!..*
AECL-7514
ATOMIC ENERGY L'ENERGIE ATOMIQUE OF CANADA LIMITED DU CANADA LIMITEE
Co AND Cd ABSORBER ROD EXPERIMENTS IN ZED-2
Experiences faites dans I'installation ZED-2 avec des barres de commande absorbant Co et Cd
G.M. ARBIQUE
Chalk River Nuclear Laboratories Laboratoires micle'aires de Chalk River
Chalk River, Ontario
February 1982 ttvrier ATOMIC ENERGY OF CANADA LIMITED
Co AND Cd ABSORBER ROD EXPERIMENTS IN ZED-2
by
G.M. Arbique
Reactor Physics Branch Chalk River Nuclear Laboratories Chalk River, Ontario, KOJ 1JO 1982 February
AECL-7514 L'ENERGIE ATOMIQUE DU CANADA, LIMITEE Expériences faites dans l'installation ZED-2 avec des barres de commande absorbant Co et Cd
par G.M. Arbique
Résume
Des expériences ont été effectuées dans l'instal- lation critique ZED-2 pour évaluer le taux de réactivitê des barres de commande du réacteur NRU absorbant les neutrons de cobalt et de cadmium. L'objectif des mesures était d'obtenir des données utiles pour valider les codes de physique du réacteur NRU. En employant une barre de commande absorbant Co et Cd dans un réseau de ZEEP, on a mesuré: Ca) le taux de réactivité de cette barre de commande, (b) les flux relatifs aux abords de la barre de commande et dans l'ensemble du réseau, (c) les valeurs r/T/Tç de Westcott pour obtenir quelques informations relatives au spectre des neutrons.
Département de physique des réacteurs Laboratoires nucléaires de Chalk River Chalk River, Ontario KOJ 1J0 Février 1982 AECL-7514 ATOMIC ENERGY OF CANADA LIMITED
Co AND Cd ABSORBER ROD EXPERIMENTS IN ZED-2
by G.I!. Arblque
ABSTRACT
Experiments have been performed In the ZED-2 critical facility to evaluate reactivity worths of NRU cobalt and cadmium absorber rods. The object of the measurements was to provide data useful in validating NRU reactor physics codes.
Using a Cd or Co absorber rod in a ZEEP rod lattice, measurements were made of: (a) absorber rod reactivity worths, t (b) relative fluxes in the vicinity of the absorber rod and throughout the lattice,
(c) Westcott r /T/To values, to obtain some neutron spectrum information.
Reactor Physics Branch Chalk River Nuclear Laboratories Chalk River, Ontario KOJ 1J0 1982 February
AECL-7514 Co AND Cd ABSORBER ROD EXPERIMENTS IN ZED-2 by G.M. Arbique TABLE OF CONTENTS Page 1. INTRODUCTION 1 2. DESCRIPTION OF FUEL LATTICE AND ABSORBER RODS 1 2.1 Lattice Configuration 1 2.2 Cobalt Rod 1 2.3 Cadmium Rod 2 3. CRITICAL HEIGHT MEASUREMENTS 2 3.1 Measurements 2 3.2 Results 2 4. FLUX MEASUREMENTS 3 4.1 Determination of Relative Neutron Flux 3 4.2) Activation Detectors 3 4.3 Determination of Detector Activities 3 4.4 Experiments 4 4.5 Flux Measurement Results 5 5. ACKNOWLEDGEMENTS 7 6. REFERENCES 7 LIST OF TABLES
Page
Table 1: Critical Height Data 9
Table 2: Pertinent Data From the Macroscopic Flux Measurements 10
Table 3: Normalized Thimble Copper Activities for Experiment G2E 11
Table 4: Normalized Thimble Copper Activities for Experiment G2A (Co rod) ...... 12
Table 5: Normalized Thimble Copper Activities for Experiment G2B (Cd rod) 13
Table 6: Normalized Thimble Copper Activities for Experiment G2C (Cd rod) 14
Table 7: Normalized Thimble Copper Activities for Experiment G2D (Cd rod) 15
Table 8: Relative Cu Activities for Cd Absorber Rod
off Centre 5 mm North (G2B Type Core) 16
Table 9: Fitted Axial Distribution Parameters ....17
Table 10: Normalized Wire Activities for Experiment G2A (Co rod) 18 Table 11: Normalized Wire Activities for Experiment G2B (Cd rod) 19
Table 12: Normalized Wire Activities for Experiment G2C (Cd rod) 20
Table 13: Normalized Wire Activities for Experiment
G2D (Cd rod) 21
Table 14: Band Segment Activities ...22
Table 15: r /YpFo Values .• 23
Table 16: In Activations and Cd Ratios Used for r /T/To Determinations 24 Table 17: Parameters Used in r / T/To Calculations 25 LIST OF FIGURES Page
Figure 1: ZEEP Rod Reference Lattice 26 Figure 2: Section of Cobalt Absorber Rod 27 Figure 3: Cobalt Absorber in ZED-2 28
Figure 4: Diagrams of Cd Absorber Rod 29 Figure 5: Lattice Used for Flux Measurements 30
Figure 6: Wire Placement About Cd Rod 31 Figure 7: Wire Placement About Co Rod 31 Figure 8: Cu Band Placement 32 Figure 9: Wire Activities for G2A 33 Figure 10: Wire Activities for G2B 34 Figure 11: Band Segment Activities for G2E 35 Figure 12;: Band Segment Activities for G2A > 36
Figure 13: Band Segment Activities for G2B 3/ Cd AND Co ABSORBER ROD EXPERIMENTS IN ZED-2
by
G.M. Arbique
1. INTRODUCTION
This report describes Cd and Co absorber rod experiments performed in the ?ED-2 critical facility^1', in support of the validation of NRU reactor' ' physics codes. The following studies were made in ZEEP rod lattices containing a Co or Cd absorber rod in the central lattice position:
- reactivity effects (as measured by critical height changes) associated with the absorber rods,
- mapping of relative neutron fluxes, by Cu activation detectors, throughout the lattice and in the vicinity of the absorber rods,
- measurement of Westcott r /T/To values throughout the lattice, in order to obtain some neutron spectrum information.
