The consistent control of a radioactive material inventory is essential for regulatory compliance. Radioactive material inventories must be available, presentable, and easily understood by an inspector. The most efficacious method is to have one inventory sheet for each vial your lab has ordered. A well-managed inventory is also considered an important measure of security. Please follow these guidelines when completing the inventory form:
1. Receipt of Vials
An inventory form should accompany isotope delivery. When opening the package be aware of the possibility of contamination and be prepared to use appropriate protection measures including a lab coat, Geiger counter, gloves and wipe tests. Notice if the packaging is damaged outside or inside. If the package integrity is good, proceed in removing the vial. If the package integrity is questionable, use a Geiger counter or wipe test to determine if there is contamination, and then proceed. Fill out appropriate information on the inventory form as soon as the isotope is brought into the laboratory and open the packaging. That information required includes:
- P.I./authorized user
- use/storage location
- date vial received
- amount received
- isotope/chemical form
- packagesSurvey results
- lot # found on vial label
2. Withdrawals by Individuals
Each time a researcher removes the vial from storage and aliquots a measure of isotope for use, the inventory form must be updated. The most efficacious method is for the individual user to update the sheet. Therefore, the inventory sheets should be readily at hand for all the researchers, posted on the cabinet where the isotopes are stored. The required information includes:
- date used
- initials of user
- amount used in either uCi or cc (cc is preferable)
- balance (in cc or uCi) remaining
As individuals use stock from the vial, the remaining balance (in cc) or the activity (in uCi) will eventually become zero. When this is the case, the vial should be disposed of in the appropriate radiation waste container. Laboratories should avoid having many empty or decayed vials of isotope in storage. Please follow these guidelines:
- Only use appropriate color-coded containers for radiation waste disposal.
- Separate vials from outer containers (aka pigs) and dispose of the vial as radioactive waste. The outer pig is not considered radioactive waste unless it is contaminated.
- Separate any lead that may be used to line the pig. Lead should not be disposed of in the regular trash; it should be stored in the laboratory, and will be removed by MHP upon request.
- After completing the previous steps, the inventory sheet can be retired to the files. Records should be stored for at least two years.
When following this protocol, every vial in storage in the laboratory will have an accompanying inventory sheet that describes in detail the history of its use. Anyone in the laboratory should be able to know how many cc's of which isotopes are available for use at any given time, which vials are expired, and which ones have been disposed of. Records should be kept for at least two years. Please follow these guidelines:
- Dispose of all old vials and pigs, so that only currently-used inventory is in the laboratory. (Note: some isotope products do expire well before radioactivity has decayed. Check with manufacturers to determine shelf life, and dispose of expired products accordingly.)
- Place Inventory sheets in a convenient location for researchers.
- Keep inventory in a locked location (such as a locked laboratory) after hours and on weekends.
- Call EHS if there are any questions about procedures.
Contamination of laboratory surfaces and equipment is considered the most hazardous radiation condition a laboratory worker can face. The primary reason for this is researchers not likely to know the existence or whereabouts of contamination. Thus, a high probability exists that the contamination will be unknowingly pickedup, spread and ingested by researchers. It is therefore most important for anyone using radioactive materials to check for contamination before and after working with the materials. Follow these guidelines:
Comprehensive wipe tests (liquid scintillation counting [LSC]) are required by law to be performed at least monthly regardless of isotope use. Tritium users are encouraged to perform wipe tests weekly, or immediately after use. Wipe tests must conform to the following standards:
- Wipe test results must be denoted in units of disintegrations per minute (DPM). If this is not possible, the efficiency of the liquid scintillation counter being used should be noted on the wipe count record.
- There must be a record for each month of the year regardless of use. Wipe tests requirements are based on possession of radioactive materials, not use.
- Only the printout from the liquid scintillation machine is considered adequate fulfillment of the requirement. Survey meters can not be used to fulfill the wipe test requirement.
- Tritium can only be detected via LSC, and is often reported as a Type I error due to organic contamination of the sample. Therefore, all positive tritium LSC results must be recounted after at least 30 minutes. A false positive sample will have a significantly lower recount, whereas a true positive result will show consistency or an increased recount.
- Results greater than 3x background should be cleaned upon discovery. Equipment must be cleaned or removed from service if wipe test results exceed 5,000 DPM.
