Probability of the iodine spike release rate during an SGTR
The Nuclear Regulatory Commission (NRC) requires utilities to determine the response of a pressurized water reactor (PWR) to a steam generator tube rupture (SGTR) as part of the safety analysis for the plant. The SGTR analysis includes assumptions regarding the presence of fission product iodine in the reactor coolant resulting from iodine spikes. Due to uncertainties in the consequences, the NRC has designated this class of accident as a generic safety issue. To get a better understanding of iodine spiking, reactor trip and associated radiochemistry data were collected from 26 PWRs. These data were compared against validation criteria to determine their applicability to an investigation of the magnitude of an iodine spike following a reactor trip. The applicable data and the results of a statistical analysis are presented. Conclusions are made concerning the magnitude of an iodine spike during an SGTR and these are compared with the NRC analysis criteria. The conclusion is made that the iodine release rate specified for analysis of an SGTR is overly conservative and could be reduced significantly while still maintaining adequate protection to the public. The formalism required by the Standard Review Plan in determining the release rate is judged to be inappropriate and an absolute release rate, based on plant electric power, is recommended as a replacement. A value of 0.710 Ci/h*MW(e) is recommended for consideration as a replacement for the current iodine release rate specification for an SGTR with coincident iodine spike.
- Research Organization:
- EG and G Idaho, Inc., Idaho Falls, ID (United States)
- Sponsoring Organization:
- Nuclear Regulatory Commission, Washington, DC (United States)
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 10168900
- Report Number(s):
- EGG-NERD--8648; ON: DE93017396
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
210200
22 GENERAL STUDIES OF NUCLEAR REACTORS
220900
CONCENTRATION RATIO
COOLANTS
FISSION PRODUCT RELEASE
IODINE
POWER REACTORS
NONBREEDING
LIGHT-WATER MODERATED
NONBOILING WATER COOLED
PROBABILISTIC ESTIMATION
PWR TYPE REACTORS
RADIOCHEMISTRY
REACTOR ACCIDENTS
REACTOR SAFETY
RECOMMENDATIONS
RUPTURES
SAFETY ANALYSIS
STATISTICAL DATA
STEAM GENERATORS
TUBES