- Email: [email protected]
Recent status on cobalt-60 gamma ray radiation sources production and its application in China
Redint.
Printed
Chem. Vol. 42, Nos 1-3, in Great Britain
Phys.
pp. 469-471,
1993
0146-5724/93
$6.00
Pergamon
+ 0.00
Press Ltd
RECENT STATUS ON COBALT-60 GAMMA RAY RADIATION SOURCES PRODUCTION AND ITS APPLICATION IN CHINA Cao Zhijian, Song Yunjiang, Zhang Chunhua, Li Maoling Nuclear Power Institute of China, Chengdu 610005, China
ABSTRACT This paperdescribesthe recentstatuson Co-60r ray radiationsourcesproduction and its applicationin China.At present,the production capacityof Co-60y ray radiationscurcesin Chinais about11.1 PBq(O.3MCI) per year,5 yearslater,it can increaseto 37 PBq(1Mci) per year.The standarddimension of Co-60f ray radiationsourcesis 9151190m, the radioactivity of each sources is 37oTBq- 74OTBq(lOfXl-2ooO Ci>. Thereare over 150 Co-60Y ray radiationfacilities with totaldesigncapacityof over 370 PE!q(lO Mci) and practicalcapacityof abcut92.5 P~q(2.5Mci) in operation. The mmber of Co-60Y ray radiationfacilities with practicalcapacityof over 3.7 PBq(O.1Mci) is 14. The main applications of the Co-60Y ray sourcesare radiationcrosslinking application, radiationsterilization of disposable medicalsuppliesand food irradiatim.'ihe prospectof Co-60 Y ray radiationsourcesproduction and its application in Chinais good. KEYWORDS Cobalt,High Flux Engineering Test Reactor&F'ET'R), Radiationfacilities INTRODUCTION The cobalt-60 radiationscurceswith differentspecificactivityand differentspecifications can be producedin China.In China,the High Flux Engineering Test Reactor@XIR) is the highestpoweredreactor(125m> withmximm therm1 nertronfluxof 6.2X1014n/an2.s and nwxinunfast neutronfluxof 1.7K1015n/crnz.s in the fuel(E> 0.625eV),mmg the Engineering Test Reactor,it ranksthirdin the world,afterthe reactorATR, E'IRin USA. Since1980,HFEIRhas been operated safelyfor nmre thanelevenyears.N-w,Nuclearl%werInstitute of China(NPIC) is the main productionbase of Co-60radiationsourcesin China.Chinahas greatabilityto designand construct different kind of Co-60 irradiation facilities. 'lhenunberof the different kind of Co-60irradiationfacilities is over 150 with totaldesigncapacityof over 670 P&O8 Ki) Co-60scurces, the nunberof Co-60irradiation facilities with designcapacityof over 3.7 PBq(O.1MX> Co-60 sourcesis 40. At present,the nunberof Co-60irradiation facilities with practical operation capacityof over 0.1 Mci Co-60sourcesis 14. Since1982,Co-60radiationsourcesof over 74 PF!q (2 Mci) have been producedwith HFEIR,and distributed to different Co-60irradiaticm facilities in China,until now Co-60radiationsourcesof over 7OXused in practical operatedCo-60irradiationfacilities in Chinawere providedby NPIC.Five yearslater,with increasing operationtime and *roving irradiation techniques, the production capacityper year of Co-60radiationsources with HFEIRwill increasefran 10.5PBq(O.3MCI) to 37 PE!q(l Mci). PRODUCTION OF Co-60 RADIATION SOURCES Co-60radiationsourcesis one of the most usefulgams sourcesfor radiation processing. Because its good characteristics: longhalf life(5.27 years),high gammaenergy(l.17 MeV ami 1.33MsV), and greatpenetrability capacityetc. The CO-6Ocanbe prcducedby(n,Y) reactimof the stable metalCo-59in reactorcore.Ihe calculatimfomla of theoretical specificactivityof Co-60 469
CAO ZHIJIAN et al
470
is
as following:
tiere: A is specificactivityof Co-60, IQ/g; No is target nuclide nmber of Co-59 per gram; l.02X1022 /g; Q is thermalneutron capture cross section of Co-59,3.7Xl@23 cm'; C)Jis thermal neutron flux, n/an2.s; t is irradiationtine, s; h is decay constant of Co-60, 4XXY9 /s. The formla (1) shms that the specificactivity A is function of 4and t, and $is the most important factor, besides, in order to increase specificactivityof Co-60 radiation sari--ces the reasonable structureof target assmbly is very important.In general, structureof target mst satisfy safety irradiationin reactor core, and must be advantageousto operationoutside reactor. For exmple, the operationof cut, disassemblyand check, mst be advantageousto increaseoutput of Co-60, thereforespecial target capsule(Fig.1) and target assembly consistingof 10 target capsule (Fig. 2) are designed. Each target capsule contains 185 gram cobalt metal pellets of +lXl, and each target assgnbly contains 1850 gram cobalt metal pellets.aen the target assembly is irradiatedsore than 180 days continuouslyin reactor core with them-alneutron flux of over 2X1014 n/an2.s. The specificactivityof Co-60 obtained is about 3.7 'Eq/g to 5.5 'Rq/g (100 Ci/g - 150 Ci/g).
