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Development of a method for measuring the MTC by noise analysis and its experimental verification in Ringhals-2

Christophe Demazière (Institutionen för reaktorfysik) ; Imre Pázsit (Institutionen för reaktorfysik)
Nuclear Science and Engineering (0029-5639). Vol. 148 (2004), 1, p. 1-29.
[Artikel, refereegranskad vetenskaplig]

This paper deals with the estimation of the moderator temperature coefficient of reactivity (MTC) by noise analysis. The current noise analysis-based MTC measurement, relying on the cross correlation between the neutron noise measured by a single in-core neutron detector and the local temperature noise given by a single core-exit thermocouple located at the top of the same fuel assembly, or of a neighboring fuel assembly, is not accurate. The MTC is systematically underestimated by a factor of 2 to 5 compared to its design-predicted value. A theoretical study shows that, in case of nonhomogeneous moderator temperature noise, the core-averaged moderator temperature noise should be used for the MTC estimation. The new estimation method can reach up to 3% accuracy as compared with the results of core calculations for the Swedish Ringhals-2 pressurized water reactor (PWR). We show via noise measurements performed at the Ringhals-2 PWR that the moderator temperature noise is actually radially strongly heterogeneous and loosely coupled. The new MTC noise estimator is demonstrated to provide an accurate MTC evaluation, with the core-averaged moderator temperature noise estimated via the use of many radial in-core gamma-thermometers. More important, different forms of weighting functions are suggested to calculate the core-averaged moderator temperature noise. This new MTC noise estimator, which is nonintrusive and free of calibration, can therefore be applied to monitor the MTC throughout the cycle.

Nyckelord: Moderator Temperature Coefficient (MTC), noise analysis, temperature noise (structure of), correlation length, point-kinetics, boron dilution method, core calculations, dynamic reactor transfer function, Gamma-Thermometer (GT)



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Denna post skapades 2006-08-29. Senast ändrad 2015-09-01.
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Institutioner (Chalmers)

Institutionen för reaktorfysik (1960-2005)

Ämnesområden

Energi
Fysik

Chalmers infrastruktur