Preliminary implementation of adjoint-weighted tally capability in Solomon solver

Solomonソルバーへの随伴重みタリー機能の予備的実装

Tuya, D.  ; 長家 康展  

Tuya, D.; Nagaya, Yasunobu

A new continuous energy Monte Carlo solver Solomon (Solver of Monte Carlo) is under development at Japan Atomic Energy Agency (JAEA). Solomon features a new model for handling a continuous and random spatial distribution of materials based on the randomized Weierstrass function. This new model is suitable for analyzing criticality characteristics of fuel debris generated in severe nuclear accidents such as Fukushima Daiichi Nuclear Power Station (NPS) accident. Currently there are various development activities on going for Solomon. This work focuses on an implementation of the sensitivity analysis capability because the composition and spatial distribution of fuel debris are uncertain. The implementation is based on an iterated fission probability method, which calculates adjoint-weighted tallies such as kinetic parameters and k-eigenvalue sensitivity coefficients to nuclear data. Currently, the kinetic parameters can be calculated by one of three methods: Non-Overlapping Block (NOB), Multi-Overlapping Blocks (MOB), and Superhistory (SH) methods, while the k-eigenvalue sensitivity coefficients can be calculated via the NOB method. The implemented adjoint-weighted capability was then applied to simple fissile systems to verify the capability. The preliminary verification calculation results showed good agreement with analytic results.