8/9/2019 Did Failure To Understand Zirconium Fuel Rod Chemistry Lead to Release of Radiation At Fukushima

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Did Failure to Understand Fuel Rod Chemical Properties Lead to theRelease of Most of the Radiation at Fukushima? ( Version Written 2!2 !" #$ Mark %ell$& '

The NHK World January 29,2015 report "New Findings on Fallout" ontains

re!ar a#le in$or!ation a#out how atte!pts #y Fu ushi!a a identresponders to ool nu lear $uel rods une%pe tedly in reased te!peratures,leading to the release o$ three ti!es the a!ounts o$ radiation that werereleased #y the e%plosions o$ the ontain!ent #uildings&'"ht(tp)**www+&nh &or& p*nh world*english*news*nu learwat h*201501+0&ht!l- Note lin is disrupted#y (&.

/n estigation into why radiation releases pea ed in the wee s a$ter thea ident rather than days a$ter ontain!ent #uilding e%plosions led to studieso$ water- nu lear $uel rod ladding rea tions at ele ated te!peratures& Their

ndings indi ate that heat generated #y the ir oniu! alloy ladding raised$uel pellet te!peratures ausing !ore o$ the olatile and solu#leradioisotopes to #e "#a ed" out o$ the $uel pellets&

Fi ure& 3e$t) Nu lear Fuel 4od ut-away iew showing $uel pellets inir oniu! ladding& enter) 6iagra! showing how radioisotopes an es ape

#rea hed ladding& 4ight) 7hoto o$ se tion o$ #rea hed $uel rod laddingwith $uel pellets& 8our e) Nu lear 4egulatory o!!ission&

lthough he!ists ha e nown that high te!perature water-- !etal rea tionsprodu e a lot o$ heat, the nu lear engineers and operators responsi#le $ordesigning the plant and planning a ident responses appear to ha e #eenta en #y surprise #y so!e o$ the onse:uen es o$ the ir oniu! rea tionswith oolant water under a ident onditions&

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;ir oniu! rea tions with water and stea! at high te!peratures produ ehydrogen gas, ir oniu! o%ides, ir oniu! hydrides, and heat& The

onse:uen es o$ the $or!ation o$ these rea tion produ ts are generally #ad&Hydrogen gas an e%plode and destroy #uildings and e:uip!ent, ashappened at Fu ushi!a& ;ir oniu! o%ides an $or! as hard #rittle oatings

on $uel rod ladding, whi h an ause ladding intended to ontainradioisotopes to lea and #rea & For!ation o$ ir oniu! hydrides an !a e

ladding #rittle, ause o!ponents to "warp" or hange shape, and an storeenergy whi h, when released, an in rease the te!peratures and se erity o$

ir oniu! res and rea tions with e!ergen y oolant water&

The nu lear industry and regulatory agen ies ha e nown o$ the ha ards o$hydrogen e%plosions, ladding e!#rittle!ent, ladding $ailures, and

ir oniu! res $or years& They ha e designed !aterials and syste!s topre ent, !ini!i e, or !itigate these $ailures, !any o$ whi h $ailedspe ta ularly at Fu ushi!a&

The NHK report e%poses an aspe t o$ ladding rea tions that designers,operators, and a ident responders apparently $ailed to anti ipate)te!perature in reases triggered #y a ident responders, apparently leadingto the highest nu lear a ident radiation releases in history&

4esponders were ordered to ta e a tions that !ade the a ident worse,whi h leads to so!e :uestions& Why were the releases une%pe ted< Whydidn=t those dire ting a ident responders now to that their atte!pts to ool

ladding would lead to te!perature in reases that would "#a e o>" !oreradioisotopes< Why was the pu#li put at ris < /$ T?7 @ and regulatorshad nown that they ould o ur, ould e a uations and other !easuresintended to prote t the pu#li #een !ore e>e ti e< What should #e done i$'when. the sa!e situation re urs during a $uture nu lear a ident<

Failures to anti ipate the onse:uen es o$ ir oniu!-water rea tions leads!ore $unda!ental and syste!i te hni al :uestions& For o er a de ade, theA8 N4 has stead$astly resisted orre tion o$ nown ina urate te hni alin$or!ation and re ords on erning properties o$ ir oniu! ladding thatinBuen e he!i al rea ti ity, iting industry sour es whose $o us was on!e hani al properties&

ould responders ha e #een trained to ta e a tions that to ontrol laddingte!peratures so as to #etter ontrol radiation releases< Coron solutions arestored at nu lear plants $or e!ergen y :uen hing o$ nu lear rea tions& rethere he!i als that ould ha e #een added to the oolant that would:uen h or allow ontrol o$ the water- ladding rea tion ti!e-te!perature#eha ior< 8o!e alloys rea t !ore igorously than others& Wereopportunities to !a e ladding that is less rea ti e under a ident onditions

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!issed #y designers<

;ir oniu! alloys are regarded as the #est pra ti al ladding !aterials $orurrent nu lear te hnology& ;ir oniu! alloys are aso used in other sa$ety-riti al ore o!ponents, su h as ontrol rod syste!s& Nu lear operators

apparently $ailed to design sa$ety syste!s that ould withstand the produ tso$ ir oniu! he!i al rea tions& ?%plosions and une%pe ted radiationreleases aused #y he!i al rea tions o$ ir oniu! at Fu ushi!ade!onstrate that the #est was not good enough under real-world a ident

onditions& What should #e done with a te hnology when the "#est" is notgood enough<

Ca ground) Dar Kelly 7h& 6& in he!istry& ?%perien e in ludes) Fuel rodladding analysis #y %-ray di>ra tion& Daterials analysis& ?le tro he!istry&

Water he!istry& Euality ssuran e&