Available online at ScienceDirect. Physics Procedia 69 (2015 )

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1 Availabl onlin at ScincDirct Physics Procdia 69 (05 ) World Confrnc on Nutron Radiography 5-0 Octobr 04 Exprinc of th Indirct Nutron Radiography Mthod Basd on th X-ray Imaging Plat at CARR Guohai Wi, Songbai Han*, Hongli Wang, Linfng H, Yu Wang, Mimi Wu, Yuntao Liu, Dongfng Chn Nutron Scattring Laboratory, China Institut of Atomic Enrgy, P.O.BOX 75(30), Bijing 043, China Abstract Indirct nutron radiography (INR) xprimnts by X-ray imaging plat wr carrid out at th China Advancd Rsarch Ractor (CARR). Th ky xprimnt paramtrs wr optimizd, spcially th xposur tim of th nutron convrtr and imaging plat. Th optimizd total xposur tim is 37.5 min, it is two-fifths of th tim basd on th film mthod undr th sam xprimntal conditions. Th qualitativ and quantitativ inspctions wr tstd with dummy nuclar ful rods and a watr tmpratur snsor of a motor vhicl. Th spring in th snsor and th dfcts of th dummy ful rod s pllts can b qualitativly dtctd. Th thicknss of th tap at on position on th cladding of th dummy nuclar ful rod was quantitativly calculatd to b 9.57 layrs with th rlativ rror of ±4.3%. 05 Th Authors. Publishd by Elsvir by Elsvir B.V. B.V. This is an opn accss articl undr th CC BY-NC-ND licns ( Slction and pr-rviw undr rsponsibility of Paul Schrrr Institut. Slction and pr-rviw undr rsponsibility of Paul Schrrr Institut Kywords: indirct nutron radiography, IP, non-dstructiv tsting, CARR. Introduction Nutron radiography is a Non-Dstructiv Tsting (NDT) tchniqu that is a complmntary tool to X-ray and gamma radiography (Hardt t al., 996; Wi t al., 0). Th uniqu advantag of nutron radiography is that it can b applid non-dstructivly to tst sampls with high radioactivity, such as irradiatd ful rods from nuclar ractors (Groschl t al., 999; Wi t al., 03). Traditionally, th mtallic nutron convrtr (In or Dy) and X- ray films wr usd in th INR mthod, and qualitativ inspctions such as dfcts of nuclar ful rod pllts and th phnomnon of hydrogn ingrss in th cladding wr carrid out (Wi t al., 0). Rcntly, th quantitativ *HAN Songbai. Tl.: addrss: hansb@cia.ac.cn Th Authors. Publishd by Elsvir B.V. This is an opn accss articl undr th CC BY-NC-ND licns ( Slction and pr-rviw undr rsponsibility of Paul Schrrr Institut doi:0.06/j.phpro

2 Guohai Wi t al. / Physics Procdia 69 ( 05 ) masurmnts of irradiatd nuclar ful rods wr rquird, such as th contnt of hydrogn accumulation in th cladding and th U-35 nrichmnt of th pllt. A comparison of X-ray film and X-ray Imaging Plat (IP) usd as th dtction systm on th st-up of NEUTRA at Paul Schrrr Institut (PSI) wr dscribd in Tabl (Lhmann t al., 003). Th IP was introducd into th INR mthod to rplac th film, for th following advantags (Lhmann t al., 003; Thoms, 999; Yasuda t al., 005; Chankow t al., 00): Much shortr rquird xposur tim compard with traditional mtallic convrtr and X-ray film tchniqu A linar dynamic rang ovr fiv ordrs of magnitud nabls quantification and visualization of signals Radiographs ar digitizd and quantifid using a storag imaging systm Tabl. Proprtis of th X-ray film and th IP usd as th dtction systm for digital nutron imaging purposs (Lhmann t al., 003) Dtction systm X-ray film and transmission light scannr Imaging plats Max. spatial rsolution ( m) Typical xposur tim for suitabl radiograph Dynamic rang Digital format min 0 (non-linar) 8 bit s 0 5 (linar) 6 bit A nw rsarch ractor calld China Advancd Rsarch Ractor (CARR) has bn constructd in China Institut of Atomic Enrgy (CIAE) in Bijing. Th INR mthod basd on X-Ray film and 0.mm-thick Dy foil nutron convrtr has bn studid at CARR with th powr of 0 MW (Wi t al., 04). This papr dscribs th optimizd xposur tim of th INR mthod basd on X-ray IP at CARR, th rsults of qualitativ inspction of a watr tmpratur snsor of a motor vhicl and a dummy nuclar ful rod, and th mthod of quantitativ tsting th thicknss of th tap on th cladding of th dummy nuclar rod.. Optimizing INR xprimntal paramtrs Th INR xprimnt procdurs includ two stps: (a) xposing th nutron convrtr in th nutron bam and (b) contacting th IP with th nutron convrtr tightly (Hardt t al., 996; Wi t al., 0). As a rsult, th ky paramtrs of th INR xprimnt ar th xposur tims. Th INR xprimnts wr carrid out basd on 0.mm-thick Dy foil nutron convrtr and X-ray IP (CR ST- VI, Fuji Film Co. Ltd ), at th nd of Cold Nutron Guid A (CNGA) at CARR, with th ractor s powr of 0MW and th nutron flux of n/cm/s. Th xposur tims wr optimizd according to th xprimntal conditions mntiond abov. Whn th nutron convrtr has bn xposd in th nutron bam for th tim of t, th radioactivity of th convrtr, A(t ), can b givn by (Hardt t al., 996): A( t ) = δnϕ( ) λt whr ϕ is th nutron flux irradiating th nutron convrtr, δ is th convrtr s nutron absorption cross sction, N is th numbr of atoms of th convrtr matrial, λ 0.693/τ, and τ is th half lif of th convrtr matrial. Aftr bing xposd in th nutron bam, th nutron convrtr was transfrrd to xpos th IP for th tim of t. Th radioactivity of th convrtr, A(t ), can b givn by (Hardt t al., 996): A ( t λ t ) = A( t ) () Th xposur that th IP rcivd from th nutron convrtr during t, K, can b givn by (Hardt t al., 996; Zhang, 985): ()