Fig. 1. The structureof Co-60 sources target capsule 1. spacer 2. Al capsule 3. Co-60 pellets
Fig. 3. lhe structureof Co-60 radiationsources for industryand agriculture. 1. argon arcweld 2. spacer 3. outer capsule 4. inner capsule 5. Co-60 pellets
Fig. 2. The structureof target assanbly consistingof 10 target capsule
8thInternational Meetingon Radiation Processing
471
In orderto ensuresafetyoperation of Co-60radiationsources,the Co-60radiationscurcesproduced in chinaare loadedintodoublestainless steel (lCrl8NisTi) capsuleweldedby plasmaarc or argonarc (Fig.3). In general,the technological processof Co-60radiationscurcesproduction includesfollowing steps:cobalttargetirradiation in nuclearreactor,cut and disassembly of targetassemblyand targetcapsuleaftertargetabssenbly discharged fromreactor,loadingcobalt pelletsintosourcecapsule,sealing,decontamination, safetyperformance testing,leakage testing,contsmination tasting,and activitymeasurerent. lhe safetyperformance of the sources has reachedthe classof E63535.lhe resultsof leakagetesting,and contamination testingof the measurerent is sourcesaccordwith the stardardof ISO1677.The overalluncertainty of activity less than +5% thataccordswith Is0 standard. co-60 RADIATION SOURCES APPLICATION IN CHINA can be proAccordingto variedpurpose,the Co-60radiationsourceswith differentspecification ducedin Chinaas listedin table1. main kind of the Co-60sourcesproducedin China Table1. l'he Item Co-60tele-therapy sources Co-60 r’ radiography sources Co-60sourcesfor afterloadingunits
Specificactivity, Ci/g 70 -120 100 -160 50 -160
Purpose cancertherapy nondestructive inspection therapyof cavitycancer
Co-60instnnnental sources
cn request
exploration ore
Co-60rod sources
anrequest
liquidleveldetection
Co-60radiationsources
30 - 50
radiation processing
for example,simplein technological process, For radiationprocessing thereare many advantages, higherefficiency, and wide application fieldetc. Therefore, easy control,save energyresource, the outputof radiationprocessing is increasing with rate of 204% per year.As one of the main means of radiation processing, in ChinaCo-60irradiation facilities are mainlyused for radiation crosslinking cableand wires,radiationcrosslinking heat shrinkable products(tube,sheet, film),radiation vulcanizing rubber,radiation rrodification of polymers(radiation grafting, polymerization,&gradatjon),research of foodpreservation, radiationsterilization of Chinesemedicinal herbs,radiationsterilization of nxxicaldevices,irradiation of topazand rock crystal,researchof biomedicaletc. In all thesefield,encouraging progresshas beenmade in China. l'heresearches of applications of radiationprocessing in Chinastartedfran 1950's.king 30 years,theyunderwentstartperiod,application researchperiodand industrial application pericd. In recent,the radiation processing is gettingin industrial application period.As a whole, in the radiationprocessing field,chinalagsbehindthe thandevelopedcountries, but it is sure that the prospectof Co-60radiationsourcesproduction and theirapplication are very good inChina. REFERENCE Cao Zhijian,'Tkvelopnent and Production of High SpecificAztivityCobalt-60SealedRadioactive Sources",in: conpilation (1980-1990), (NPIC,Ed.), PP. 366.
