NAA ko method
The Paper presented at The International Graduate on Engineering and Science (IGCES'08) UTM, Malaysia
Published on: Mar 3, 2016
Transcripts - NAA ko method
Proceedings of the International Graduate on Engineering and Science (IGCES08)Fundamental Science 23 - 24 December © 2008 IGCES Technical development of Instrumental Neutron Activation Analysis (INAA) based on ko method at The National Nuclear Agency of Indonesia Nursama Heru Apriantoro*, Sutisna£, Ahmad Termizi Ramli* £ The National Nuclear Energy Agency of Indonesia (BATAN), Serpong, Tangerang, Indonesia. * Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia ABSTRACT Key word : ko INAA, bi-isotopic, tripe bare method Quantitative multi-element determination using 1. Introduction Instrumental Neutron Activation Analysis (INAA) technique based on ko method was implemented As a multi-element analytical technique, neutron experimentally in INAA laboratory. Parameters activation analysis based on relative method has of canal irradiation and counting geometry were been applied widely in many studied and determinated in the experiment. The activities,,,. This method has relative f parameter was obtained by bi-isotropic good accuracy, especially for trace elemental method, while for parameter by bare triple analysis. However, this technique hardly monitor technique. The determination of P/T and depends on the availability of comparator which reference position was taken in primary and is usually in the form of standard primer secondary application. The validation of ko was solution, and also requires a long time for conducted using SRM/CRM based on SNI 2000- preparation and data analysis . These are the 17025. Efficiency curve characteristic for main constraint, especially for analyzing detector was found to be in-line with HPGe numbers of samples. detector characteristic. Canal irradiation characteristic of RS01 to RS04 facility yielded to Various experiments have been done to increase thermal neutron flux average and fast neutron the effectiveness and efficiency of this method, around 1.33 x 1017 nm-2 s-1 and 2.20 x 1016 nm-2 one of which was with single comparator or s-1 respectively, while for f and parameter was automatization system. Recently, a method with 41.9 and 0.02 respectively. Validation result of special concern from various NAA laboratories precision test, accuracy test and reputability is the use of composite nuclear constant ko for linearity obtained with standard reference elements quantity calculation ,. The materials and certificate reference material is members of Forum of Nuclear Cooperation in presented. Elements of Al, As, Br, Co, Cl, Cu, Asia (FNCA), at annual meeting in Bangkok, Fe, I, K, Na, Rb, Sc, U and Zn were suitable for Thailand have agreed to apply INAA based on ko precision test, while the materials for accuracy method as standard procedure in NAA laboratory test were As, Ag, Br, Co, Cl, Fe, I, K, Na, Rb, Sb, . The same attention was also given by IAEA Sc, Se, U and Zn. Thus, as a conclusion, the ko with the releasing of ko-IAEA software to method offer better identification ability than the calculate quantity of elements in any samples comparability method. The technique of ko-INAA based on ko method . nuclear was successfully implemented in The National Nuclear Energy Agency of Indonesia Several publications show that usage of the ko (BATAN). This technique increases the Neutron constant, which is then called ko-INAA method, Activation Analysis ability for quantitative can increase ability of INAA laboratory support determination of elements in various materials system, by eliminating the usage of chemicals by eliminating the dependency of standard for comparator without a long preparation time. materials usage as well as the improvement of This method also has high selectivity and analysis time efficiency. sensitivity if combined with reliable -spectrum
Proceedings of the International Graduate on Engineering and Science (IGCES08)Fundamental Science 23 - 24 December © 2008 IGCES analysis, with relative good accuracy and Some important parameters that have to be precision compared to comparability method . determined experimentally accurately are the Thus, this method could be used in trace efficiency of counting geometry and the elements analysis because of its high accuracy characteristic of irradiation canal, as well as the and precision. software capability for -spectrum peak fitting. Quantitative element determination based on ko In the ko-INAA method, in contrast to method was calculated using equation proposed comparability method, the parameters of reactor by Frans de Corte  ; canal, counting geometry, efficiency detector and peak-to-total ratio should be accurately determined before running the analysis. Two important parameters, f and are determined (1) experimentally, for those are dependent on reactor type and irradiation facility. The f parameter is determined by bi-isotopic method using 94Z(n, )95Zr and 96Zr(n, )97Zr. On the other Thus, the p, f and parameters would depend hand the triple bare monitor method based on at on the condition of irradiation canal and the 95 Zr , 97Zr and 198Au was used to determine detector used. parameter, as presented by De Coerte . 