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30/01/15 The fourth ARCHER Newsletter was released on 30 January 2015. Read online here

21/01/15 The second ARCHER EUROCOURSE, hosted by NRG, was held in Petten from 19-20 January 2015. Click here for more info

26/11/14 The third ARCHER Newsletter was released on 26 November 2014. Read online here

28/10/14 The ARCHER final meeting was held on 21-22 Jan 2015 at NRG in Petten (NL).

27/10/14 The High Temperature Reactor (HTR) Conference was held from 27-31 October 2014 in Weihai, Shandong Province, China. Click here for more info

29/03/14 The second Newsletter was released on 28 March 2014. Read online here

Supported by

European Commission

In detail: KüFA testing

The Cold Finger Apparatus (KühlFinger-Apparatur – KüFA) in operation at JRC-ITU is designed to experimentally scrutinise the effects of Depressurization LOss of Forced Circulation (D-LOFC) accident scenarios on irradiated High Temperature Reactor (HTR) fuel pebbles.

During the HFR-EU1/3 KüFA test started on 7 May and ended on 13 June 2014, the releases were significantly higher than the ones performed following the HFR-K6 and the HFR-EU1bis irradiation campaigns. Hence, the entire Ag-110m inventory of the pebble was released and the Cs release increased to about 70 % at the end of the 1800 0C plateau. The release of Kr-85 became significant during this last plateau and amounted to the inventory of about 12.1 coated particles. On the contrary to most of the ITU KüFA tests, during the HFR-EU1/3 test some Eu was also clearly released. The Figure 3 presents the fractional releases for the investigated fission products during the KüFA test.

In order to investigate the coated particles during the PIE campaign, several samples were obtained by carrotage through the diameter of the HFR-EU1/3 sphere, followed by axial cutting into segments. On the contrary to what was seen during the HFR-EU1bis PIE campaign, radial cracks and very little breakouts were observed in the SiC layers of most of the particles which suggests that there was a significant mechanical or chemical deterioration (CO attacks) of the SiC layer through the Küfa heating test. The release to birth (R/B) ratio calculated during the HFR-EU1 irradiation being rather low, no specific SiC deterioration was expected during this phase. The external PyC layers still intact after the KüFA test may certainly explain the gap in Kr-85 and Cs release. Some cracks and delaminations phenomena on particles present at the center of the HFR-EU1/3 pebble are presented in the SEM micrographs Figure 4.