RPT 223Instructional Resources

Module 1:Using OSLDs to Monitor for External Radiation Dose

Table of Contents:

Resources Key......

Module Readings and Homework......

Primary Scenario “Dose Monitoring During Pump Impeller Replacement”......

Transfer Scenario “Dose Monitoring During Pump Impeller Replacement (Gamma-only)”

Module Assessment Items

Primary Scenario “Dose Monitoring During Pump Impeller Replacement”......

ACAD References......

Resources Key

This refers to: / This reference:
ACAD / National Academy for Nuclear Training, Uniform Curriculum Guide for Nuclear Power Plant Technician, Maintenance, and Nonlicensed Operations Personnel Associate Degree Programs, ACAD 08-006.
DOE-SG / Office of Environmental, Safety and Health: Radiological Control Technician Training Site Academic Training Study Guide Phase I, Project Number TRNG-0003
Available at: File is located under the Docs/General Curriculum/DOE materials folder.
G. / Gollnick, D. (2006). Basic Radiation Protection Technology, 5th Ed. Pacific Radiation Corporation, Altadena, CA.

Module Readings and Homework

Primary Scenario “Dose Monitoring During Pump Impeller Replacement”

Core Concept: Dose units
Homework (end of chapter)
Readings / Calculation Items / Non-calculation Items
G., Chap 5, 126-136
G., Chap 15, 681
DOE-SG Mod 1.06-30 to 1.06-35 / G., Chap 5, #12, S-5 / G., Chap 5, #5, 6, 7, 8 , 10, 11, S-2, S-4
DOE-SG Mod 1.16.05, 1.16.06
Core Concept: Occupational dose limits
Homework (end of chapter)
Readings / Calculation Items / Non-calculation Items
G., Chap 8, 346-7
G., Chap 15, 682-686
DOE-SG Mod 2.04-3 to 2.04-5 / G., Chap 15, #8, 12, S-1
Core Concept: Operation and characteristics of OSLD dosimeters
Homework (end of chapter)
Readings / Calculation Items / Non-calculation Items
G., Chap 8, 327-332 / G., Chap 8, #1. 20

Transfer Scenario “Dose Monitoring During Pump Impeller Replacement (Gamma-only)”

Refer to readings and homework for primary scenario above.

Module Assessment Items

Note: If instructors wish to increase the difficulty of any item,then we suggest you use it as the basis for an in-class discussion, and / or require students to write an explanation for why a particular choice is correct.

Primary Scenario “Dose Monitoring During Pump Impeller Replacement”

