Simplified failure sequence evaluation of reactor pressure vessel head corroding in-core instrumentation assembly
- Baltimore Gas and Electric Co., Lusby, MD (United States)
- Hopper and Associates Engineers, Redondo Beach, CA (United States)
In-Core Instrumentation (ICI) assemblies located on a Reactor Pressure Vessel Head have a history of boric acid leakage. The acid tends to corrode the nuts and studs which fasten the flanges of the assembly, thereby compromising the assembly`s structural integrity. This paper provides a simplified practical approach in determining the likelihood of an undetected progressing assembly stud deterioration, which would lead to a catastrophic loss of reactor coolant. The structural behavior of the In-Core Instrumentation flanged assembly is modeled using an elastic composite section assumption, with the studs transmitting tension and the pressure sealing gasket experiencing compression. Using the above technique, one can calculate the flange relative deflection and the consequential coolant loss flow rate, as well as the stress in any stud. A solved real life example develops the expected failure sequence and discusses the exigency of leak detection for safe shutdown. In the particular case of Calvert Cliffs Nuclear Power Plant (CCNPP) it is concluded that leak detection occurs before catastrophic failure of the ICI flange assembly.
- OSTI ID:
- 122552
- Report Number(s):
- CONF-950740-; ISBN 0-7918-1349-5; TRN: 95:024201
- Resource Relation:
- Conference: Joint American Society of Mechanical Engineers (ASME)/Japan Society of Mechanical Engineers (JSME) pressure vessels and piping conference, Honolulu, HI (United States), 23-27 Jul 1995; Other Information: PBD: 1995; Related Information: Is Part Of Structural integrity of pressure vessels, piping, and components -- 1995. PVP-Volume 318; Chung, H.H.; Ezekoye, L.I.; Fujita, K.; Garic, G.; Goodling, E.C. [eds.]; PB: 383 p.
- Country of Publication:
- United States
- Language:
- English
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