Health Physics Questions and Answers - Question 451

Question 451: May the codes "ND" (not detectable), "NR" (not required), and "NC" (not calculated) be used more generally in the radiation dose data blocks on the NRC Forms 4 and 5 than is implied by the instructions on the forms? The purpose in asking this question is to clarify the guidance for filling out the forms provided in the regulatory position and in the instructions on the reverse side of the NRC Forms 4 and 5. The Form 5 instructions appear to limit the use of the "NR" and "NC" codes to the committed effective dose equivalent (CEDE) and the committed dose equivalent (CDE), "ND" is not referenced in the Form 5 instructions, and the NRC Form 4 instructions do not appear to refer to any of these codes. We believe that the references to the codes in the guidance and instructions on the forms are as examples for emphasis, and that the intent of the guidance is that "NR" and "ND" are appropriate for use, as applicable, in any of the dose blocks, and are not specifically limited for use by the manner in which referenced or described in the guidance. However, we do note that "NC" may only be applicable to the CDE (e.g., if the CEDE were less than 1 rem).

Answer: Yes. As indicated in the second paragraph of regulatory position 1.1 of the guide, "NR" should be entered in the blocks on Forms 4 and 5 to indicate the areas for which monitoring was not required and "ND" should be entered on these forms to indicate "where monitoring was provided but not measurable [detectable]". As indicated in regulatory position 2.2 of the guide, the use of "NC" is appropriate only for items 16 and 18 on NRC Forms 4 and 5 for cases in which the CEDE does not exceed 1 rem and there are no overexposures in any dose category within the monitoring year.

(References: Regulatory Guide 8.7, Rev. 1; 10 CFR 20.2104, 10 CFR 20.2106)