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16 March 2010

Answer to Question #779 Submitted to "Ask the Experts"

Category: Doses and Dose Calculations — External dose calculations

The following question was answered by an expert in the appropriate field:

Can you provide me with the equation for calculating the gamma dose rate at a point away from a rectangular source (slab)?

There is no solution to this problem that can be expressed in the form of a single equation. Hubbell, Bach, and Lamkin addressed this problem in their paper "Radiation Field from a Rectangular Source" published in J. Res. Nat. Bur. Stand., C, 64: 121 (1960). Results are summarized in Appendix H of the 1973 book Reactor Shielding for Nuclear Engineers, N.M. Schaeffer (ed), TID-25951, National Technical Information Service, Springfield, VA 22151. Software such as MicroShield (Grove Engineering, Framatome Technology) or QAD (RSICC, Oak Ridge National Laboratory) allow precise solutions to the problem of the gamma-ray source distributed in a parallelepiped. Richard E. Faw, Ph.D.

Answer posted on 16 March 2001. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.