Determination of Neutron Flux Parameters after Installation of Cd-Lined for Implementations of ENAA and FNAA with NIRR-1

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1 Determination of eutron Flux Parameters after Installation of -Lined for Implementations of E and F wi IRR-1 R.L. jinga Physics Department Ibrahim Badamasi Babangida University Lapai, iger State igeria Y.V. Ibrahim Center for Energy Research and Training hmadu Bello University Zaria, igeria M.O. deleye frican Leadership cademy Johannesburg, Sou frica S.. Jonah Center for Energy Research and Training hmadu Bello University Zaria, igeria bstract permanent -lined irradiation channel has been installed in one of e large outer channel of IRR-1 for use in ermal and procedures. Measurements performed wi Cu-wires and (.1)%u-l foils to characterize e ermal, ermal column and check its effect on e neutron flux distributions via e specific activities obtained using (n,γ), (n,p) and (n,α) reactions in oer channels (-1, B-2, B-3, and B-4) shows at e flux distributions have not been affected by e -liner in outer channel -3. The ermal neutron flux and neutron flux in e -lined Channel -3 were determined using.1%u-l foil monitor via e 197 u(n, γ) 198 u and 27 l(n, p) 27 Mg reactions and results were 3.96E+9 ncm -2 s -1 and 1E+1ncm -2 s -1 respectively at an operating power of 15.5kW which correspond to a ermal neutron flux setting of 5.E+11ncm -2 s -1 on e control console. The ermal flux evaluation was 4.89E+11ncm -2 s -1 in e inner channels -1, B-2, B-3 and 2.45E+11ncm -2 s -1 in e outer channel B-4. The ermal flux in e inner channels was 2.55E+1ncm -2 s -1 and 1.28E+11ncm -2 s -1 in e outer B-4. The ermal and neutron flux in e -lined channel provides a platform for implementation of ermal and techniques in IRR-1. Keywords: IRR-1, -lined channel, neuron flux, and flux characterization 1. Introduction The first and only Miniature eutron Source Reactor (MSR) in igeria called IRR-1 was designed by e China Institute of tomic Energy (CIE) (Zhou Yongmao, 1986). This reactor achieved first criticality on 3 February 24 and has been operated safely till date (Jonah et al., 25; 26). This reactor however, was specifically designed for use in eutron ctivation nalysis () and limited radioisotope production (Balogun et al., 25). The reactor (IRR-1) has a tank-in-pool structural configuration and a core of 23 x 23 mm square cylinder fueled by U-l4 enriched to 9% in l-alloy cladding. It has a total number of 347 fuel pins and ree l dummies in e fuel lattice and a nominal ermal power rating of 31 kw. The leng of e fuel element is 248 mm meanwhile e active leng is 23 mm wi 9 mm l-alloy plug at each end (Jonah et al., 26). The reactor (IRR-1) is basically functioning wi only one Control Rod serving as shim rod, regulation rod as well as safety rod. 186

