## Abstract

At the Kernforschungsanlage Juelich, core physics experiments with core 1 and core 2 of the critical facility for high temperature reactors KAHTER were carried out in 1973. Core 2 corresponds to the THTR initial core in its moderation ratio S = 7500. Selected experimental results on the critical mass, on control rod worths, and reaction rate distributions were used for testing the most important procedures for the THTR core physics design. The zero-dimensional spectrum program MUPO with its cross section library and the and neutron flux calculations in two-dimensional diffusion approximation by CRAM are of central importance. It proved to be important to introduce modifications specific to the KAHTER plant into the standard models. Thus the void effect (void above the pebble bed) was investigated with DOT-2 by transport theory and a correction was introduced for the critical masses calculated by diffusion theory. Another feature already contained in the standard procedure, the increase of the diffusion constants for the hollow spaces between the spheres, results in a correction of 3.8% < delta-k for KAHTER, whereas in the THTR 300 it only amounts to several tenths % delta-k. Critical masses are predicted with accuracies of < 1.5 % or with regard
More>>

## Citation Formats

Hofmann, K., Huebner, A., Brandes, S., and Krings, F.
Test of the core design methods for the THTR 300 with experimental results from the critical facility KAHTER.
NEA: N. p.,
1974.
Web.

Hofmann, K., Huebner, A., Brandes, S., & Krings, F.
Test of the core design methods for the THTR 300 with experimental results from the critical facility KAHTER.
NEA.

Hofmann, K., Huebner, A., Brandes, S., and Krings, F.
1974.
"Test of the core design methods for the THTR 300 with experimental results from the critical facility KAHTER."
NEA.

@misc{etde_1352328,

title = {Test of the core design methods for the THTR 300 with experimental results from the critical facility KAHTER}

author = {Hofmann, K., Huebner, A., Brandes, S., and Krings, F.}

abstractNote = {At the Kernforschungsanlage Juelich, core physics experiments with core 1 and core 2 of the critical facility for high temperature reactors KAHTER were carried out in 1973. Core 2 corresponds to the THTR initial core in its moderation ratio S = 7500. Selected experimental results on the critical mass, on control rod worths, and reaction rate distributions were used for testing the most important procedures for the THTR core physics design. The zero-dimensional spectrum program MUPO with its cross section library and the and neutron flux calculations in two-dimensional diffusion approximation by CRAM are of central importance. It proved to be important to introduce modifications specific to the KAHTER plant into the standard models. Thus the void effect (void above the pebble bed) was investigated with DOT-2 by transport theory and a correction was introduced for the critical masses calculated by diffusion theory. Another feature already contained in the standard procedure, the increase of the diffusion constants for the hollow spaces between the spheres, results in a correction of 3.8% < delta-k for KAHTER, whereas in the THTR 300 it only amounts to several tenths % delta-k. Critical masses are predicted with accuracies of < 1.5 % or with regard to reactivity < 0.65 % delta-k. The calculated values for the radial neutron flux distributions deviate from the measured values in the core area by approximately lo %. In the case of the axial profiles, deviations are observed at the pebble bed surface which can be explained by the upper void, which cannot be satisfactorily represented by the diffusion theory. Control rod worths are predicted quite well, i.e., to within +/- 5%. An exception is the bank of 4 reflector rods, where the applied model of the "grey curtain" is not accurate because of the large distances between rods. The calculated control rod worths for that case were found to be too low, which does, however, not result in a safety problem.}

place = {NEA}

year = {1974}

month = {Oct}

}

title = {Test of the core design methods for the THTR 300 with experimental results from the critical facility KAHTER}

author = {Hofmann, K., Huebner, A., Brandes, S., and Krings, F.}

abstractNote = {At the Kernforschungsanlage Juelich, core physics experiments with core 1 and core 2 of the critical facility for high temperature reactors KAHTER were carried out in 1973. Core 2 corresponds to the THTR initial core in its moderation ratio S = 7500. Selected experimental results on the critical mass, on control rod worths, and reaction rate distributions were used for testing the most important procedures for the THTR core physics design. The zero-dimensional spectrum program MUPO with its cross section library and the and neutron flux calculations in two-dimensional diffusion approximation by CRAM are of central importance. It proved to be important to introduce modifications specific to the KAHTER plant into the standard models. Thus the void effect (void above the pebble bed) was investigated with DOT-2 by transport theory and a correction was introduced for the critical masses calculated by diffusion theory. Another feature already contained in the standard procedure, the increase of the diffusion constants for the hollow spaces between the spheres, results in a correction of 3.8% < delta-k for KAHTER, whereas in the THTR 300 it only amounts to several tenths % delta-k. Critical masses are predicted with accuracies of < 1.5 % or with regard to reactivity < 0.65 % delta-k. The calculated values for the radial neutron flux distributions deviate from the measured values in the core area by approximately lo %. In the case of the axial profiles, deviations are observed at the pebble bed surface which can be explained by the upper void, which cannot be satisfactorily represented by the diffusion theory. Control rod worths are predicted quite well, i.e., to within +/- 5%. An exception is the bank of 4 reflector rods, where the applied model of the "grey curtain" is not accurate because of the large distances between rods. The calculated control rod worths for that case were found to be too low, which does, however, not result in a safety problem.}

place = {NEA}

year = {1974}

month = {Oct}

}