Neptunium Recovery and Purification at Hanford

Abstract

Neptunium is routinely recovered from irradiated fuel elements at Hanford's two main separations plants. Initial development tests were started in the Purex plant in 1958^ then in the Redox plant in 1959, and recently culminated in the installation of new production systems in both plants for improved recoveries. Both recovery flowsheets employ solvent extraction techniques based on the relative extractability of neptunium-VI. The neptunitim is co-extracted with uranium and plutonium in the plants' first extraction cycles and then partitioned and decontajDinated in sepai^te neptunium cycles. Excellent decontamination from fission products is achieved without interfering with mainline uranium and plutonium production. Recovered neptunium is purified by anion exchange and shipped offsite for subsequent irradiation to plutonium-238. Overall separation factors of uranium and fission products from neptunium are greater than 10"i^ and lO-l-^ respectively.

Application of Amberlite Xe-270 resin to purification of neptunium

“…Except as noted in the subsequent discussion, the flowsheet conditions shown in Table I apply equally well, generally, to both resins and differ only slightly from those previously published. [1,2] One important change is the omission of a reducing wash to remove plutonium; adequate decontaminatioh from plutonium is now obtained in the preceding solventextraction cycles.…”

“…Details of the neptunium ion exchange processes and equipment used at these sites have been reported elsewhere. [1][2][3] The strong-base exchangers have generally provided adequate service in recovery and decontamination of neptunium;…”

Chemical and Process Development Branch Annual Report, Fiscal Year 1965

“…[a] Neptunium-237 is needed for research and for the production of plutonium-238 which has become an important heat source in space power units [36]. Neptunium is formed from radioactive capttire of neutrons by uranium as shown by the following reactions:…”

“…The ion-exchange system for final decontamination of the neptunium product, shown on Figure 13, is based on development work performed at Savannah River Laboratory [37,38,40,41,42] and Hanford [36,43,44,45]. This system has been designed but will not be installed until sufficient concentrated neptunium solution has been collected to warrant the installation.…”

Ligand structure and diluent nature in defining improved Am3+ and Cm3+ separation using diglycolamides: a combined solvent extraction and DFT study

“…1 Unlike Am and Cm, Np shows multiple oxidation states, which is commonly exploited for the separation of this long-lived radioactive element. 3,4 Am and Cm, on the other hand, exhibit +3 as the most stable oxidation state with very close ionic radii, 5 which makes their mutual separation most difficult in the back end of the nuclear fuel cycle. 6,7 The strategy for the long-term safe management of these radiotoxic elements is to vitrify and bury them in deep geological repositories in suitable geological host formations so that they can be isolated from the biosphere.…”