3 60 Guohai Wi t al. / Physics Procdia 69 ( 05 ) t λ t Kr A( t) tdt 0 K = R whr K r is th xposur rat constant of th nutron convrtr matrial, R is th distanc from th convrtr to th IP. Th valu of R is th half-thicknss of th convrtr bcaus th IP and th convrtr wr in tight contact during xposur. Whn th xposur that th IP obtaind from th convrtr is qual to th IP s LOD (Limit of Dtction) xposur, xprssd as K 0, th IP can produc a visibl radiograph. At this tim, th xposur tims t and t ar th minimum valus. Th intgral valu of Eq. (3) can b xprssd as: λt K r λt ( + λt ) K = δnϕ( )[ ] K 0 (4) R λ Eq. (4) can also b xprssd as: λt K 0R λ ( + λt) = (5) λt K δnϕ( ) r Whn th valu of t is /5τ, /0τ, /5τ, /0τ, /8τ, /5τ, /4τ, /3τ and /τ, th valu of t can b calculatd sparatly by th Eq. (5). Whn th total xposur tim of th INR xprimnt (th valu of t plus t ) is th minimum valu, th valus of t and t ar th optimizd xprimntal paramtrs. Th nutron convrtr usd for th study of th INR mthod basd on IP at CARR is 0.mm-thick Dy foil. Th half lif of Dy is.3 hours. Fig. shows th thortical rlationship btwn th total xposur tim and th tim that th convrtr was xposd in th nutron bam. Whn th valu of t is 7.5 min (/8τ ) and th valu of t is 0 min, th total xposur tim achivs th minimum valu of 37.5 min, just two-fifths of th tim (95.5 min) basd on th film mthod undr th sam xprimntal conditions (Wi t al., 04). (3) Fig.. Thortical rlationship btwn th total xposur tim and th tim of th convrtr xposd in th nutron bam.

Guohai Wi t al. / Physics Procdia 69 ( 05 ) 58 64 6 3. INR masurmnts and quantitativ calculation Som INR xprimnts for th qualitativ inspction of spcimns wr carrid out at CARR. Fig.

3 shows th qualitativ tsting of on dummy nuclar ful rod (5cm-long, th matrial of dummy pllts is lad, th matrial of dummy cladding is aluminium ), in which th dfcts of th dummy pllts can b dtctd. Fig.

