ASTM C1233-15(R2021) pdf free download

ASTM C1233-15(R2021) pdf free download.Standard Practice for Determining Equivalent Boron Contents of Nuclear Materials
1. Scope
1.1 This standard details a recommended practice for the calculation of the Equivalent Boron Content (EBC) for nuclear materials. The EBC is used to provide a measure of the macroscopic neutron absorption cross section of a nuclear material. EBC factors for the natural elements are determined from their atomic masses and thermal neutron absorption cross sections. This practice is illustrated by using EBC factors that are based on thermal neutron (2200 m/s) absorption cross sections. Other EBC factors may be used depending upon the actual neutron energy spectrum. 1.2 The EBC is a characteristic of a homogeneous material. Characterization of inhomogeneous materials and calculation of neutron multiplication factors require techniques that are beyond the scope of this practice. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Significance and Use
4.1 Use of this standard practice yields an equivalent boron content (EBC) that can be used to characterize the neutron- absorbing properties of a nuclear material. The elements included in the calculation are typically chosen so that the EBC represents either the entire material (for example, for a mod- erator) or the impurities in the material (for example, for a nuclear fuel). This practice is typically used for materials in which thermal neutron absorption is undesirable. The EBC is not intended for use as an input to any neutronic calculation. The EBC factors in Table 1 were selected to represent neutron absorption in water reactors under normal operating condi- tions. It is the responsibility of the user to evaluate their suitability for other purposes.
5. Procedures for EBC Determination
5.1 Agreement shall be reached between the buyer and seller as to which elements shall be analyzed for calculation of their EBC. It is recommended that B, Cd, Dy, Eu, Sm, and Gd be included in this calculation. Analytical methods for such elements shall be those given in Test Methods C696, C698, C761, and C799 as applicable or as otherwise agreed upon between buyer and seller. 5.2 The individual EBC values are calculated using the EBC factors from Table 1 as follows:The EBC factors have been calculated using a value of 764 barns for the neutron absorption cross section (σa) of boron. This value may vary in nature according to the isotopic composition of the elements. If an alternative value is chosen the EBC factors must be recalculated using the chosen value. 5.3 If the concentration of any of the elements used in the calculation is reported as a “less than” value, that value shall be used in calculating the EBC. 5.4 A total EBC value, if required, is determined by the summation of individual EBC values. 5.5 Plutonium and uranium have not been included, as they are fissionable elements. 5.6 Table 1 includes elements that may provide a negligible contribution to the total EBC. In particular, elements with both small concentrations and very small EBC factors (less than 2E-4) will generally provide a negligible contribution to the EBC of the material as a whole. Such elements should be excluded from determinations of the total EBC.