Radiation Wipe (Smear) Test Procedure
Using the Radiation Alert® Ranger with Wipe Test Plate
Document Type: Radiation Safety Procedure
Purpose: Detection of removable radioactive contamination
Instrument: Radiation Alert® Ranger Survey Meter with Wipe Test Plate
Prepared For: Radiation Safety Programs, Industrial Radiography, Nuclear Gauge Programs, Research Laboratories, Medical Facilities, and Licensed Radioactive Material Users
- Purpose
This procedure establishes a standardized method for performing radiation wipe (smear) tests using the Radiation Alert® Ranger Survey Meter equipped with the Radiation Alert® Wipe Test Plate. The procedure is intended to detect and quantify removable radioactive contamination on surfaces and to support compliance with applicable radiation safety regulations and license requirements. The Wipe Test Plate positions the smear sample at a fixed 1 cm distance from the Ranger’s GM detector window, improving measurement consistency and repeatability.
- Scope
This procedure applies to:
- Sealed source leak testing screening activities
- Radioactive material storage areas
- Nuclear gauge storage locations
- Hot labs and research facilities
- Medical isotope use areas
- Waste accumulation areas
- Radiological work areas
- Transportation package surveys where required by license or procedures
This procedure does not replace NRC, Agreement State, DOT, facility license, or Radiation Safety Officer (RSO) requirements.
- References
- U.S. Nuclear Regulatory Commission (NRC) regulations
- State Radiation Control Regulations
- Facility Radioactive Materials License
- ALARA principles
- Radiation Alert® Ranger User Documentation
- Radiation Alert® Wipe Test Plate Product Information seintl.com
- Responsibilities
Radiation Safety Officer (RSO)
- Establish testing frequency.
- Review and maintain records.
- Evaluate abnormal results.
- Initiate corrective actions.
Authorized User / Radiation Worker
- Perform wipe tests as trained.
- Wear required PPE.
- Accurately document results.
- Report elevated contamination immediately.
- Required Equipment
Instrumentation
- Radiation Alert® Ranger Survey Meter
- Ranger Wipe Test Plate
- Current calibration certificate
- Operational battery
Sampling Materials
- Approved smear/wipe test discs
- Filter paper (if approved by site procedure)
- Sample envelopes or holders
- Permanent marker
Personal Protective Equipment
- Disposable gloves
- Laboratory coat or protective clothing (as applicable)
- Eye protection when required
Documentation
- Wipe Test Log Sheet
- Survey Record Form
- Facility contamination action levels
- Safety Precautions
General Radiation Safety
- Follow ALARA principles:
- Minimize time.
- Maximize distance.
- Use shielding where appropriate.
- Wear disposable gloves during sampling.
- Prevent cross-contamination between samples.
- Never touch the detector window with contaminated gloves.
- Do not eat, drink, smoke, or apply cosmetics in radioactive material areas.
- Treat all unknown contamination as potentially radioactive until evaluated.
Instrument Care
- Avoid puncturing or contacting the GM detector window.
- Verify calibration is current before use.
- Perform source response checks as required by site procedures.
- Frequency of Testing
Perform wipe tests:
- At the frequency specified by license conditions
- Following radioactive material use
- When contamination is suspected
- Before unrestricted release of equipment
- During routine contamination surveys
- Following contamination events or spills
Typical licensed programs perform wipe tests monthly or quarterly depending on regulatory requirements and source type.
- Pre-Test Instrument Checks
Before testing:
8.1 Visual Inspection
Verify:
- Housing is intact
- Detector window is undamaged
- Wipe Test Plate is clean
- Screen functions correctly
8.2 Battery Check
Confirm battery level is acceptable.
8.3 Calibration Verification
Verify instrument calibration is current per facility requirements.
8.4 Operational Response Check
Perform a response check using an approved check source if required by facility procedure.
Document all checks.
- Background Count Determination
Prior to evaluating smears:
- Move to a known clean area.
- Attach the Wipe Test Plate.
- Insert an unused clean wipe.
