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University of Pittsburgh
Program Areas

Surveys of Radiation Laboratories

Laboratory personnel are required to perform and document laboratory surveys in accordance with the following program

Documented Radiation Laboratory Survey Program

Purpose

The purpose of a survey is to identify sources of radiation contamination and exposure. All laboratory personnel should be aware of these sources of exposure. Corrective action should be taken as necessary to insure a safe work environment. Documentation of radiation surveys must be retained. This policy does not eliminate the need for daily checks of the workplace and routine surveys of personnel.

Frequency of Surveys

Surveys must be performed weekly in all laboratories where radioactive material was in use during that week.

"Use" means removal from stock vial for experiment and/or processing radio-labeled compounds or probes in open containers, waste handling, or discharge to sink. Receipt and placement into storage of stock vials does not constitute use. Analysis of samples in liquid scintillation or gamma counters is not considered use of radioactive materials.

"Laboratories" do not include darkrooms, freezer/refrigerator rooms, and counting equipment rooms. Common equipment rooms and cold/warm rooms are considered to be laboratories; however, they are exempt from surveys by laboratory personnel if there is no use of unsealed radioactive material. Detection of contamination by the Radiation Safety Office (RSO) will revoke the exempt status in these rooms.

Survey procedure

Meter surveys are required for all laboratories except those exclusively using C-14, H-3, S-35, Ca-45 or other weak-beta-emitting (<200 Kev) radionuclides.

Perform a radiation survey with an operational portable survey instrument. Survey with detector end caps and beta shields removed. Select the most sensitive (lowest) range of the instrument. Turn the speaker on. Survey all work and storage areas, waste containers, accessible surfaces, and Rad-labeled equipment. Record (in CPM) the background reading and all readings above background on the report form.

Smear surveys are required for all laboratories except those exclusively using microspheres.

Perform a contamination survey, taking smears representative of both Rad work and clean areas. A one-inch dry paper filter or a cotton swab is a good smear. For uniformity of results, smear an area of 100 cm2 (sixteen square inches). All areas with radiation levels above background should be smeared. Pay particular attention to areas that may have been contaminated, such as switches and handles. Be careful not to inadvertently contaminate the smears or transfer contamination to a clean surface in the process.

Count smears with an appropriate instrument. Low-energy beta emitters (C-14, H-3, S-35, Ca-45) must be counted in a liquid scintillation counter. Medium- and high-energy beta emitters or beta/gamma emitters may be counted with a thin window "GM" survey instrument. Smear analysis should be made in a low background environment. Photon emitters such as I-125 and Cr-51 should be counted in a gamma counter or with a thin crystal NaI detector.

Using the counting efficiency for the instrument selected (see Table 1), calculate dpm/smear. Record background and net (gross minus background) dpm on the survey report. Also record the counting instrument used.

 

TABLE 1
Average Counting Efficiency for Standard Instruments1,2
Betas Scintillation
counter
Pancake GM3 End Window GM3
H-3, Fe-55, Ni-63 50 %
NOT APPLICABLE
NOT APPLICABLE
C-14, S-35 90 % 2 % 1 %
P-33, Ca-45 90 % 15 % 10 %
P-32, Cl-36, Rb-86 100 % 35 % 20 %
Photons NaI (Thin) Gamma counter
Cd-109, I-125 45 %
60 %
Na-22, Cr-51, Zn-65, In-111, I-131, Sc-46, Nb-95, Ru-103, Sn-113, Ce-141 30 %
Unit specific

1 Specific efficiency data may be determined for the specific instruments and nuclides in use in a particular laboratory. That information may be used on survey records.

2 Efficiency may be reduced if the emission rate from a particular radionuclide is less than 100 percent.

3 (Detector window 1 cm above source)

Action Levels

Evaluate contamination removed and take action per Table 2:

 

TABLE 2
Action Levels for Removable Surface Contamination in Radiation Laboratories
“Clean areas”—bench tops, floors, freezers, refrigerators, desks, etc
<220 dpm Acceptable level
> 220 dpm but < 2200 dpm Decontamination recommended
> 2200 dpm Decontamination required
Radiation labeled equipment—rad sinks, centrifuges, fume hoods, waste cans, etc
< 2200 dpm Acceptable level
> 2200 dpm but < 22,000 dpm Decontamination recommended
> 22,000 dpm Decontamination required

Documentation and record keeping

The survey form used to document laboratory surveys must contain the following information AT A MINIMUM:

Location, date of survey, name of individual performing the survey, isotopes in use, survey instrument(s) used, room layout drawing, counting equipment used, efficiency of counting equipment, results of surveys, and notation as to corrective actions taken.

The survey forms may be patterned after the Radiation Safety Office laboratory survey form. An acceptable generic form is included in the Lab Survey Report. Complete all information requested on the form. Sign and date the form.
For weeks when no use of radioactive materials occurs, an entry should be made on the Laboratory Survey Master Calendar sheet that no survey is required that week.

File the completed forms in a file folder or loose-leaf binder. The survey reports are subject to review by both RSO and Pennsylvania DEP personnel.

Survey reports must be retained for two years.

Common use or shared laboratories

For laboratories which are used by multiple Authorized Users, the responsibility for performing the weekly survey should be given to a mutually agreed upon individual.

Availability of training

The Radiation Safety Office will conduct training on how to perform proper surveys for any laboratory that requests it.

Laboratories authorized for the use of radioactive materials will be surveyed and audited periodically by RSO personnel to assure safe working conditions.