Abstract

Calculated critical and subcritical data for systems of mixed oxides of plutonium and uranium are presented for review and subsequent incorporation into a revision of ANSI/ANS 8.12. The system specifications were prepared in parallel with the ISO standard ISO 11311:2011, involving experience from international mixed oxide fuel fabrication facilities. Data are presented for two mass fractions of plutonium to uranium plus plutonium (at 12.5% and 35%), damp mixed oxide density up to a theoretical density of 11.03 g/cm³ (for the 12.5% mass fraction, ignoring the variation due to plutonium isotopic content) and up to a density of 3.5 g/cm³ (for the 35% mass fraction), three plutonium isotopic mass fractions (100% ²³⁹Pu, 95% ²³⁹Pu with 5% ²⁴⁰Pu, and a reactor grade composition with 20% ²⁴⁰Pu and the balance ²³⁹Pu, ²⁴¹Pu, and ²⁴²Pu), systems at two moderation conditions (water mass fractions at 3% and at optimal conditions) and systems at two water reflector conditions (nominal 2.5 cm and full 30.0 cm). Parameters of interest presented are values of volume (L), infinite cylinder diameter (cm), infinite slab thickness (cm), mass (kg), cylinder linear density (g/cm), and slab areal density (g/cm²). Values are presented at calculated multiplication factors of 1.000, 0.980 and 0.950. Calculations were made by various subject matter experts with various computational programs and cross section libraries. Validation methods were reviewed and discussed herein though data propagated to revision of ANSI/ANS 8.12 will reflect a conservative subcritical margin selected based on expert judgment.

摘要

计算出的钚和铀混合氧化物系统的临界和亚临界数据供审查并随后纳入 ANSI/ANS 8.12 的修订版。系统规范与 ISO 标准 ISO 11311:2011 并行编制，涉及国际混合氧化物燃料制造设施的经验。给出了钚到铀加钚的两种质量分数（分别为 12.5% 和 35%）的数据，混合氧化物密度高达 11.03 g/cm ³的理论密度（对于 12.5% 的质量分数，忽略由于钚同位素含量）和高达 3.5 g/cm ³的密度（对于 35% 质量分数），三种钚同位素质量分数（100% ²³⁹ Pu、95% ²³⁹ Pu 和 5%²⁴⁰ Pu，以及具有 20% ²⁴⁰ Pu 和余量²³⁹ Pu、²⁴¹ Pu 和²⁴² Pu）的反应堆级成分，两种慢化条件（水质量分数为 3% 和最佳条件）的系统和两个水反射器的系统条件（标称 2.5 厘米和全长 30.0 厘米）。感兴趣的参数是体积 (L)、无限圆柱直径 (cm)、无限厚板厚度 (cm)、质量 (kg)、圆柱线密度 (g/cm) 和板面密度 (g/cm ²）。数值以计算出的乘法因子 1.000、0.980 和 0.950 表示。各种主题专家使用各种计算程序和横截面库进行了计算。尽管传播到 ANSI/ANS 8.12 修订版的数据将反映基于专家判断选择的保守的亚临界裕度，但本文对验证方法进行了审查和讨论。