Reaction Rates Measurement across the Pressure Vessel of Chooz-A Pwr by Self-Dosimetry Technique

CHOOZ-A, a French-Belgian power plant was the first PWR in operation in France; it was definitively shut down in 1991. A large feedback program has been realized during the decommissioning. In this framework, several core samples have been machined from the pressure vessel. They have been used for the determination of the attenuation of the cobalt and iron reaction rates inside the steel. The first one follows an exponential(x²) type shape. ⁵⁴Fe reaction rate decreases throughout the vessel according to an exponential law with a coefficient of -0.0165 ±0.0011 mm^-1 (for a coverage factor of 2). The results of a sample located near the inner surface are in agreement with previous measurement and calculation.