2.1 Detector efficiency This research studied the usage of ko method of INAA, for environmental monitoring study, Detection efficiency p, was determined at health and industry application. The study coincidence- free reference position, usually at a included the determination of reactor parameter, distance more than 10 times detector diameter stipulating of reference position, calculation of from detector surface. To calculate correction geometry efficiency, validation to SNI-17025- factor caused by "summing out" true-coincidence 2000, and applying of ko method for pre- effect, the total detection efficiency parameter, t, elementary study. was obtained from conversion of P/T ratio toward peak efficiency, p, according to equation 2. Methods (2). Determination of f and canal irradiation parameters was obtained by bi-isotopic and triple (2) bare method using isotopes of 95Zr, 97Zr and 198 Au as result of reaction (n, ). The efficiency of counting geometry in the reference was determined using a number of standard sources. 2.2 Canal irradiation of rabbit facility Total efficiency was calculated through characteristic geometry efficiency conversion and peak-to-total ratio using secondary standard. Zr and Au Different from comparability method, the ko- irradiation for determination of flux, f and INAA method was largely based on the value of parameters was done at all irradiation canals in f and for every position of irradiation canal. At rabbit facility P2TRR (RSO1 to RS04). For this experiment, f and parameters was quantitative element determination in standard determined by triple bar method and bi-isotopic material, each sample and comparator (Al-0.1% technique as recommended by de Corte and Au) were irradiated simultaneously for ten times. Blaauw . The average results were then calculated using weighted mean. The f parameter determination with bi-isotopic technique used reaction of 94Zr(n, )95Zr and According to IAEA method and SNI-17025- 96 2000, SRMCRM of sea biota and sediments Zr(n, )97Zr from the foil target of Zr (Nilaco, were used to validate the method. The validation 99.98%). Furthermore f value was calculated included the tests for precision, accuracy, using equation: detection limit, repeatability and linearity.
Proceedings of the International Graduate on Engineering and Science (IGCES08)Fundamental Science 23 - 24 December © 2008 IGCES (3) 2.4 Detection Limit Table 1 shows detection limit of elements measurement in standard material. Detection limit is determined based on formula from Currie by the equation: Meanwhile, the a parameter was determined by triple-bar-method technique not only with previous reaction but also with 197Au(n, )198Au, (8) then a value was calculated using equation (4). where NB is background count, m is number of (4) channels selected before and after peak, and n is number of channels below the peak. or qo, a and b parameter was calculated using equation (5) – (7), respectively: As many as 19 elements could be selectively identified within detection limit value based on (5) sample type that was analyzed. (6) 2.5 Validation Method (7) Based on SNI 17205-200, some examination criteria must be fulfilled for validation of nonstandard method, that are the precision test, accuracy test, linearity, repeatability, detection limit and reproducibility. For this purposes, the IAEA examination method was held. 2.3 Element quantification in SRM sediment and sea biota For elemental identification, standard samples was used that are SRM NIST 1566b Oyster Tissue for 22 elements identification, CRM NIES No.9 Sargasso for 22 elements identifications and CRM NMIJ 7302a Sediment for 18 elements identifications. Not all detected elements could be validated, due to uncompleted validation requisites. The detected elements for SRM NIST 1566b were Ag, Al, Ace, Cl, Co, Cu, Fe, Na, Se, U and Zn, while for CRM NIES No. 9 Sargasso were Ag, Al, Ace, Br, Co, Fe, I, K, Na, Rb, Sc, U, and Zn. For CRM NMIJ 7302a limited sediment of elements As, Co, Fe, Mn, Rb, Sb and Zn were detected.
