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French approach in fuel pin modelling for fast reactors

Abstract

The purpose of this paper is to present the general philosophy on the problem of fuel modelling now prevailing in France after a twelve years period of tremendously increasing knowledge on fuel behavior. When the Rapsodie fuel pin was designed in 1962 , little was known about the behavior of a mixed oxide fuel pin under fast flux ; but a large body of knowledge on UO{sub 2} behavior in thermal reactor was available together with some sparse irradiation results on (U Pu)O{sub 2} in French experimental reactors. The performances assigned to the pin were then rather modest in rating (400 w/cm) and in burnup (30,000 MWd/t). The AISI 316 steel in solution annealed state was chosen as cladding material. The clad itself was supposed to deform by thermal creep due to fission gas pressure (100% release), and was affected consequently by a strain limit criteria. The importance of clad temperature ({approx}650 deg.) was considered only in connection with thermal creep, the possibility of a chemical reaction between mixed oxide and clad being at that time hardly suspected. Rapsodie had only been at full power for a few months when appeared the evidence of stainless steel swelling under a fast  More>>
Authors:
Pascard, R [1] 
  1. CEA-Centre de Fontenay-aux-Roses, Fontenay-aux-Roses (France)
Publication Date:
Dec 01, 1979
Product Type:
Conference
Report Number:
IWGFR-31
Resource Relation:
Conference: IAEA-IWGFR specialists' meeting on theoretical modelling of LMFBR fuel pin behaviour, Fontenay-aux-Roses (France), 28 May - 1 Jun 1979; Other Information: 2 figs; PBD: Dec 1979; Related Information: In: Specialists' meeting on theoretical modelling of LMFBR fuel pin behaviour. Summary report, 183 pages.
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; BURNUP; CALCULATION METHODS; FISSION PRODUCTS; MATHEMATICAL MODELS; NEUTRON FLUX; RAPSODIE REACTOR; REACTOR CORES; STAINLESS STEEL-316; SWELLING; THERMAL EXPANSION
OSTI ID:
20243552
Research Organizations:
International Atomic Energy Agency, International Working Group on Fast Reactors, Vienna (Austria)
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
TRN: XA0200901016317
Availability:
Available from INIS in electronic form
Submitting Site:
INIS
Size:
page(s) 8-10
Announcement Date:

Citation Formats

Pascard, R. French approach in fuel pin modelling for fast reactors. IAEA: N. p., 1979. Web.
Pascard, R. French approach in fuel pin modelling for fast reactors. IAEA.
Pascard, R. 1979. "French approach in fuel pin modelling for fast reactors." IAEA.
@misc{etde_20243552,
title = {French approach in fuel pin modelling for fast reactors}
author = {Pascard, R}
abstractNote = {The purpose of this paper is to present the general philosophy on the problem of fuel modelling now prevailing in France after a twelve years period of tremendously increasing knowledge on fuel behavior. When the Rapsodie fuel pin was designed in 1962 , little was known about the behavior of a mixed oxide fuel pin under fast flux ; but a large body of knowledge on UO{sub 2} behavior in thermal reactor was available together with some sparse irradiation results on (U Pu)O{sub 2} in French experimental reactors. The performances assigned to the pin were then rather modest in rating (400 w/cm) and in burnup (30,000 MWd/t). The AISI 316 steel in solution annealed state was chosen as cladding material. The clad itself was supposed to deform by thermal creep due to fission gas pressure (100% release), and was affected consequently by a strain limit criteria. The importance of clad temperature ({approx}650 deg.) was considered only in connection with thermal creep, the possibility of a chemical reaction between mixed oxide and clad being at that time hardly suspected. Rapsodie had only been at full power for a few months when appeared the evidence of stainless steel swelling under a fast neutrons flux. This swelling was observed on Rapsodie pins as soon as they experienced sufficient neutrons dose, roughly one year later. This entirely new problem came immediately in the front stage (and is still of major importance today), and was at the origin of the change from the Rapsodie to the Fortissimo core in order to accelerate materials testing versus void swelling by multiplying the flux by a factor two. Even with unforeseen swelling, the design of the Rapsodie and later on Fortissimo pin, allowed not only to reach the goal burnup, but to increase it steadily to roughly 100,000 MWd/t. Since then, the French approach in fuel pin design has still retained something of its original simplicity, and technological efficiency, attitude which is justified by the following considerations: many problems concerning fuel pin behaviour which have been encountered when developing LMFBR , have been mostly solved by a judicious extrapolation of the previously obtained experimental results. In order to perform this type of extrapolation, we need, first of all, a correct analysis of the technological key-phenomena (e.g. clad deformation) as a function of the known irradiation parameters, and then the inventory of the other phenomena which may be implied in the above analysis in order to unknot the inter-linkage and cross effects. When no such effect exists, it is of no need for the desired extrapolation general and complex behaviour code. A simple calculation dealing with the few implied parameters is quite sufficient.}
place = {IAEA}
year = {1979}
month = {Dec}
}