High-Temperature Studies of Glass Dissolution Rates Close to Saturation

Zavarin, M ; Roberts, S ; Zhao, P ; Williams, R ; Rose, T ; Rainer, A ; Pawloski, G

Lawrence Livermore National Laboratory

关键词: Saturation;    Source Terms;    38 Radiation Chemistry, Radiochemistry, And Nuclear Chemistry;    Dissolution;    Radioisotopes;   

DOI  :  10.2172/15014327
RP-ID  :  UCRL-TR-204874
RP-ID  :  W-7405-ENG-48
RP-ID  :  15014327

美国|英语

来源: UNT Digital Library

【 摘 要 】

Most long-lived radionuclides associated with an underground nuclear test are incorporated into a melt glass and are released by glass dissolution to become part of the hydrologic source term (HST) (Pawloski et al., 2001). Although the rates of rhyolite glass dissolution are well known under conditions where the fluid is far from saturation with respect to glass, the rates are not well known under conditions where the fluid approaches saturation. These rates are commonly much lower than the far-fromsaturation rates, often by a factor greater than 100. In recent HST simulations (Pawloski et al., 2001; Pawloski et al., 2000; Tompson et al., 1999), we conservatively estimated steady-state release rates based on a far-from-saturation fluid conditions. In recent CHESHIRE near-field simulations (Pawloski et al., 2001), it was predicted that {approx}30% of the nuclear melt glass dissolved over 1000 years. Although the ''far-from-saturation rate'' approach provides a conservative estimate of glass dissolution, it may greatly overestimate the rates of melt glass dissolution. At CHESHIRE, less conservative estimates suggest that only {approx}1% of the nuclear melt glass will dissolve in 1000 years. Lower glass dissolution rates result in lower radionuclide release rates from nuclear melt glass. The following report documents glass dissolution experiments performed to measure glass dissolution rates close to saturation.