4 Guohai Wi t al. / Physics Procdia 69 ( 05 ) INR masurmnts and quantitativ calculation Som INR xprimnts for th qualitativ inspction of spcimns wr carrid out at CARR. Fig. shows th qualitativ tsting of th watr tmpratur snsor of a motor vhicl, in which th spring in th snsor can b dtctd. Fig. 3 shows th qualitativ tsting of on dummy nuclar ful rod (5cm-long, th matrial of dummy pllts is lad, th matrial of dummy cladding is aluminium ), in which th dfcts of th dummy pllts can b dtctd. Fig.. Qualitativ tsting th watr tmpratur snsor of a motor vhicl (lft figur is its photo) by th nutron radiograph (right). Th bas matrial of th snsor is coppr (th thrmal nutron attnuation cofficint is 0.94 cm - ) and th spring matrial is stl (th thrmal nutron attnuation cofficint is.5 cm - ), so thrmal nutron pntrats asily through th bas matrial to qualitativly tst th snsor. Fig. 3. Nutron radiograph (top) and th photo (bottom, pllts in th cladding during tsting) of on dummy nuclar ful rod with dfcts indicatd with arrows. On dummy pllt in th middl of th rod missd som matrial at th uppr dg, th othr dummy pllt at th right sid of th rod missd much matrial at th right dg. Hydrogn agglomration in th cladding surfac can limit th stability of th cladding tub considrably. Th quantitativ tsting of th hydrogn contnt in th cladding has bn paid much attntion (Lhmann t al., 003). Th uniqu advantag of using th IP in th INR xprimnt is that mor accurat quantitativ analysis rsults can b achivd for largr linar dynamic rang compard with using films. Th sampl was a dummy nuclar ful rod and its cladding was wrappd with diffrnt layrs of tap to simulat th hydrogn accumulation. Th tap is a kind of BOPP (Biaxially Orintd Polypropyln) adhsiv mmbran and its nutron absorbing ability is much highr than Al cladding. Fig.4 shows th sampl and its nutron radiograph. Th pixl gry scal valus at diffrnt positions wr masurd by Imag-J softwar and indicatd in Fig. 5. Fig.6 shows th schmatic viw of th nutron bam transmission through th dummy nuclar ful rod with taps. Whn th ful rod was xposd in th nutron bam, th transmittd nutron intnsity, I, can b givn by (Hardt t al., 996; Lhmann t al., 003): I = I xp[ ( d + d + d )] (6) 0 p p c c t t

5 6 Guohai Wi t al. / Physics Procdia 69 ( 05 ) whr I 0 is th incoming nutron intnsity, d p is th diamtr of pllts, p is th Pb pllt s nutron macroscopic cross sction, d c is th thicknss of th cladding, c is th Al cladding s nutron macroscopic cross sction, d t is th thicknss of th tap with th unit of on layr, t is th tap s nutron macroscopic cross sction with th corrsponding unit for on layr. Fig. 4. Photo (top) and th nutron radiograph (bottom) of on dummy ful rod simulating hydrogn accumulation on th cladding, in which th layrs of th tap from lft to right at 5 diffrnt positions ar to 0 with th incrmnt of layrs, th thicknss of th tap is 0.05mm and th width is 0mm. Fig. 5. Pixl gry scal valu of th nutron radiograph at diffrnt tap positions, whr from lft to right is position to position 5. Th pixl valu at ach position was takn in xactly th middl. According to th charactristic curv of th CR ST-VI IP (Wbsit of th Fujifilm company, 03), th nutron radiograph s pixl gry scal valu is invrsly proportional to th logarithm valu of th xposur th IP achivd, at som configuration of th radout systm. Th quation of th pixl gry scal valu and th xposur can b xprssd as: ' D = m lg K + l (7) whr D is th pixl gry scal valu of th nutron radiograph, K is th nutron xposur of th IP obtaind ' from th nutron convrtr, K is proportional to th transmittd nutron intnsity and K ' = gi, g, m and l ar cofficints. '

6 Guohai Wi t al. / Physics Procdia 69 ( 05 ) Fig. 6. Modl of th dummy nuclar ful rod simulating th hydrogn accumulation in th cladding (bird viw), and th schmatic viw of th nutron bam transmission through th dummy nuclar ful rod (Lhmann t al., 003). According to Eq. (6) and Eq. (7), th rlationship of th pixl gry scal valu of th nutron radiograph and th incoming nutron intnsity can b xprssd in an quation as : gi0 D = mlg Σ d + mlg ( d + d ) + l mlg (8) t t c c p p In Eq. (8), d t is th thicknss of th tap at diffrnt positions, it is th only variabl and Eq. (8) can also b xprssd as: D = Adt + B (9) 0 whr A= mlg Σt, B= mlg ( c dc + p d p ) + l mlg, A and B ar cofficints. Th calibration curv of thicknss of th tap on th cladding is ncssary for quantitativly masuring th thicknss of th tap unknown at som position. Assuming that th thicknss of th tap from position to position 4 had bn known (Fig.5), th calibration curv could b obtaind by fitting th data with Eq. (9), as shown in Fig.7. Th thicknss of th tap at position 5 assumd unknown can b calculatd by th pixl gry scal valu with this calibration curv. gi Fig. 7. Calibration curv of thicknss of th tap on th cladding, obtaind with wll known thicknss of th tap from position to position 4.

