Abstract
An irradiation program DV50 was carried out from 2002 to 2006 in the OSIRIS material testing reactor (CEA-Saclay center) to assess the pressure vessel steel toughness curve for a fast neutron fluence (E > 1 MeV) equivalent to a French 900-MWe PWR lifetime of 50 years. This program allowed the irradiation of 120 specimens out of vessel steel, subdivided in two successive irradiations DV50 n∘1 and DV50 n∘2. To measure the fast neutron fluence (E > 1 MeV) received by specimens after each irradiation, sample holders were equipped with activation foils that were withdrawn at the end of irradiation for activity counting and processing. The fast effective cross-sections used in the dosimeter processing were determined with a specific calculation scheme based on the Monte-Carlo code TRIPOLI-3 (and the nuclear data ENDF/B-VI and IRDF-90). In order to put vessel-steel experiments at the same standard, a new dosimetric interpretation of the DV50 experiment has been performed by using the Monte-Carlo code TRIPOLI-4 and more recent nuclear data (JEFF3.1.1 and IRDF-2002). This paper presents a comparison of previous and recent calculations performed for the DV50 vessel-steel experiment to assess the impact on the dosimetric interpretation.
Highlights
Within the framework of the French NPPs lifetime extension program, an R&D irradiation program DV50 was carried out from 2002 to 2006 in the OSIRIS material testing reactor (CEA-Saclay center) [1] to assess the pressure vessel steel toughness curve for a fast neutron fluence (E >1 MeV) equivalent to a 900-MWe PWR lifetime of 50 years.Material Toughness is governed by the energy absorbed as the crack moves forward
In order to put vessel-steel experiments at the same standard, a new dosimetric interpretation of the DV50 experiment has been performed by using more recent tools and nuclear data:
The final measured fast neutron fluence was the average of the four ones obtained by the 4 types of dosimeters; the difference between measured fast fluences determined by initial and new dosimetric interpretations is less than 3%
Summary
Within the framework of the French NPPs lifetime extension program, an R&D irradiation program DV50 was carried out from 2002 to 2006 in the OSIRIS material testing reactor (CEA-Saclay center) [1] to assess the pressure vessel steel toughness curve for a fast neutron fluence (E >1 MeV) equivalent to a 900-MWe PWR lifetime of 50 years. Material Toughness (resistance to crack growth) is governed by the energy absorbed as the crack moves forward This mechanical property depends on chemical composition, temperature and neutron fluence for a material under irradiation. The nil-ductility temperature (above which a material is ductile and below which it is brittle) increases with the fluence of fast neutrons (E >1 MeV) The dosimetric interpretation initially performed for the DV50 experiment was based on the following tools and nuclear data:. In order to put vessel-steel experiments at the same standard, a new dosimetric interpretation of the DV50 experiment has been performed by using more recent tools and nuclear data:. Results of initial and new interpretations will be compared and discussed
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