Document: NUREG-0800
Document ID: 9738c583-ac33-4836-b8f1-580dc98eb7f0
Document Type: srp
Title: RADIOLOGICAL CONSEQUENCES OF THE FAILURE OF SMALL LINES CARRYING
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350147.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.6.2
CFR Part: 
CFR Title: 

Content:
release to the atmosphere, without credit for plateout, is equal to the fraction of the coolant flashing into steam in the depressuri- zation process. The flash fraction is determined by assuming the discharge to be a constant enthalpy process. e. For a plant with a dual containment system, it is assumed that the small line failure occurs outside the secondary containment if the line penetrates or bypasses the secondary containment. The release is assumed to occur within the secondary containment if the line terminates inside the secondary containment. The reviewer verifies, in a coordinating review effort with the CSB the integrity and leak- tightness of the secondary containment during the pressure transient associated with the postulated small line failure within its boundaries. An approximate mixing volume is determined from the location of the assumed failure location and the proximity to the secondary containment ventilation system assumed to be operating (if any). The release of the airborne radioactivity-from the secondary containment to the outside atmosphere is evaluated in accordance with the assumption of SRP Section 15.6.5, Appendix A, subsection 111.3. f. The operation and effectiveness of an ESF-grade filtration system for removal of airborne radioiodine will be reviewed on a case-by- case basis. The reviewer verifies that all potential locations for a small line break are within ventilation zone of the system. Depending on the type of air treatment system credited in the analysis, a ground-level or elevated (stack) release is assumed. The appropriate atmospheric dispersion factors (X/Q values) are provided by the assigned meteorologist in accordance with SRP Section 2.3.4. 4. Review of dose calculations. The'whole-body and thyroid doses calculated by the staff and by the applicant are compared with the acceptance criteria stated in subsection II of this SRP section. If the doses calculated by the staff are not within the exposure guidelines (i.e.,