2 Centre for Promoting Ideas, US The startup, steady-state operation, and shutdown of e reactor are accomplished by moving e control rod which is made up of absorber of about 266 mm long and 3.9 mm in diameter wi stainless steel of.5 mm ickness as e cladding material (Jonah et al., 26). IRR-1 is operated using e control console, e micro computer control system and e two rabbit systems all connected to a power source and during normal operation e reactor water temperature varies between 23 C and 46 C. However, e temperature difference rises rapidly and attains a stable value due to e insufficient natural circulation phenomenon. One basic feature of IRR-1 (similar facilities) is e inherent safety due to limited core excess reactivity designed to be less an ½βeff and large negative total temperature coefficient of reactivity. This feature of IRR-1 limits e operation time for full power to 4½ hours maximally (Jonah et al., 27). IRR-1 was acquired for elemental analysis by meod. On e basis of e neutron spectrum characteristics in e irradiation channels, two regimes of irradiation depending on e half-life of product radionuclide have been adopted. For e analysis of elements via very shortlived nuclides in seconds e regime is called S1 and is recommended in conjunction wi Rabbit Type B. Generally, for multi-element determination, e irradiation and counting regimes S2 and S3 are specified in Table 1. For e analysis of basic food diets and some major elements as shown in Table 1, irradiations are performed in any of e outer channels to minimize nuclear interference. Irradiations are also performed in any of e inner channels for important elements as shown in Table 1. Table 1: Irradiation and Counting Regimes dopted for Routine nalysis wi IRR-1 Facility eutron flux 8.1 E+11 ncm -2 s -1, B cycles 2.25E+11 ncm -2 s -1 Outer irradiation channels B-4,-3 5.E+11 ncm -2 s -1 Inner irradiation channels B-2, B-3, and -1 Irradiation time Delayed time Measurement Element of interest. (T irr ) (T d ) time (T m ) 3-6s 3-5s 4-6s Se, F, Rb, O, Sc 2-1m 1-1m 3-5h 5-1m 5-1m l, Mg, Cl, Ca, Cu, Ti, V, Br, Sr, I, S a, K, Dy, Mn, 6-7h 2-3d, 2-3m a, K, s, Zn, Sb,Dy Br, Mo, La, Sm, u, W, Ho, U, Ga, Lu, Ba, Yb 1-15d 6m Sc, Ce, Co, Cr, Cs Eu, Gd, Lu, Ba, Mo, d, Rb, Sb, Se, Ta, Tb, Th, Yb, Zn,, Fe, Sr, g, Hf, Ir, Hg, Zr, Te, Os Thus, careful and complete characterization of e neutron flux parameters in e irradiation channels in order to optimize its operation for via relative, absolute and single comparator meods are basically very necessary as aimed in is paper after a permanent -liner was installed in -3 outer irradiation channel. The cross sectional view of IRR-1 showing all e channel locations has been shown in a published work by Jonah et al., (24). s aimed in is work, e neutron flux spectrum parameters such as ermal flux ermal flux and flux measurements are vital in e k -standardization meod in neutron activation analysis () and neutron activation analysis (De Corte, 1992, 1994, 21). The specific activity ratio measurements wi respect to e (n, γ), (n, p), (n, α) reactions in IRR-1 irradiation channels; -1, -3, B-2, B- 3, and B-45 to ascertain neutron flux stability measurements after e recent -lined installation in -3 was evaluated. This was aimed to assess e extent of neutron fluxes perturbation caused by e installation. The lined installation in -3 is basically targeted toward e use of ermal neutrons for (n, γ) reactions and neutrons for reshold nuclear reactions involving e ejection of more an one nuclear particles such as (n,p), (n,α), and (n,2n) and typical examples includes; 16 O(n,p) 16, 14 (n, 2n) 13, 29 Si(n,p) 29 l, 27 l(n,p) 27 Mg and 27 l(n,α) 24 a (Yavar et al., 211). 187

3 Generally, neutrons are essential in detection of metal contamination in soil, analysis of oxygen content in a wide variety of matrices including geologic materials, coal, liquid fuels, ceramic materials, petroleum derivatives, and fractions and chemical reaction products. The determination of nitrogen content in biological materials as an indication of protein content and e determination of nitrogen content of fertilizers, explosives, and polymers are also important applications. Oer elements at are routinely analyzed by neutrons include g, l, u, Si, P, F, Cu, Mg, Mn, Fe, Zn, s, and Sn (Witkowska et al., 25). 2. Theory For e fact at detected peak intensities of irradiated samples under investigation depend solely on e induced activities, specific intensity are obtained from e relation below: sp p t av m sp epi Pi f p (1) M SDCm t Thus, for irradiation channels; -1, B-2, B-3, and B-4 we employed SDCm p t m channel -3 we used lined, where bare = activity of non shield monitored foils and, = SDCm activity of -lined channel of monitored foils, S = saturated factor e t i 1, D = decay factor e t d, C = m 1 e t counting factor, m = mass of e monitored foils. The cadmium ratio meod in which a set of tm =3 monitors ( 197 u 96 Zr 94 Zr) were irradiated wi and wiout cover in e inner and outer irradiation channels; -1, B-2, B-3 and B-4, and e induced activities were obtained using Eq. 1. Due to e fact at all used monitors flux obeyed e () v versus 1/v dependance concept, and by means of an iterative procedure for e set of =3 monitors, log root of e equation (Jonah et al., 25): E ri, F. R, i 1Q, i G G ei,, i p m bare,while for e -lined can be written as Eq. 2 and value obtained as e Er, i log log, i 1 Er i F. R 1 Q G, / G 1 Eri,, i, i ei, i log Er, ii. log i1 F. R 1 Q G, / G, i, i ei, i 2 log Er, i log Er, i i1 i1 (2) 188 I Q.429Ea.429Ea where Q and Q oi, I / is e ratio of resonance integral to E 2 1 r E ermal neutron capture cross section at neutron velocity of 22m/s for e i monitor and i denotes e i monitor, e number of monitor used, F is e -transmission factor for ermal neutrons; F ( 198 u) =.991, Gei, is e ermal neutron self shielding factor for e i monitor; G ei, ( 95 Zr) =.983, G, i is e ermal neutron self shielding factor for e i monitor, I is e modified resonance integral, E r is e effective resonance energy (ev), E a 1 is e 1eV arbitrary energy and E.55 is e effective cadmium cutoff energy.

