Initial version of an integrated thermal hydraulics and neutron kinetics 3D code X3D

The Coolant Channel Module CCM — A Basic Element for the Construction of Thermal-Hydraulic Models and Codes

“…Such models and modules can be needed for the simulation of the steady state and transient behaviour of different types of steam generators, of 3D thermal-hydraulic compartments consisting of a number of parallel channels (reactor cores, VVER steam generators etc.). It shows special advantages in view of the determination of the mass flow distribution into different coolant channels after non-symmetric perturbations see (Hoeld, 2004a) or (Jewer et al, 2005), a problem which is far from being solved in many of the newest 3D studies.…”

“…Then this factor can be assumed to be valid for all the other (identical) parallel channels too (See Jewer et al, 2005). For the transient case there arises the question how the validity of both friction factors could be expanded to this situation too.…”

“…Such a special method can be very helpful in describing complex physical systems with eventually inner loops. As an example the simulation of a 3D compartment by parallel channels can be named (Jewer et al, 2005).…”

The Thermal-hydraulic U-tube Steam Generator Model and Code UTSG-3 (Based on the Universally Applicable Coolant Channel Module CCM)

“…Distinguished by corresponding key numbers (KEYBC =1, 2, etc.) it can, for example, be applied for the simulation of the steady state and transient behaviour of different types of steam generators with sometimes very complex primary and secondary loops (vertical U-tube, vertical once-through or horizontal VVER-440 ensembles) but also for the construction of 3D thermal-hydraulic codes which are needed for the simulation of nonsymmetric single-or two-phase flow situations within large NPP (PWR or BWR) cores (Jewer et al, 2005). Special attention is given to the sometimes very complicated mass flow situations in these types.…”

“…', 'reactor scram (at 60 % nom. power) together with turbine trip' (Bencik et al, 1991) and (the nonsymmetric case of) 'a loss of 1 out of 4 main circulation pumps in a multi-loop simulation' (Bencik et al, 1993), • 'coupled thermal-hydraulic and neutron kinetics behavior of a 3D core' (Jewer et al, 2005), The good agreement of the above presented test calculations with respect to similar calculations with earlier versions applied to the same transient cases demonstrates that despite of the continuous improvements of the code UTSG and the incorporation of CCM into UTSG-3 the newest and advanced version has still preserved its validity. Besides the V&V actions for this code combination it has to be noted that an important verification step was based on the fact that UTSG calculations have always been accompanied with strong quality control measures.…”