2. DESCRIPTION OF FUEL LATTICE AND ABSORBER RODS
2.1 Lattice Configuration
The reference lattice used in these studies is illustrated in Figure 1. It consisted of 73 ZEEP rods, heavy water moderated, in a hexagonal array at a 19.685 cm (NRU) pitch. ZEEP rods are natural uranium metal cylinders (3.25 cm diameter, 15 cm long) stacked within a 2S aluminum alloy tube of 1 mm wall thickness. The fuel length in the rods is 285 cm and when suspended in ZED-2 the lowest edge of the fuel was 15 cm above the calandria floor. Whenever the Co or Cd absorber rod was present in the core it replaced the central ZEEP rod.
2.2 Cobalt Rod
The Co absorber rod was a MKII HIGH DENSITY COBALT CONTROL ROD, borrowed from NRU. The rod consisted of aluminum wafers, containing square pockets of cobalt pellets, sandwiched between two concentric 57S aluminum tubes (see Figure 2). Each wafer was 10.16 cm x 9.04 cm, and contained 14.0 g of nickel-plated Co pellets (1 mm long x 1 mm diameter) in 49 separate pockets (7 on a wafer side). Wafers were sandwiched between -2-
the inner (I.D. 8.10 cm, 0.0. 8.57 cm) and outer (I.D. 8.89 cm, O.D. 9.37 en) tubes in three 24 wafer columns. The rod had openings at the top and bottom to allow the D2O moderator to occupy the inside of the assembly.
When the Co absorber rod was suspended in ZED-2, the lower edge of the bottom-most wafer was 15 cm above the calandria floor (see Figure 3).
2.3 Cadmium Rod
The Cd absorber rod employed in the experiments was a mock-up of an NRU "20% Cd" ABSORBER ROD . The mock-up rod consisted of 4 columns of Cd strips (8 strips per column) attached by screws at 90° intervals on the surface of an aluminum alloy tube (I.D. 82.5 mm, 2.67 am wall) (see Figure 4). Each Cd strip measured 295.3 mm long, 15.5 mm wide, and 1.57 mm thick. The rod also had openings at the top and bottom to allow heavy water moderator to fill the tube.
The Cd absorber rod was suspended in ZED-2 with the lower edges of the bottom-most Cd strips at 15 cm above the calandria floor (see Figure 4).
3. CRITICAL HEIGHT MEASUREMENTS
3.1 Measurements
Critical D2O height measurements were made with both Co and Cd absorber rods. The measurements determined critical height changes associated with placing either the Cd or the Co absorber rod in the central site, KO (see Figure 1), of the reference core with varying nearest neighbour ZEEF rod environments. Descriptions of the experiments are contained in Table 1 (refer to Figure 1 for rod locations).
3.2 Results
Data collected in the critical height measurements may be found in Table 1. The table also contains critical height changes, AH, with respect to reference core critical heights. The variation of reference core critical height with time of measurement was obtained from linear interpolations of reference core critical height measurements made at the beginning and end of each day. The uncertainty in AH is estimated to be +0.06 cm.
From the critical height changes listed in Table 1, it is clear that the Cd rod has the larger reactivity worth. -3-
A. FLUX MEASUREMENTS
A.I Determination of Relative Neutron Flux
To determine relative thermal neutron fluxes throughout the experimental lattices Cu activation detectors were placed at various locations. After irradiation the gamma activity of Cu6^ (half life » 12.9 h) was measured for each detector.
Spectrum information at various locations throughout the lattices was obtained by determining Westcott r /T/To values. An r may be evaluated at a location by comparing a Cu*>4 and ^ (half life - 5A.3 min) activation ratio to the same ratio obtained at a reference location, where r /T/To has also been obtained from a Cd ratio measurement. A full description of this method may be found in references (3), (A) and (5).
A.2 Activation Detectors
The following activation detectors were used throughout the experiments:
(a) Cu foils (11.3 mm diameter, 0.25 mm thick) were used for macroscopic flux and r /T/To measurements. These foils were held in thin- walled Al thimbles which were suspended in the core in the same manner as the ZEEP fuel rods.
(b) Cu wires (10 mm long, 0.76 mm diameter) were used for fine structure flux measurements in the vicinity of the absorber rods.
(c) Cu bands (108 mm long, 0.13 mm thick, 5 mm wide) were used to determine flux profiles around ZEEP fuel rods. After irradiation these bands were cut into shorter segments, for counting purposes (see Figure 8).
(d) In-Al foils (11.3 mm diameter, 0.13 mm thick), containing 1% indium by weight, were used in the r /T/To measurements.
Cd and Al boxes with 0.76 ran thick walls were used to cover the In-Al foils used in the cadmium ratio measurements.
A.3 Determination of Detector Activities
The gamma activity of a Cu or In-Al detector was measured by two 51 mm diameter by 25 mm thick Nal (Tl) crystals mounted above and below the detector being counted. An automatic restacking sample changer repeatedly cycled a stack of detectors through the counters.
