Sen. Joseph R. Biden Jr. (D-Del.) underwent successful surgery to correct an aneurysm on an artery that supplies blood to the right side of the brain, a Walter Reed Army Medical Center spokesman said. The spokesman, Peter Esker, said Biden, 45, was awake, resting comfortably and talking with his family after the operation--his second this year to correct an aneurysm, a ballooning of an artery. The procedure in the 4 1/2-hour operation in which the surgeon pinches the aneurysm with a clip, was similar to the one performed Feb. 12 on Biden’s left side. The clip remains in the patient. Esker said there are no signs of other aneurysms.