摘要:

AbstractThe response of a reactor to step changes inδkis reviewed for two cases; small positive cangesh inδk, and changes inδkgreater thanβ. Analytical expressions are derived which give the negative change inδkrequired to terminate each type of excursion. Expressions for obtaining power overshoot are also obtained for each case for various types ofδkremoval. The analytical results are confirmed by more exact calculations with an analog and a digital computer. It is shown that to terminate an excursion produced by a change inδk<β, it is only necessary to reduceδkat a rate such that zeroδkis reached in about 2½sec. The fact that, to terminate a super-prompt-critical excursion, it is only necessary to reduceδkto a value equal to approximatelyβ, is demonstrated analytically.

ISSN:0029-5639    

DOI:10.13182/NSE59-A25599

出版商:Taylor&Francis    

年代:1959

数据来源: Taylor

摘要:

AbstractThe radioactive In116produced by the In115(n,γ) In116reaction has been utilized in a simple personnel monitoring device at the ORGDP for several years as a method for estimating the total radiation dosage received in the event of a possible accidental nuclear reaction. A 1-gm indium foil is placed in a standard plastic security badge; after a suspected exposure to an accidental burst, this foil is monitored by aβ-γsurvey meter, and the reading obtained used to determine the estimated dosage. A time-after-exposure correction factor is also used. For calibration of indium foil, an exposure to a light-water moderated critical reactor of highly enriched uranyl fluoride was evaluated and the results are indicated briefly. An instantaneous exposure of about 60 mrad is detectable immediately after an exposure even with the unsplit badges and one of about 120 mrad is detectable an hour after the occurrence.

ISSN:0029-5639    

DOI:10.13182/NSE59-A25600

出版商:Taylor&Francis    

年代:1959

数据来源: Taylor

摘要:

AbstractIt has been shown (1) that a two-delayed neutron group model will accurately represent the asymptotic behavior of the reactor transfer function. Correspondingly, the requirement that this asymptotic behavior be accurately represented is sufficient to specify completely the two-delayed neutron group constants. Further, a three-delayed neutron group model has been evolved which is designed to represent both the asymptotic behavior of the transfer function and shutdown behavior. The inhour equation, transfer function, and transient behavior for step inputs of reactivity with and without reactivity feedback loops for the two- and three-delayed neutron group representations are compared with those given by the standard one group and many delayed neutron group treatments. Important consequences of such reduced group representations are savings in machine time in making kinetic studies and increased tractability of the reactor kinetic equations.

ISSN:0029-5639    

DOI:10.13182/NSE59-A25601

出版商:Taylor&Francis    

年代:1959

数据来源: Taylor

摘要:

AbstractA method of computing thermal activation shapes in critical assemblies is formulated and compared with experiment. Corrections are made for local variations of the flux and for inadequacies of diffusion theory. For the assemblies studied, these corrections range between 4 and 10 per cent of the calculated thermal activation; a more important change of approximately 20 per cent is introduced by taking account of the core and reflector thermal spectra.

ISSN:0029-5639    

DOI:10.13182/NSE59-A25602

出版商:Taylor&Francis    

年代:1959

数据来源: Taylor

摘要:

AbstractThe use of the method of discrete ordinates as a numerical tool in reactor calculations is described. A scheme for the numerical integration of the discrete ordinate equations is developed, and the results compared with known exact solutions. The problem of reflection and transmission of neutron beams in stratified slab geometry is considered from the point of view of the method of discrete ordinates. A matrix formalism is derived which permits the calculation of transmitted and reflected distributions if the incident beam is given. Asymptotic expressions for the relevant matrices are given, and comparison is made with the work of Chandrasekhar. Tables of the matrix elements in the P7approximation are presented.

ISSN:0029-5639    

DOI:10.13182/NSE59-A25603

出版商:Taylor&Francis    

年代:1959

数据来源: Taylor

摘要:

AbstractA measurement of the Doppler temperature effect has been made in the fast spectrum of a mockup of the EBR-I reactor in ZPR-III. The effect was measured by thermal cycling samples of enriched uranium, natural uranium, and plutonium and detecting the small changes in reactivity. The pile oscillation technique using a resonant detector was employed to measure the small oscillating component of the neutron flux. An upper limit of 0.5×10−8Δk/ΔTwas obtained for a 506-gm sample of U235in the spectrum of an EBR-I mockup, and for a 235-gm sample of Pu239in a plutonium-fueled assembly of the same configuration. The results for natural uranium were inconclusive.

ISSN:0029-5639    

DOI:10.13182/NSE59-A25604

出版商:Taylor&Francis    

年代:1959

数据来源: Taylor

摘要:

AbstractAn experimental investigation was made of the statistical fluctuations in neutron intensity which occur in a nuclear reactor. An ion chamber was exposed to reactor flux, and the fluctuations in its output current were analyzed in a tunable bandpass filter to get the frequency spectrum of these fluctuations, which has the shape of the square modulus of the transfer function. Results are presented of some measurements made on various low-power experimental reactors at Argonne National Laboratory. For reactors with prompt neutron lifetime between 15 and 70μsec, the quantityl/βwas determined within 5 per cent or better from a least squares fit to the transfer function thus measured.

ISSN:0029-5639    

DOI:10.13182/NSE59-A25605

出版商:Taylor&Francis    

年代:1959

数据来源: Taylor

摘要:

AbstractAn integral equation is derived for the function giving the average number of collisions required to thermalize neutrons by elastic collisions with nuclei of relative massM. An asymptotic solution is obtained which corrects the customary result by betweenand 1 collision (depending onM). Numerical results for small lethargy increments are presented for the casesM= 2 andM= 235.

ISSN:0029-5639    

DOI:10.13182/NSE59-A25606

出版商:Taylor&Francis    

年代:1959

数据来源: Taylor

摘要:

AbstractThe thermal neutron energy spectrum in a homogeneous medium has been studied by many authors. In case of heterogeneous reactors, the absorption in fuels is so strong that the thermal neutron energy spectrum in the fuel will have a higher energy than in the moderator. The different temperatures of these media will also cause a difference of spectra. The thermal neutron energy spectra of each medium in a heterogeneous reactor are studied in this paper. The thermal neutron energy spectrum and the neutron temperature in light-water moderated and UO2fueled reactors were calculated by a numerical method and the approximate Wigner-Wilkins method.

ISSN:0029-5639    

DOI:10.13182/NSE59-A25607

出版商:Taylor&Francis    

年代:1959

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE59-A25608

出版商:Taylor&Francis    

年代:1959

数据来源: Taylor