The Cu*>4 activity was determined by counting the Cu detectors beginning ~2 h after irradiation with the counter bias set at ~50 keV. -4-
The time between irradiation and start of counting allowed for decay of the 5.1 rain Cu66 activity. The 54 min InHGm activity was determined by counting foils beginning 1 hour after irradiation with the counter Mas also set at ~50 keV.
The count output of the two Nal (Tl) crystals was collected by a PDP-11 minicomputer. A data reduction program on the PDP-11 was used to correct the accumulated data for counter dead time, natural and room background radiation, and decay of the activity. The program also checked the cycle data for reproducibility. The program output consisted of an activity per unit mass, Ag, along with associated reproducibility and statistical counting errors for each detector in the sample stack. The detector activities are shape dependent due to differing self-shielding and flux depression effects.
To obtain a consistent set of shape independent relative activi- ties (Ax), Cu detectors of each type, i.e. wires, foils, and band segments, were placed on a rotating wheel located in a well-thermalized flux (so that all detectors would see the same flux) in ZED-2 (see Figure 5, and Section 4.4). These detectors were then counted and analysed to produce a set of shape reference activities, A,.. The previously determined shape dependent relative activities were then normalized to the corresponding shape reference activities, thus producing shape independent relative activities, i.e.
A A -—£ X A r
4.4 Experiments Measurements were performed on the following lattice config- urations in ZED-2 (refer to Figure 1):
(i) Reference lattice, G2E
(ii) Co absorber in position KO of reference lattice, G2A
(iii) Cd absorber in position KO of reference lattice, G2B
(iv) Cd absorber in KO with ZEEP rods at LIE, K2W, and J1E removed from the lattice, G2C
(v) Cd absorber in KO with ZEEP rods at K2E, LIE, LIW, K2W, J1W, and J1E removed from the lattice, G2D.
Each of these experiments will henceforth be referred to by the designations given in the above lattice configuration list. Pertinent data for these irradiations may be found in Table 2. -5-
The experimental lattice is illustrated in Figure 5, where a rotating wheel placed in a thermal flux 78 cm away from the nearest fuel rod is also shown. All thimbles, except those at K5W and K5E, contained Cu foils at elevations of 95 cm, 85 cm, and 75 cm (all elevations and radii quoted are measured from the calandria floor and core centre, respectively). Thimbles at K5W and K5E contained Cu foils at 10 era intervals extending from 15 cm elevation to the surface of the D2O moderator *
Thin Al frames were attached to the Cd and Co absorber rods at an elevation of 85 cm, see Figures 6 and 7. The frames, which extended from the rods out into the moderator in several directions, supported Cu wires which were placed at 1 cm intervals. An Al frame supporting Cu wires was also placed inside the Cd rod at 85 cm elevation (see Figure 6).
Cu bands were wrapped around fuel rods at K2R and K4E, except in experiment G2D where the fuel rod at K2E was removed. Figure 8 is an illustration of the placement of the Cu bands at these positions.
In-Al foils were placed with all Cu foils at 85 cm elevation. Cu and In-Al pairs were also placed on the rotating wheel (see Figure 5) which was used as a reference position. For the Cd rod experiments Cu and In-Al pairs were placed along the axis of the Cd rod at elevations 75 cm and 95 cm.
Reference locations used for Cd ratio measurements were located at K3W, K3E and at the rotating wheel at K16W-85 cm (see Figure 5). At K3W and K3E, Cd covered and bare In foils were separated by 40 cm with a Cu and In-Al pair between them at 85 cm. The differing axial flux was corrected for by obtaining a correction factor from a cosine curve fit to the axial Cu foil activities at the nearest neighbour thimbles (either at K5W or K5E). When using thimbles as reference locations one assumes no axial variation in neutron spectrum parameters over the region of reference foil placements. No such considerations are necessary at the wheel reference location since all foils may be separated and still see the same neutron flux.
A.5 Flux Measurement Results
All Cu detector activities (except those in Table 8) have been normalized to the average of the Cu foil activities from thimbles K9H and K9E at 85 cm elevation, for each respective experiment. Based on counting statistics, uncertainties associated with these normalized Cu activities (and In activities) are typically~0.2%.
Tables 3 to 7 contain the Cu foil activities measured at thimble positions, Cu foil activities at 85 cm are included in these tables even though In-Al foils were also placed in these positions. Some asymmetry is apparent, e.g. from n< rth to south, in the results of the absorber rod experiments. This is thought to be due to the sensitivity of the macroscopic flux shape to the positioning of the absorber rod. Moving the -6-
Cd absorber off centre 5 mm north in the G2B core induced 7% difference between foil activities at LO and JO (see Table 8).
From the data in Tables 3 through 5 relative flux depressions, associated with replacing the central ZEEP rod in the reference lattice with either of the absorber rods, may be obtained. In the case of the cobalt absorber, depressions of 18% and 13% were seen at radii of 17.0 cm (thimbles at JO and LO) and 29.5 cm (thimbles at K3W and K3E), respectively. Depressions of 30% and 20Z were observed at these positions when the cadmium absorber rod was in the core. When calculating these depressions the effects of the absorber rods at the normalizing thimbles at K9W and K9E (88.7 cm radius) were assumed to be negligible.
Table 9 contains fitted axial activity distribution parameters for the Cu activity distributions at K5W and K5E. Data close to the boundaries and at 85 cm have been dropped (see bracketed data in Tables 3 to 7). The function used to fit the data was
A(Z) = Aocosa (Z-Zo)
where Ao is a normalization constant, a is the square root of the axial buckling, and Zo is the elevation at which maximum flux occurs. Using a and Zo, upper, lower, and total extrapolation lengths (dZu, dZj and dZt, respectively) were found where
H = •7T ex a
H ex dZ u 2
H _ ex dZ (Z -15) l o 2
dZt = dZu +
Hex is called the extrapolated height and Hc (see Table 2) is the measured critical height for the particular lattice.
