CONTRIBUTIONS TO TWO PROBLEMS IN SPACE-INDEPENDENT, NUCLEAR-REACTOR DYNAMICS: I. CALCULATION AND MEASUREMENT OF THE REACTOR DESCRIBING FUNCTION. II. ANALYSIS OF THE EFFECT OF A REFLECTOR ON REACTOR DYNAMICS (thesis)
Submitted to Massachusetts Inst. of Tech., Dept. of Chemical Engineering, Cambridge. Analytical and experimental studies on the describing function of a nuclear reactor and analytical studies on the effect of a refiector on reactor dynamics were carried out. Earlier analytical work on the reactor describing function both at low and high power levels was substantially extended and clarified. Some of the earlier results on the high-power reactor describing function were shown to be incomplete or incorrect. Several IBM-650 programs were written to facilitate accurate calculation of the low- and high-power reactor describing function for a variety of reactor types, and illustrative calculations were presented. The analytical results for the low-power describing function were confirmed by pile-oscillator, frequency-response measurements in a small, enriched, plate-type, H/sub 2/Omoderated and -refiected reactor (the Spert-I P-18/ 19 reactor), for reactivity amplitudes up to 145 and for frequencies from 0.002 to 18.4 cps. A reflector-located, rotary, reactivity-oscillator mechanism of adjustable reactivity amplitude was used. Agreement between the experimental and theoretical describing-function results was shown to be better when a slightly modified version of Keepin and Wimett's U/sup 235/ fast-fission delayed- neutron data were used for the calculations than when Keepin and Wimett's thermal- fission data were used, regardless of the reactivity amplitude or the method of data handling. By means of tests with the neutron detector placed in various positions about the core periphery, the space and time variations of the neutron density, for a reactivity amplitude of 064 and frequencies up to 18.4 cps, were shown to be separable everywhere except in the immediate vicinity of the asymmetrically located oscillator. The prompt-neutron generation time was deduced from the experimental results and found to be in good agreement with results obtained in short-period, step-transient tests and in static, l/v-poison perturbation tests. Analysis of the effect of a reflector on reactor dynamics showed that, under appropriate conditions, the effective lifetime of a reflected reactor can become frequency-dependent at high frequencies, causing the reactor response to rapid reactivity changes to differ from that of an equivalent bare reactor having the same lifetime as the reflected reactor at criticality. Several aspects of this phenomenon were examined, and the results of a number of previously reported experiments illustrating this effect were summarized. (auth)
- Research Organization:
- Phillips Petroleum Co. Atomic Energy Div., Idaho Falls, Idaho
- DOE Contract Number:
- AT(10-1)-205
- NSA Number:
- NSA-16-028365
- OSTI ID:
- 4811316
- Report Number(s):
- IDO-16755
- Country of Publication:
- United States
- Language:
- English
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CONFIGURATION
CROSS SECTIONS
DELAYED NEUTRONS
DIFFERENTIAL EQUATIONS
ERRORS
FREQUENCY
FUEL ELEMENTS
LIFETIME
MEASURED VALUES
NEUTRON DETECTION
NEUTRON FLUX
PERTURBATION THEORY
PLATES
PROMPT NEUTRONS
REACTIVITY
REACTOR CORE
REACTOR OSCILLATORS
REACTOR TECHNOLOGY
REACTORS
REFLECTORS
TRANSFER FUNCTIONS
TRANSIENTS
VARIATIONS
WATER MODERATOR