Earnings rose at BWX Technologies (BWXT), Lynchburg, Va., in the first quarter, which the Department of Energy contractor attributed to opportunities in nuclear manufacturing and the company’s recent acquisition. Net earnings for the first quarter ended March 31 were $91.2 million, or $0.99 a share, up from $75.5 million, or $0.82 a share, in the year-ago quarter. Quarterly revenue was $860.2 million, up year-over-year from $682.3 million, the company reported last week. Quarterly segment operating income for government operations was…