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EPA issues final rule regulating “forever chemicals”
The Environmental Protection Agency announced that it will issue a rule aimed at limiting public exposure to per- and polyfluoroalkyl substances (PFAS). The final rule will designate two widely used PFAS chemicals, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as Superfund.
According to the EPA, both PFOA and PFOS meet the statutory criteria for designation as hazardous substances.
Taro Ueki
Nuclear Science and Engineering | Volume 158 | Number 1 | January 2008 | Pages 15-27
Technical Paper | doi.org/10.13182/NSE08-A2735
Articles are hosted by Taylor and Francis Online.
On-the-fly diagnostics of the number of particles per iteration cycle in iterated-source Monte Carlo computation, which output diagnostic measures for a given spatial resolution of binning cells as iteration cycles progress, have been studied using relative entropy and chi-square distance. A source ratio vector is defined whose components are the ratio of the sources of adjacent iteration cycles at the individual binning cells. This enables one to define a problem-independent reference vector based on the integral equation representation of the static eigenvalue problem of particle multiplication. These vectors are normalized so that they represent discrete probability distribution. The relative entropy of the source ratio vector and the weighted difference between the relative entropy and the chi-square distance of the source ratio vector, all with respect to the reference vector, have been shown to be effective measures of particle population. Numerical examples presented include the initial core of a pressurized water reactor (PWR), the vault of PWR fresh fuel bundles, and the Whitesides' keff-of-the-world problem.