CSNI2100: CABRI-REPNa-1 TEST, Assessment of fuel behaviour mechanisms relevant for RIA transients

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CSNI2100 CABRI-REPNA-1 TEST. (Abstract last modified 02-MAR-2006)

CABRI-REPNa-1 TEST, Assessment of fuel behaviour mechanisms relevant for RIA transients

Abstract Table of Contents:

1. NAME OR DESIGNATION - CABRI-REPNa1 test.

2. COMPUTER FOR WHICH PROGRAM IS DESIGNED AND OTHER MACHINE VERSION PACKAGES AVAILABLE -

To request or retrieve programs click on the one of the active versions below. A password and special authorization is required.

Explanation of the status codes.

Program-name Package-ID Status CABRI-REPNA-1 TEST CSNI2100/01 Arrived

Machines used: Package-ID Orig.Computer Test Computer CSNI2100/01

3. DESCRIPTION OF TEST FACILITY -
The CABRI REP Na test data provide a very consistent basis for the assessment of fuel behaviour mechanisms relevant for RIA transients. For the CABRI REP Na rods that did not fail, valuable information on fission gas release and especially on cladding deformation have been generated in the test programme. REP Na cladding strain data have been used as a start point for deriving an admittedly simple RIA failure criterion. This is based on a maximum strain which can be tolerated by the cladding, i.e. failure can occur only when this strain level is exceeded.
- For cladding that still retains ductility, failure at high burn-up (50-60 MWd/kg) is predicted beyond a 1% (permanent) diameter strain.
- For cladding that has been embrittled due to e.g. large corrosion, spalling and hydriding, a zero ductility is assumed, i.e. the failure threshold is at onset (0%) of permanent strain.

The conditions under which the ductility decreases from 1% to zero are provisionally set in the paper, taking into account the evidence from the CABRI tests and from ANL laboratory tests. Based on the above, one derives that the lowest failure limit at 60 MWd/kg is ~65-70 cal/g, which applies to heavily corroded/hydrided fuel, i.e. for oxide thickness of ~80 mm and in presence of oxide spalling. For corrosion resistant fuel, i.e. for oxide thickness well below 80 mm and in absence of spalling, the failure threshold at the same burnup is ~100 cal/g.

This failure criterion predicts well three of the four failed REP Na tests, but not the REP Na-1 test. For this, the predicted failure threshold is 63 cal/g, whereas the reported experimental value is 30 cal/g. For CABRI unfailed rods, the predicted failure limit is very close to the enthalpy achieved during the test. When used at its higher degree of conservatism (i.e. ductility = 0), the proposed failure threshold predicts reasonably well also the failed NSRR PWR and BWR rods. In general, more data at prototypical conditions are needed in order to arrive to comprehensive, best-estimate failure predictions. The PIE data of unfailed REP Na rods show a remarkable similarity between the trend exhibited by the cladding strain and by the fission gas release. This is briefly discussed in this paper with regard to a possible FGR mechanism (i.e. it is implied that the gas may mostly be released upon cooling, when cladding constraints are reduced). In any case, it appears that FGR as such has little to do with the mechanism of failure when this occurs at low enthalpy.

For more detailed information visit
http://www.nea.fr/html/dbprog/cabrirepna/CABRI-REPNa.htm  and
http://www.nea.fr/html/dbprog/ccvm/csni-rest.html

4. DESCRIPTION OF TEST -
The objective of this test is the behaviour of a pin subject to a rapid energy injection. Such a transient is related in case of a reactor to the ejection of a control rod bank.

The tested pin was refabricated by the FABRICE process from an EdF pin irradiated during 5 cycles in the Gravelines reactor (mean burn-up of 50 GWd/t leading to average burnup of 65 GWd/t in the section of the refabricated pin). The power transient, initiated from a 100 kW power plateau, led to a maximum energy release into the pin of 110 cal/g, which is compatible with the CABRI reactor possibilities.

A clad rupture was detected, confirmed by the non-destructive post-irradiation examinations, which show three rupture regions along the whole pin. The hodoscope has not detected any movement of fuel during the power transient, but the comparison between the initial and final state shows a small deficit of fuel between 220 and 330 mm BCF corresponding to one of the rupture areas evidenced by the non-destructive examinations.

