Summary Report on the Up-Scaling of the Retention Properties by Matrix Diffusion in Fractured Rock

Transkriptio

1 Working Repor Sary Repor on he Up-Scaling of he Reenion Properies y Mari iffsion in Fracred Rock Ani Poeri Ferary 009 POSIVA OY Olkiloo FI-760 EURAJOKI FINLAN Tel Fa

2 Working Repor Sary Repor on he Up-Scaling of he Reenion Properies y Mari iffsion in Fracred Rock Ani Poeri VTT Ferary 009 Working Repors conain inforaion on ork in progress or pending copleion. The conclsions and viepoins presened in he repor are hose of ahors and do no necessarily coincide ih hose of Posiva.

3 ABSTRAT Fracred rocks are coposed of poros alos ipereale rock ari and aer condcing fracres. The ain characerisic of he fracred rock is he grea heerogeneiy in differen scales ha leads o preferenial flo pahs and channelling of he flo. Three disinc flo environens can e idenified: channeling ha cases variale flo in he individal fracre planes ransissiviy differences eeen fracres ha leads o preferenial flo pahs and eensive fracre ones ha provide highly ransissive connecions over long disances. Large and ransissive fracres have an iporan role o he flo and ranspor properies of he fracred rock. Flo pahs end o acclae on he large feares ha carry he ajoriy of he flo. Modelling eercises have indicaed persisence of he flo properies along he flo pahs. This eans ha once a paricle has enered a ajor flo pah i ends o follo he high flo rae channel. The ain challenge in spaial p-scaling of he reenion properies is conneced o he descripion of he flo characerisics in he fracred rock. The iporance of individal fracres o he overall reenion is proporional o he flo rae along he fracre. This eans ha silaions need o consider individal fracres. Fracre neork odelling offers a siale approach ha is ale o ake ino accon he liscale srcre of he fracred rock and o deerine reenion properies of he flo pahs. I also provides a sraighforard ay o p-scale ranspor properies along he preferenial flo pahs hrogh he fracre neork. Hoever he copaional feasiiliy of he sie scale applicaions in he perforance assessen liis he range of differen sie fracres ha can e aken ino accon in he fracre neork silaions. Heerogeneiy in he ioile one properies ay inflence effecive reenion properies if he heerogeneiy is copled ih a liied capaciy of he ioile one. Silaions sho ha iporance of he liiaion in he hickness of he ioile one can e esiaed y siply coparing peneraion deph of he pore diffsion in he ioile one o he acal hickness of he ioile one. Applying ypical properies of he liied ri ones arond he aer condcing fracres indicaes ha nder PA flo condiions especially non-soring nclides ill sarae os of he ioile ones in he ri ones. In he PA condiions i is sally ore iporan o ake ino accon heerogeneiy of he flo field han heerogeneiy in he ioile one properies hen he sole reenion is assessed. Heerogeneos flo properies lead o channelling of he flo ha can ake place eeen differen flo roes and inside individal flo pahs. iffsional iing inside an individal flo pah ill average o heerogeneiy of he flo field hereas iing eeen differen flo pahs is possile only in he inersecions of he flo pahs and he sole fl is doinaed y he flo roes of he highes flo rae. Modelling indicaes ha iing along an individal flo pah is qie efficien in he PA condiions. Therefore channelling in he fracre planes is nlikely o e a ajor concern for he PA flo pahs variailiy eeen differen flo pahs needs o e aken ino accon.