Tables 10 through 13 contain the normalized Cu wire activities. The data from experiments G2A and G2B have also been illustrated in Figures 9 and 10, respectively. The flux gradient approaching a strip of cadmium on the cadmium absorber is ~6 times greater than that approaching the cobalt rod. In fact, reference to Figure 9 reveals that the thermal flux depression associated with the Co absorber is less than that at the nearest neighbour ZEEP rods. One may also infer from Figure 10 the discrete nature -7-
of the cadmium on the cadmium absorber rod by the reduction of the flux gradient When approaching the absorber rod surface from directions N30 or N60.
Table 14 contains normalized ZEEP rod band segment activities. Figure 8 displays the identification scheme for the individual band segments. Data from experiments G2E, G2A, and G2B have also been illustrated in Figures 11 through 13, respectively. A reduction in flux at the K2E ZEEP rod relative to the flux at the K4E ZEEP rod is evident when the absorber rods are in the core. The effect of the Cd absorber is to actually make the relative flux at the K2E ZEEP rod less than that at the K4E ZEEP rod. Also a reduction in the flux profile, induced by the Cd absorber, at the K2E ZEEP rod is apparent at ~27O° in Figure 13.
Values of the Westcott spectrum parameter r/ T/TQ are listed in Table 15. Each v/ T/To value is an average of the values derived from each reference location (i.e. locations K1W, K3E, K16W). The uncertainty indicated is the standard deviation of the average values and reflects the experimental error associated with the measurement. If one were to consider statistical uncertainties associated with the foil activities the uncertainty in a r /T/To value would typically be ~2%. The indium activities, Cd ratios, and Cu activities (not included in other tables) measured for the r /T/To determinations may be found in Table 16, where the typical statistical error is~^0.2%. Uncertainties which also affect the r /T/To values are those for the self-shielding factors and other Westcott parameters used in the derivations (see Table 17 for values used for these parameters), the largest of which being ~+2.5% in SQ(In).
5. ACKNOWLEDGEMENTS
The author wishes to thank all those involved in this experimental program, in particular, from the ZED-2 reactor, P.D.J. Ferrigan, E.J. Pleau and D.J. Roberts; for foil counting, D.A. Kettner and G.A. Doncaster; and for assistance for producing this report, D.E. Goldberg, who drew the figures, and E. Havey, who typed the manuscript.
6. REFERENCES
1. "ZED-2", Atomic Energy of Canada Limited, Reprint AECL-2132 (1964).
2. "NRU", Atomic Energy of Canada Limited, Reprint AECL-1333 (1959).
3. Bigham, C.B., Chidley, B.G. and Turner, R.B., "Experimental Effective Fission Cross-Section and Neutron Spectra in a Uranium Fuel Rod Part II. CANDU Type Uranium Oxide Clusters", Atomic Energy of Canada Limited, Report AECL-1350 (1961). -8-
4. Westcott, C.H., Walker, W.H., and Alexander, T.K., "Effective Cross Sections and Cadmium Ratios For the Neutron Spectra of Thermal Reactors, Atomic Energy of Canada Limited, Report AECL-612 (1958).
5. Westcott, C.H., Effective Cross-Section Values for Well Moderated Thermal Reactor Spectra, Atomic Energy of Canada Limited, Report AECL-1101 (1970). TABLE 1: CRITICAL HEIGHT DATA
Lattice Date D20 % wt Critical Height* Critical Height Temp °C D20 of Perturbed of Reference A H (+0.10°) (40.003%) Lattice (cm) Lattice (cm) (cm)
i) Reference Lattice (Fig.l) 20/01/81 22.78 99.659 153.849
ii) KO ZEEP Rod Removed 20/01/81 22 .89 99 .659 156 .817 153 .86 2.96 a) Cd Absorber Rod in KO 20/01/81 22 .91 99 .659 183 .229 153 .87 29 .36 b) Co Absorber Rod in KO 20/01/81 23 .04 99 .659 170 .992 153 .91 17.08 iii) Reference Lattice 20/01/81 23.11 99.659 153.917
