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ECN publication
Neutron metrology in the HFR: MINiaturized cOmpact tenSion SpEcimens irradiation R301-03 (MINOSSE-3)
Published by: Publication date:
ECN NUC 1-2-1999
ECN report number: Document type:
ECN-I--98-023 Other
Number of pages: Full text:
34 Download PDF  

Within the framework of the European Fusion Technology Programme and theInternational Thermonuclear Experimental Reactor (ITER), NRG Petten is investigating the irradiation behaviour of structural materials for ITER. The irradiation of twenty out of thirty reduced size CT-specimens (thickness 2.5 mm) all loaded in specimen holder R301-03 (MINOSSE-3), in the HFR Petten, is part of this programme. The remaining ten CT-specimens in this specimen holder were irradiated as part of a NRG programme concerning the investigation of radiation effects on austenitic stainless steel pressure vessel (PV) cladding materials. The CT-specimens were manufactured from four types of austenitic stainless steel alloys. The R301-03 assembly was irradiated in channel 3 and 2 of two different TRIO type facilities for two HFR operation cycles, subsequently in the core-positions G7 and C3, up to a target dose level of 1 dpa (displacements per atom) in stainless steel at a nominal target temperature of 325 deg C. This report presents the final metrology results obtained from activation monitor sets placed inside the specimen holder, including the thermal and fast neutron fluences, displacements per atom and the generated helium content. Additionally detailed information concerning an estimation of the fluence and damage doses received by each specimen and its temperature during irradiation are presented. The main results of the thermal and fast neutron fluence measurements, indicate that the obtained damage levels in the steel specimens loaded in this specimen holder vary from 0.56 and 0.99 dpa. For relatively short irradiations, like this one, the He generation in stainless steel alloys depends rather strongly on the B-content present in this type of materials. For the specimens manufactured from the A-MA steel alloy finally He-production data are not presented in the tables 5a and 5b, because the B-weight percentage was not analysed for this material. The importance of the B-content for the He generation is also accentuated by the He data for the ERHII-TIGDEP steel alloy (6.9-10.3 appm) compared with those for the 308L and ERHII alloys (25.4-31.1 appm). The reason of this substantial difference is caused by the fact that the B-concentration in ERHII-TIGDEP exceeds the concentration of this element in both the 308L and ERHII alloys by a factor of three. A valuable statement about the precise operation temperature of each specimen separately during irradiation is rather arbitrary, because the irradiation was performed in two very different core-positions. Due to this fact the general temperature history of the specimens can be separated into two phases, i.e. 240-270 deg C during the first HFR-cycle (G7) and 310-360 deg C for the last irradiation step (C3). Detailed data are presented in the tables 3, 4 and 5, as well as in figure 2.16 refs.

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