Proceedings of the International Graduate on Engineering and Science (IGCES08)Fundamental Science 23 - 24 December © 2008 IGCES Table 2. Detection limit of ko INAA measurements for standard elements using fluks neutron thermal 3.9 x 1013 n cm-2 s-1, iradiation time 2 h, time decay 2 – 3 weeks, and counting time 0.5- 2 hours. Standard samples SRM NIST 1566b CRM NIST CRM NMIJ 7302a Elements Unit Oyster Tissue No.9 Sargasso Sediments Na mg kg-1 50.91 622 16,850 Co mg kg-1 0.48 0.25 0.3 Zn mg kg-1 14.56 7.58 11.38 As mg kg-1 0.86 4.73 35.08 Se mg kg-1 4.1 1.73 6.18 Ag mg kg-1 1.8 1.83 0.91 U mg kg-1 0.25 1.85 12.6 Fe mg kg-1 216 164 259 Br mg kg-1 0.53 2.02 10.74 Rb mg kg-1 17.48 12.27 20.47 Sb mg kg-1 0.15 0.42 0.51 Sc mg kg-1 0.02 0.01 0.02 Zr mg kg-1 151.4 202.7 520.6 Cd mg kg-1 8.43 25.34 69.81 La mg kg-1 0.13 0.55 1.99 Ce mg kg-1 1.78 2.35 2.8 Au mg kg-1 0.003 0.02 0.04 Hg mg kg-1 0.97 0.97 6.54 Th mg kg-1 0.38 1.85 0.35 2.6 Precision test where Ns and Na are values from the certificate and measurement result, respectively, Us and Ua Precision test was conducted based on IAEA expressed uncertainty for 95 % (2 ) confidence standard formula, by using F1 and F2 indicators level, H is Howitzh constant ( H = 0.02. c0.8495), defined as: and c is recommended concentration from the certificate. Based on this criteria, analysis results is acceptable if F1 value is lower than F2. (9) 2.7 Accuracy test The accuracy test was conducted based on IAEA standard procedure, as well as the precision test. (10) At this examination the F3 and F4 parameters are defined as follows:
Proceedings of the International Graduate on Engineering and Science (IGCES08)Fundamental Science 23 - 24 December © 2008 IGCES (11) recommended has average accuracy of 78.47% except Ag (12.90%). CRM NMIJ 7302a sediment, all element recommended has average accuracy of 85.22% except Mn (70.44%). (12) The precision test result for elements recommended to 3 standard materials in test as shown in table 4. From 11 elements evaluated at SRM NIST 1566b Oyster Tissue that is Ag, Al, As, Cl, Co, Cu, Fe, Na, Se, U and Zn, three All the test results are acceptable if F3 value is elements (Ag, Co and Se) were rejected as they smaller than F4. failed the precision test. In the case of CRM NIES NO. 9 Sargasso, from 13 evaluated elements, two 2 elements were rejected (Co and Ag). The majority of elements have been 2.8 Linearity evaluated and fitted with precision test standard. In case of CRM NMIJ 7302a sediments, only As one of validation criteria, linearity test was one element (Sb) was rejected from precision observed on representative elements i.e. Cr, Br, test. Sc, Fe, As and Zn. Number of measurement varied from 4 to 7 point of observation. Linear regression values R2 were in the range of 0.81 – 0.96 for evaluated elemen 3 RESULTS AND DISCCUSION Table 2 shows irradiation canal characteristic in all position, including th, fast , f and for RS01 to RS04 canals. These data indicates that the averages of thermal neutron flux and fast neutron are 1.33 x1017 nm-2 s-1 and 2.20 x1016 nm-2 s-1 respectively, while for f and are 41.9 and 0.02 respectively. Table 2 shows irradiation canal characteristic in all position, including th, fast , f and for RS01 to RS04 canals Canal fth ffast f a (n m-2 s-1) (n m-2 s-1) RS01 1.33 x 1017 1.07 x 1016 41.6 0.02 RS02 9.75 x 1016 9.31 x 1015 40.6 0.02 RS03 1.62 x 1017 4.68 x 1016 41.61 0.02 RS04 1.39 x 1017 2.29 x 1016 43.95 0.02 The analysis result of elements recommended by SRM NIST 1566b Oyster Tissue, CRM NIES 9 SARGASO and CRM NMIJ 7302a sediment, respectively shown in Tables 3. For SRM NIST 1566b Oyster Tissue, all element recommended has average accuracy more than 79.36% except Cu (32.82%), Al (56.85%) and Co (56.76%). For CRM NIES 9 SARGASO, all element