- Wipe tests should include areas where isotopes are known to be used, and areas where isotopes are not generally used.
A survey meter should be used to check for contamination prior to, during, and after completing any work with radioactive materials.
- A standard GM probe is adequate for gamma isotopes, except for I-125 (where a special NaI probe is required).
- A standard GM probe is adequate for all betas, except for tritium (which cannot be detected using a survey meter). A wipe test is required to detect tritium contamination. Make sure to budget enough time to check for tritium contamination as part of protocol.
- All survey meters are required by law to be calibrated each year. Calibration can be performed either by an outside vendor or by MHP.
- Labeling of all equipment used with radioactive materials is an essential part of minimizing the spread of contamination. Equipment identified as potentially contaminated should not be used for non-radioactive purposes.
Radioactive waste will be generated in either liquid or solid form. All radioactive waste must be segregated according to color-coded buckets. If you are not sure which bucket to use for waste, choose the isotope waste bucket with the closest half-life. To request replacement buckets and/or radioactive waste pickup, complete the Radioactive Waste Disposal Request Form. To request radioactive waste disposal labels, or for general assistance, contact MHP: firstname.lastname@example.org.
- Waste labels should be attached to every waste bucket. Every time something is placed in a waste container, an entry should be made on its waste label. A container with waste should never have a blank waste label.
- All waste containers must have a radiation symbol and indicate the specific isotope present. This is required for color buckets as well as any other container being used for radioactive waste disposal or storage. Examples include bench top pipette containers, vacuum flasks, beakers, etc.
- Waste containers for P32 and all gamma isotopes should be checked to determine if shielding is necessary.
- Waste that is being stored in the laboratory for decay-in-storage must conform to Department of Health regulations. Additional information is also available in the MHP Radiation Safety Manual.
- Do not overfill waste containers. Liquid containers should not be filled past the shoulder.
- Remove all decayed waste from the laboratory prior to inspection.
- Request radioactive material waste disposal pickups from EHS on a regular basis.
- Periodically check waste labels. If there is something in a waste bucket, there must be something on the waste bucket label.
- Wipe test waste containers and decontaminate if greater than 5,000 DPM.
- Do not leave waste on bench tops. Move waste to colored buckets immediately after working.
- Make sure all containers holding radioactive material are properly labeled with the radiation symbol and isotope present.
Personal Protection Equipment (PPE) is designed to prevent harmful substances from entering onto or into your body. PPE for laboratory radiation safety differs from that for chemical safety in only one category: dose measurement. Doses from radioactive material handling can be measured by wearing a dosimeter. The three common types of dosimeters a laboratory worker might wear are a full body dosimeter, an extremity dosimeter and a fetal monitor.
- Full body dosimeters are worn on the torso, between the waist and neck, outside the lab coat. These are designed to measure the dose a worker receives to the body from a wide radiation field. Only high-energy betas, such as P32 and gamma radiation, can be measured. These dosimeters are not practical for low-energy betas such as H3, C14 and S35.
- Extremity dosimeters are designed to measure a near-field dose delivered to the hands, arms and feet. The most useful type is a ring dosimeter that is worn on the index finger of the dominant hand. In laboratory work, the hands will generally receive most of a radiation dose. Ring dosimeters have the same limitations as whole body dosimeters.
- Fetal monitors are worn by pregnant laboratory workers who have declared their pregnancy in writing. Please contact MHP: (646) 962-5566 for details regarding fetal monitoring.
- Chemical hoods are part of the laboratory PPE. Malfunctioning or misused chemical hoods can create a dangerous situation for laboratory workers. Always check for hood certification and proper flow rates - between 75 and 130 ftm. Hoods that flow too much are as dangerous as ones that don’t flow enough. Check that hoods are not overcrowded with equipment that will prevent proper laminar flow.
- Dosimeters must be requested from via the Dosimeter Request Form.
- P32 workers must have a full body and ring dosimeter.
- Anyone using the irradiator must have a full body and ring dosimeter.
All isotopes must be secured against unauthorized removal. Labs must be locked unless there are workers present. Any isotopes stored in hallways must be locked up at all times.
Only laboratory workers possessing a radiation safety training certificate are authorized to handle isotopes.