Corrosion Behavior of Developmental Iron Phosphate Waste Forms: FY20 Status Report

Program Document · Wed Oct 28 04:00:00 EDT 2020

OSTI ID:1755930

Stariha, S. A.; Ebert, W. L.

Corrosion tests were performed to assess the dissolution behaviors of developmental iron phosphate materials that are being evaluated as an alternative to the glass-bonded sodalite ceramic waste form to immobilize salt wastes from electrochemical separation operations. Production of the iron phosphate waste form results in dehalogenation of the waste salt that increases potential waste loading. Ferric oxide is added to the waste form to increase the chemical durability. Tests conducted to optimize the amount of ferric oxide used to make the waste form are summarized in this report. Specimens prepared from materials made with between 17 and 34 mole % ferric oxide were subjected to two test methods to assess the effects of the iron content on the relative durability and retention of immobilized salt cations including cesium, strontium, and neodymium. Modified ASTM C1308 test results show the intrinsic durability was significantly higher for materials made with 27 mol % ferric oxide. Further additions generated iron-rich inclusion phases and did not improve durability. Modified ASTM C1285 test results show that solution feedback attenuates the dissolution rate similar to what is observed for borosilicate glasses within seven days. Analyses of test specimens after 42 days show no evidence that surface layers formed. Combined with previous studies addressing the salt loading, a composition region of the ammonium (di)hydrogen phosphate-waste salt-ferric oxide ternary has been defined for durable waste form compositions. Materials with that composition can be used to determine optimal processing conditions, assess long-term performance, and parameterize a degradation model.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE Office of Nuclear Energy - Nuclear Technology Research and Development Program
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1755930
• Report Number(s): ANL/CFCT-20/34; 164259
• Country of Publication: United States
• Language: English