Proceedings of the International Graduate on Engineering and Science (IGCES08)Fundamental Science 23 - 24 December © 2008 IGCES Table 4 Precision test of elements measurement in standard samples Standard sample Element Precision Test SRM NIST 1566b Oyster Tissue F1 F2 F1 < F2 Conclusion Ag 8.6 1.6 No rejected Al 3.5 241.6 Yes accepted As 9 11.5 Yes accepted Cl 4.4 2801.5 Yes accepted Co 4.6 1.2 No rejected Cu 7.5 116.5 Yes accepted Fe 5.3 201.3 Yes accepted Na 2.8 1810 Yes accepted Se 8.7 3.3 No rejected U 198.8 392.2 Yes accepted Zn 3.3 957.9 Yes accepted CRM NIST No.9 Sargasso Ag 16.4 1.5 No rejected Al 7.3 400.4 Yes accepted As 8.2 105.4 Yes accepted Br 6.1 218.6 Yes accepted Co 8.9 0.9 No rejected Fe 5.3 167.1 Yes accepted K 11.1 2,183.80 Yes accepted l 5 118.7 Yes accepted Na 5 6,356.60 Yes accepted Rb 9.1 26.3 Yes accepted Sc 333.3 1,111.10 Yes accepted U 158.8 250 Yes accepted Zn 8.4 18.7 Yes accepted CRM NMIJ 7302a Sediments Na 1.7 6,838.60 Yes accepted Co 13 15.7 Yes accepted Zn 4.9 309.7 Yes accepted As 9.6 23.7 Yes accepted Sb 8.8 2.3 No rejected Rb 11.9 70.4 Yes accepted Fe 1 17.665.7 Yes accepted Mn 3.8 424.00 Yes accepted matrix were rejected in examination, whereas the Table 5 show the accuracy test result for remains (Zn, As, Se, Ag, U, Fe and Cl) could be elements which passed the precision test using accepted. From 13 elements evaluated at standard material SRM NIST 1566b Oyster Sargasso. about 50 % of elements (Na, Co, Ag, Tissue, CRM NIES NO9 SARGASO, and CRM Al, K and I) were is unaccepted in this NMIJ 7302a sediments. From precision test, the examination while the remains accepted. For elements Na, Co, Al, and Cu at Oyster Tissue CRM NMIJ 7302a sediment, only 3 elements were unaccepted for this test (Na, Fe and Mn).
Proceedings of the International Graduate on Engineering and Science (IGCES08)Fundamental Science 23 - 24 December © 2008 IGCES Table 5 Accuration results of elements measurement in standard samples. Standard sample Accuration Test SRM NIST 1566b Oyster Tissue F3 F4 F3 < F4 Conclusion 0.11 0.13 Yes accepted 85.3 14.9 No rejected 0.1 1.3 Yes accepted 84.3 439.5 Yes accepted 0.2 0.04 No rejected 48.1 17.10 No rejected 22.1 22.8 Yes accepted 274 171.30 No rejected 0.3 0.3 No rejected 0.3 1 Yes accepted 5.4 91.4 Yes accepted CRM NIST No.9 Sargasso 0.4 0.2 No rejected 296.9 39.4 No rejected 8.6 18.2 Yes accepted 18.9 32.3 Yes accepted 0.12 0.02 No rejected 4 20.7 Yes accepted 57,229.10 3,976.60 No rejected 397.7 44.8 No rejected 3,736.70 1,613.80 No rejected 3.2 4.2 Yes accepted 0.02 0.59 Yes accepted 0.7 1.3 Yes accepted 1.8 2.5 Yes accepted CRM NMIJ 7302a Sediments 4,545 514.60 No rejected 1.1 3.1 Yes accepted 22.7 37.9 Yes accepted 3.7 3.8 Yes accepted 0.1 0.2 Yes accepted 7.8 17.1 Yes accepted 9,822,1 925.5 No rejected 162,3 52.70 No rejected From the result of precision and accuracy tests, many material types by eliminating dependency determination of elements with short decay time of standard materials usage, as well as the (obtained through short time irradiation ~ 1 improvement of analysis time efficiency. The minute) such as Mn, Na, Al, Cu and I, still have existence of irradiation canal parameter value technical constrain. The irradiation time was and proper irradiation handling subsequently believed as the constraint factor for this problem increased performance of ko technique. In yet to be determined in accurate figure. contrast with relative method, this technique was mainly influenced by the availability of accurate CONCLUSION irradiation canal parameter data and loading - unloading precision time. The ko-INAA nuclear technique was Based on test result obtained, the sampling successfully implemented in NAA laboratory of matrix was significant to accuracy and precision Indonesia’s National Nuclear Energy Agency result of measurement. As a conclusion, this (BATAN). The technique increases the ability of method is better in element identification NAA for quantitative elements determination in compared to comparative method.
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