AEC research and development reports. NBL-238. Analysis of reactor fuel element solutions: pt. 1, Separations and preparation of samples for mass spectrometry and alpha spectrometry [with list of references, by] C. E. Pletrl and A. W. Wenzel; pt. 2, Mass spectrometric determination of uranium and plutonlum concentration and isotopic composition [with list of references, by] L. J. Jasper, jr., and H. O. Finley; pt 3, Alpha spectrometric determination of plutonium-238, [by] L. C. Nelson, jr.