4 Yheenveo rakoilleen kiven ariisidiffsiosa aihevan pidäyisen kvaksen sovelaisesa sreassa iakaavassa TIIVISTELMÄ Rakoill kallio odos hokoisesa kallioariisisa ja veä johavisa raoisa. Pohjaveden viras apah käyännössä pääasiasiassa pikin veä johavien rakojen odosaia reiejä. Rakoilleen kallion erkiävipiä piireiä on eri iakaavoissa havaiava heerogeeniss joka johaa viraksen kanavoiiseen. Rakoilleessa kalliossa voidaan nnisaa ainakin kole erilaisa virakseen vaikavaa iliöä: viraksen kanavoiinen yksiäisissä raoissa rakojen vedenjohokykyeroisa johva hallisevien yksiäisen virasreiien odosinen rakoverkosojen läpi sekä yksiäise laaja rakovyöhykkee joka odosava hyvin johavia yheyksiä pikien eäisyyksien yli. Srin haase eri iakaavoissa apahvan pohjaveden viraksen kvaksessa liiyy viraksen kvakseen rakoilleessa väliaineessa. Tällä hekellä ei ole oleassa yleisä eneelää jolla pienen iakaavan virasiliö olisi ahdollisa oaa hoioon loppsijoisilan oiinakykyanalyyseissa arviavissa sren iakaavan alleissa. Kenäkikse ja allinns ova osoianee eä yksiäise hyvin johava hydralise yheyde voiva hallia viras- ja klkeisreiejä pikilläkin eäisyyksillä. Saanaikaisesi seissa iakaavoissa vaikava heerogeeniss on ahdollisa oaa rakoverkkoallinnksen avlla joka saalla arjoaa ahdollisden käsiellä klkeisreiejä kispaikan iakaavassa. Eri skaalojen heerogeenisksia jodaan vielä kienkin karsiaan kispaikan iakaavan rakoverkkoalleisa niiden vaaian sren isinarpeen akia. Liikkaoaan hokosveeen liiyvä heerogeeniss voi vaikaa aineiden pidäyisoinaisksiin jos heerogeeniss liiyy hyvin rajoien hokosvesikapasieeiin. Mallinnksen perseella havaiiin eä rajois hokosvesikerroksen paksdessa lee näkyviin aineiden pidäyisessä klkeisajoilla joka voidaan soraan arvioida diffsiosa hokosvesikerroksessa. Tyypillise oinaisde veäjohavien rakojen ypärillä oleville kallioariisin nneille vyöhykkeille osoiaa eä yypillisissä oiinakykyanalyysin virasoloissa seia kerrokse saroiva klkevalla aineella eriyisesi soroiaoien aineiden apaksessa. Toiinakykyanalyysissä on ärkeäpää oaa hoioon viraskenään liiyvä heerogeeniss kin hokosvesien oinaisksiin liiyvä heerogeeniss. Heerogeeniss viraskenässä johaa viraksen kanavoiiseen sekä eri virasreiien kesken eä yksiäisissä raoissa. Yksiäisellä virasreiillä olekyläärinen diffsion asoiaa kanavoiisen vaiksa. Kanavoiiseen eri reiien välillä olekyläärinen diffsio ei seinkaan pysy kienkaan vaikaaan. Reiien välillä sekoiisa apah reiien leikkaksissa joissa klkeisen kannala hallisee srian viraaan reii. Mallinnksen perseella oiinakykyanalyysin virasoloissa kanavoiisen asoiinen yksiäisellä reiillä on sheellisen ehokasa. Kanavoiinen yksiäisissä raoissa ei sien ole ensisijainen pidäyiseen vaikava prosessi PA virasoloissa a eri virasreieihin liiyvä kanavoiinen on oeava allinnksessa hoioon.

5 PREFAE This ork has een carried o as a par of he Eropean research projec FUNMIG: Fndaenal processes of radionclide igraion.fnig.co. FUNMIG is a for year projec ha ill e carried o eeen years 005 and 008. Paricipaion of he VTT o he FUNMIG projec is joinly fnded y EU and Posiva Oy. The presen repor is an inernal projec delivery PI4.6.7 of he ork package 4.6 ha sarises he ain findings of he VTT s sdies dring corse of he FUNMIG projec. Work package 4.6 covers p-scaling processes of he reenion and ranspor processes in he crysalline rock.

6 TABLE OF ONTENTS ABSTRAT TIIVISTELMÄ PREFAE INTROUTION... TRANSPORT PATHWAYS IMMOBILE ZONE PROPERTIES Assyeric properies of ari Liied hickness of he ioile one oparison of he odelling resls ih laoraory es HANNELING hanneling cased y geological aerial oncepal odel Maheaical odel Model verificaion Asypoic ehavior Enhanceen of he WL/Q de o channeling Velociy variaion oncepal odel alclaed cases Resls SUMMARY AN PA RELEVANE Spaial p-scaling Up-scaling of he flo condiions... 3 PUBLIATIONS URING THE PROJET REFERENES... 34

7 INTROUTION

8 3 TRANSPORT PATHWAYS Figre -. oncepal illsraion of he hydralic feares of he fracred rock in differen scales fro Marek e al. 003.

9 4 Figre -. Illsraion of he heerogeneiy in he fracred rock fro Winerg e al. 00.

