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Description: A mechanism for shutting off a power excursion in a homogeneotns reactor by the rapid formation of bubbles was investigated. Equations are derived which give upper and lower bounds for the radius of a bubble, as a function of time, under conditions present in a reactor. Deduction of the bubble nuclei growth rate from observations of void volume and pressure can be made. (auth)
Date: January 15, 1960
Creator: Flatt, H. P.
Partner: UNT Libraries Government Documents Department


Description: The velocity of sounmd in water containing bubbles of hydrogen gas is computed as a function of the volume fraction of gas for various bubble sizes. Results indicate that the marked reduction in sound velocity caused by the presence of gas voids is not as great if the gas is present as very small bubbles. The results are used in qualitative observations concerning inertial pressures in fast excursions in the KEWB reactor. The qualitative conclusions are listed. (J.R.D.)
Date: November 1, 1958
Creator: Hetrick, D.L.
Partner: UNT Libraries Government Documents Department

Estimates of fission yields in nuclear criticality excursions

Description: There is a need for computer simulation of hypothetical criticality excursions involving significant quantities of fissionable materials, especially in fissile aqueous system. The need arises due to the requirements for the emergency planning of facilities where the fissionable materials are handled, processed, or stored; and the regulatory requirements associated with facility operation or conversion. It is proposed here that a data base of fission yeilds for critical experiments and known accidents (both aqueous and solid) should be generated by using existing or new computer codes. The success in compiling this data base would provide useful source-terms for criticality excursions, realistic estimates of emergency-response boundary, as well as a replacement for the ``rule-of-thumb`` or ``bounding`` method. 10 refs.
Date: June 1, 1995
Creator: Choi, J.S.; Thompson, J.W. & Reed, R.
Partner: UNT Libraries Government Documents Department

Dynamic Properties of Heterogeneous Water Reactors

Description: The types of tests performed in SPERT-I, and the tests proposed for SPERT-II and -III, are described. These reactors are described, and factors influencing their dynamic behavior are discussed. The tests are classed as static, step, ramp, and oscillatory. The correlation between the test results and the reactor dynamic safety characteristics (stability, self-shutdown under excursion conditions, etc.) is investigated. (T.F.H.)
Date: July 20, 1961
Creator: Forbes, S. G. & Nyer, W. E.
Partner: UNT Libraries Government Documents Department


Description: A description is given of a program by which the behavior of a nuclear reactor during various thermal transients may be studied. The program is written for a 32,000-word IBM-704 computer with six tape units. It is designed to predict the behavior of a water-cooled and moderated reactor with flat plate fuel elements during transients which are slower than a prompt excursion and during which the reactor flow. inlet temperature, and control rod motion may be specified as a function of time. (auth)
Date: November 1, 1959
Creator: Meyer, J.E.; Smith, R.B.; Gelbard, H.G.; George, D.E. & Peterson, W.D.
Partner: UNT Libraries Government Documents Department

A Status Report on Reactivity Coefficients in Fast Reactors and Methods of Investigating Their Effects on Reactor Stability

Description: BS>Methods for predicting the stability of fast reactors in the presence of both positive and negative reactivity coefficients are surveyed. Experimental methods of determining reactor stability are reviewed: excursion, transient, and oscillator. Sources of reactivity coefficients are discussed for both zero power and nonzero power operation. Representative reactivity coefficient values are presented, and positive coefficients due to Doppler effect, fuel bowing, and sodium coolant expansion are discussed. (D.L.C.)
Date: March 1, 1961
Creator: Agresta, J.
Partner: UNT Libraries Government Documents Department


Description: A calculation, coded for a fast computer, is discussed that can fairly accurately match the experimental resuIts obtained from the LASL Lady Godiva prompt burst program. In particular, the code can predict the reactivity where the burst yield deviates from a linear dependence on reactivity and commences to rise much more rapidly. The burst width and maximum rates can be predictcd with reasonable accuracy. The calculation is applied to other simple systems, with the result that there appear to be general rules that one can use to relate the bursts of thcse systems. The calculation can predict what fraction of the energy of the system is converted into kinetic energy. It appears that step-function increases of reactivity of about 1O cents or less in homogeneous metal systems develop only a trivial explosive energy. The method was extended to hypothetical accidents in very idealized reactors. Two general models of reactor cores were considered. These are (1) a core of low density in which the characteristic o a threshold is important, and (2) a model in which the spherical shells are alternately normal density and void. The numbers quoted should be regarded only as establishing upper and lower limits. (auth)
Date: January 1, 1957
Creator: Stratton, W.R. & Colvin, T.H.
Partner: UNT Libraries Government Documents Department


Description: Design, testing, and early operation of the Argonne Low Power Reactor (SL- 1) that was subsequently destroyed in a nuclear incident are reviewed. Motives determining the design of the control system are explained; and information from tests, operation, and the incident itself is analyzed for the purpose of improving reactor design and operation. (D.C.W.)
Date: November 1, 1962
Creator: Kann, W.J. & Shaftman, D.H.
Partner: UNT Libraries Government Documents Department


