Shut-down Boric Acid Concentration for Different Fuel Loading Patterns
25th Symposium of AER on VVER Reactor Physics and Reactor Safety (2015, Balatongyörök, Hungary)
Fuel management issues
Abstract
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SHUT?DOWN?BORIC?ACID?CONCENTRATION?
FOR?DIFFERENT?FUEL?LOADING?PATTERNS?
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Martin?B?rta?
CEZ?Inc.,?Dukovany?NPP?
Czech?Republic?
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ABSTRACT?
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The? purpose? of? this? paper ? is? to? show? different? approaches? to? calculations? of? shut?down? boric?
acid? concentration? and? to? show? problems? connected? with?this?type?of?calculation.?Attention ?is?
also? paid? on? subcriticality? calculations? during? the? fuel? rearrangement?in?the?reactor?core.?This?
issue? was? opened? due? to? the? requirement? for? revision? of? the?definition?of?the?shut?down?boric?
acid?concentration?on?the?Dukovany?NPP?in?the?Czech?republic.?
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1.??SHUT?DOWN?BORIC?ACID?CONCENTRATION?
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Correct? calculation? of? the? shut?down? boric? acid? concentration? is? one? of? the? most? important?
safety? calculations? used? on? NPP.? It? allows? to? reach? sufficient? subcriticality? during?the?reactor?
outage.?Since?1985?the?definition?used?on?Dukovany?NPP?is?worded?as?follows:?
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Shutdown? boric? acid? concentration? ?the? critical? H3BO3? concentration? of?the?cold?(20?C),?
is?
un?poisoned? reactor ? with? zero? power? and? with? all? control? rods? fully? extended? from? the ? core,?
incremented?by?1?g/kg.?
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Shutdown? boric? acid? concentration? for? refueling? ?the? shutdown? boric? acid? concentration?
is?
for? the? parameters? of? the? core? after? completed? refueling.? The? minimum? value? is? 12? g/kg?
H? 3?
BO?
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3?
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In? spring? 2015? appeared? the? new? proposal? of? the? prescription? for? the? boric? acid? shutdown?
concentration? calculation? from? the? State? Office.? The?main?difference?is,?that?there?are?specific?
values?of?k?
,?which?have?to?be?reached:?
eff?
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