  1. An OSLD (primary personal dosimeter) is read and gives a dose of 15 mrem (0.15 mSv). What does this mean in terms of exposure and dose? (Answer each question true or false.)
  2. I can determine the radioactivity of the source that exposed the dosimeter (F).
  3. I can determine the energy of the radiation creating the dose (F).
  4. I can determine the exact exposure to air at the place where the dosimeter is exposed (F).
  5. I can determine the distance from the radioactive source (F).
  6. I can determine the exposure to which I have been exposed (F).
  7. I can determine the dose to a person at this location (T)
  1. Gamma-rays interacting with a gas-filled ionization chamber create a total of 1.53 x 1016 electron/ion pairs. If the mass of air in the chamber is 2.49 milligrams, what can be calculated? Check ALL that are correct.
  2. Dose in air (T)
  3. Dose in tissue (F)
  4. Exposure in air (T)
  5. Exposure in tissue (F)
  6. Activity of source (F)
  7. The radiation type (F)
  8. Dose equivalent (F)
  1. To convert exposure to dose in air, what does one need to know? Check ALL that are correct.
  2. The density of air that was exposed to radiation (F)
  3. The mass of air that was exposed to radiation (F)
  4. The type of particle creating the exposure/dose (F)
  5. The distance from the source to the dosimeter (F)
  6. The energy to create an electron/ion pair in air (T)
  1. Which of the following statements concerning exposure are correct? Check ALL that are correct.
  2. If the charge deposited in a given mass of air is known, exposure can be calculated (T)
  3. If the energy deposited in a given mass of air is known, exposure can be calculated (F).
  4. Exposure is only defined for photons which are depositing charge in air (T).
  5. The energy of the incident radiation is needed to calculate exposure (F).
  1. Which of the following statements concerning dose are correct? Check ALL that are correct.
  2. If the charge deposited in a given mass of air is known, dose can be calculated (F)
  3. If the energy deposited in a given mass of air is known, dose can be calculated (T).
  4. Dose is only defined for photons which are depositing charge in air (F).
  5. The energy of the incident radiation is needed to calculate dose (F).
  1. One ion chamber is twice as big (i.e., has twice the volume and mass) as another and both collect the same amount of charge. Which of the following statements is correct about the exposures measured by the two ion chambers?
  2. The exposure in the large one is ½ as much as in the smaller one (T)
  3. The exposure in the larger one is twice as much as in the smaller one (F)
  4. The exposure to both is the same (F)
  5. There is not enough information to determine the relative exposure (F)
  1. Two dosimeters are exposed to the same radiation field and one dosimeter is twice as big as the second. Which of the following statements are correct about the two dosimeters?
  2. The larger one will absorb twice as much energy (T)
  3. The two will record the some dose (T)
  4. The larger dosimeter records twice the dose (F)
  5. There is not enough information to determine the relative dose (F)
  1. A dosimeter collects 1.5 x 105 MeV of energy in 70 mg of gas. In the same radiation field a 70 kg individual would absorb 1.5 x 1011 MeV of energy. Which of the following statements are correct about the two delivered doses?
  2. The amount of energy deposited per unit of mass is the same, but this is just a coincidence in this particular case. (F)
  3. The amount of energy deposited per unit of mass is the same because the dose is the same in both situations (T)
  4. Although the amount of energy deposited per unit of mass is the same, no conclusions about relative dose can be drawn about the dose ratio (F)
  1. If a vented, air filled ion chamber is calibrated at room temperature and is then used outside on a day below freezing, what would happen to the exposure reading?
  2. There would be no effect on its reading (F)
  3. There would be no reading below freezing (F)
  4. The exposure reading will be incorrect (T)
  5. There is no way to correct for the change in temperature (F)
  1. A radiation worker gets 1 Rem of radiation in the first three quarters of the year. During the fourth quarter she is accidently exposed to an additional, accidental 4.2 Rem due to an internal contamination event. Which of the following statements are correct? Check ALL that are correct.
  2. Her annual occupational limit of 50 mSv has not been exceeded. (F)
  3. The total dose she received is above the occupational limit for radiation workers. (T)
  4. Since the whole body limit for dose is 5 Sv, no dose limits have been exceeded. (F)
  5. Since the accidental dose is due to internal contamination, the doses are not additive. (F)
  1. A radiation worker in a laboratory is processing a medical isotope in a hot cell. When his TLD dosimeters are read at the end of the month, it is discovered that he received an extremity dose (from a ring badge) of 49.2 Rem and a whole body dose of 1.1 Rem. Which of the following statements are correct? Check ALL that are correct.
  2. The extremity dose limit has been exceeded since 49.2 + 1.1 = 50.3 Rem. (F)
  3. The extremity dose is close to, but has not exceeded the occupational limit (T)
  4. This monthly whole body dose can be recorded every month for a year and not exceed the limit (F)
  5. The whole body dose should be subtracted from the extremity dose before comparing with dose limits (F)
  1. A hypothetical member of the public could receive an external dose of 55 mRem per year of gamma radiation (at 1.25 MeV) by spending 24 hours a day at the side of a radioactive material processing facility and an additional internal dose of 65 mRem per year from releases from the same facility. Does this facility exceed general public limits for radiation dose? Answer yes or no and provide a written justification for your mathematical answer.

Answer – the gamma radiation would give 55 mRem DDE and the CEDE from the internal dose is 65 mRem. TEDE = DDE + CEDE = 55 + 65 mRem = 120 mrem = 1.2 mSv > 1 mSv annual limit. Exceeds limit.

