Technical Basis for Safe Operations with Pu-239 in NMS and S Facilities (F and H Areas)

Technical Report · Thu Mar 18 04:00:00 EST 1999

DOI:https://doi.org/10.2172/4769· OSTI ID:4769

Bronikowski, M G

Plutonium-239 is now being processed in HB-Line and H-Canyon as well as FB-Line and F-Canyon. As part of the effort to upgrade the Authorization Basis for H Area facilities relative to nuclear criticality, a literature review of Pu polymer characteristics was conducted to establish a more quantitative vs. qualitative technical basis for safe operations. The results are also applicable to processing in F Area facilities.The chemistry of Pu polymer formation, precipitation, and depolymerization is complex. Establishing limits on acid concentrations of solutions or changing the valence to Pu(III) or Pu(VI) can prevent plutonium polymer formation in tanks in the B lines and canyons. For Pu(IV) solutions of 7 g/L or less, 0.22 M HNO3 prevents polymer formation at ambient temperature. This concentration should remain the minimum acid limit for the canyons and B lines when processing Pu-239 solutions. If the minimum acid concentration is compromised, the solution may need to be sampled and tested for the presence of polymer. If polymer is not detected, processing may proceed. If polymer is detected, adding HNO3 to a final concentration above 4 M is the safest method for handling the solution. The solution could also be heated to speed up the depolymerization process. Heating with > 4 M HNO3 will depolymerize the solution for further processing.Adsorption of Pu(IV) polymer onto the steel walls of canyon and B line tanks is likely to be 11 mg/cm2, a literature value for unpolished steel. This value will be confirmed by experimental work. Tank-to-tank transfers via steam jets are not expected to produce Pu(IV) polymer unless a larger than normal dilution occurs (e.g., >3 percent) at acidities below 0.4 M.

• Research Organization: Savannah River Site (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC09-96SR18500
• OSTI ID: 4769
• Report Number(s): WSRC-TR-99-00008
• Country of Publication: United States
• Language: English

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