Radiation Embrittlement of PWR Reactor Vessel Weld Metals : Nickel and Copper Synergism Effects

2009 ◽  
pp. 392-392-20 ◽  
Author(s):  
C Guionnet ◽  
B Houssin ◽  
D Brasseur ◽  
A Lefort ◽  
D Gros ◽  
...  
Keyword(s):  
Reactor Vessel ◽  
Radiation Embrittlement ◽  
Weld Metals

Radiation and Temper Embrittlement Processes in Advanced Reactor Weld Metals

1972 ◽  
Vol 94 (3) ◽  
pp. 807-814 ◽  
Author(s):  
J. R. Hawthorne ◽  
E. Fortner
Keyword(s):  
High Resistance ◽  
Copper Content ◽  
Temper Embrittlement ◽  
Radiation Sensitivity ◽  
Composition Series ◽  
Strength Increase ◽  
Radiation Embrittlement ◽  
Weld Deposit ◽  
Weld Metals ◽  
Filler Metals

Experimental weld filler metals having high resistance to radiation embrittlement at ≃550 F (288 C) have been developed for quenched and tempered A543 and A542 steel. The filler metals are from a special 2-1/4 Cr-1 Mo-0.40Si-0.10C composition series formulated to study the effects of variable copper, nickel, and manganese contents on weld performance. This report presents an advanced evaluation of weld deposit performance based on new Charpy-V (Cv) and tension data and an analysis of temper embrittlement and radiation embrittlement processes. High fluence assessments confirm the high resistance to radiation embrittlement of the low copper content filler metal group. A 530 F (277 C) irradiation of one typical submerged arc weld deposit to a fluence of 3.8 × 1020 n/cm2 > 1 MeV did not elevate its Cv 30 ft-lb transition temperature to above 275 F (135 C) or reduce its Cv shelf energy level to below 50 ft-lb. Radiation embrittlement saturation was not evident. Temper embrittlement and radiation embrittlement development and the probable mechanisms of copper and phosphorus influences on radiation embrittlement sensitivity are analyzed with the aid of experimental data for the weld metals and A543 plate. Temper embrittlement and radiation embrittlement are shown to be additive effects which can occur simultaneously or sequentially. A separate component of irradiation effects, manifested as a strength increase without embrittlement, is revealed. The enhancement of radiation sensitivity by high copper content (≧0.16–0.27 percent Cu) is related to a copper influence on the radiation elevation of yield strength; the enhancement of radiation sensitivity of phosphorus is ascribed to a detrimental effect similar to that of temper embrittlement. It is proposed that copper acts to pin radiation-induced defect aggregates and dislocation arrays in the matrix and that phosphorus segregates during irradiation to weaken the interface of ferrite platelets and carbides.

Alternative Method of RTNDT Determination for Some Reactor Vessel Weld Metals Validated by Fracture Toughness Data

1995 ◽  
Vol 117 (4) ◽  
pp. 378-382 ◽  
Author(s):  
K. K. Yoon
Keyword(s):  
Fracture Toughness ◽  
Test Data ◽  
Reactor Vessel ◽  
Test Method ◽  
Transition Range ◽  
Weld Metals ◽  
Drop Weight ◽  
Safety Margins ◽  
Weight Test ◽  
Drop Weight Test

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 (RTNDT). The original method to determine the RTNDT was formulated more than 20 yr ago when Section III 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 RTNDT 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 RTNDT value for unirradiated material where Charpy transition temperature is the dominating criterion, an alternative RTNDT 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 (TNDT) from drop-weight test data as the sole mean for determining initial RTNDT value.

On the radiation embrittlement of materials of support structures for WWER RPV. Part 1. Experimental studies

2019 ◽  
pp. 175-192
Author(s):  
B. Z. Margolin ◽  
E. V. Yurchenko ◽  
V. I. Kostylev ◽  
A. M. Morozov ◽  
A. Ya. Varovin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Experimental Studies ◽  
Irradiation Temperature ◽  
Radiation Embrittlement ◽  
Support Structures ◽  
Metal Structures ◽  
Weld Metals ◽  
Sem Investigation ◽  
Low Irradiation

The features of the radiation embrittlement of materials of support structures for WWER RPV are considered. These features are connected with low irradiation temperature no exceeding90°Cand also with a use of the steels which are usually applied for building of the metal structures and have not a high resistance to the radiation embrittlement. It has been shown that support structure (SS) of WWER-440 of V-179, V-230 types may cause the operation life limit. The experimental data on the standard mechanical properties and fracture toughness are presented for different steels and weld metals in the initial and irradiation conditions. SEM investigation of fracture surface of broken specimens and atomic tomography have been performed.

Radiation Embrittlement Mechanistic Modelling

1993 ◽  
Vol 46 (5) ◽  
pp. 162-170
Author(s):  
W. A. Pavinich ◽  
W. L. Server ◽  
T. J. Griesbach
Keyword(s):  
Heat Treatment ◽  
Thermal Annealing ◽  
Temperature Effects ◽  
Reactor Vessel ◽  
Post Weld Heat Treatment ◽  
Mechanistic Models ◽  
Radiation Embrittlement ◽  
Initial Direction ◽  
Predictive Equations ◽  
Mechanistic Modelling

The mechanistic models of radiation embrittlement for reactor vessel steels are reviewed and direction for improving these models is provided. Improvement in these mechanistic models will lead to predictive expressions for parameters of engineering interest. This paper provides the initial direction of modelling efforts that will improve existing or develop new predictive equations for damage attenuation, temperature effects, thermal annealing, the effect of post weld heat treatment, transition behavior and upper shelf behavior of reactor vessel steels.

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