- Conduct a count for the established count time.
Recommended count times:
- 1 minute minimum
- 5 to 10 minutes for greater sensitivity
Record:
- Gross background count
- CPM (Counts Per Minute)
- Count duration
Background values shall be recorded before counting samples.
- Sample Collection Procedure
10.1 Identify Survey Locations
Examples:
- Source storage containers
- Gauge surfaces
- Transport cases
- Work benches
- Door handles
- Hood interiors
- Waste containers
10.2 Sampling Area
Sample approximately:
100 cm² (10 cm × 10 cm)
This surface area is commonly used for contamination monitoring.
10.3 Collection Method
- Put on clean gloves.
- Label the wipe before collection.
- Apply moderate pressure.
- Wipe the area in an “S” pattern.
- Rotate the wipe while sampling if practical.
- Fold contaminated side inward.
- Store in labeled envelope if not counted immediately.
This method promotes consistent sample recovery.
- Counting Procedure
11.1 Sample Placement
- Place the smear into the recessed area of the Wipe Test Plate.
- Ensure the wiped surface faces the detector.
- Insert the plate into the Ranger.
The Wipe Test Plate positions the sample directly in front of the GM tube at a fixed distance of approximately 1 cm.seintl+1
11.2 Count Setup
Configure:
- CPM Mode or Total Counts Mode
- Count duration consistent with site procedure
Recommended:
- Routine surveys: 1 minute
- Compliance surveys: 5–10 minutes
11.3 Acquire Reading
- Start count.
- Avoid instrument movement.
- Record:
- Sample ID
- Count time
- Gross counts
- CPM reading
- Data Evaluation
Net Count Rate
Calculate:
Plain Text
Net CPM = Sample CPM − Background CPM
If result is negative:
Plain Text
Net CPM = 0
Conversion to Activity
When required:
Plain Text
dpm = net cpm / detector efficiency
Where:
- dpm = disintegrations per minute
- Detector efficiency is established by calibration or site-specific efficiency factors
The detector efficiency must be determined and documented by the RSO or calibration laboratory.
- Action Levels
Action levels shall be based on:
- License requirements
- NRC guidance
- State regulations
- Facility contamination control limits
Typical Responses
No Detectable Removable Contamination
- Record result.
- Return area to service.
Detectable but Below Action Level
- Record result.
- Continue routine monitoring.
Above Action Level
- Notify supervisor and RSO immediately.
- Restrict area if necessary.
- Perform confirmatory survey.
- Decontaminate area.
- Repeat wipe testing.
- Document corrective actions.
- Abnormal Conditions
Immediately notify the RSO if:
- Unexpected contamination is identified.
- Multiple locations show elevated activity.
- Instrument response is abnormal.
- Radioactive material is suspected outside controlled areas.
- Contamination exceeds facility limits.
- Post-Test Activities
- Remove and properly dispose of used wipes.
- Survey gloves if contamination is suspected.
- Remove gloves per contamination-control practices.
- Clean Wipe Test Plate if needed.
- Store Ranger in designated location.
- Complete documentation.
- Records
Maintain records including:
- Date and time
- Technician name
- Instrument serial number
- Calibration due date
- Background count
- Sample locations
- Count time
- Gross count results
- Net count results
- Calculated dpm (if applicable)
- Corrective actions
- RSO review
Records should be retained in accordance with license and facility document retention requirements.
- Acceptance Criteria
A wipe test is considered acceptable when:
- Instrument passes operational checks.
- Background is documented.
- Samples are collected using approved methods.
- Results are below established contamination limits.
- Documentation is complete.
Revision Note
This procedure is intended as a comprehensive operational procedure for contamination wipe testing using the Radiation Alert® Ranger and Wipe Test Plate. Site-specific contamination limits, detector efficiency factors, regulatory requirements, and license conditions must be incorporated before implementation. The Ranger Wipe Test Plate is designed specifically to hold wipe samples at a fixed 1 cm geometry for repeatable contamination measurements.