Transport and retention of radioiodine on the secondary side of U-tube steam generator during tube rupture event

Corrosion and mechanically induced damage can result in rupture of the pressurized water reactor steam generator tubes. Such a rupture will result in the leakage of the radioactive primary-side fluid to the secondary-side of a steam generator. A fraction of the leaked primary-side radioactive species will be retained in the secondary side, and the rest will be released in the form of vapor and entrained aerosols. The STARRS (secondary-side transport and retention of radioactive species) computer code was developed to simulate the transport and retention of aerosols and gaseous fission products on the secondary side of a U-tube steam generator during a steam generator tube rupture (SGTR) transient and to quantify the activity dose associated with the release. This paper provides an overview of the modeling approach and validation and application results. Validation calculations used the data generated at the Model Boiler No. 2 (MB-2) test facility. Plant calculations measured the release of radioiodine and the resulting thyroid dose for SGTR transients involving high and low secondary-side water levels