Design criteria for the spacing of nozzles and reinforced openings in cylindrical nuclear pressure vessels and pipe. [PWR]
The minimum separation distance between any two nozzle penetrations in a nuclear pressure vessel or piping system is governed by design rules given in Section III of the ASME Boiler and Pressure Vessel Code. A broad-based generic study of these rules was conducted to assess their validity and/or develop more appropriate rules as needed. During the course of the study, we determined that the various rules given in the Code are not always consistent with its basic stress criteria and may be either unduly conservative or nonconservative depending on the dimensional details of a given design. A new separation rule was therefore developed and is presented in the form of proposed changes to the ASME Code. The new rule is based on a comprehensive collection of finite-element stress-analysis studies and experimental data that span the range of dimensional parameters permitted for the design of nozzles in cylindrical vessels. These include data for both isolated and closely spaced nozzles. The proposed rule was also examined by comparison with a detailed finite-element analysis study for the placement of an emergency core-cooling system nozzle in a prototypical four-loop pressurized-water-reactor pressure vessel. The proposed rule would permit placing the nozzle in the vessel approximately at its optimum design location, whereas the current rules could not be used without performance of a detailed stress analysis. The comparison study also showed that the proposed rule is conservative, as it should be, but less conservative than the current rules.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5663204
- Report Number(s):
- NUREG/CR-2308; ORNL-5809; ON: DE82007896
- Country of Publication:
- United States
- Language:
- English
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