On March 14, 2016 (81 FR 13263), the Nuclear Regulatory Commission (NRC) published a notice in the federal register requesting general and specific comments on the overall effectiveness and clarity of the requirements for security measures to protect category 1 and category 2 sources of radioactive material as defined in Appendix A to 10 CFR Part 37. For example, the NRC would like to gain insight on different regulatory requirements in 10 CFR Part 37 that may conflict or need to be modified to maximize effectiveness and provide greater clarification. The NRC is also requesting comments on the usefulness of the guidance documents associated with its regulations in 10 CFR Part 37. To facilitate comments, questions are listed in this federal register notice and categorized by the specific Subparts of 10 CFR Part 37: Subpart A—General Provisions; Subpart B—Background Investigations and Access Control Program; Subpart C—Physical Protection Requirements During Use; and Subpart D—Physical Protection in Transit. The NRC plans to hold a series of public meetings to facilitate public participation. These meetings will consist of a public meeting and a series of webinar teleconferences; and will be announced on the NRC’s public meeting Web site at least 10 calendar days before the meeting. The NRC is planning to conduct these meetings in March of 2016. Please submit comments by May 13, 2016. Comments received after this date will be considered if it is practical to do so, but the NRC is able to ensure consideration only for comments received on or before this date.