# Temperature field in gas-cooled reactor core in transient conditions under different principles of mass flow profiling

9/30/2019 2019 - #03 Physics and technology of nuclear reactors

https://doi.org/10.26583/npe.2019.3.05

### UDC: 621.039.51

Positive effect of profiling the gas-cooled reactor core within the framework of the GT-MHR project was investigated in [1 – 3]. The necessity arises to supplement already implemented analysis of equilibrium conditions of core operation with investigation of effects of profiling on the temperature field in transient modes of reactor core operation.

The present paper is dedicated to the investigation of development of transients in gas-cooled nuclear reactor core subject to the implementation of different principles of core profiling.

Investigation of transients in reactor core represents complex problem solution of which by conducting direct measurements is beyond the reach of the authors. Besides the above, numerical simulation based on advanced CFD software complexes [4 – 10] is also fairly demanding in terms of required computer resources.

The algorithm for calculating temperature fields using the model where the reactor core is represented as the solid medium with gas voids and the assumption is made that heat transfer due to molecular heat conductivity can be described by thermal conductivity equation written for continuous medium with thermal physics parameters equivalent to respective parameters of porous object was developed by the authors in order to get the possibility of obtaining prompt solutions of this type of problems.

Computer code for calculating temperature field in gas-cooled reactor in transient operation modes was developed based on the developed algorithm. Proprietary computation code was verified by comparing the results of numerous calculations with CFD modeling of respective transients in the object imitating the core of gas-cooled nuclear reactor. The advantage of the developed computer code is the possibility of variation of real-time evolution of conditions in complex configurations of gas-cooled reactor cores with different channel diameters. This allows using the computer code in the calculations of transients in loops of reactor facility as a whole, in particular in developing simulators.

Results are provided of calculations of transients for reactor core imitating the core of gas-cooled nuclear reactor of GT-MHR project performed for different approaches to profiling coolant mass flow. Results of calculations unambiguously indicate the significant difference of temperature regimes during transients in the reactor core with and without profiling and undeniable enhancement of reliability of nuclear reactor [11 – 13] with profiling of coolant mass flow in the reactor core as a whole.

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reactor core profiling transient conditions temperature field porous body thermal conductivity equation heat sink