Chapter 7 - Sealed Sources

7.0  Sealed Radioactive Sources (Top)



The possession and use of sealed radioactive sources at Cornell is authorized by a radioactive materials license issued by the State of NYSDOH.  As required by the license, the use of sealed sources is restricted to specific individuals and locations authorized by the University RSC. This requirement applies to all radioactive material, including generally licensed and exempt quantity material.  

Possession and use of sealed sources at Cornell requires a formal written authorization issued by the RSC in the form of a permit or a registration: 

  1. A Sealed Source Permit is required for the use of sealed sources that produce a radiation field equal to or greater than 50 mrem/hr at 1 centimeter.

  2. A Sealed Source Registration is required for sources less than 50 mrem/hr at 1 centimeter that poses a very low risk to the user.

 Applications for permits are reviewed by the RSO before being submitted to the RSC.


7.1 General Requirements (Top)

7.1.1 Sealed Source Permits  (Top)

The RSC is responsible for ensuring that sealed radioactive sources are used safely and in compliance with ALARA. A permit or registration must be obtained from the RSC in advance of any use or acquisition (by purchase, transfer, or otherwise) of sealed sources.  

The application describes the isotope(s), amount(s), facilities, experimental procedures, hazards, handling precautions and the qualifications of the applicant. Depending on the degree of hazard and risk either a permit or a registration application is completed. The content of the application is tailored to reflect the degree of risk posed by the sealed source. Qualifications  

In order to qualify for a permit, an applicant must be a member of the Cornell faculty or a senior research associate. Other individuals wishing to utilize radioisotopes must work under the supervision of a permit holder. 

The training and experience required to be granted a permit depend on the type and relative hazards associated with the sealed source to be used, and on the manner in which it will be used. In general a permit applicant will be expected to have previous training and experience with similar sealed source and be able to demonstrate adequate knowledge of: Radiation measurements, standardization, monitoring techniques, and instrumentation. Mathematics and calculation techniques basic to the use of radioactivity. The biological effects of radiation. Emergency procedures.   

This knowledge is obtained through required radiation safety training provided by the RSO and from training and/or experience received prior to Cornell. 

If a faculty member or senior research associate does not have adequate qualifications to be granted a permit, additional experience can be gained by working under the supervision of a more experienced colleague who is a permit holder. When the experience gained is sufficient to work independently, the application will be considered.  


To become a permit holder, an individual contacts the RSO and indicates a need to use sealed radioactive materials. The RSO meets with the individual to discuss the Cornell radiation safety program, the duties and responsibilities of a permit holder, and the application form and process. When completed, the permit application is submitted to the RSO who reviews it for completeness and then is submitted to the RSC. A subcommittee of the RSC reviews the application and visits the laboratory or other use location to discuss the application with the applicant and to review the adequacy of the facilities. The subcommittee will either approve the application or return it to the applicant for revision. Permit Issuance  

When an application is approved, the applicant will receive a written copy of the permit. On occasion, the RSC may impose restrictions on the use of the equipment if warranted for radiation safety and ALARA reasons. These will be stated in the permit.  

Permits are issued for periods of two years. Permit holders may be notified in advance of the date that the permit is due to expire, however, permit holders are responsible for having a current permit in effect at all times. The permit holder may choose to terminate the permit or submit a request for renewal. The renewal request should specify any needed changes.

Between renewals, the permit holder may submit to the RSO written requests for amendments to the permit. The RSO will assist the permit holder as needed to provide the appropriate information. The chair of the RSC will review the request and may at his/her discretion approve it or forward  it first to a sub-committee for review. 

When a permit holder is expected to be away for up to six (6) weeks, the Alternate Contact (AC) will be in charge of the laboratory on behalf of the permit holder. The AC will be contacted for permit related issues and will perform most of the permit holder responsibilities and functions including minor requests for permit amendments such as adding/deleting users or rooms. The permit holder will, upon return, countersign all those items which required signatures during the absence. When the permit holder and the AC are expected to be away at the same time, the permit holder must advise the RSO so that an alternate arrangement can be made. 

When a permit holder is expected to be away from Cornell for six (6) weeks or more, the permit holder and RSO will select a substitute permit holder who has the knowledge and expertise to be responsible for the laboratory. The substitute permit holder must agree in writing to accept the responsibility for the permit during the leave. A permit amendment will be issued to reflect the change. Permit Termination  

When termination of a permit is desired, the permit holder must notify the RSO as far in advance as possible. This is particularly important when the termination is due to the permit holder’s leaving the University. The permit holder will assist the RSO to ensure that: All sealed sources still in the possession of the permit holder are properly transferred or disposed of. Area/ personnel monitoring is discontinued, where applicable.  Postings and labels are removed from the authorized area. Documentation of the transfer or disposal of any sealed source.  

7.1.2 Sealed Source Registrations (Top)

Individuals who wish to use sealed sources that pose a very low risk to the user will be issued a Sealed Source Registration. Registrations are generally granted by the RSC chair, with recommendations from the RSO, without a RSC site evaluation.  

The following are examples of the kinds of sources or equipment that can generally be handled or operated without concern for dose to personnel: Electron capture detectors (ECD) Liquid Scintillation Counters (LSC) Low activity calibration and check sources 

Sealed Source Registrations are issued for periods of two years. Registrants may be notified in advance of the date that the registration is due to expire, however, registrants are responsible for having a current registration in effect at all times. The registrant may choose to terminate the registration or submit a request for renewal. The renewal request should specify any needed changes.