4 Centre for Promoting Ideas, US The flux ratios (f) in IRR-1 are obtained from experimentally determined cadmium ratio using e induced activity meod in Eq.1. Thus, e experimental equation used in obtaining e activity ratio R using Eq.1 was as follows: I bare R R (3) F R I where F = cadmium transmission factor Simplifying Eq. (3) yield R 1 I where is defined as e ermal to ermal flux ratio f and I o ermal cross-section ratio Q. Hence, from Eq. 4 e ermal to ermal ratio of e irradiation channels were obtained as; f R 1 Q (5) (4) is defined as e resonance integral to From Eq. (5), it became obvious at e neutron flux ratio (f) is a factor of only two parameters Q and R. The monitors fluxes 197 u, a and 94 Zr, b were irradiated in e inner and outer irradiation channels; -1, B-2, B-3, and B-4 of IRR-1 under uniform neutron distribution and making use of Eq. (4) we obtained: R 1 Q R 1 Q (6) a a b b Putting e value of Q R R 1 1 a Q ( ) b f Qa ( ) b into Eq. (6) and rearranged yield: where e subscripts a and b represent 197 u and 94 Zr respectively. In measurement of e ermal neutron spectrum flux measurement, e correction of resonance integrals I to I I (α) values given as I E a was done and e equation use was given as Er 2 1 E (De Corte et al., 25); pm (8) t S D 1 e m I I w p c The nuclear reactions employed in e evaluation of ermal neutron spectrum flux measurement using Eq. 8 are shown below; Cu(n, γ) 66 Cu (139 kev, 511keV; T 1/2 =5mins) Cu(n, γ) 64 Cu (1346 kev; T 1/2 =12.7hrs) u(n, γ) 198 u (411.8 kev; T 1/2 =2.7days ) (7) 189

5 For e measurement of e ermal neutron spectrum flux parameter, e correction of ermal to neutron cross I Q.429Ea.429Ea section Q to Q (α) values given as Q was used. The flux E 2 1 r E was evaluated as; pm t Q (9) S D 1 e m 1 I w p c f The nuclear reactions employed for is measurement were 1, 2, and 3 above. For e neutron flux measurements, e average cross section values were used and e measurement was obtained as follows; pm (1) t S D 1 e m f I w p c The nuclear reactions employed for is measurement were; l(n, p) 27 Mg (114 kev, 843 kev; T 1/2 =9.46mins) l(n, α) 24 a ( kev, T 1/2 =14.96hrs) where = isotopic abundance, = decay constant= ln 2/T1/ 2, c= concentration of foil monitor, p = peak efficiency, I = gamma abundance, w=weight of foil monitor, t irr irradiation, t m = measuring time, f number, p = net peak area. 3. Experimental = irradiation time, t c = cooling time after =average cross section for neutron, M=atomic weight, =vogadro s The,, and for e two irradiation channels -3, B-2, were measured at a neutron ermal flux rate of 5.E+11 n/cm 2 s in e inner channels and 2.5 E+11 n/cm 2 s in e outer channels. The vials were of 1mm wall ickness, 1 cm diameter, and 3cm leng used for inner irradiations channels while 1mm wall ickness, 2.5 cm diameter, and 3 cm leng for outer irradiation channels. Two monitors made of.1% u-l foil alloy;.1 mm ick, IRRM-53; weight from.129 to.134g were irradiated in turn in -lined outer irradiation channel -3 and inner irradiation channel B-2 of IRR-1 to check absolute neutron flux distribution. The irradiation time in inner channel B-2 lasted 3 minutes while in outer channel -3 lasted 2 hours. waiting period of 114 seconds was observed for e irradiation in B-2 before a measurement of 6seconds was carried out for e first gammaray measurements at a distance of 17cm from e HPGe detector s end cap. fter a day waiting of 7674seconds, e irradiated u-l foil at B-2 was re-measured at 2cm for 18 seconds. The first measurement (S1) was done at 17cm geometry after a waiting time of 8 minutes while for second counting (S2) at 2 cm geometry, e delayed period was 7512 seconds. The measurement time was 6 seconds for e first count while 18 seconds for e second count. The flux measurements of,, and were performed following Eq. 8, 9, & 1 and results obtained are shown in Table 2. 19