10 5 3 IMMOBILE ZONE PROPERTIES 3. Assyeric properies of ari Figre 3-. onrol vole sed o calclae ass echange eeen fracre and ioile ones. 0 0 e e f f v

11 6 0 e f f v R R v R p p p p e e f f a c c f 0 c c f R R v s R p p p p e e f f a s f s f s f s f 0 0 f f 0 0 ep 0 f v f v v s R s e e a f 0 H c s c / 0 0 M 0 v W M 0 0

12 7 3. Liied hickness of he ioile one a p ~ R R L / p 3.3 oparison of he odelling resls ih laoraory es

13 8 Tale 3-. iension of he ceraic fracre coln and paraeers of he racer es as given in Hölä e al. 99. iensions Radionclides Noinal flo rae of he pp /in Flo channel: HTO + 36 l 6 Lengh 0.45 HTO + 36 l 8 Widh Aperre 0-5 Ioile one: Porosiy 30% eph HTO + 36 l HTO + 36 l HTO + 36 l HTO + 99 Tc 4 Voleric flo rae in he coln /in Residence ie in fracre in

14 9 Tale 3-. Fied odel paraeers for he racer ess ih 36 l. iensions Flo channel: Lengh 0.5 Widh Aperre 0-5 Ioile one: Porosiy 3% eph Noinal flo rae of he pp /in Voleric flo rae in he coln /in Effecive diffsion coefficien in ari 0-0 /s Added advecive delay h Figre 3-. Modeled reakhrogh crves resls for all es ih 36 l.

15 0 Figre 3-3. Silaed and easred 36 l reakhrogh crves for differen flo raes along he flo channel. Modelled reakhrogh crves are presened for he liied ioile one solid crve and for an infinie ioile one dashed line.

16 4 HANNELING 4. hanneling cased y geological aerial 4.. oncepal odel Figre 4-. The syse ha is sdied is coposed of a flo channel and sagnan one in he fracre plane ne o he ioile pore space in he rock ari.

17 4.. Maheaical odel d d f g / ep / ep / ep / f 3/ ep Q WL W Q L s s ep 3/ d g

18 3 ep / 3 f s W s s s L L W s so ha 0 and Model verificaion L L 4

19 4 Figre 4-. Rando alk silaions dos and analyical solion of he racer reakhrogh for diffsion fro flo channel o rock ari le and o sagnan ones red.

20 5 Figre 4-3. Breakhrogh crve for sole ranspor hrogh a flo channel ha is srronded y a sagnan one in he fracre plane and rock ari. Sole paricles can diffse o he rock ari direcly fro he flo channel and hrogh he sagnan one. Resls for rando alk silaion dos and nerical evalaion of eqaion sho raher good agreeen Asypoic ehavior

21 6 W / Ls 0.05

22 7 Figre 4-4. Tailing of he reakhrogh follos ~ -5/4 in he case of an infinie sagnan one in he fracre plane and an infinie rock ari. Ble crve is inegraed nerically sing eqaion 4 and red line indicaes ~ -5/4.

23 8 Figre 4-5. For a liied sagnan one in he fracre plane he reak-hrogh crve ill have he ~ -3/ ehavior in he very lae reak-hrogh ies. Ble crve is calclaed for a liied sagnan one and green crve for an nliied sagnan one. Red line indicaes he ~ -3/ ehavior and ligh le line he ~ -5/4 ehavior Enhanceen of he WL/Q de o channeling 3 3

24 9 / 3 Figre 4-6. Esiaion of he reakhrogh sing only he peak ie of he eqaion.

25 0 s / / Ls s L W L / W s / s / s / / / s / s L L

26 L ~ / R p p Figre 4-7. Break-hrogh crves for o differen cases ih liied hickness of sagnan aer / Ls 0.5 or. 0. Solid crves represen nerical inegraion of eqaion 4 for liied sagnan one. ashed lines represen approiaions of he reak-hrogh crves y assing coplee iing over he flo channel and sagnan one in he fracre.

27 Figre 4-8. Break-hrogh crves in case of hick liied sagnan one in fracre plane. Solid lines indicae nerically inegraed eqaion 5 reak-hrogh crves for o differen hicknesses of he sagnan ones. ashed-doed line is an approiae reak-hrogh crve ha is calclaed y increasing WL/Q ased on he peak ie of he ari diffsion o an infinie sagnan one. ashed line is an approiae reak-hrogh crve ased on asspion of effecive reenion layer of in he sagnan one and alloing coplee iing of he sole concenraion eeen he reenion layer of he sagnan one and flo channel. 4. Velociy variaion 4.. oncepal odel

28 3 Figre 4-9. Waer residence ie disriions sed in his sdy. WL / Q / pr p WL / Q p R p /

29 4 0 3 / ep d k W L ; 0 3/ 0 ep 5 5 ;5 d 5 0 ;5 d 0

30 5 Figre 4-0. laive inegral of he eigh fncion in eqaion as fncion for a fied =5 his eans 4.. alclaed cases 5 ;5 d / ;5 d Resls a j 3/ ep

31 6 a ep 3/ j d j j d / 3 / / a / e j peak

32 7 Figre 4-. Break-hrogh crves for advecion-ari diffsion in case he aer residence ie disriion is narro _a / _in = and he srengh of he ari diffsion varies. Break-hrogh crves are presened in a diensionless for iho advecive delay. Gray crve represens analyical solion for a ell ied flo channel eqaion 4.