Printed
Chem. Vol. 42, Nos 1-3, in Great Britain
Phys.
pp. 469-471,
1993
0146-5724/93
$6.00
Pergamon
+ 0.00
Press Ltd
RECENT STATUS ON COBALT-60 GAMMA RAY RADIATION SOURCES PRODUCTION AND ITS APPLICATION IN CHINA Cao Zhijian, Song Yunjiang, Zhang Chunhua, Li Maoling Nuclear Power Institute of China, Chengdu 610005, China
ABSTRACT This paperdescribesthe recentstatuson Co-60r ray radiationsourcesproduction and its applicationin China.At present,the production capacityof Co-60y ray radiationscurcesin Chinais about11.1 PBq(O.3MCI) per year,5 yearslater,it can increaseto 37 PBq(1Mci) per year.The standarddimension of Co-60f ray radiationsourcesis 9151190m, the radioactivity of each sources is 37oTBq- 74OTBq(lOfXl-2ooO Ci>. Thereare over 150 Co-60Y ray radiationfacilities with totaldesigncapacityof over 370 PE!q(lO Mci) and practicalcapacityof abcut92.5 P~q(2.5Mci) in operation. The mmber of Co-60Y ray radiationfacilities with practicalcapacityof over 3.7 PBq(O.1Mci) is 14. The main applications of the Co-60Y ray sourcesare radiationcrosslinking application, radiationsterilization of disposable medicalsuppliesand food irradiatim.'ihe prospectof Co-60 Y ray radiationsourcesproduction and its application in Chinais good. KEYWORDS Cobalt,High Flux Engineering Test Reactor&F'ET'R), Radiationfacilities INTRODUCTION The cobalt-60 radiationscurceswith differentspecificactivityand differentspecifications can be producedin China.In China,the High Flux Engineering Test Reactor@XIR) is the highestpoweredreactor(125m> withmximm therm1 nertronfluxof 6.2X1014n/an2.s and nwxinunfast neutronfluxof 1.7K1015n/crnz.s in the fuel(E> 0.625eV),mmg the Engineering Test Reactor,it ranksthirdin the world,afterthe reactorATR, E'IRin USA. Since1980,HFEIRhas been operated safelyfor nmre thanelevenyears.N-w,Nuclearl%werInstitute of China(NPIC) is the main productionbase of Co-60radiationsourcesin China.Chinahas greatabilityto designand construct different kind of Co-60 irradiation facilities. 'lhenunberof the different kind of Co-60irradiationfacilities is over 150 with totaldesigncapacityof over 670 P&O8 Ki) Co-60scurces, the nunberof Co-60irradiation facilities with designcapacityof over 3.7 PBq(O.1MX> Co-60 sourcesis 40. At present,the nunberof Co-60irradiation facilities with practical operation capacityof over 0.1 Mci Co-60sourcesis 14. Since1982,Co-60radiationsourcesof over 74 PF!q (2 Mci) have been producedwith HFEIR,and distributed to different Co-60irradiaticm facilities in China,until now Co-60radiationsourcesof over 7OXused in practical operatedCo-60irradiationfacilities in Chinawere providedby NPIC.Five yearslater,with increasing operationtime and *roving irradiation techniques, the production capacityper year of Co-60radiationsources with HFEIRwill increasefran 10.5PBq(O.3MCI) to 37 PE!q(l Mci). PRODUCTION OF Co-60 RADIATION SOURCES Co-60radiationsourcesis one of the most usefulgams sourcesfor radiation processing. Because its good characteristics: longhalf life(5.27 years),high gammaenergy(l.17 MeV ami 1.33MsV), and greatpenetrability capacityetc. The CO-6Ocanbe prcducedby(n,Y) reactimof the stable metalCo-59in reactorcore.Ihe calculatimfomla of theoretical specificactivityof Co-60 469
CAO ZHIJIAN et al
470
is
as following:
tiere: A is specificactivityof Co-60, IQ/g; No is target nuclide nmber of Co-59 per gram; l.02X1022 /g; Q is thermalneutron capture cross section of Co-59,3.7Xl@23 cm'; C)Jis thermal neutron flux, n/an2.s; t is irradiationtine, s; h is decay constant of Co-60, 4XXY9 /s. The formla (1) shms that the specificactivity A is function of 4and t, and $is the most important factor, besides, in order to increase specificactivityof Co-60 radiation sari--ces the reasonable structureof target assmbly is very important.In general, structureof target mst satisfy safety irradiationin reactor core, and must be advantageousto operationoutside reactor. For exmple, the operationof cut, disassemblyand check, mst be advantageousto increaseoutput of Co-60, thereforespecial target capsule(Fig.1) and target assembly consistingof 10 target capsule (Fig. 2) are designed. Each target capsule contains 185 gram cobalt metal pellets of +lXl, and each target assgnbly contains 1850 gram cobalt metal pellets.aen the target assembly is irradiatedsore than 180 days continuouslyin reactor core with them-alneutron flux of over 2X1014 n/an2.s. The specificactivityof Co-60 obtained is about 3.7 'Eq/g to 5.5 'Rq/g (100 Ci/g - 150 Ci/g).