iv) Reference Lattice 21/01/81 23.20 99.659 153.933 v) KO,L1E,K2W, and J1E 21/01/81 23.24 99.659 166.719 153.94 12.78 ZEEP Rods Removed a) Cd Absorber Rod in K0 21/01/81 23.25 99.659 194.955 153.94 41.02 b) Co Absorber Rod in KO 21/01/81 23.39 99.659 181.984 153.96 28.02 c) ZEEP Rod in KO 21/01/81 23.40 99.659 162.609 153.96 8.65
vi) Reference Lattice 21/01/81 23.43 99.659 153.969
vii) Reference Lattice 22/01/81 23.53 99.659 153.991 viii) KO,L1E,L1W,K2W,J1W,J1E 22/01/81 23.56 99.659 179.755 154.00 25.76 and K2E ZEEP Rods Removed a) Co Absorber Rod in KO 22/01/81 23.58 99.659 196.289 154.00 42.29 b) Cd Absorber Rod in KO 22/01/81 23.66 99.659 210.026 154.01 56.02 c) ZEEP Rod in KO 22/01/81 23.72 99.659 174.110 154.02 20.09
ix) Reference Lattice 22/01/81 23.77 99.659 154.022
*Critical heights were measured after the reactor remained stable for 30 minutes at a nominal power of 5 W". -10-
TABLE 2
PERTINENT DATA FROM THE MACROSCOPIC FLUX MEASUREMENTS
Experiment Date D2° %wt Critical Nominal Length of Temp °C D20 Height (cm) Power W Irradiation <+ 0.10°) (+ 0.008%;) +_ 0.5* cm
G2A 28/01/81 23.51 99.658 172.394 50 30 min
G2B 23/03/81 23.33 99.643 185.833 100 30 min
G2C 10/02/81 23.50 99.656 196.983 50 30 min
G2D 16/02/81 23.40 99.652 212.290 50 30 min
G2E 23/02/81 23.61 99.649 155.345 50 30 min
The accuracy of the height probe is as follows:
Per 3.0 cm Measurement: +_0.003 cm Per 30.0 cm Measurement: +0.03 cm Over 30.0 cm Measurement: +0.5 cm TABLE 3: NORMALIZED THIMBLE COPPER ACTIVITIES FOR EXPERIMENT G2E
Elevation Location and Radius (cm) (ca)
K9W K7W K5W K3W K3E K5E K7E K9E HO JO LO NO 88.58 68.90 49.21 29.53 29.53 49.21 68.90 88.58 51.14 17.05 17.05 51.14
145 (0.397) (0.393) 135 0.673 0.679 125 0.936 0.929 115 1.143 1.156 105 1.321 1.327 95 0.944 1.158 1.466 1.699 1.674 1.463 1.160 0.944 1.439 1.788 1.776 1.427 85 1.003 1.211 (1.552) 1.806 1.778 (1.557) 1.212 0.997 1.520 1.891 1.885 1.510 75 1.020 1.255 1.583 1.843 1.831 1.579 1.245 1.022 1.551 1.923 1.923 1.551 65 1.579 1.561 55 1.496 1.493 45 1.376 1.362 35 (1.212) (1.196) 25 (1.032) (1.022) 15 (0.867) (0.855) TABLE 4: NORMALIZED THIMBLE COPPER ACTIVITIES FOR EXPERIMENT G2A (Co rod)
Elevation location and Radius ( K9W K7W K5W K3W K3E K5E K7E K9E HO JO LO NO 88.58 68.90 49.21 29.53 29.53 49.21 68.90 88.58 51 .14 17.05 17 .05 51 .14 145 0. 715 0.703 135 0. 915 0.905 125 1. 087 1.070 i 115 1. 225 1.214 105 1. 335 1,321 95 0.975 1. 160 1. 407 1.519 1,.504 1.389 1.157 0.976 1.,388 1 .493 1.,504 1.,383 85 1.002 1. 183 (1. 441) 1.554 1 .541 (1.420) 1.183 0.998 1.,422 1 .533 1.,540 1.,413 75 0.996 1. 178 1. 433 1.550 1,.541 1.422 1.182 0.990 1.,413 1 .522 1.,536 I.,407 65 1. 386 1.362 55 1. 300 1.293 45 1.171 1.164 35 (1.,026) (1.015) 25 (0. 871) (0.852) 15 (O.,723) (0.714) TABLE 5: NORMALIZED THIMBLE COPPER ACTIVITIES FDR EXPERIMENT G2B (Cd rod) Elevation Location and Radius ( (cm) K9W K7W K5W K3W K3E K5E K7E K9E HO JO LO NO 88.58 68.90 49.21 29.53 29.53 49.21 68.90 88.58 51.14 17.05 17.05 51.14 175 (0.301) (0.306) 165 0.510 0.518 155 0.704 0.712 145 0.878 0.887 I 135 1.034 1.039 u> 125 1.153 1.174 115 1.255 1.267 105 1.329 1.348 95 0.993 1..154 1.363 1,.404 1.430 1.384 1.172 1.009 1.369 1.307 1,294 1.,353 85 0.995 1,.157 (1.365) 1.417 1.439 (1.383) 1.181 1.005 1.,374 1.,304 1.302 1.,353 75 0.978 1,.132 1.341 1,.388 1.410 1.353 1.154 0.983 1.,334 1.282 1.270 1.,334 65 1.283 1.299 55 1.188 1.201 45 1.071 1.085 35 (0.929) (0.942) 25 (0.784) (0.788) 15 (0.651) (0.653) TABLE 6: NORMALIZED THIMBLE CCJPER ACTIVITIES FOR EXPERIMENT G2C (Cd rod) Elevation Location and Radius (cm) (cm) K9W K7W K5H K3H K3E K5E K7E K9E HO JO LO NO 88.58 68.90 49.21 29.53 29.53 49.21 68.90 88.58 51.14 17.05 17.05 51.14 205 (0.035) (0.035) 195 (0.089) (0.,093) 185 (0.299) (0.,302) 175 0.489 0..493 165 0.665 0.,671 155 0.829 0.,837 145 0.970 0.,979 135 1.094 1..109 125 1.191 1.,203 115 1.270 1..275 105 1.312 1,.322 95 1.004 1,.152 1.325 1.462 1.360 1,.338 1.,164 1.006 1.,339 1.,370 1.326 1.,314 85 0.997 1,.135 (1.321) 1.453 1,.345 (1..324) 1..148 1.003 1,.323 1,,353 1.311 1..304 75 0.964 1,.103 1.282 1.409 1.310 1,.291 1,.119 0.973 1..286 1..314 1.272 1.,269 65 1.213 1..215 55 1.118 1.126 45 0.996 1.005 35 (0.865) (0.868) 25 (0.719) 10,.727) 15 (0.600) (0.601) TABLE 7: NORMALIZED THIMBLE COPPER ACTIVITIES FOR EXPERIMENT G2D (Cd rod) Elevation Location and Radius (cm) (cm) K9W K7W K5U K3W K3E K5E K7E K9E HO JO LO NO 88.58 68.90 49.21 29.53 29.53 49.21 68.90 88.68 51.14 17.05 17.05 51.14 205 (0.187) (0.187) 195 (0.368) (0.373) 185 0.543 0.544 175 0.701 0.705 165 0.850 0.848 155 0.978 0.982 145 1.097 1.095 r 135 1.188 1.183 125 1.248 1.254 115 1.301 1.290 105 1.319 1.320 95 1.030 1.159 1.315 1..413 1..419 1.314 1.170 1.031 1,,327 1.428 1.371 1.302 85 0.997 1.130 (1.286) 1,.384 1..399 (1.295) 1.144 1.003 1,.291 1.,398 1.340 1.,265 75 0.963 1.091 1.239 1.328 1,.336 1.235 1.098 0.964 1..239 1.344 1.287 1.,215 65 1.156 1.161 55 1.061 1.062 45 0.944 0.940 35 (0.809) (0.801) 25 (0.679) (0.673) 15 (0.588) - (0.555) -16- TABLE 8 RELATIVE Cu ACTIVITIES FOR Cd ABSORBER ROD OFF CENTRE 5 mm NORTH (G2B Type Core) MODERATOR Position Relative DATA Activity K3E-95 cm 1.053 K3E-85 c i - Critical Height K3E-75 cm 1.035 185.029+0.5 cm K3W-95 cm 1.060 K3W-85 cm 1.065 £^0 Temp. K3W-75 cm 1.045 23.49+0.10 °C LO-95 cm 0.926 LO-85 cm 0.930 DgO Puricy LO-75 cm 0.911 99.640+0.005X wt JO-95 cm 0.994 JO-85 cm 0.996 JO-75 cm 0.983 -17- TABLE 9 FITTED AXIAL DISTRIBUTION PARAMETERS Experiaent Location a dZ dz dz, Z H t u 1 o sex m cm cm cm cui G2A K5W 1.670 30.8 3.7 27.1 82.0 188.1 K5E 1.666 31.2 3.7 27.5 81.8 188.6 G2B K5W 1.552 31.6 3.9 27.7 88.5 202.4 K5E 1.554 31.3 3.7 27.6 88.5 202.2 G2C K5W 1.474 31.2 3.5 27.7 93.9 213.1 K5E 1.475 31.0 3.6 27.4 94.1 213.0 G2D K5W 1.374 31.3 3.5 27.8 101.5 228.6 K5E 1.371 31.9 3.8 28.1 101.5 229.1 G2E K5W 1.834 30.9 3.6 27.3 73.3 171.3 K5E 1.841 30.3 3.8 26.5 73.8 170.6 -18- TABLE 10 NORMALIZED WIRE ACTIVITIES FOR EXPERIMENT G2A (Co rod) Direction Radius (cm) N3O N60 N90 17.69 1.489 16.69 1.233 1.500 1.232 15.69 1 .327 1.487 1.324 14.69 1 .391 1.498 1.381 13.69 1.421 1.501 1.426 12.69 1.453 1.494 1.440 11.69 1.468 1.490 1.459 10.69 1 .477 1.489 1.478 9.69 1.483 1.483 1.472 8.69 1 .463 1.472 1.463 7.69 1.445 1.446 1.446 6.69 1 .412 1.410 1.409 5.69 1.354 1.343 1.356 A.79 1.272 1.262 1.261 -19- TABLE 11 NORMALIZED WIRE ACTIVITIES FOR EXPERIMENT G2B (Cd rod) Radius Direction (cm) N3O N6O N9O N N45 N180 N270 17 .39 1.284 16 .39 1.083 1.268 1.105 15 .39 1.135 1.255 1.154 14 .39 1.170 1.242 1.184 13 .39 1.179 1.237 1.197 12 .39 1.179 1.208 I.197 11,.39 1.162 1.191 1.184 10,.39 1.154 1.164 1.162 9,.39 1.123 1.135 1.134 8,.39 1.091 1.095 1.094 7..39 1.043 1.050 I,039 6,.39 0.978 0.985 0.949 5..39 0.925 0.924 0.809 4.,65 0.500 4.,50 0.845 0.844 4.,00 0 .5)3 0.544 0.833 0.517 0.540 3..50 0.646 3.,00 0. 