SPERT PROJECT. Quarterly Technical Report, October-December 1962

Technical Report · Fri May 17 00:00:00 EDT 1963

OSTI ID:4695326

Schroeder, F ed

A successful integral-core destructive test was performed in the Spert I facility with a highly enriched, platetype, water-moderated core. A 3.2-msec- period power excursion was initiated by an essentially stepwise addition of 3.5 dollars of reactivity The excursion was self-limiting, with a peak power of 2.3 Gw and with a nuclear energy release in the burst of 31 Mw-sec. After the nuclear excursion had self-limited and the power had returned to a level of about 5% of the peak value, a sudden pressure rise occurred which disassembled the core and produced widespread damage to associated equipment. The maximum fuel alloy temperature was slightly in excess of 1200 deg C, in agreement with calculations based on the measured nuclear energy release. The characteristics of the nuclear burst for the destructive test were in agreement with predictions based on extrapolation of the results of previous nondestructive tests. The peak pressure in the explosion, which occurred after the nuciear burst, was of the order of several thousand psi and the rise time of this pressure puise was significantly less than 1 msec. A series of static experiments was performed in the Spert II facility for a close-packed core with D/sub 2/O as the moderator in order to obtain information to aid in the design of necessary structural components for kinetic testing of this type of core under various initial system conditions, including forced coolant flow. Critical experiments were performed and a 57- assembly core was determined to have a cold, clean excess reactivity of 9.6 dollars and a shutdown reactivity margin of about 6.6 dollars. A 52-assembly core having a shutdown margin of about 10 doilars was used for a series of reactivity worth measurements of fuel assemblies in various positions on the core perimeter and of typical structural components in the reflector region around the core. An experimental program was undertaken in the Spert lV reactor to determine if any significant changes in neutron flux distribution, ion chamber power calibration, or reduced prompt neutron lifetime could be measured as a result of a large population of voids in the central region of the core, such as might arise during an excursion test. The thermal neutron flux in the center of the core is depressed by the presence of voids, and the flux spectrum is slightly hardened. However, the power calibration of typicai neutron-sensitive ion chambers in the reflector and the value of the reduced prompt neutron lifetime (measured by analysis of statistical fluctuations of the core neutron population) are relatively insensitive to the presence of a centrally located void population worth approximately two dollars in reactivity. The isothermal temperature coefficient for the Spert PIV core was measured over the temperature range of approximately 20 to 35 deg C and found to vary from --0.7 to --1.2 DEC. An analysis was performed of the dynamics of reflector-perturbed reactors. This analysis has shown that the dynamic behavior of a reflected reactor perturbed by changes within the reflector differs both from the behavior of the statically- equivalent bare reactor and from the behavior of the same reflected reactor perturbed within the core, because the perturbation alters the values of the reflector delayed-group parameters. While for the case of a reflected reactor perturbed in the core it is possible to out-run the reflected neutrons, for the reflectorperturbed case this is not possible. Thus, the parameters which define the inhour relation or the transfer function representing the response of the reactor to reactivity feedback mechanisms acting within the core cannot be completely determined by experiments in which reflector perturbations are used to vary the reactivity of the system. An illustrative example is presented for an enricheduranium, plate-type D/sub 2/O-moderated and -reflected reactor. (auth)

• Research Organization: Phillips Petroleum Co. Atomic Energy Div., Idaho Falls, Idaho
• DOE Contract Number: AT(10-1)-205
• NSA Number: NSA-17-028436
• OSTI ID: 4695326
• Report Number(s): IDO-16890
• Resource Relation: Other Information: Orig. Receipt Date: 31-DEC-63
• Country of Publication: United States
• Language: English

Related Subjects

REACTOR TECHNOLOGY
ACCIDENTS
ALLOYS
BUBBLES
CONFIGURATION
COOLANT LOOPS
COOLANTS
CRITICALITY
DELAYED NEUTRONS
DISTRIBUTION
EXCURSIONS
EXPLOSIONS
FLUID FLOW
FUEL ELEMENTS
FUELS
GROUP THEORY
HEAVY WATER MODERATOR
HIGH TEMPERATURE
INHOURS
IONIZATION CHAMBERS
LIFETIME
MEASURED VALUES
NEUTRON DETECTION
NEUTRON FLUX
NUMERICALS
PERFORMANCE
PLANNING
PLATES
POWER
PRESSURE
PROMPT NEUTRONS
PULSES
REACTIVITY
REACTOR CORE
REACTORS
REFLECTORS
SHUTDOWN
SPECTRA
SPERT-1
SPERT-4
STANDARDS
STATISTICS
TEMPERATURE
TEMPERATURE COEFFICIENT
TESTING
THERMAL NEUTRONS
TRANSFER FUNCTIONS
URANIUM
WATER MODERATOR
ZONES