Document: NUREG-0800
Document ID: 23a67737-6e7e-4dfc-9090-dca6a186a7dc
Document Type: srp
Title: RADIOLOGICAL CONSEQUENCES OF MAIN STEAM LINE FAILURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070679.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.1.5
CFR Part: 
CFR Title: 

Content:
akage. Normal operating primary-to-secondary leakage is assumed to exist in the steam generators. The leakage rate should be the maximum allowed by the technical specifications. This value is 1 gpm in the STS standard technical specifications but may be lower, if required, 34 35 because of the radiological consequences of a rod ejection accident. The leakage should be apportioned between affected and unaffected steam generator(s) in such a manner that the calculated dose is maximized. 7. Determination of iodine transport to the atmosphere. During periods of steam generator dry-out, all iodine transported to the secondary side by primary coolant leakage is assumed to be released to the atmosphere. During periods of total submergence of the tubes, the fraction of iodine released is equal to the flash fraction of the primary coolant leakage. Appropriate credit for scrubbing by the secondary coolant may also be claimed using models presented in Reference 78. Any iodine transferred to the secondary 36 coolant system will become airborne at a rate which is a function of the steaming rate and iodine partition coefficient. An iodine partition coefficient of 100 between steam DRAFT Rev. 3 - April 1996 15.1.5-6 generator water and steam phases may be conservatively assumed, unless the applicant presents reasonable evidence that the use of some other value is justified. 8. Determination of atmospheric dispersion characteristics (X/Q values). The appropriate X/Q values are determined by the assigned meteorologist in accordance with SRP Section 2.3.4. 9. Calculation of the exclusion area boundary (EAB) and low population zone (LPZ) boundary doses. The reviewer performs an independent calculation of the doses for the steam line break accident, using the two iodine concentrations in item 4 above. The breathing rates and dose conversion factors are in accordance with Regulatory Guide 1.4 (Ref. 8).37 10. Review of dose calculations. The whole-body and thyroid doses calculated by the