Description: The Early Program is designed to compute the peak power and total energy release vhich will occur in a reactor due to a step increase of reactivity. These excursions may be terminated by one of several automatic shutoff mechanisms caused by the power excursion itself. The calculation assumes no thermodynanaic delays and assumes void formation is due to heat conduction from the cladding to the moderator. (W.D.M.)
Date: February 26, 1959
Creator: Reiback, E.M. & Stueck, C.J.
Partner: UNT Libraries Government Documents Department


Description: An experimental determination of the reduced prompt neutron generation time LAMBDA / BETA in the Spert IV reactor utilizing a technique based on the statistical behavior of the neutron population is described. A mathematical model including the effects of delayed neutrons that relates the statistic variance-to-mean ratio of the count rate as a function of counting time'' to integral reactor parameters is derived. This model is used in conjunction with subcritical counting measurements from the Spert IV reactor to provide a value of LAMBDA / BETA that is in good agreement with an independent measurement obtained from super promptcritical excursion experiments. (auth)
Date: August 1, 1963
Creator: Johnson, R.L.
Partner: UNT Libraries Government Documents Department

Flow excursion time scales in the advanced neutron source reactor

Description: Flow excursion transients give rise to a key thermal limit for the proposed Advanced Neutron Source (ANS) reactor because its core involves many parallel flow channels with a common pressure drop. Since one can envision certain accident scenarios in which the thermal limits set by flow excursion correlations might be exceeded for brief intervals, a key objective is to determine how long a flow excursion would take to bring about a system failure that could lead to fuel damage. The anticipated time scale for flow excursions has been examined by subdividing the process into its component phenomena: bubble nucleation and growth, deceleration of the resulting two-phase flow, and finally overcoming thermal inertia to heat up the reactor fuel plates. Models were developed to estimate the time required for each individual stage. Accident scenarios involving sudden reduction in core flow or core exit pressure have been examined, and the models compared with RELAP5 output for the ANS geometry. For a high-performance reactor like the ANS, flow excursion time scales were predicted to be in the millisecond range, so that even very brief transients might lead to fuel damage. These results should prove useful whenever one must determine the time involved in any portion of a flow excursion transient.
Date: April 1995
Creator: Sulfredge, C. D.
Partner: UNT Libraries Government Documents Department

FFTF transient overpower accident: a perspective

Description: This paper is a reflection on the current understanding of the unprotected transient overpower (TOP) accident, in order to place it in perspective with regard to FFTF core energetics. The experimental data base is addressed, wtih particular emphasis on the E and H-series data, and its relevance to axial failure location and hydraulic fuel sweepout is considered. It is shown that the only way in which TOP could lead to a sizeable energy release is if either total plugging takes place or a plug at the radial center of the subassemblies propagates to the hex can walls prior to neutronics shutdown. (DLC)
Date: February 1, 1975
Creator: Waltar, A.E.
Partner: UNT Libraries Government Documents Department

Runaway electron damage to the Tore Supra Phase III outboard pump limiter

Description: Operation of the Phase III outboard pump limiter (OPL) in Tore Supra in 1994 was terminated prematurely when runaway electrons during the current decay following a disruption pierced leading edge tube on the electron side and caused a water leak. The location, about 20 mm outside the last closed flux surface during normal operation, and the infrared (IR) images of the limiter indicate that the runaways moved in large outward steps, i.e. tens of millimeters, in one toroidal revolution. For plasma (runaway) currents in the range of 155 to 250 kA, the drift orbits open to the outside. Basic trajectory computations suggest that such motion is possible under the conditions present for this experiment. Activation measurements made on sections of the tube to indicate the area of local damage are presented here. An understanding of this event may provide important guidance regarding the potential damage from runaways in future tokamaks.
Date: August 1996
Creator: Nygren, R.; Lutz, T.; Walsh, D.; Martin, G.; Chatelier, M.; Loarer, T. et al.
Partner: UNT Libraries Government Documents Department

Proceedings of the 1960 Idaho Conference on Reactor Kinetics Held at Sun Valley, Idaho, October 12-14, 1960

Description: >Thirty papers are included on reactor kinetics with emphasis being placed on reactor safety and design considerations resulting from kinetic work. Information is presented on power excursion programs, reactor transfer function determination and application, reactor instability and thermal-hydraulic problems, and analytical methods in reactor kinetics. The accomplishments in the field and areas needing emphasis are discussed and summarized. Constructive suggestions are made on program direction and information dissemination. Separate abstracts were prepared for each paper. (N.W.R.) lOl2 Data and analytical work on various power excursion tests are summarized and discussed in order to show the present position and understanding of reactor kinetics under accident conditions. The results show that our understanding of plate-type, water-moderated systems of the low power research type seem to be in good shape. On the other hand, information on radiolytic gas formation and transient boiling phenomena is not understood too well. Data are primarily presented on safety experiments with SPERT I and KEWB; however, some information is presented on power excursion tests of Borax I, SPERT III, Triga, Treat, and Godiva. Results show that the problem of predicting the response of reactor systems is on a much firmer basis, even without knowing very much about details. (N.W.R.)
Date: July 1, 1962
Creator: Haire, J. C. & Bright, G. O.
Partner: UNT Libraries Government Documents Department