The Nuclear Regulatory Commission (NRC) has issued a regulatory issue summary (RIS) which states agency intends to pursue rulemaking to clarify the 0.5 millisievert (mSv) (0.5 rem) limit in 10 CFR 35.75 as an annual limit, rather than a per-release limit.
10 CFR 35.75 provides that a “licensee may authorize the release from its control of any individual who has been administered unsealed byproduct material or implants containing byproduct material if the total effective dose equivalent to any other individual from exposure of the released individual is not likely to exceed 5 mSv (0.5 rem).”
The rulemaking is being pursued because the NRC said it has determined that the regulation as it is now written does not incorporate the commission’s intent in having promulgated this regulation.
According to the NRC RIS, the “wording of the §35.75, which does not indicate that the dose limit is an annual limit, was based on the presumption that an individual who received a therapeutic radiopharmaceutical dosage or a therapeutic sealed source permanent implant and was released under the restriction under the §35.75, was highly unlikely to receive another treatment and again be released within the same year.”
The NRC will follow the normal procedures for rulemaking, including the opportunity for public comment.