33 8 Figre 4-. Break-hrogh crves in log-log scale for advecion-ari diffsion in case he aer residence ie disriion is narro _a / _in = and he srengh of he ari diffsion varies. Break-hrogh crves are presened in a diensionless for iho advecive delay. Gray crve represens analyical solion for a ell ied flo channel eqaion 4. Figre 4-3. Break-hrogh crves for differen flo rae disriions hrogh he flo channel corresponding aer ravel ie disriions are presened in Figre 4-9. Reenion y he ari diffsion doinaes all cases =00 in eqaion. Breakhrogh crves are presened in a diensionless for iho advecive delay. Gray crve represens he analyical solion for a ell ied flo channel eqaion 4. Silaions indicae ha large flo rae egin o doinae he reak-hrogh crve hen he spread in differen flo raes is large enogh.

34 9 Figre 4-4. Break-hrogh crves in log-log scale for differen flo rae disriions hrogh he flo channel corresponding aer ravel ie disriions are presened in Figre 4-9. Reenion y he ari diffsion doinaes all cases =00 in eqaion. Break-hrogh crves are presened in a diensionless for iho advecive delay. Gray crve represens he analyical solion for a ell ied flo channel eqaion 4. Silaions indicae ha large flo rae egin o doinae he reak-hrogh crve hen he spread in differen flo raes is large enogh. Silaions indicae ha a ide flo rae disriion changes he reak-hrogh crve so ha he peak is ore governed y he large flo raes. This eans ha he peak ie oves earlier and he level of he ai release rae increases. ependence of he peak level on he variailiy in flo raes is shon in Figre 4-6. The dependence of he ai release rae on he idh of he flo rae disriion is no as srong as for he ie of he peak. Proaly ecase he reak-hrogh crve in any case spreads over a longer period of ie e.g. he genle par of ailing of he red crve in Figre 4-4

35 30 Figre 4-5. Tie of he peak discharge shon for differen flo rae disriions. Spread of he flo raes is in he -ais and raio of he peak ies for he acal flo rae disriion W RT and for he average flo rae ave is on he y-ais. Figre 4-6. Level of peak discharge for differen flo rae disriions. Spread of he flo raes is in he -ais and raio of he peak ies for he acal flo rae disriion peak W RT and for he average flo rae peak ave is on he y-ais.

36 3 5 SUMMARY AN PA RELEVANE 5. Spaial p-scaling 5. Up-scaling of he flo condiions

37 3 L p / Rp

38 33 PUBLIATIONS URING THE PROJET Kekäläinen P. Poeri A. and Tionen J.. Effec of finie peneraion deph in an advecion-diffsion syse. In preparaion. Poeri A. Spaial Up-scaling of he Reenion y Mari iffsion. Posiva Oy. Posiva Working Repor Poeri A. Inflence of flo channeliaion on ari diffsion in fracred rock. A paper sied o he proceedings of he FUNMIG 3rd annal eeing.

39 34 REFERENES Marek M. Jako A. and Bossar P Sole ranspor in crysalline rocks a Äspö I: Geological asis and odel caliraion Jornal of onainan Hydrology Winerg A. Andersson P. Poeri A. vekovic V. ershoi W. oe T. Heranson J. Góes-Hernánde J. Haojärvi A. Billa. Tllorg E-L. Holon. Meier P. and Medina A. 00. Final Repor of he TRUE Block Scale Projec. 4. Synhesis of flo ranspor and reenion in he Block Scale. SKB Technical Repor TR 0-6. Hölä P. Haojärvi A. and Hakanen M. 99. Transpor and reardaion of nonsoring radionclides in crysalline rock fracres. Radiochiica Aca 58/ Kekäläinen P. Poeri A. and Tionen J.. Effec of finie peneraion deph in an advecion-diffsion syse. In preparaion. Poeri A. Spaial Up-scaling of he Reenion y Mari iffsion. Posiva Oy. Posiva Working Repor