Document: NUREG-0800
Document ID: 96cbc2a1-0072-44c5-ae86-aadfa416183c
Document Type: srp
Title: RADIOLOGICAL CONSEQUENCES OF MAIN STEAM LINE FAILURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350118.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.1.5
CFR Part: 
CFR Title: 

Content:
he NSSS vendor standard technical specifications or from the plant specific technical specifications, as appropriate (i.e., concurrent iodine spike case). 5. Evaluation of the effects of fuel failure. As a result of the MSLB accident, fuel failures can occur, releasing fission products into the reactor coolant and thus making additional activity available for release to the atmosphere. The RSB reviews, under SRP Section 15.1.5, the effects of the MSLB on the core thermal margins and the associated amount of fuel failures, assWuin9 that the highest worth control rod is stuck at its fully withdrawn position. The RSB, as a secondary review branch, will inform the AEB of the fuel failure estimate. If the MSL accident is predicted to cause such fuel failure, a dose analysis will be performed with the corresponding iodine activity but without a concurrent iodine spike. 6. Determination of the primary-to-secondary leakage. Normal operating irimary-to-secondary leakage is assumed to exist in the steam generators. he leakage rate should be the maximum allowed by the technical specifica- tions. This value is 1 gpm in the STS but may be lower if required 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 7. Any iodine transferred to the secondary coolant system will become airborne at a rate which is a function of the steaming rate and iodine partition