A daily contamination survey is required each day after any work with unsealed forms of radioactive material.

A daily survey should cover the hands, lab coat, work area, floor adjacent to the work area, shoes (top and bottom), and potentially contaminated equipment.

• Any area found to be contaminated must be decontaminated immediately and re-surveyed. For decontamination procedures click here.
• Contaminated lab equipment that is dedicated for radioactive material work (and likely to be re-contaminated) should be appropriately labeled.

A portable survey meter is acceptable as long as the sensitivity of the instrument allows for efficient detection of the radionuclides used.

For low-energy beta emitters, a smear survey is required (with an appropriate counting technique). Portable survey meters are not appropriate, due to their extremely low efficiency.

Monthly Surveys

A thorough contamination survey of the entire lab module is required to be performed once each calendar month. How lab modules are determined can be found in the supplement for the survey form.

A minimum of ten locations must be surveyed, including at least two smears on the floor. Smear locations should include areas and items that have a higher potential for contamination. Locations should be varied from month to month. Some suggested areas to swipe for contamination are:

• Work areas, lab benches, and desks
• Sinks
• Lab equipment used with radioactive materials
• Refrigerators and freezers
• Incubators
• Floor adjacent to work areas and near hallway entrances
• Door handles

Smears should be counted by an appropriate counting technique (LSC or gamma counter).

Any contamination identified on a monthly survey must be decontaminated and re-surveyed to satisfy the ALARA policy and demonstrate compliance with the removable contamination limits for restricted areas.

Monthly surveys must be documented on a Form NIH 88-12 , with:

• A diagram of the laboratory
• Locations of smears
• Description of contamination identified during the survey
• Description of re-survey results
  

The original copy of the completed survey form must be submitted to DRS, along with the counter printout. A copy of the survey must also be kept on file in the lab's Radiation Safety Records, and retained for a minimum of three years (for inspection by DRS personnel or NRC inspectors).

If radioactive materials are not used for the month a survey from must still be completed and submitted to DRS, however smears are not required.

Monthly Survey Service

Monthly surveys may be contracted out to Clym Environmental Services (Clym), DRS’s regulatory compliance support contractor.

The cost per lab module is $40 per month and may be paid by CAN, credit card, or purchase order.

To make arrangements for this service or for more information, contact Clym at 301-435-7953, 888-289-2324 or beth@clymenvironmental.com.

Comprehensive (Contractor) Surveys

Like daily and monthly surveys, comprehensive surveys are designed to monitor for contamination. However, these surveys also include the measurement of radiation levels, inspection of lab records, and evaluation of general compliance with the NIH Radiation Safety Program.

Results of a comprehensive survey are reported to DRS on a Radiation Survey Report [contractor survey form], including any items of noncompliance. The Area Health Physicist reviews each comprehensive survey and determined an appropriate course of action.

A copy of each Radiation Survey Report is also furnished to the Authorized User of the lab, along with a set of Radiation Safety Survey Information Sheets to describe the survey results and suggest corrective actions.

The smear (or wipe/swipe test) is the universal method of assessing removable contamination, and the required method for monitoring certain radionuclides.

A small cloth, filter paper, or fiberglass disk is used to "wipe" a sample of removable contamination. Fiberglass disks are preferable for low-energy beta emitters, since they dissolve or become transparent in liquid scintillation fluid.

A smear should cover a minimum surface area of 100 cm² (approximately equal to a square measuring 4" by 4"). Smears should be dry, and taken using moderate pressure.

Smears must be separated to avoid cross contamination. Smear packets make this easy, and are commonly available at the NIH Self Service Stores.

If counting results are reported in counts per minute (cpm), they must be converted to decays per minute (dpm) using the counting efficiency:

The maximum allowable limits for removable contamination are as follows:

Data should be maintained regarding the date and location of each smear. For monthly surveys, the smears should be documented on the survey form (NIH 88-12).

Smears demonstrate that there is not more removable contamination, but survey meter indicates a count rate of greater than 1000 cpm. Contact your Area Health Physicist for further instructions. Don't waste your time scrubbing when you can't remove anymore contamination. The Area Health Physicist can apply regulatory limits for fixed contamination and advise you accordingly.

Counting Methods

An LSC may be used to assess gamma contamination, but close attention must be given to the efficiency of the counter for the radionuclide in question.

The manufacturer or qualified service representative should calibrate counters on an annual basis. This calibration determines the counting efficiency for common radionuclides used at NIH, which must be used to convert between cpm and dpm.

When possible, liquid scintillation samples should be dark adapted before analysis to reduce the effect of chemiluminescence. This can be accomplished by simply leaving the rack in the counter (with the cover closed) for 30 minutes or more.