U.S. Nuclear Regulatory Commission

Question 47: Will the NRC provide guidance on preparation

of applications pursuant to 10 CFR 20.1204 (c) (2) for

approval to adjust DAC or ALI values to reflect the actual

physical and chemical characteristics of airborne

radioactive materials (e.g., aerosol size distribution or

density)?

Answer: The NRC staff is considering developing such

guidance. Some limited guidance on "adjusting DAC's for

particle size" is included in draft Regulatory Guide 8.25,

Rev. 1, Section 3.7; however, the staff recognizes that

more extensive guidance, including considerations of other

physical and chemical characteristics of particles, may be

needed. (Reference: 10 CFR 20.1204 (c) (2))