APPENDIX A CHEMICAL AND RADIOCHEMICAL PROCEDURES A.1 DETECMINATION OF OXIDATION STATES OF NEPTUNIUM The procedures employed in determining the oxidation states of Np are given below. 1. To the sample in a 100-ml beaker add concentrated HCl dropwise while warming gently; keep volume as small as possible. 2. If solid material remains undissolved, centrifuge, retain supernatant, and add additional HCl to precipitate, boil, centrifuge; add supernatant to that already obtained and discard precipitate. 3. Measure total volume of sample in graduate cylinder for activity assay. Take an aliquot for gamma spectrum and decay. 4. 5. 6. Evaporate solution to 6N-HCl. Dilute solution to 2N-HCl and transfer to a separatory funnel. Add approximately 20 cc of 0.4 M TTA in benzene to the solution and stir vigorously for 30 min. 7. Separate the phases. Wash the benzene phase containing Np IV with 5 co 8N-HCl ( saturated with TTA) for 10 min and then discard the benzene. 8, Treat the 8N-HCl which now contains the Np IV by the procedure given below starting with step 9, Also treat the aqueous phase contain- ing Np V and Np VI starting with step 9. 9. Add several drops of 30 per cent H,0, and 10 cc concentrated HCl keeping the volume as small es possible, 10. Boil the solution to destroy the H,0, to bring the HCl concen- tration to 6N and to reduce volume. 11. Dilute the solution to 2N and transfer to a 125-cc separatory funnel, 12. Add 20 ml of 0.4 M TTA in benzene to the solution and atir vigorously for 30 min. 13. Separate the phases, The benzene phase contains Zr, Pa, and a amall amount of Np. Wash this with 5 ml of 8N-HCl (saturated with TTA) for 10 min and discard the benzene phase, The 8N-HCl which now contains the Np is retained for later use, 14. The aqueous phase from the extraction contains all of the other substances including the greater fraction of the Np. Add 2 al of formic 135