Fig. 1. The structureof Co-60 sources target capsule 1. spacer 2. Al capsule 3. Co-60 pellets
Fig. 3. lhe structureof Co-60 radiationsources for industryand agriculture. 1. argon arcweld 2. spacer 3. outer capsule 4. inner capsule 5. Co-60 pellets
Fig. 2. The structureof target assanbly consistingof 10 target capsule
8thInternational Meetingon Radiation Processing
471
In orderto ensuresafetyoperation of Co-60radiationsources,the Co-60radiationscurcesproduced in chinaare loadedintodoublestainless steel (lCrl8NisTi) capsuleweldedby plasmaarc or argonarc (Fig.3). In general,the technological processof Co-60radiationscurcesproduction includesfollowing steps:cobalttargetirradiation in nuclearreactor,cut and disassembly of targetassemblyand targetcapsuleaftertargetabssenbly discharged fromreactor,loadingcobalt pelletsintosourcecapsule,sealing,decontamination, safetyperformance testing,leakage testing,contsmination tasting,and activitymeasurerent. lhe safetyperformance of the sources has reachedthe classof E63535.lhe resultsof leakagetesting,and contamination testingof the measurerent is sourcesaccordwith the stardardof ISO1677.The overalluncertainty of activity less than +5% thataccordswith Is0 standard. co-60 RADIATION SOURCES APPLICATION IN CHINA can be proAccordingto variedpurpose,the Co-60radiationsourceswith differentspecification ducedin Chinaas listedin table1. main kind of the Co-60sourcesproducedin China Table1. l'he Item Co-60tele-therapy sources Co-60 r’ radiography sources Co-60sourcesfor afterloadingunits
Specificactivity, Ci/g 70 -120 100 -160 50 -160
Purpose cancertherapy nondestructive inspection therapyof cavitycancer
Co-60instnnnental sources
cn request
exploration ore
Co-60rod sources
anrequest
liquidleveldetection
Co-60radiationsources
30 - 50
radiation processing
for example,simplein technological process, For radiationprocessing thereare many advantages, higherefficiency, and wide application fieldetc. Therefore, easy control,save energyresource, the outputof radiationprocessing is increasing with rate of 204% per year.As one of the main means of radiation processing, in ChinaCo-60irradiation facilities are mainlyused for radiation crosslinking cableand wires,radiationcrosslinking heat shrinkable products(tube,sheet, film),radiation vulcanizing rubber,radiation rrodification of polymers(radiation grafting, polymerization,&gradatjon),research of foodpreservation, radiationsterilization of Chinesemedicinal herbs,radiationsterilization of nxxicaldevices,irradiation of topazand rock crystal,researchof biomedicaletc. In all thesefield,encouraging progresshas beenmade in China. l'heresearches of applications of radiationprocessing in Chinastartedfran 1950's.king 30 years,theyunderwentstartperiod,application researchperiodand industrial application pericd. In recent,the radiation processing is gettingin industrial application period.As a whole, in the radiationprocessing field,chinalagsbehindthe thandevelopedcountries, but it is sure that the prospectof Co-60radiationsourcesproduction and theirapplication are very good inChina. REFERENCE Cao Zhijian,'Tkvelopnent and Production of High SpecificAztivityCobalt-60SealedRadioactive Sources",in: conpilation (1980-1990), (NPIC,Ed.), PP. 366.