Neutron noise measurements on pressurized water reactors

Noise analysis contributes to increase significantly understanding of safety and monitoring of PWR. The difficulties of a correct interpretation of noise signal in a power reactor encourage a deeper insight into the theoretical model. Following, this paper is dealing with 4 topics:

• - theoretical model

• - measurements made in PWR's, and evolution of power spectral densities,

• - experimental test of models,

• - future study in this range : methodology for early detection of failure and to indicate incipient failure.

Using the expressions for linear system and for feedback loop, we obtain a simplified diagram for PWR with reactivity, temperature, velocity of fluid inputs and movement of internal structures.

Neutron noise measurements are performed periodically on the “Centrale Nucléaire des Ardennes”. An investigation is also performed, in order to detect core barrel movements.

The change of neutron noise at several power levels is shown, and used to check the model.

The development of signal analysis and models for PWR is investigated in the last chapter.     

Pouvons-nous diminuer ou prevenir 1'apparition des reactions de stress post-traumatiques? Analyse critique de 1'efficacite du debriefing.

The goal of this article is to analyze the efficacy of debriefing techniques to prevent psychological consequences following traumatic events. The type of traumatic incident, the method, the model of debriefing, the types of measures, and the results of the interventions are examined in the analysis of fifteen studies. Even though, victims in general appreciate debriefing, results from controlled studies seem to indicate that debriefing does not reduce or prevent post-traumatic stress reactions. Implications of these findings and hints for future interventions and research are discussed. It seems of great importance to promote more complete interventions that take into account the different characteristics of the traumatic events and the specific needs of the victims. (PsycINFO Database Record (c) 2010 APA, all rights reserved)