A joint program between Babcock & Wilcox (B&W) and the Central Electricity Generating Board (CEGB) was undertaken to develop a three-point bend procedure for generating J₁-R curves from irradiated and unirradiated Charpy specimens.

Precracked Charpy specimens provided by the CEGB were tested to verify similarity of room temperature single and multiple specimen tests. Close agreement between critical J values and tearing moduli was found. Several single specimen tests were carried out at temperatures between 20C and 350C to verify elevated temperature test performance. Upper shelf behavior was observed in all these tests. Measured crack lengths were usually within .125 mm of calculated crack lengths.

J₁-R curves generated from precracked Charpy specimens were compared with J₁-R curves of 1T and 0.5T compact fracture specimens. Results were similar provided that side-grooving depths of the Charpy specimens did not exceed 10% of specimen thickness.