5. EXPERIMENTAL LIMITATIONS OR SHORTCOMINGS -

6. PHENOMENA TESTED -

7. SPECIAL FEATURES OF EXPERIMENT -

8. COUNTERPART EXPERIMENTS -

9. STATUS
CSNI2100/01: 02-MAR-2006 Masterfiled restricted

10. REFERENCES -
A RIA Failure Criterion based on Cladding Strain by C. Vitanza
OECD Halden Reactor Project
Paper presented at the IAEA Technical Committee Meeting on Fuel Behaviour under Transient and LOCA Conditions
CSNI2100/01:
- M.C. Anselmet, C. Hee, J. Furlan, F. Arreghini and M. Balourdet:
- Rapport de l'Essai CABRI REP Na1.
Note Technique LERES no. 10/94 (1994) (in French)
- Ch. Marquie and F. Jeury:
- Dating and Localisation of the Clad Failure in the CABRI REPNA 1 TEST
Rapport NT/DRS/PECSA/02-005
- J. Wolff:
Mechanical Energy Releases in CABRI Experiment REPNA1
Communication Interne LERES No.3/95
- REPNa-1 data sheet
- M. Vouillot:
Compte-Rendu de Refabrication du Crayon FABRICE CABRI REP1 (GRA2 - Q02)
Rapport DMT 93/396 9 (in French)
- J.P. Breton:
REP NA1 data (Note Technique SEMAR 95/56)
- J.M. Girard and J.J. Cochaud:
Resultats Experimentaux des Examens non Destructifs relatifs a l'Essai REPNA1
Note Technique LERES no.12/95
- Th. Bredel:
Etuvage CABRI
Rapport DMT 93/585 Revision 0 (in French)
- Th. Bredel:
Dosage de l'Hydrogene CABRI RIA
Rapport DMT 94/214 Revision 0 (in French)
- D. Lespiaux:
Last Examinations performed at the LECA on the REP NA 1 Rod
Note Technique no.95.2018 Ind: 0 (November 1995)
- F. Couvreur and M. Trotabas:
Caracterisations Metallographiques, MEB et Microsonde de deux Echantillons
(cotes 285 mm/bcf et 295 mm/bcf) issus du crayon CABRI REP Na1
Rapport DMT 95/427 / NT LERES 11/96 (in French)
- D. Lespiaux:
Examens Metallographiques sur le Crayon FABRICE issu du Crayon 5 Cycles
GRAV2-Q02, apres Tir "REP Na-1" dans CABRI
Partie II: Examen du Troncon 138-298 mm/bcf
Note Technique no.94/2024 Ind: A (in French)
- P. Menut:
Examens Destructifs sur le Crayon FABRICE issu du Crayon 5 Cycles GRAV2-Q02,
apres Tir "REP Na-1" dans CABRI
Partie I: Recherche d'un Effet Systeme
Note Technique no.94/2015 Ind: A (in French)
- M. Balourdet:
Examens Post Mortem de REP-Na1
Memo SEMAR 94/01 (in French)
- J. Noirot, B. Pasquet, I. Rochas and C. Lemaignan:
Examen au MEB de la Rupture de la Gaine de REPNa1 entre 87,5 et 102,5 mm/bcf
Compte-rendu de travaux CRT no.96-4006 Ind:0 (in French)
- O. Rabouille and L. Belin:
Expertise au MEB de la Rupture de Gaine de l'Aiguille Combustible CABRI REP Na1
Rapport DMT 96/144 (in French)

11. TEST DESIGNATION - REP Na1

12. PROGRAMMING LANGUAGE -CSNI2100/01:

15. ESTABLISHMENT -
Institute de Radioprotection et de Surete Nucleaire
CE Cadarache
13108 St PAUL-LEZ-DURANCE Cedex

16. MATERIAL AVAILABLE -CSNI2100/01:
Data\ data files + software for plotting curves and extracting to other formats
Experimental reports\ Technical notes on the test results (PDF format)
FABRICE\ Technical notes on the tested rod before test
Other reports\ Other technical notes
Post-test examinations\ Technical notes on the post-test examinations
Read Me First.pdf Description of the files

17. CATEGORIES -

- Y. Integral Experiments Data, Databases, Benchmarks

Keywords: FUEL BEHAVIOUR, TRANSIENTS