control, warning lights, and exposure indicators are required safeguards.

Increasing source-to-film distance reduces dose rate by the inverse square law but requires increased exposure time to maintain film density.

Sealed sources used in radiography are leak-tested at intervals not exceeding 6 months and after damage; the removable contamination limit is 0.005 μCi (185 Bq).

10 CFR Part 34 governs industrial radiography; 10 CFR Part 20 contains occupational dose limits; agreement states enforce equivalent requirements.

A specific NRC or agreement-state license is required to possess and use radioactive sources for industrial radiography.

The license specifies authorized sources, equipment, personnel, storage locations, and operating conditions.

Sealed source leak tests are performed at intervals not exceeding 6 months; results above 0.005 μCi removable contamination require removing the source from service.

Radiation area: 5 mrem/h at 30 cm from the source or surface; high radiation area: 100 mrem/h at 30 cm; both require posting and access control.

Radiographers require certification such as IRRSP or a state equivalent; trainees work under required supervision.

Records include surveys, instrument calibrations, leak tests, dosimetry, training, and source inventories; retention follows 10 CFR Part 34 and license conditions.

DOT transport requires Type A or Type B packaging as applicable, radioactive labels, shipping papers, and the source secured in a shielded container.

Lost or stolen sources, overexposures, and failed leak tests require notification to the NRC or agreement state as specified by regulation.

If a gamma source fails to retract, stop work, secure the area, survey dose rates, use remote handling tools if needed, and notify the radiation safety officer immediately.

If a source is lost or stolen, secure the area, notify the licensee and radiation safety officer, and report to regulatory authorities; do not handle it bare-handed.

For a suspected overexposure, remove the person from the area, obtain medical evaluation, reconstruct dosimetry, and notify the RSO and regulator.

For a fire involving a radiography source, evacuate personnel, account for the source, inform firefighters of the radiation hazard, and survey before reentry.

An emergency radiography kit contains a calibrated survey meter, personal dosimeters, remote handling tools, lead shielding, warning signs, barrier tape, and communication equipment.

Gamma dose rate can be estimated as R/h at 1 ft ≈ 6 × C × E × N, where C is curies, E is MeV per photon, and N is photons per disintegration.

Emergency boundaries are established from measured dose rates and controlled to prevent unauthorized entry.

Decontamination includes removing contaminated clothing, surveying the person and area, preventing spread, and assessing internal exposure potential.

Significant events require notification to the NRC Operations Center and follow-up written reports within required time periods.