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22 Cards in this Set
- Front
- Back
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Explain why audible response is used. |
The audible output response is always faster than the meter response because the instrument responds instantly to each individual ionizing event |
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List when an audible response is recommended and required during radiological surveys |
-Surveying areas or equipment where small intense beams of radiation can be present -Surveying personnel -Searching for fixed contamination -Trying to find he most highly contaminated portion of contaminated materials or areas -Performing low radiation level evaluations -Using the AN/PDR-70 on the lowest scale |
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State the methods for performing a contamination survey |
-Swipe -Frisk -Large Area Wipe -As directed per TWD |
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State the units used to document measurements of surface contamination and describe the manner in which these measurements are obtained. |
100 cm^2- firmly swipe a 100 cm^2 area. Unit to document is uuCi/100cm^2 SWIPE- Firmly swipe a 100cm^2 area the units to document are uuCi/100cm^2. If area is less than 100cm^2, the entire are should be swiped, and documented using uuCi/SWIPE LAW- Damp absorbent wiped over an area covering 1m by 1m Units used are uuCi/LAW FRISK- a frisk is a direct reading on the surveyed item or surface within 1/2 inch using a DT-304 probe or equivalent. Units are uuCi/PROBE Per TWD- the TWD will direct you if any methods are to be used. The units used will be documented in TWD |
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State why dry swipes are used |
-Dry swipes are used because they are more representative of how contamination is spread by personnel brushing past these surfaces, than other methods -Swipe surveys should be used when background is too high to permit direct frisking or when the area to be surveyed is wet |
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State the basis for performing swipes of 100 cm^2 |
-Swipes tend to disintegrate when wiped over a larger area -Area gives nearly optimum efficiency for collecting and measuring contamination -Area is convenient |
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State when wet swipes are allowed |
Taking swipes on wet surfaces When surface contamination is suspected that is not detectable using dry swipes |
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Explain how to take and count wet swipes |
-Counted and taken in the same method as dry swipes -Shall be counted again when dry, because moisture in the swipes will shield beta activity |
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State when and why LAW can be used |
LAWs may be used to survey potentially contaminated areas to determine that an area is fee of loose surface contamination. |
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Discuss how LAWs are not used for quantitative measurement, but can be used to document that an area is free of contamination. |
-LAWs cannot be used as quantitative measures of surface contamination greater than 450 uuCi/100cm^2 -LAWs can be used to determine that an area is free of loose surface contamination. |
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Explain how to perform s survey using a large area wipe |
-Label LAW with numbers or a short description -LAW is dampened with water or other liquid not containing hazardous constituents and folded into a 6 in square -Wipe 1m^2 area, making six passes over the area. If area is less than 1m^2 wipe entire area -Count LAWs in a location where background is <100. Increase count time if background is 100-300 CPM. LAWs need not be dried before counting -Frisk LAW within 1/2 inch of all wiped surfaces. If an audible increase, count LAW for at least 15 seconds -LAWS used to monitor Zn are to be submitted for gamma analysis -Control LAWs as RAM until released as bulk waste Document the survey results on the survey record as "per LAW"
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State the time required to count swipes when using a DT-304 or HP-260 probe |
5 seconds If clicks or background increase, count swipe for at least 15 seconds and until the counts/meter stabilizes |
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State the minimum time required to count an air sample filter using a DT-304 |
At least 15 seconds or until the meter stabilizes |
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State background limitations for a DT-304 probe in a non casualty situation |
-Use the DT-304/PDR probe where the background count rate is <100 CPM -Permissible to use the DT-304/PDR probe where background is 100-300 CPM -Do not use the probe where the background is >300 CPM |
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State the background count rate limitations for a HP-260 probe |
-Use the HP-260/PDR probe where the background count rate is <100 CPM -Do not use the probe where the background count rate exceeds 100 CPM |
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Discuss the use of the DT-304 probe in casualty situations where the background count rate is >300 cpm |
There is no background limit when using the DT-304 probe in casualty situations. However the following restrictions apply -The frisk results can only be used to estimate the magnitude of surface contamination present -The frisk results cannot be used to declare the area is free of surface contamination |
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State why direct frisking is preferred over swiping for contamination surveys |
-Direct frisking requires less time than taking and counting swipes -Direct frisking can measure either fixed or loose surface contamination |
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State the sample volumes for normal and casualty situation portable air samples |
Co-60 -Normal: 1m^3 -Casualty: 0.3m^3
Zn-65 -Normal: 3m^3 -Casualty: 1.5m^3 |
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State the approximate times required to draw a normal and casualty situation portable air sample for Co-60 |
Normal: 5-6 min Casualty: 2-3 min |
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State the approximate times required to draw normal and casualty situation portable air samples for Zn-65 |
Normal: 8-9 min Casualty: 4-5 min |
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Explain how to use a friskier to measure airborne activity |
-Determine background count rate -Hold air filter paper within 1/2 in of DT-304 probe -Count sample for at least 15 seconds, and until the meter stabilizes -Subtract background fm to get CCPM -Calculate air concentration using applicable thumb rule |
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Discuss how to use an alpha survey meter to measure airborne radioactivity |
Hold air filter paper within 1/8 of inch of probe Count sample for at least 30 seconds Verify meter is not responding to beta-gamma -insert a sheet of paper between air filter and probe -if alpha, the reading will return to background, and alpha is the difference between the readings Calculate air concentration using applicable thumb rule -50 CPM = 1x10^-9 uCi/ml for 0.3m^3 air sample -50 CPM = 3x10^-10 uCi/ml for 1m^3 air sample |
