WORKING WITH RAM
Working with radioactive material at Columbia University is a privilege that comes with many responsibilities. Radioactive materials are regulated on the federal, state and local levels. The University also has developed internal guidelines and protocols to ensure that radioactive material are used safely and within compliance.
Monthly Surveys
Authorized Users are required to perform monthly surveys of RAM work areas during each month in which radioactive materials were used. These surveys are designed to detect fixed and removable contamination and areas with excessive radiation levels. These surveys must be performed by all labs in possession of a Radiation Permit issued by the CU RSO.
A Monthly Survey Form must be completed and retained in the lab for three years. Laboratories are no longer required to submit the results of their wipe test to the RSO. However, the forms will be reviewed by a Radiation Safety Office Representative during the lab’s quarterly inspection.
Survey Methods
The objective of the monthly survey is to find sources of fixed and removable contamination as well as excessive radiation levels. Below is a brief description of how to conduct your lab’s required monthly survey:
Removable contamination survey (“wipe test”) • Pre-label vials with wipe numbers starting with number 2; Number 1 is reserved for a standard. • Identify corresponding wipe location on lab map. • In each wipe location, wipe limited areas (4x4”) using dry wipe or Q-tip with moderate pressure. • Use liquid scintillation counter to find levels. • Complete monthly wipe test form. All readings should be reported in both CPM and DPM. • SC vials should be disposed of as - LSC waste
Fixed contamination survey • Select appropriate instrument for survey – see Table A below: o [Note: only wipe tests are required for H-3, C-14, S-35, or Fe-55] • Identify corresponding locations on lab map • Step outside of lab and record background radiation level on survey meter • Survey lab areas. Indicate meter readings at each location. Do Not Write “0”
Radiation level • Select appropriate instrument for survey – see Table A below: o [Note: only wipe tests are required for H-3, C-14, S-35, or Fe-55] • Use an ion-chamber survey meter • Turn on the meter and allow it to warm up for 1-2 minutes • Identify corresponding locations on the lab map • Step outside of lab and record background radiation level on survey meter • Survey lab areas. Indicate meter readings at each location. Do Not Write “0”
Action Levels
Action must be taken immediately if contamination or excessive radiation levels are detected. If a survey for removable or fixed contamination finds contamination in excess of three times background levels, the area or item must be decontaminated. If the radiation level exceeds 0.5 mR/hr, shielding must be added.
Experiment-Based Surveys
To prevent the spread of contamination, surveys must be performed before, during, and after each experiment when radioactive materials are used. The appropriate survey instrument is dependent on the isotope used (see above). Use the procedures described above. Please see Table A for further detail. As a best practice, labs are encouraged to document and keep records of experiment-based surveys; labs are required to report any radioactive contamination found to the RSO.
Survey Methods
In addition to surveying the immediate work area(s) and equipment, it is important survey your hands, clothing and shoes to ensure no contamination is present.
When detection of an isotope requires the use of a survey method other than scintillation counting, please follow the brief description below and review to Table A for further instruction.
1. Use meter to survey hands, footwear, clothing, countertop (work area) and lab floor before and after each use of radioactive material.
2. Any reading more than three times background should be treated as contamination and is required to be reported to the RSO immediately.
3. Please contact the RSO for information regarding area monitoring when needed.
Note: holders of inactive permits do not have to conduct monthly surveys
Table A Instrument Selection for Laboratory Surveys
Type of Instrument Isotope Half‐Life Type of Radiation or Probe for surveys
Alpha scintillation; Am‐241 432.7 years alpha, gamma NaI(Tl) scintillation; and Ion chamber positron emission, NaI(Tl) scintillation; C‐11 20:38 min twin 511 keV and Ion chamber annihilation photons Wipes; GM efficiency C‐14 5715 years beta very low Ca‐45 167.2 days beta GM NaI(Tl) scintillation; Co‐60 5.271 years beta, gamma and Ion chamber NaI(Tl) scintillation; Cr‐51 27.7 days gamma and Ion chamber NaI(Tl) scintillation; Cs‐137 30.07 years beta, gamma and Ion chamber Fe‐55 2.7 years x‐ray (low energy) Wipes NaI(Tl) scintillation; Fe‐59 44.51 days beta, gamma and Ion chamber NaI(Tl) scintillation; Ga‐67 3.261 days gamma and Ion chamber H‐3 12.32 years beta Wipes NaI(Tl) scintillation; I‐125 59.4 days gamma and Ion chamber NaI(Tl) scintillation or I‐131 8.02 days beta, gamma GM; and Ion chamber positron emission, NaI(Tl) scintillation; N‐13 10 minutes twin 511 keV and Ion chamber annihilation photons positron emission, NaI(Tl) scintillation or Na‐22 2.6 years twin 511 keV GM; annihilation photons Ion chamber Ni‐63 101 years beta Wipes P‐32 14.28 days beta GM and Ion Chamber P‐33 25.3 days beta GM Alpha scintillation; Ra‐226 1599 years alpha, gamma NaI(Tl) scintillation; and Ion chamber NaI(Tl) scintillation or Rb‐86 18.66 days beta, gamma GM; and Ion Chamber S‐35 87.2 days beta Wipes
NaI(Tl) scintillation; Tc‐99m 6 hours gamma and Ion Chamber Alpha scintillation; Th‐nat. 140e10 years alpha, gamma NaI(Tl) scintillation; and Ion chamber
Alpha scintillation; U‐nat. 4.47e9 years alpha, gamma NaI(Tl) scintillation; and Ion chamber
Y‐90 2.67 days beta GM and Ion Chamber
Revised October 2012