Two-region kinetic model for reflected reactors

Spriggs, G.D.; Busch, R.D.; Williams, John G.

doi:10.1016/0306-4549(96)00062-x

Cited by 54 publications

(34 citation statements)

References 17 publications

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“…Moreover, the f cr parameter is found using the fraction of system neutrons absorbed in the core as Spriggs et al described (Spriggs et al, 1997). 1 Furthermore, Λ c and Λ r are estimated by the same technique as described in section 2.1 by partially poisoning the sub regions of the complete model of ELECTRA:…”

Section: Methodsmentioning

confidence: 99%

“…Spriggs et al (Spriggs et al, 1997) pointed out that the static reproduction time is predicted by the perturbation method whereas the dynamic reproduction time could correspond to the Rossi-alpha experimental result. According to Avery-Cohn's model, the point kinetics equivalent reproduction time would be the dynamic reproduction time.…”

Section: Electra Assembly Only Model In a Reflectormentioning

confidence: 99%

“…Avery-Cohn (Avery et al, 1958;Cohn, 1961Cohn, , 1962 proposed the method of arbitrarily subdividing the multiplying system where each region considered has a multiplication factor contribution k i and an effective neutron lifetime l i and the idea was further developed by Spriggs et al (Spriggs et al, 1997). If we divide the reactor into two regions: core and the reflector, then the simplified inhour equation would become, according to Avery-Cohn theory as shown by Spriggs et al:…”

Section: Avery-cohn's Two-region Prompt Neutron Modelmentioning

confidence: 99%

“…In such reactors, it is known that the kinetic parameter Λ becomes extremely sensitive to the geometry and composition of the reflector region. Therefore, a reliable evaluation of Λ in these systems is difficult to accomplish (Spriggs et al, 1997;Dulin et al, 1997). In ELECTRA, the presence of rotating absorbers in the reflector adds complexity to the geometry and introduces streaming effects, which are challenging to treat with deterministic neutron transport tools.…”

Section: Introductionmentioning

confidence: 99%

“…However, it is known in the literature that in some reflector dominated cases that simple point kinetics is not satisfactory for dynamic modeling (Vollaire, 2004) meaning that applying a single average value for Λ is not sufficient. More detailed dynamic models may need to be considered, including for instance, a two-region prompt neutron reproduction time (Spriggs et al, 1997;Avery et al, 1958;Cohn, 1961Cohn, , 1962). Thus we should investigate whether the time behavior of ELECTRA can be represented by a single reproduction time (evaluated by the above methods), or if multiple region reproduction times should be defined.…”

Section: Introductionmentioning

confidence: 99%

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An assessment of prompt neutron reproduction time in a reflector dominated fast critical system: ELECTRA

Suvdantsetseg

Wallenius

2014

Annals of Nuclear Energy

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In this paper, an accurate method to evaluate the prompt neutron reproduction time for a reflector dominated fast critical reactor, ELECTRA, is discussed. To adequately handle the problem, explicit time dependent Monte Carlo calculations with MCNP, applying repeated time cut-off technique, is used and compared against the σ ∼ 1/v time dependent absorber method, applying artificial cross section data in the Monte Carlo code SERPENT. The results show that when a reflector plays a major role in criticality for fast neutron reactor, the two methods predict different physical parameters (Λ = 69 ± 2 ns and Λ = 83 ± 1 ns for time cut-off and the 1/v method respectively). The reason is explained by applying Avery-Cohn's two-region prompt neutron model.

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Section: Methodsmentioning

confidence: 99%

Section: Electra Assembly Only Model In a Reflectormentioning

confidence: 99%

Section: Avery-cohn's Two-region Prompt Neutron Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

An assessment of prompt neutron reproduction time in a reflector dominated fast critical system: ELECTRA

Suvdantsetseg

Wallenius

2014

Annals of Nuclear Energy

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On the rossi-α measurement of βeff in reflected reactorsin reflected reactors

Dulin¹,

Spriggs²

1997

At Energy

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In unreflected reactors, the probability of detecting chain-related counts is given by the well known Rossi-a expression as originally derived by Feynman [1-2] D k2C ..where C is the detector count rate, D is the adjoint-weighted neutron dispersion factor (i.e., D = gI'), F is the total fission reaction rate, k is the effective multiplication factor, r is the adjoint-weighted neutron removal lifetime, and [~x[ is the magnitude of the alpha-eigenvalue, defined by I a =-It -k0 -~)1 (2) T where B is the effective delayed neutron fraction. The integral of the correlated part of Eq. (1) is given by s -.rico -a) 2 ~._~... (3) zr 721o, i = Using the definition of alpha from Eq. (2) and using the &fruition of the magnitude of the reactivity of the system (in units of dollars), IOsl ffi ~. (4) Eq. (3) can also be written as ZF 02(1 + IosL) 2 (5) Solving for/3 in Eq. (5) yields the following expression [3]:We shall now demonstrate that this expression for/3 is equally applicable for a reflected system in which two alphas are experimentally observed. We begin by assuming the Rossi-ot solution for a simple reflected system as derived by Kistner [4]. That is, R(t)dt = Cdt + Ale-lC*,ltdt + A2e-I~'-Itdt (7) Institute of Physics and Power Engineering, Bondarenko sq., Obninsk, Kaluga Region, Russia. Los

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