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Recently, series of 18 specimens of SEN(B) type and 18specimens of SEN(T) type were tested in Nuclear Research Institute .e.with the goal to quantify the effect of shallow crack (in-plane constraint) onfracture toughness for steel 15CH2MFA of WWER 440 reactor pressurevessel, for two types of loading: bending and tension. The tests wereperformed at temperature near reference temperature T0 determinedaccording to Master Curve concept, in the brittle-ductile transition region.Specimens contained deep or shallow cracks. Values of two fractureparameters J and Q were determined. Due to different characters of stressfields found for the two types of loading, the Q-stress parameter wasexamined in dependence on values of normalized distance r J 0 ƒÐ . Differentvalues of the normalized distance were examined, 2, 4, 6, 8 and 10. Basedon a reasonable criterion, the J-Q locus for WWER 440 RPV steel wassuggested, open for further discussion.