الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
This thesis is concerned with the studyin~ and investi~ation of the thermal and mechanical behaviour
of PWR fuel rod under LOCA conditions due to its relative importance to the area of PWR safety. The
study is performed throu~hout two
safety system
analysis computer codes; the thermal-hydraulic system
I code DRUFAN and fuel rod behaviour safety system code
SSYST. The LOBI-MOD2 test facility (JRC-Ispra. and behaviour ( ” KfK~ fuel rod
experiment ”REBEKA Germany) are used’ for asessment of the codes predictions.
The code ’DRUFAN’ system has been pplied perform LOCAs analysis at various break sizes. small,
intermediate and lar~e breaks: 1%.3%.5%.10%.25% and100%
at the cold le~ for LOBI-MOD2 test facility. The experimental Data of 1.% af 1.0% cl-break LOCA used to compare between predicitve and experimetal results for code assessment studv. Parameters affectin~ fuel rod
deformation behaviour are investi~ated.
Interactions between thermohydraulics and fuel rod deformation behaviour, coolin~ channel bl~cka~e and coolability of deformed fuel rods are examined. PWR fuel rod behaviour
analvsis usin~ the safety system code SSYST are performed and assessed in view of the experimental data’
of REBEKA ~est facility.
The results showed that. the DRUFAN CODE s~stem predicts most Of the important thermal h~draulic events; s~stem presSure. break and HPI flow rates and clad temperatures in ~ood a~reement with experiment.
However. there were some differences
were which 1nvest1~ated. It was felt Worth-while to compare the
results of both ~X and 3% (ISP- ~8 & BL02-LOBI TestS0 since the study of the differences in the results
lead to a better understsndinc o~ the underlYinc Physical Phenomena. In comparison. the code predicted
~or 3% CL-bresk thst the\uPpermost Psrt the test section is voided for a si~nificant period of the
trsnsient which csuses DNS to occur above the haated occur. The heater rod
temperature in the heated len~th. for both break size’s I do not rise above Satu~at~on temperatures. On the other
hand. the steam cenerators ~or 3% is rather Quickly Voided and decOUPlinlt between primary and seCOndar”
sides is demonstrated in contrast to 1% break where s stron~ COUPlin~ oCCured.
Reverse heat trensfer is
expected and steam ltenerators may act as hest sources and sUperheat the vapOUr in the primar~ side.
When appIYin”’~~intermediate and larce break sizes. the reSults demonstrated too ~ast blowdown rates and
decreasin~ in transient time as the
break size