Fast Reactors and Accelerator Driven Systems Knowledge Base

Conference Article: SPX significant events and whether it would have happened on EFR

Abstract

In the 13 years since commissioning of the Creys-Malville nuclear power plant, exactly 100 unusual events were recorded on the French and later on the INES scales. The resultant ratio is slightly lower than the French PWR average. This is a noteworthy accomplishment, considering that the plant is a prototype, went through significant design changes, was repeatedly put to test in operating transients and, in addition, holds roughly twice the number of components as a PWR of comparable power. It may be inferred that fast reactors are not more difficult to operate than PWRs, which is also the opinion of most people having taken shifts in both types of reactors. Although Superphenix was labelled a white elephant by public opinion makers, this little known characteristic should remain part of its legacy. In this period 7 events are registered at the level 1 of the French and INES scales, owing either to misconception, material or operational failure. At the level 2 of the scales, 2 events are registered, which is admittedly quite high. The first one was the sodium leakage from and pervasive cracking of the revolving “drum” of the fuel handling line, in retrospect the result of the choice of steel grade not fully compatible with sodium, which questions the designer’s decision making process. The second level 2 event started as a massive air ingress in the primary circuit atmosphere, bringing on a pollution of the sodium up to 15,s ppm of oxygen (although its significance in terms of corrosion was shown to be minimal). Although this event originated from a maintenance mix-up, it revealed a lack in understanding of sodium chemistry and the inadequacy of the instrumentation. The operational feed-back of the Superphenix reactor was thoroughly combed for clues to potential anomalies by a working group comprising representatives of the operator, utility, designer and R&D bodies. All the gathered information (together with experience gained from other FBRs, most notably PFR and Phenix) was then analysed in periodic project reviews validating the European Fast Reactor project, mainly in the areas specific to FBR technology (referring to Superphenix’ second level 2 event, it led to the addition of a gas analyser). That feed-back process, with complementary contributions and mutual checks of designer teams of various backgrounds, allows an optimistic view of EFR’s seaworthiness.

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Reference:

Technical committee meeting on unusual occurrences during LMFR operation. Vienna (Austria) 9-13 Nov 1998

International Atomic Energy Agency, Vienna (Austria)

IAEA-TECDOC--1180, pp:63-102