Project PISA: Phosphorus Influence on Steel Ageing
The integrity of the pressure vessel is vital to the safe operation of a nuclear reactor. It is therefore necessary to monitor or predict the changes in the reactor pressure vessel (RPV) material during operation. Exposure to irradiation (or elevated temperatures) causes the segregation of phosphorus to internal grain boundaries in RPV steels. This, in turn, encourages brittle intergranular failure of the material. The PISA project had the objective of reducing the uncertainties associated with the impact of this failure mechanism on the properties of the RPV, both during service and at the end-of-life.
This report presents the experimental results on the segregation of P and C during irradiation and thermal treatments, and the associated mechanical property changes, generated within PISA. The new data cover a range of bulk P levels, irradiation temperatures and fluences, steel types and product forms. In all cases only modest increases of P level on the grain boundary have been observed in commercial steels. Segregation is higher in pre-strained than in unstrained material. In addition a model for P segregation under irradiation has been developed, and shown to be capable of fitting the experimentally observed changes in P level after irradiation. Significant insight into the development of the microstructure under irradiation has thereby been obtained. Overall, the data and modelling together indicated that relatively small amounts of segregation are likely to occur under most reactor operational conditions in homogeneous commercial steels, and an (unexpectedly) small amount of additional embrittlement likely to derive from this process during reactor service.
ACOSTA IBORRA Beatriz;
ENGLISH Colin;
GILLEMOT Ferenc;
DONALDSON Andrew;
ORTNER Susan;
KIZLER Peter;
BRUMOVSKY Milan;
LANGER Reinhard;
NEONEN Pentti;
BALLESTEROS Antonio;
SEVINI Filippo;
BACON David;
SAILLET Sebastian;
HORVATH Marta;
KYTKA Milos;
2008-08-21
European Commission
JRC46587
1018-5593,
EUR 23450 EN,
https://publications.jrc.ec.europa.eu/repository/handle/JRC46587,
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