703 0.706 0.796 0.703 2.,50 0.745 2.,00 0.755 0.747 0.768 0.763 1.,50 0.767 1.,00 0,.765 0.770 0.774 0.773 0.,50 0 .772 0.764 0.764 -20- TABLE 12 NORMALIZED WIRE ACTIVITIES FOR EXPERIMENT G2C (Cd rod) Radius Direction (cm) N3O N6O N9O N N45 N180 N270 17.39 1.323 16.39 1.380 1.312 1.061 15.39 1.359 1.295 1.118 14.39 1.324 1.274 1.139 13.39 1.292 1.243 1.155 12.39 1.262 1.220 1.153 11.39 1.232 1.197 1.153 10.39 1.191 1.156 1.128 9.39 1.149 1.121 1.103 8.39 1.101 1.080 1.057 7.39 1.042 1.022 0.996 6.39 0.971 0.972 0.913 5.39 0.903 0.902 0.778 4.65 0.475 4.50 0.825 0.830 4.00 0,,485 0.509 0.796 0.485 0.491 3.50 0.607 3.00 0,.683 0.678 0.777 0.674 2.50 0.706 2.00 0..733 0.727 0.745 0.732 1.50 0.738 1.00 0.,743 0.735 0.742 0.739 0.50 0.,737 0.742 0.736 TABLE 13 NORMALIZED WIRE ACTIVITIES FOR EXPERIMENT G2D (Cd rod) Radius Direction (cm) N3O N60 N9O N N45 N180 N270 17.39 1.336 16.39 1.334 1.329 1.340 15.39 1.319 1.293 1.327 14.39 1.229 1.314 1.298 13.39 1.271 1.268 1.269 12.39 1.233 1.235 1.242 11.39 1.199 1.212 1.211 10.39 1.165 1.165 1.163 9.39 1.123 1.119 1.124 8.39 1.072 1.058 1.066 7.39 1.007 1.014 1.000 6.39 0.947 0.948 0.912 5.39 0.875 0.880 0.764 4.65 0.469 4.50 0.800 0.797 4.00 0.478 0. 494 0.794 0 .431 0 .431 3.50 0 .589 3.00 0.655 0. 658 0 .744 0 .649 2.50 0 .686 2.00 0.699 0. 698 0 .729 0 .702 1.50 0 .711 1.00 0.720 0. 710 0 .711 0 .706 0.50 0.714 0 .706 0 .708 -22- TABLE 14 BAND SEGMENT ACTIVITIES Segment Degrees Band Activity From 62A G2B 62C G2D G2E # North K2E K4E K2E K4E K2E K4E K2E K4E K2E K4E I 16.36 0.967 0.933 0.844 0.896 0.815 0.839 0.821 1.168 1.029 2 49.09 0.986 0.944 0.864 0.906 0.829 0.847 0.838 1.172 1.038 3 81.82 0.978 0.948 0.878 0.910 0.830 0.861 0.835 1.163 1.039 4 114.55 0.977 0.944 0.883 0.908 0.836 0.853 0.833 1.163 1.039 '5 147.27 0.966 0.945 0.878 0.894 0.829 0.842 0.835 1.160 1.046 6 180.00 0.959 0.938 0.861 0.891 0.826 0.844 0.823 1.156 1.044 7 212.73 0.968 0.962 0.846 0.901 0.796 0.848 0.837 1.163 1.069 8 245.45 0.976 0.967 0.839 0.911 0.797 0.865 0.843 1.187 1.090 9 278.18 0.969 0.971 0.845 0.911 0.802 0.871 0.839 1.198 1.087 10 310.91 0.973 0.965 0.845 0.900 0.809 0.858 0.835 1.200 1.068 11 343.64 0.960 0.940 0.845 0.885 0.800 0.842 0.824 1.175 1.036 -23- TABLE 15 r/T/To VALUES Position Experiment G2A G2B G2C G2D G2E* (+0.0003) (+0.0015) (+_0.0007) (+0.0005) (+0.0006) K9W-85 cm 0.0087 0.0109 0.0097 0.0101 0.0097 K7W-85 cm 0.0222 0.0230 0.0219 0.0225 0.0223 K5W-85 cm 0.0237 0.0248 0.0236 0.0227 0.0224 K3W-85 cm 0.0239 0.0238 0.0180 0.0158 0.0249 K3E-85 cm 0.0238 0.0235 0.0219 0.0161 0.0252 K5E-85 cm 0.0240 0.0241 0.0243 0.0239 0.0218 K7E-85 cm CU0238 0.0225 0.0232 0.0216 0.0219 K9E-85 cm 0.0094 0.0108 0.0094 0.0110 0.0099 HO-85 cm 0.0245 0.0252 0.0232 0.0233 0.0234 JO-85 cm 0.0214 0.0249 0.0156 0.0086 0.0230 LO-85 cm 0.0216 0.0234 0.0157 0.0091 0.0229 NO-85 cm 0.0245 0.0259 0.0241 0.0241 0.0234 KO-75 cm - 0.0329 0.0195 0.0070 - KO-95 cm — 0.0323 0.0195 0.0081 - The In-Cu ratio at K3W was dropped in these calculations because of a relatively low value for the In activation (i.e. only the wheel and K3E reference locations were used in the averaging, the r/T/T0 value at K3W was derived from the K3W Cd ratio only). It is suspected that this low value was due to an error incurred during counting. -24- TABLE 16: In ACTIVATIONS AND Cd RATIOS USED FOR r DETERMINATIONS * Experiment Detector Position G2A G2B G2C G2D G2E K9W-85 cm 0.996 0.995 0.999 0.991 1.001 K7W-85 cm 1.409 1.356 1.336 1.322 1.427 K5W-85 cm 1.746 1.636 1.588 1.508 1.832 K3W-85 cm 1.889 1.677 1.630 1.493 2.109 K3E-85 cm 1.870 1.696 1.586 1.503 2.170 K5E-85 cm 1.728 1.642 1.606 1.541 1.824 In K7E-85 cm 1.436 1.375 1.375 1.323 1.421 K9E-85 cm 1.004 1.005 1.001 1.009 0.999 HO-85 cm 1.740 1.652 1.583 1.525 1.815 JO-85 cm 1.807 1.563 1.472 1.361 1.247 LO-85 cm 1.819 1.533 1.427 1.313 2.237 NO-85 cm 1.729 1.640 1.577 1.509 1.804 WHEEL-85 cm 0.162 0.166 0.171 0.174 0.154 KO-95 cm - 1.033 0.882 0.719 - KO-75 cm — 1.072 0.885 0.697 — Cu WHEEL-85 cm 0.180 0.193 0.197 0.204 0.181 KO-95 c« - 0.794 0.771 0.745 - KO-75 cm 0.819 0.774 0.734 Cd WHEEL-85 cm +25% 1534 1253 546 