ML19347A386
| ML19347A386 | |
| Person / Time | |
|---|---|
| Site: | University of Buffalo |
| Issue date: | 09/23/1963 |
| From: | NEW YORK, STATE UNIV. OF, BUFFALO, NY |
| To: | |
| References | |
| NUDOCS 8104080570 | |
| Download: ML19347A386 (4) | |
Text
V - REACTIVITY REQUIREMENIS ll O For the referen.:o six-by-five loading, with the thermal column ia place, the reactivity requirements at an ambitat tem-porature of 72 F for two megawatt, design pulse operation are tabulated below:
Item
% delta k/1(
Temperature Coefficient 1.05 (Ambient to apecating) o
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In Core Experiments 2.00 Beam Tubes and Conveyors 0.73 Burnup 2.37 Equilibrium Xenon 1.19 Equilibrium Samarium 0.83 Power Coefficient 0.35 Design Pulse 1,63 10.15
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+ 1.40 Thermal Column Net fuel contribution 8.75 1
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A.
Temperature C., efficient The temperacure coefficient of reactivity is calculated to be
-3 x 10-2% delta L/k per F* for the 9 mperature range of 100* 7 to 140 F.
For temperature rise of 35 F (from cold, to design water temperature), the required excess reactivity to compensate for the temperature coefficient is calculated to be 1.05% delta k/h.
B.
In-Core E:meriments The total worth of all experiments installed in the reactor core will be limited to 2.0% delta h/h. No individual operiment c,
will have a negativo reactivity in excess of 1.;I delta h/k.
C.
Beam Tubes and Pneumatic Conveyors The reactor presently contains six 6-inch diameter beam tubes, one 12-inch square chamber, and two rabbit tubes. The beam tubes
-I can be flooded'.ith water or operated dry. T,ccause the Ucrmi acc of neutrons in the oxide core and in the previous 1{rR-type core J ""
differ only slightly, ths reactivity requiracents of these voided chambers are expected to be similar to the previously measured values:
Six 6-inch beam tubes 0.12% delta k/h 1I One 12-inch square tube 0.50 j,
Two 2-inch rabbit tubes 0.03 TOTAL 0.73% delta k/k D.
grnup. and Lotr Cross Section Fission Products
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l For.1000-day operation at a therual power of 2000. kilowatts, an excess reactivity of 2.37% delta h/k will be required to compensate E
- Ig for the loss of U-235 by burnup, and for the accumulation of low
,;L cross section fission products.
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I il E.
Equilibrium Xction h-At 2000 kilowatts, the average thermal flux in the fuel will i
1 2
be 2.77 x 10 n/cm /sec. At this flux level, the excess reactivity j-to compensate for equilibrium xenon is calculated to be 1.19% delta k/k.
After 1-1/2 days of continuous operation at 2000 kilowatts, the maxiuum xenon override was calcula*ed to be approximately 1.25%
delta k/k, occurring at about three hours after shutdown.
I F.
Partini Sannriun (30 dovs)
Samarium-149 is a stabic isotope formed during the fission process.
Its equilibrium level is independent o f the core neutron flux. It has been determined that the excess reactivity required for scmarium during a nominal period of operation will be 0.83% delta k/k.
G.
Power Coefficient I
The computed Doppler coefficient for the range of interest (100 F to 332 F, the average oxide fuel temperatures for criticality
-5 and 2 megawatts) is -1.5 x 10 delta k/k/ F.
The total change in reactivity over this increment is therefore 0.35% delta k/k.
H.
Thermal Column The lead nosepiece of the thermal column constitutes a reflector, and as such, represents a reactivity savings of 1.4 delta k/k.
I, Pulco Renetivity Requirements The calculated reactivity inputs necessary to produce the routino pulse of 39.5 megawatt seconds, and the design pulse of '89 megawatt seconds, are 1.17 and 1.63% delta k/k respectively.
I
0 J.
Lona, Teru Opo ntion Uithout provision for pulsing the reactor, burnup has been calculated to be 11,300 megawatt-days /conne of UO ; however, since 2
1.177. delta k/h is required to initiato a routine pulse of 39.5 I
megawatt-ceconds release, burnup will be limited to 8,900 cegauatt-days /conne, and core lifetime vill therefore be approximately 2000 days at 2 megavatts.
K.
Typical core Londing, and control Rod Effects Calculations for physical and performance characteristics of the il reactor vore based upon a core containing 30 fuel assemblies (Figure 19 ), or 370 kilograms of uranium,
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For this configuration, calculations show that the worths for the four shim safety, the regulating, safety and the transient rods are as follous:
t Rod
-7, delta k/k Shim Safety No.1 5.34 Shim Safety No. 2 0.21 m
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Shim Safety No. 3
- 5. '*4 l,
Shin Safety No. 4 5.34 L
Regulating Safety 3.54 l-Transiant 3.54 i
TOTAL 31.31 The minimum shutdown margin is predicted, therefore, to be 21.27, delta k/h, not considering the positive reactivity contribution of the thermal column nosepiece.
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