6 Centre for Promoting Ideas, US Table 2: uclear Data Generated and Measured Thermal, Epiermal and Fast eutron Fluxes B-2 Inner -3 Outer -3 Outer B-2 Inner Irradiation Channel B-2 Inner -3 Outer 1 st 2 nd 1 st 2 nd 1st 1 st Geometry (cm) Saturated Factor Decay Factor Counting Factor 1.78E E E E E E u 197 u Pro-Isotope Measuring time (t m ) Irradiation time (t irr ) E γ (kev) Cooling time (t c ) u eutron Flux Thermal Flux Thermal Flux Epiermal Epiermal Fast Flux Fast Flux Measurements ( ) ( ) Flux ( ) Flux ( ) ( ) ( ) (ncm -2 s -1 ) 4.75E E E E E+1 1.8E+1 In oer to check e stability of neutron flux distribution of IRR-1 irradiation channels, we determined e specific activity in -1, -3, B-2, B-3, and B-4 based on e nuclear reactions 1-5 above. For e measurement of flux stability, five Cu wires of weights.987g to.1388g were irradiated in channels; -1, -3, B-2, B-3, and B-4 and two u-.1% l foils of.1mm ick (IRRM-53), were irradiated in channels -3 and B-2. The Cu wires irradiation procedures in e five channels -1, -3, B-2, B-3, and B-4 are shown in Table 3 and e measurement at 17cm using GEM-3195 are shown in Table u 197 Mg Table 3: Cu Wires Irradiation and Measurements Procedures in e Five Channels Channels Irradiation time (sec.) Delayed time (sec) Measured (seconds) B B B The irradiation of u-.1% l foils -3 was 3 seconds 12 seconds in B-2 and e measurements for first count at 17cm were 6 seconds bo channels while second count at 2cm were 18seconds bo channels. The results of e specific activity in terms of nuclear reaction 27 l (n, p) 27Mg, 27 l (n, α) 24a, and 197u (n, γ) 198 u are shown in Tables 4-6. Table 4: Specific ctivity Measurement in B-2 and -3 using (n, p) and (n, α) Reactions Channels B-2 Inner 1 st -3 Outer 1 st B-2 Inner 2 nd (2cm) -3Outer2nd (2cm) Sample ID 69M186 69M188 69M186 69M188 Wieght Peak energy (KeV) Irradiation time (sec) Waiting time (sec) Measuring time (sec) Decay Constant (λ) E E-5 uclear reaction 27 l(n,p) 27 Mg 27 l(n,p) 27 Mg 27 l(n,α) 24 a 27 l(n,α) 24 a Specific ctivity (Bqkg -1 ) a 191

7 Table 5: Specific ctivity Measurement in B-2 and -3 using (n, p) Reactions Channels B-2 Inner 1 st -3 Outer 1 st Sample ID 69M186 69M188 Wieght Peak energy (KeV) Irradiation time (sec) Waiting time (sec) Measuring time (sec) 6 6 Decay Constant (λ) 1.2E-3 1.2E-3 uclear reaction 27 l(n,p) 27 Mg 27 l(n,p) 27 Mg Specific ctivity (Bqkg -1 ) Table 6: Specific ctivity Measurement in B-2 and -3 using (n, γ) Reactions Channels B-2 Inner 1 st -3 Outer 1 st B-2 Inner 2 nd (2cm) -3 Outer 2 nd (2cm) Sample ID 69M186 69M188 69M186 69M188 Wieght Peak energy (KeV) Irradiation time (sec) Waiting time (sec) Measuring time (sec) Decay Constant (λ) E E E E-6 uclear reaction 197 u(n,γ) 198 u 197 u(n,γ) 198 u 197 u(n,γ) 198 u 197 u(n,γ) 198 u Specific ctivity (Bqkg -1 ) The specific activity measurements for all channels; -1, -3, B-2, B-3, and B-4 wi respect to e nuclear reaction 63 Cu (n, γ) 64Cu are shown in Table 7. Table 7: Specific ctivity Measurements in -1, -3, B-2, B-3 and B-4 using (n, γ) Reaction Channels -3 outer B-2 Inner B-3 Inner B-4 Outer -1 Inner Sample ID 69M163 69M167 69M171 69M165 69M169 Wieght Peak energy (KeV) Irradiation time (sec) Waiting time (sec) Measuring time (sec) Decay Constant (λ) 1.52E E E E E-5 uclear reaction 63 Cu(n,γ) 64 Cu 63 Cu(n,γ) 64 Cu 63 Cu(n,γ) 64 Cu 63 Cu(n,γ) 64 Cu 63 Cu(n,γ) 64 Cu Specific ctivity (Bqkg -1 ) Results and Discussion The average values of e neutron flux spectrum parameters measured in e first and second counts (17cm and 2cm) for resulted to 4.89E+11 n/cm 2 s in B-2 inner irradiation channel. This value confirmed very well wi e recommended value of 5E+11n/cm 2 s wi uncertainty of.22% for inner channel of IRR-1 on e operation control console. Due to e stability nature in flux distribution in IRR-1, e in -1, B-3 were evaluated and was equal to at in B-2. However, since e flux in e inner channel doubles at in e outer channel, en e flux in B-4 outer channel was obtained to be 2.45E+11 n/cm 2 s wi uncertainty of.22%. 192