2453 1034 Ratio* K3W(corrected) 3.647 3.664 3.812 4.873 3.583 K3E * Normalized Cu activities not included in previous tables are also included. -25- TABLE 17 PARAMETERS USED IN r / T/T CALCULATIONS o Parameter Cu Foils In Foil Westcott g 1.000 Westcott SQ 0.893 18.8 Thermal neutron 0.975 0.999 self-shielding Resonance neutron 0.508 0.944 self-shielding F** °*917 K** 2.198 h 0.00001 W 0.335 * See reference (5) for g(T) polynomial, vrtiere T is set equal to the moderator temperature. ** See reference (3) for definitions. -26- Calandria Wall P 0 N M L K J I H G F 10 8 8 10 FIG. 1: ZEEP ROD REFERENCE LATTICE -27- Al wafer dinner Al tube (I.D. 8.10 cm, O.D. 8.57 cm) Outer Al tube (I.D. 8.89 am, O.D. 9.3? am) n D D N D D D -1 \ n D OS CJ i 9.04 am— FIG. 2: SECTION OF COBALT ABSORBER ROD -28- 258.8 cm Al wafers r- 15 am — 1 am Calandria Floor FIG. 3: COBALT ABSORBER IN ZED-2 -29- 257.9 am 1.57 mm k-15.5,rm Cd strip 44.5 am Cd strip 15.0 am Al tube 82.55 mm I.D. 2.67 mm wall Calandria Floor FIG. 4: DIAGRAMS OF Cd ABSORBER ROD -30- © Thimble Position FIG. 5: LATTICE USED FOR FLUX MEASUREMENTS (THE CENTRAL RODS ARE NOT BLACKENED BECAUSE THE CONTENTS OF THIS REGION VARY THROUGHOUT THE EXPERIMENTS) -31- N 30 N 60 N 90 N 270. N 180 FIG. 6: WIRE PLACEMENT ABOUT Cd ROD N 30 N 60 N 90 FIG. 7: WIRE PLACEMENT ABOUT Co ROD -32- ZEEP Rod WWWWW 85 CM Cu Band a) Cu band on ZEEP rod, side view. N W N I 11 S 10 i 9 i 8 ( 7 ! 6 •' 5 i 4 I 3 •' 2 «' 1 1 b) Cutting of Cu band. 270*' 180° a) Cu band on ZEEP rod* c/ioii izcjU.cn. FIG. 8: Cu BAND PLACEMENT FIG: 9 WIRE ACTIVITIES FOR G2A WIRE ACTIVITY VS. WIRE POSITION 1.54 i i I r T i i r --CO ABSORBER SURFACE 1.52 ~ • N3O 1.50 — x N6O _ + N90 1.48 1.46 SURFACE OF > 1.44 — K2E OR LIE- ZEEP ROD 1.42 — 1.40 — 1.38 ACT P 1.36 134 — WIR E 1.32 1.30 — 1.28 — 1.26 — 1.24 — 1.22 I I I J_l I I I I I 1 I 0 6'" S 10 12 14 16 18 20 WIRE POSITION (cm) FIG 10- WIRE ACTIVITIES FOR G2B WIRE ACTIVITY VS. WIRE POSITION 1.5 I I I I I • N30 H—Cd ABSORBER (Al TUBE) 1.4 - x N60 + N90 1.3 x M (inside Cd rod) A N45 1.2 1.1 1.0 SURFACE OF K2E OR LIE - .9 ZEEP ROD l±J 0T .6 .7 .6 jj] I 4 6 8 10 12 14 16 18 20 WIRE POSITION (cm) FIG. II: BAND SEGMENT ACTIVITIES FOR G2E SEGMENT ACTIVITIES VS ANGULAR POSITION (DEGREES FROM NORTH) + ROD K2E x ROD K4E i—i—r ~i i r i—i—r 1.25 1.20 UJ 1.15 1.10 ACTIV I 1.05 1.00 .95 SEGMEN T .90 J L_L I I I I 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 DEGREES FROM NORTH FIG. 12: BAND SEGMENT ACTIVITIES FOR G2A SEGMENT ACTIVITIES VS ANGULAR POSITION (DEGREES FROM NORTH) + ROD K2E x ROO K4E III 1 1 l l l l l | ll 1.05 — >- 1.00 > I .i - 1 • . «i 1 o "H -^=^5S=S*^ .95 ~ ¥ ¥ y n .90 UJ •85 l l ll 1 1 I 1 I i I 20 40 60 80 100 120 140 160 ISO 200 220 240 260 280 300 320 340 360 DEGREES FROM NORTH FIG. 13: BAND SEGMENT ACTIVITIES FOR G2B SEGMENT ACTIVITIES VS. ANGULAR POSITION (DEGREES FROM NORTH) + ROD K2E x ROD K4E > > LJ .80 20 40 60 80 100 120 140 160 BO 200 220 240 260 280 300 320 340 360 DEGREES FROM NORTH ISSN 0067 - 0367 ISSN 0067 - 0367 To identify individual documents in the series Pour identifier lea rapports individuals faisant we have assigned an AECL- number to each. partie de cette se>ie nous avons assign* un numim AECL- a chacun. Please refer to the AECL- number when re- Vauillez faire mention du numero AECL- si questing additional copies of this document vous demandez d'autres exemplaires de ce rapport from Scientific Document Distribution Office Service de Distribution des Documents Officials Atomic Energy of Canada limited L'Energie Atomique du Canada Umitee Chalk River, Ontario, Canada Chalk River, Ontario, Canada K0J1J0 KOJ 1J0 Price $4.00 per copy Prix $4.00 par exemplaire 396-82