Caple AUF900 Manual de usuario descargar pdf (Pagina 205)

203

ENSI Erfahrungs- und Forschungsbericht 2011

netics is strongly dependant, especially at high

temperature, upon the initial oxide layer thickness

and therefore, uncertainties in measured data

(with regards to the pre-oxide layer thickness in

both axial and azimuthal directions) makes it diffi-

cult to fully assess the obtained code results. Fur-

thermore, some cracks were found in the oxide

layer, something that was so far not considered

in the FALCON analyses. These studies are there-

fore planned to be continued in the perspective

of further enhancing the FALCON code predictive

capabilities related to both oxidation kinetics as

well as hydrogen pickup during accidents in gen-

eral and LOCAs in particular.

Fuel behaviour during reactivity-initiated-

accidents

Related to fuel safety criteria for reactivity-ini-

tiated-accidents (RIAs), an OECD/CSNI RIA code

benchmark was initiated during 2011 with the

objective to assess the reliability of fuel behav-

iour codes to reproduce the results of RIA tests

conducted at the IRSN CABRI and JAEA NSRR test

reactors. Within STARS, the objective is to partici-

pate to this benchmark with FALCON coupled to

GRSW-A in order to further address and under-

stand the role of transient gaseous swelling under

RIA conditions. Consequently, a first series of se-

lected CABRI tests were modeled and the analysis

results were presented at a recent meeting of the

OECD-CSNI Work Group for Fuel Safety (WGFS).

In spite of a considerable scatter in the solutions

obtained by the different participants, the PSI re-

sults using FALCON with GRSW-A were found to

yield feasible estimations of FGR, fuel and cladding

temperatures, cladding failure and residual hoop

strain for the CABRI CIP01 case. Indeed, as shown

on the left-hand side of Fig. 10, the predicted axial

profile of the residual cladding hoop strain shows

a rather good agreement with the corresponding

measurement.

On the other hand, the PSI predictions stood apart

from other solutions with respect to the cladding

elongation that occurred during this test. The rea-

son for this was recently found to be an inadequate

restart option in the current FALCON scheme for

base irradiation including fuel refabrication. To

overcome this, an alternative scheme was applied,

resulting in a much better agreement with mea-

surements and showing at the same time, as illus-

trated on the right-hand side of Fig. 10, an impor-

tant impact from the predicted gaseous swelling for

a successful interpretation of the measured data.

Multi-physics and coupling methodologies

One central mission of STARS is to develop multi-

scale and multi-physics computational method-

ologies to improve the reliability of models and

simulations applied for transient/accident safety

evaluations. During 2011, emphasis was given

to multi-physics activities aimed at establishing

numerical coupling schemes between simulation

codes handling different physical domains (e.g.

thermal-hydraulics, neutronics, thermo-mechan-

ics) in order to take into account the relevant

spatial/temporal feedback occurring between the

governing physical phenomena handled by each

stand-alone code.

Figure 10:

Modeling and Analysis

with FALCON coupled to

GRWS-A of CABRI CIP01

Test.

1 2 ... 200 201 202 203 204 205 206 207 208 209 210 ... 303 304

Caple AUF900 Manual de usuario Pagina 205

Comentarios a estos manuales

Caple AUF900 Manual de usuario Pagina 205

Comentarios a estos manuales

Relacionado con productos y manuales para No Caple AUF900