8 Centre for Promoting Ideas, US From e relationship in Eq. 5, making use of e generated nuclear data in Table 3, e in e inner channels -1, B-2, and B-3 are obtained to be 2.55E+1 ncm -2 s -1 while in e outer B-4 channel, e ncm -2 s -1. The measurement of e average value of was 1.28E+1, in e -lined irradiation channel -3 was 4.22E+9 n/cm 2 s wi uncertainty of.5%. The flux in e inner B-2 channel was 9.15E+1 n/cm 2 s while e outer -lined -3 was 1.8E+1 n/cm 2 s. These values tally very well wi e ermal flux reading on e control console as shown in Fig. 1. These results indicate at neutron flux distributions have not been affected by e installation of -liner in e outer channels -3. In eory, e specific activity ratios evaluation of inner-to-inner and outer-to-outer irradiation channels are calculated as follow: Cu B2 Cu B3 Cu 1 bare inner bare inner bare inner CuB4 Cu3 bareouter bare outer CuB2 bareinner 1 1I CuB4 bareouter 2 2I CuB2 bare inner CuB4 bare outer where 1 2 I 2 2 I and Cu B2 1 obtained from Table 2 and bare inner (11) (12) = Specific activity of Cu in B-2 The experimental specific activity ratios, inner-to-inner (i.e., -1/B-2, B-3/B-2, and -1/B-3) were found to be 1.1 (.1%), 1.3 (.3%), and 1.6 (.6%) respectively as shown in Table 8. Between e inner-to-outer, eoretical calculations shows at; 2 (13) Cu B2 Cu B4 bare inner bare outer where and 1 2 Cu B2 bare inner 1 1I Cu B4 bare outer Cu B2 bare inner Cu B4 bare outer we have; (14) I 2 I 2 2 I From e experimental determination of specific activity ratios, inner-to-outer (-1/B-4, B-2/B-4, and B-3/B-4) were determined to be 2.1 (.1%), 1.9 (-.1%) and 2. (.1%) as shown in Table 8. Finally, between e inner-to-outer wi -lined -1/-3 measurements, e specific activity ratios was while e outer-to-outer wi -lined B-4/-3 was obtained to as shown in Table 8. (15) 193

9 Table 8: Specific activity ratios between irradiation channels of IRR-1 for ermal, ermal, and neutron reactions Channel Relationship Specific ctivity Ratios Theory Specific ctivity Ratios Inner-to-inner (1/B2) Inner-to-inner (B3/B2) Inner-to-inner (1/B3) Inner-to-outer (1/B4) Inner-to-outer (B2/B4) Inner-to-outer (B3/B4) Inner-to-outer -liner (1/3) Outer-to-outer -liner (B4/3) In eory, e inner-to-outer wi -lined and outer-to-outer wi -lined are estimation given as; Cuirradiation ' channel ' Cuirradiation ' channel ' 2 bare inner outer (16) Cuirradiation ' channel ' Cuirradiation ' channel ' bareinner where outer Cu irradiation ' channel ' outer =Specific activity ratio of -lined (-3) These specific activity ratios values indicates at neutron flux distributions have not been affected by e installation of -liner in e outer channel -3 and e ratio of 2:1 for e inner-to-outer irradiation channels. The graphical interpretations of ese results are shown in Figure 1-2. B-2 (control Console) B-2 (2cm) Thermal Flux Ф B-2.E+ 5.E+11 Figure 1: Thermal eutron Flux Measurement of B-2 Inner Irradiation Channel of IRR-1 at two different instances. 194