7 64 Guohai Wi t al. / Physics Procdia 69 ( 05 ) Th fittd valu of A is.84 with th rror of ±0.6 and B is -.35 with th rror of ±0.. So, th fittd Eq. (9) can b givn by: D.84d.35 (0) = t Assuming that th thicknss of th tap at position 5 (0 layrs) was unknown, it could b calculatd to b 9.57 by Eq. (0) with th rlativ rror of ±4.3%. By comparison, th rsult calculatd with th radiograph obtaind by film at th sam xprimntal conditions (th sam nutron convrtr, th sam xposur tim) is 9.5 with th rlativ rror of ±7.5% (Wi t al., 04). 4. Summary and conclusion Th INR xprimnts basd on X-ray IP hav bn carrid out at CARR. Th optimizd xprimntal paramtrs hav bn compard, and th total xposur tim basd on IP is two-fifths of that basd on film. A watr tmpratur snsor of a motor vhicl and a dummy nuclar ful rod wr qualitativly inspctd by thir nutron radiographs. Th spring in th snsor and th dfcts of th rod s pllts can b dtctd. Th quantitativ inspction of a dummy nuclar ful rod simulating hydrogn accumulation in th cladding was carrid out. Th thicknss of th tap at on position was calculatd to b 9.57 layrs with th rlativ rror of ±4.3% by th nutron radiograph with th calibration curv of thicknss of th tap on th cladding. Acknowldgmnts This work was supportd by th National Scinc Foundation of China (grant No and ). Rfrncs F. Groschl, P. Schlunigr, A. Hrmann, E. Lhmann, L. Wizl, 999. Nutron radiography of irradiatd ful rod sgmnts at th SINQ: loading, transfr and irradiation concpt. Nuclar Instrumnts and Mthods in Physics Rsarch A 44,pp:5-0. E.H. Lhmann,P. Vontobl,A. Hrmann, 003. Non-dstructiv analysis of nuclar ful by mans of thrmal and cold nutrons. Nuclar Instrumnts and Mthods in Physics Rsarch A 55, M. Thoms, 999. Nutron dtction with imaging plats Part II. Dtctor charactristics. Nuclar Instrumnts and Mthods in Physics Rsarch A, 44, pp: Nars Chankow, Suvit Punnachaiya, Sarinrat Wongl, 00. Nutron radiography using nutron imaging plat. Applid Radiation and Isotops 68, pp: P. Von dr Hardt, H. Rottgr,98. Nutron Radiography Handbook. D. Ridl Publishing Company Holland, pp.-30. Th wbsit of th Fujifilm company [EB/OL] Wi Guohai, Han Songbai, Wang Hongli, Hao Liji, Wu Mimi, H Linfng, Wang Yu, Liu Yuntao, Sun Kai, Zhao Zhixiang, 0. Application of nutron radiography for non-dstructiv tsting nuclar ful lmnts. Nuclar Tchniqus 35, Wi Guohai, Han Songbai, Wang Hongli, Hao Liji, Wu Mimi, H Linfng, Wang Yu, Liu Yuntao, Sun Kai, Chn Dongfng, 03. Dsign of th Tsting St-up for a Nuclar Ful Rod by Nutron Radiography at CARR Physics Procdia 43, Wi Guohai, Han Songbai, Chn Dongfng, Wang Hongli, Hao Liji, Wu Mimi, H Linfng, Wang Yu, Liu Yuntao, Sun Kai, Zhao Zhixiang, 04. Prliminary Study of th Indirct Nutron Radiography Mthod at CARR. Atomic Enrgy Scinc and Tchnology 48, pp0-07. R. Yasuda,M. Matsubayashi,t al.,005. Application of Nutron Imaging Plat and Nutron CT Mthods on Nuclar Fuls and Matrials, IEEE Transactions on Nuclar Scinc, Vol. 5, No., Fbruary 005, pp Zhang Zhonglun, 985. Exposur Rat Constants Basd on Diffrnt Low Enrgy Limit Valus. Acta. Mtrologica. Sinica, 6(4), pp:

Radiation Physics Laboratory - Complementary Exercise Set MeBiom 2016/2017

Radiation Physics Laboratory - Complementary Exercise Set MeBiom 2016/2017 Th following qustions ar to b answrd individually. Usful information such as tabls with dtctor charactristics and graphs with th proprtis of matrials ar availabl in th cours wb sit: http://www.lip.pt/~patricia/fisicadaradiacao.