Health Physics Position on the Controlling of Beam Ports, Thermal Columns, and Flux Traps as High Radiation Areas
See the memorandum from L. J. Cunningham to J. H. Joyner (and others) dated May 31, 1991.
The narrow radiation beams from beam ports, thermal columns and flux traps at reactor facilities may expose major portions of the head and trunk, and therefore, must be controlled as high radiation areas. The health physics position was written in the context of 10 CFR 20.201 and 20.203, but it also applies to "new" 10 CFR 20.1601 and 20.1902.
This memo clarified the NRC staff position that the subject areas must be controlled as high radiation areas. A number of Notices of Violation (NOV) concerning the posting and control requirements of 10 CFR 20.201 and 20.203 have occurred at research and test reactors. These licensees were not properly controlling high radiation areas, specifically those involving beam ports. [Note: The posting and control requirements for high radiation areas are contained in "new" 10 CFR 20.1601 and 20.1902.]
The argument is made by licensees that the radiation streaming from these beam ports will not cause an exposure to the whole body. These licensees have taken the position that narrow beams don't meet the current 10 CFR 20.202 (b) (3) definition that state in part, " ... a major portion of the body could receive, in any one hour, a dose in excess of 100 millirems."
The 10 CFR Part 20 definition of the whole body as specified in 10 CFR 20.101 (b) (3) includes the head and trunk; active blood forming organs; lens of the eyes; or gonads. [Note: The "new" 10 CFR 20.1003 definition states: "Whole body means, for purposes of external exposure, head, trunk (including male gonads), arms above the elbow, or legs above the knee."] Whether these beams are narrow or not, if they could possibly expose the lens of the eyes, the gonads or any other major portion of the head and trunk or active blood forming organs, then the beams must be controlled as high radiation areas. The revised Part 20 will support this position, and will further clarify it by avoiding the term "the major portion of the whole body," when defining a high radiation area. [Note: The "new" 10 CFR 20.1003 definition states: "High radiation area means an area, accessible to individuals, in which radiation levels could result in an individual receiving a dose equivalent in excess of 0.1 rem (1 mSv) in 1 hour at 30 centimeters from the radiation source or from any surface that the radiation penetrates."]
Pursuant to 10 CFR 20.203 (c) (5) [or 10 CFR 20.1601 (c)], if the stated alternatives of 10 CFR 20.203 (c) (2) and (4) [or 10 CFR 20.1601 (a) and (b)] are not feasible, a licensee may apply to the Commission for approval of methods not included in paragraphs 20.203 (c) (2) and (4) [or paragraphs 20.1601 (a) and (b)] for controlling access to high radiation areas. If a licensee chooses 10 CFR 20.203 (c) (2) (iii) [or 10 CFR 20.1601 (a) (3)] as the control option, positive entry control is required. Methods of positive entry control may include, but are not limited to, the following:
All entries into high radiation areas are controlled by requiring issuance of a Radiation Work Permit (RWP) or a work procedure. This controlling permit or procedure contains any special instructions and the requirements for entry into the high radiation area, which may include: a pre-briefing on the actions to be performed, a review of current radiation surveys, the requirements of a film badge or TLD, and a pocket ionization chamber or extremity dosimeters, signs and barriers to avoid contact with the beam, and directions not to alter any shielding or experiment without health physics supervision.
Due to the nature of the potential hazards involved, all facilities having these types of radiation beams need to control these areas as high radiation areas. However, given the diverse nature of reactor types and experimental configurations in the nonpower reactor community, we could expect these licensees to implement a wide variety of practices and controls to satisfy the regulatory requirement for positive entry control.
This Health Physics Position has been reviewed by all Regions; the Division of Advanced Reactors and Special Projects, NRR; the Office of Nuclear Material Safety and Safeguards; and the Office of Enforcement.
Regulatory references: 10 CFR 20.201, 10 CFR 20.203, 10 CFR 20.1601, 10 CFR 20.1902
Subject codes: 4.1, 4.7