ASTM C1233:15(R2021) pdf free download – Standard Practice for Determining Equivalent Boron Contents of Nuclear Materials.
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 moderator) 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 I were selected to represent neutron absorption in water reactors under normal operating conditions. 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 he those given in Test Methods C 96. C698, C76 I 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 (ca) 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’s 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 I 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.
6. Keywords
6.1 boron; neutron absorption; nuclear materials; nuclear poisons.