7.1.3 New Facilities / Major Renovations (Top)

Plans and specifications for the construction of new radiation facilities, or the major modification of existing facilities,  must be approved by the RSC. The information provided to the RSC must include, at a minimum, the technical specifications of the equipment, the facility layout, beam orientation, shielding (location and construction), occupancy of adjacent areas, and a summary of proposed operations, source use times, and expected radiation levels within and immediately outside controlled areas.   

7.1.4 Acquisitions / Transfers / Movement / Disposal  (Top)

All purchase requisitions and acquisitions must be reviewed and approved in advance by the RSO before the acquisition may proceed. See Chapter 6, Acquisition of Radioactive Material and Sealed Sources. 

All transfers, movement, and disposal of sealed sources must be reviewed and approved in advance by the RSO. See Chapter 9, Transfer, Shipping, and Disposal of Radioactive Material and Sealed Sources.   

7.1.5 Radiation Monitoring  (Top) Personnel dosimetry will be assigned as needed to meet the requirements of Chapter 8.   When not required, the decision to use personnel monitoring is left to the discretion of the permit holder in consultation with the RSO. Area dosimetry badges or monitoring equipment (e.g. GM meters) are required and must be used for all sealed sources of emitting a level of radiation greater than 0.5 mrem/hr at 5 cm from the surface. Dosimeters and GM meters are available from the EHS.  

7.1.6 Personnel Dose Limits  (Top)

The University policy requires that radiation doses be maintained ALARA. Chapter 8 of this Manual specifies the limits and guidelines for radiation workers, pregnant radiation workers, non-radiation workers and members of the public.   

7.1.7 Area Classification, Dose Limits & Identification (Top)

Areas where personnel may be exposed to radiation are classified according to the dose rates listed in Table 7.1. The RSO, or designee, will determine controlled areas during a pre-operational survey. Only the RSO, or designee, may make changes in these designations.  Noncontrolled Area: An area to which access is neither controlled nor restricted. Controlled Area: An area authorized for the use and/or possession of radiation sources where access is restricted to authorized radiation users and accompanied visitors.  Temporary access to high radiation areas is allowed only to qualified personnel with permission of the RSO and the department head. Personnel monitoring devices are required and portable survey instruments must be used during access to all such areas. Portable radiation survey instruments must be available to personnel who work adjacent to radiation/high radiation areas. Written safety operating procedures must be prepared by the permit holder and submitted to the RSO as part of the permit application. All area designations, safety procedures and precautions  must be clearly spelled out. All qualified workers must be required to be familiar with the requirements of the procedure before starting work. Exclusion Area: An area authorized for source use where access is strictly prohibited when the source is in use. Continuously operating radiation monitoring devices must be installed in and adjacent to these areas. Such devices must provide an audible and visual warning to personnel in the vicinity when the preset maximum dose rate is exceeded. 

Table 7.1 classification of Areas and Dose Limits

Area Dose Limits​
Noncontrolled ​Less than 2.0 mrem in 1 hour and less than 100 mrem in 1 year*
Controlled​ ​More than 2.0 mrem in 1 hour or more than 100 mrem in 1 year*
Radiation Area​ ​More than 5.0 mrem in 1 hour at 30 cm
​High Radiation Area ​More than 100 mrem in 1 hour @ 30 cm
​Exclusion ​Potential dose exceeds a high radiation area

*A year is defined as January 1 to December 31. 

7.1.8 Security/Access To Sources (Top) All sealed  sources must be secured against unauthorized operation when left unattended. When a sealed source is in use and unattended security may be accomplished by preventing access to the controlled area. Certain sources with “quantities of concern” will have special security requirements. The RSO will indicate which sources are in this category.  


7.1.9 Posting of Notices and Labeling (Top)

The following are required to be posted or present in source use areas: NY State Notice to Employees Radiation Safety Manual (See Chapter 2, section 2.4.9) A copy of the permit and application, or registration, all use procedures, and other safety documentation required by the permit or application  

7.1.10 Inspections (Top)

The RSO, or designee, must, at six month intervals must perform an inspection and report the findings and recommendations to the permit holder. The permit holder must take steps to correct any violations upon receipt of such notice.  Inspections are not required for sealed source registrations.  

7.1.11 Violations (Top) Major  

Deviations from approved procedures which pose a potential for excessive radiation dose to personnel must be considered a major violation. Such activities must cease immediately and the RSO will be advised. The permit or registration holder must promptly correct the violation, and report to the RSO the corrective actions taken to prevent a reoccurrence. Follow up actions may be taken by the RSO in consultation, or under the direction, of the RSC.  Minor  

Situations not posing a potential for excessive radiation dose to personnel, but violating any item of this chapter, must be designated minor violations. The permit or registration holder and RSO will be advised of the inspection findings. The permit or registration holder must promptly correct the violation, and report within 30 days to the RSO the corrective actions taken to prevent a reoccurrence.  


7.1.12 Exceptions (Top)

Any exception to the requirements of this chapter must be applied for in writing and granted by the RSC upon demonstration by a permit holder that the requirement is unreasonable and that radiation safety can be maintained.