Development of J-integral based UT flaw acceptance criteria for Savannah River reactor tanks

Conference · Tue Dec 31 04:00:00 EST 1991

OSTI ID:10131276

Mehta, H S; Ranganath, S ^[1]; Awadalla, N G; Sindelar, R L; Caskey, Jr, G R; Daugherty, W L ^[2]

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1. General Electric Co., San Jose, CA (United States). Nuclear Energy Div.
2. Westinghouse Savannah River Co., Aiken, SC (United States)

The tank of a Savannah River Site reactor is a cylinder approximately 16 feet in diameter and 14 feet high and is not pressurized except for a 5 psig helium blanket gas in addition to the hydrostatic head of the heavy water (D{sub 2}O) moderator. The tank is made of Type 304 Stainless steel fabricated into cylindrical shells with 0.5 inch thick four to six wrought plates per vessel. The shell was made up in two flat half-sections for later rolling and welding. The tank bottom section containing the moderator effluent nozzles was welded to the shell in a T-Joint configuration. An ultrasonic (UT) in-service inspection program has been developed for the examination of these reactor tanks. Prior to the initiation of these inspections, criteria for the disposition of any indications that may be found were required. This paper describes the fracture mechanics evaluations that formed the technical bases for the flaw acceptance criteria. The fracture mechanics evaluation considered detailed finite element calculated stress states in the various regions of the tanks, measured irradiated fracture toughness properties (irradiated condition material J-R curves), fluence levels in the tanks, and intergranular stress corrosion cracking growth rates in the reactor environment. The irradiation program was conducted at the High Flux Isotope Reactor at Oak Ridge National Laboratory. Tensile and fracture toughness data were obtained from 36 compact tension, tensile and Charpy V-notch specimens. Through wall cracks are postulated in various regions of the tank and critical crack lengths are calculated by the elastic-plastic fracture mechanics based J-Integral/Tearing Modulus (J/T) approach. The applied values of J-integral were calculated by the well-known GE/EPRI estimation scheme. Acceptable crack lengths are then calculated following generally accepted safety factors based on the ASME Pressure Vessel Code. The acceptance criteria are then briefly described.

• Research Organization: Westinghouse Savannah River Co., Aiken, SC (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC09-89SR18035
• OSTI ID: 10131276
• Report Number(s): WSRC-MS--91-179; CONF-910817--29; ON: DE92009657
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210400
36 MATERIALS SCIENCE
360105
CORROSION AND EROSION
CRACKS
FINITE ELEMENT METHOD
FRACTURE MECHANICS
HEAT TRANSFER
HEAVY WATER MODERATED REACTORS
HYDRAULICS
INTERGRANULAR CORROSION
POWER REACTORS
NONBREEDING
OTHERWISE MODERATED OR UNMODERATED
SAVANNAH RIVER PLANT
STAINLESS STEEL-304
STRESS CORROSION
TANKS