10 Centre for Promoting Ideas, US Inner-to-inner (1/B3) Inner-to-inner (B3/B2) Inner-to-inner (1/B2) Outer-to-outer -liner (B4/3) Inner-to-outer -liner (1/3) Specific ctivity Ratios Inner-to-outer (B3/B4) Inner-to-outer (B2/B4) Inner-to-outer (1/B4) 5. Conclusion Figure 2: Channel Specific ctivity Ratios This work concludes at e operational routine in analysis, it is sufficient to operate IRR-1 at half power, which corresponds to a neutron flux of 5.E+11 n/cm 2.s, in e inner irradiation channels. This confirmed e installation of -lined in -3 and has expand e margin of elemental investigation in all ramifications since during is steady state of operation at ½ power, e control rod is gradually widrawn to compensate for reactivity loss due e large overall negative temperature coefficient of reactivity. Consequently, magnitude of e neutron flux remains constant during operation before and after e -lined channel -3. This work also confirmed e fact at e stability of e neutron flux is one of e hallmarks of IRR-1 and similar facilities, which run on is same fuel loading for over 1 years. However, since e fuel is not modified at all for its entire core life time, e neutron spectrum in e irradiation channels does not change even when a -lined was recently installed in e outer irradiation channel -3 and e neutron flux is reproducible to wiin 1%. This erefore, allows convenient neutron activation analysis of all elements of interest in any of e channels -1, - 3, B-2, B-3 and B-4 wiout e need to continually repeat e standardization measurements for all elements. cknowledgment The auors ank CERT-igeria for e enabling environment and used of eir facility for is research work. 195

11 References Balogun G.I, Jonah S.., Umar I.M., Measures aimed at enhancing safe operation of e igeria Research Reactor-1 (IRR-1). In Book of Contributed Papers, International Conference on Operational Safety Performance in uclear Installations, 3 ovember 2 December, 25, IE, Vienna ustria, IE- C-133/19, pg De Corte F., Dejaeger M., Hossain S. M., Vandenberghe D., De Wispelaere., Van den Haute P. performance comparison of k-based E and in e (K, Th, U) radiation dose rate assessment for e luminescence dating of sediments. Journal of Radioanalytical and uclear Chemistry, Vol. 263, o. 3 (25) De Corte, F. The standardization of standardless. Journal of Radio- analytical and uclear Chemistry (21) 248 (1), De Corte, F., Problems and solutions in e standardization of reactor neutron activation analysis. Journal of Radio-analytical and uclear Chemistry (1992) 16 (1), Jonah S., Umar I.M., Oladipo M.O., Balogun G.I., deyemo D.J., Standardization of IRR-1 Irradiation and Counting Facilities for Instrumental eutron ctivation nalysis. ppld Rad. & Isotopes, 64, (26), Jonah S.., Balogun G.I., Umar I.M., Mayaki M.C., eutron spectrum parameters in irradiation channels of e igeria Research Reactor-1 (IRR-1) for e k standardization. J. Radiaonal. ucl. Chem.266, (25), Jonah S.., Liaw J.R., Matos J.E., Monte Carlo simulation of core physics parameters of e igeria Research Reactor-1(IRR-1). nnals ucl. Energy 54, (27), Witkowska, E., Szczepaniak, K., Biziuk, M. Some applications of neutron activation analysis. Journal of Radioanalytical and uclear Chemistry (25) 265 (1), Yavar.R., Sarmani S.B., Wood.K., Fadzil S.M., Radir M.H., Khoo K.S. Determination of neutron flux distribution in irradiation sites of e Malaysian uclear gency research reactor. Journal of pplied Radiation and Isotopes 69 (211) Zhou Yongmao, IE-TECDOC-384 Technology and Use of Low Power Research Reactors. Report of IE Consultants Meeting, Beijing, China 3 pril 3 May 1985, (1986) pg

Operational Experience and Programmes for Optimal Utilization of the Nigeria Research Reactor-1

Operational Experience and Programmes for Optimal Utilization of the Nigeria Research Reactor-1 S.A. Jonah, G.I. Balogun, A.I Obi, Y.A. Ahmed, B.Nkom Reactor Engineering Section, Centre for Energy Research