Document: NRC Regulatory Guide
Document ID: 96baa826-d3bb-478b-8f38-e74500f6d433
Document Type: regulatory_guide
Title: 06/2009 (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0911/ML091170109.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.21
CFR Part: 
CFR Title: 

Content:
d. A well-designed and documented evaluation of a release point can include an evaluation of the potential for an unplanned or uncontrolled release. The evaluation can establish bounding criteria that establish a threshold for an abnormal release based on planning and control. Generally, releases that may reasonably be categorized as both unplanned and uncontrolled should be considered abnormal releases. For example, consider an underground pipe that carries radioactive liquid to an outside storage tank. If this pipe develops a leak, and licensed radioactive material escapes into the surrounding soil, it is considered an abnormal release if some portion or all of the radioactive material remains on site. This type of leak should be reported as an abnormal release in the next ARERR. If the licensee predicts (e.g., based on site conceptual model and subsequent ground water monitoring results) that the radioactive material will enter the unrestricted area in 2 years, the resulting radioactive discharge (that would occur 2 years hence) will be considered an abnormal discharge. Therefore, the resulting radioactive discharge should be reported along with other data for the affected calendar year in a future ARERR (i.e., in this example, 3 years later). Both releases and discharges (either routine or abnormal) should be reported on a calendar- year basis for the year in which the release or discharge occurred. Consider another example involving a volume of radioactive gas from the containment atmosphere that escapes the equipment hatch during a refueling outage (especially during the time interval when the containment purge exhaust fans are off). This would generally not be considered an abnormal discharge if (1) the duration was preplanned (e.g., for a “short” duration such as 12 hours), (2) the containment activity (gas, particulate, tritium, and iodine) was preplanned, known, and very low (e.g., such that a bounding estimate of the radioactive material discharged