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PRLlMENARY STU!)¥, OF NEUTRON DIFFUSION PARAMETERS IN WATER FOR TWO DIIFERENT VOID - f~-~=-:-::-= - :::--~- ~ ---, :"-- ~,. "-'- - :- FRAcTIONS - --,~~'. -~ .::.-- • \
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' " -ICriticatsystems based on fission reactiOi1S- require"e~n- ' -1+-L'"""'B", .. ltally determined diffusion parametelS to design optimum i}lel ' . lIattice structure and conlrol cells. These parametelS include The Diffusion area (1.') and Fermi-age(» appear in above ~age, Diffusion area, and Migrntion area A numbe r, of equation as part of non-leakage factolS. Here, Kro is infmit'l , ,;studies ' !ReL..L.L~] have been conducted to measUre multiplication factor for a system having zero leakage; The B . - ,diffUSion length~age in moderato IS 'including waier, is BUCkling incm ' , ;graphi~ and Be. However, these studies were limited: to 2.1 FERMI -AGE (» {measurements in pure moderatOIs without voids. ; :Local voids are created in ;he reacior coolant and moderator According 10 slowing-down theory, Fermi age is@ore-sixth the average of square of the crow flight distance from the point :when it undergoes a power or a fl ow-rale perturbation. The 'p resence of voids deform the moderation and slowing-down where the neutronentelS a system with ze~ age to a poiJ,lbyhere propenies of the system, It then affects the criticality o[ the it acquire the age 'C, Many studies@used this definition to h reactor. Thus, from reactor safety point of view, it is imponant e' pcrimentally determine the Fermi-age for moderato rs [Ref. 3 & 4]. In this work a simple approach based on relative neutron to know how (both quantitatively as well as qualitatively) the 'f lux measurements have been used , .1 n this ,approach only , 'd iffusion parameters are affecled as the voids are created in the neutron flu.x measurements along one-dimension is employed 'coolanl or moderator to calculate the Fermi-age using one-group neutron diffusion The dominant effect in water-moderated reactolS is the reactivmodel. ity changes arising 'from the creation of voids if local boiling Consider a plane source, emitting Sf neutrons per em::! per ","~urs: Ii@usually in the form o[ a decrement in moderation second next to a semi-infmite homoge neous medium. The aue 'to a decrease in moderator number 'of atorr.s per cmJ It further causes an increase in lhe rescnance abs-0-4 : 75iE·O'" 6.3lE+-04 $.31E·Q-4 J.9SE·o.t
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