Bhaskar, You are correct that 1 TU = 3.2 pCi/L, not the other way around. Sorry for the misinformation. I'll go a little slower before I hit the reply button next time. - Tim ***************************************************************** Timothy P. Rose Analytical and Nuclear Chemistry Division, L-231 Lawrence Livermore National Laboratory Livermore, CA 94550 Phone: 925-422-6611 Fax: 925-422-3160 email: [log in to unmask] *****************************************************************