  1. How does an OSLD measure dose?
  2. By recording the amount of energy deposited in the dosimeter (F)
  3. By recording the type of radiation to which it has been exposed (F)
  4. By recording the amount of light produced by radiation (F)
  5. By recording the amount of charge produced by radiation (T)
  1. An OSLD badge typically has 4 active elements, some of which are covered by different “filters” to block certain types of radiation. The differences in response between the 4 elements can be used to determine the types and energies of radiation in the radiation field. Which of the following statements are true? Check ALL that are correct.
  2. The difference in the reading between an element that has no filter and an element that has a filter designed to approximate the attenuation of skin, can provide the skin dose (T)
  3. The difference between an element that blocks all betas and an element that has no filter will provide the beta dose (T).
  4. To determine beta dose, there is a filter over one of the elements that blocks all gamma-rays and is used to provide the beta dose (F)
  5. It the beta filtered element and an unfiltered element read the same dose in a beta radiation field, it is possible that the beta filter is missing. (T)
  6. If the beta filtered element and the unfiltered element read the same dose in a beta only radiation field, it is possible that the badge was covered with clothing during use. (T)
  1. Which of the following conditions could affect the reading of an OSLD ? Check ALL that are correct.
  2. The photomultiplier tube in the reader has dust on its window (T)
  3. The laser source emits less laser light than it is designed to (T)
  4. The heating element in the reader malfunctions (F)
  5. The readout chamber has a light leak, allowing ambient light to enter (T)
  6. The OSLD is not properly aligned under the laser beam (T)
  7. The OSLD gets contaminated with radioactive material immediately before reading (F)
  8. The temperature in the reading chamber is higher than normal (F)
  1. Which of the following types or characteristics of radiation would be measured by an OSLD badge used in a containment building? Check ALL that are correct.
  2. Betas (T)
  3. Gammas (T)
  4. Neutrons (T)
  5. Alphas (F)
  6. Radiation energy (F)
  7. Deep dose (T)
  8. Skin dose (T)

ACAD References

ACAD
1.1.8 RADIATION PROTECTION AND DETECTION
  • Explain the principles and operation of radiation detection and monitors including the following
–Personnel dosimetry (for example, thermoluminescent detectors)*
  • Perform calculations that involve radioactive dose and matter as follows:
–Units of measurement
3.3.1 RADIOACTIVITY AND RADIOACTIVE DECAY
  • Identify and use radiological quantities and their units including
–Exposure (roentgens)
–Dose (rads and grays)
–Dose equivalent (rems and sieverts)
  • Identify, calculate and use the following significant dose terms.
–Deep
–Eye (lens, shallow, effective (using weighting factors)
  • Equate radioactivity to dose rate through simple rules of thumb and associated calculation for various source geometries (for example, 6CEN, pont source, line source, plane source).

3.3.6 EXTERNAL DOSIMETRY
  • Describe the principles of operation and characteristics of the types of dosimetry used at the plant (thermo luminescent dosimeters, film badge, alarming dosimeters, pocket ion chamber, teledosimetry, optical-luminescent dosimeters) including:
–Range(s) of each device
–Effects of fading and drift
–Advantages of each type of device
–Limitations of each type of device
3.3.8 EXTERNAL EXPOSURE CONTROL
  • State the purpose of having plant administrative limits for radiation exposure (such as margin from regulatory limits).

  • Identify techniques for controlling workers' exposure to beta radiation, such as the wearing of protective clothing, face shields and glasses

3.3.12 RADIOLOGICAL INCIDENT EVALUATION AND CONTROL
  • Describe how to estimate beta and gamma dose rates from the following:
–Pipes or tanks that contain radioactive liquids

*ACAD is also referenced in other courses of the curriculum

Module 1Using OSLDs to Monitor for External Radiation Dose

The Curators of the University of Missouri

Copyright © 2008-2009

A Product of DOL Grant #HG-15355-06-60

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