Alternative method of RT{sub NDT} determination for some reactor vessel weld metals validated by fracture toughness data
- B and W Nuclear Technologies, Lynchburg, VA (United States)
The fracture toughness curves used for nuclear power plant operation pressure-temperature limits and for pressurized thermal shock evaluations are dependent on the reference temperature for nil-ductility transition (RT{sub NDT}). The original method to determine the RT{sub NDT} was formulated more than 20 yr ago when Section 3 of the ASME Code was adopted. At that time, there were insufficient data to judge whether some of the weld metals used in reactor vessel fabrication were unsuitable for this procedure. Presently, this causes a compliance problem for some weld metals used in nuclear reactor vessels, whereas there is no technical problem in meeting required safety margins. The RT{sub NDT} is a parameter to index degrees of irradiation embrittlement to adjust the Code reference fracture toughness curves to represent the actual degraded fracture toughness at a given fluence of a reactor vessel beltline region. When there is a problem determining RT{sub NDT} value for unirradiated material where Charpy transition temperature is the dominating criterion, an alternative RT{sub NDT} based solely on a drop-weight test was investigated for some of the weld metals. Using a new test method for fracture toughness in the transition range (ASTM, 1993), a fracture toughness curve was directly generated from a set of compact tension test data and used for validating the nil-ductility temperature (T{sub NDT}) from drop-weight test data as the sole mean for determining initial RT{sub NDT} value.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 131630
- Journal Information:
- Journal of Pressure Vessel Technology, Vol. 117, Issue 4; Other Information: DN: Paper presented at the Pressure Vessels and Piping Conference, Minneapolis, MN (US), June 19--23, 1994; PBD: Nov 1995
- Country of Publication:
- United States
- Language:
- English
Similar Records
Exploratory investigations of low Charpy-V upper shelf energy steels with irradiation. Final report
Ductile fracture toughness of modified A 302 Grade B Plate materials, data analysis. Volume 1