chemical thermodynamics of neptunium and plutonium - U.S. ...

2.5 Uncertainty estimates 31Table 2.7: Fundamental physical constants. These values have been taken fromCODATA [86COD]. The digits in parentheses are the one-standard-deviation uncertaintyin the last digits of the given value.Quantity Symbol Value Unitsspeed of light in vacuum c 299 792 458 m · s −1permeability of vacuum µ ◦ 4π × 10 −7= 12.566 370 614 ... 10 −7 N · A −2permittivity of vacuum ɛ ◦ 1/µ ◦ c 2= 8.854 187 817 ... 10 −12 C 2 · J −1 · m −1Planck constant h 6.626 0755(40) 10 −34 J · selementary charge e 1.602 177 33(49) 10 −19 CAvogadro constant N A 6.022 1367(36) 10 23 mol −1Faraday constant,F 96 485.309(29) C · mol −1N A × emolar gas constant R 8.314 510(70) J · K −1 · mol −1Boltzmann constant,R/N Ak 1.380 658(12) 10 −23 J · K −1Non-SI units used withSI:electron volt, (e/C) J eV 1.602 177 33(49) 10 −19 Jatomic mass unit,1u = m u =12 1 m(12 C)u 1.660 5402(10) 10 −27 kg2.5 Uncertainty estimatesOne of the principal objectives of the NEA-TDB development effort is to provide anidea of the uncertainties associated with the data selected in the reviews. In general theuncertainties should define the range within which the corresponding data can be reproducedwith a probability of 95%. In many cases, a full statistical treatment is limited orimpossible due to the availability of only one or few data points. Appendix C describesin detail the procedures used for the assignment and treatment of uncertainties, as wellas the propagation of errors and the standard rules for rounding.2.6 The NEA-TDB systemA data base system has been developed at the NEA Data Bank that allows the storageof thermodynamic parameters for individual species as well as for reactions. Thestructure of the data base system allows consistent derivation of thermodynamic datafor individual species from reaction data at standard conditions, as well as internalrecalculations of data at standard conditions. If a selected value is changed, all thedependent values will be recalculated consistently. The maintenance of consistency ofall the selected data, including their uncertainties (cf. Appendix C), is ensured by thesoftware developed for this purpose at the NEA Data Bank. The literature sources of