| 1. |
- Dykin, Victor, 1985, et al.
(författare)
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Investigation of the space-dependent noise induced by propagating density fluctuations
- 2010
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Ingår i: International Conference on the Physics of Reactors 2010, PHYSOR 2010. - 9781617820014 ; 2, s. 963-978
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The space-dependent behavior of neutron noise induced by a propagating perturbation, represented by the fluctuations of the absorbtion cross section propagating with the coolant of a PWR, is investigated in a one-dimensional one-group approach. The general space-frequency problem is solved for this specific noise source with the help of Greens function technique. All calculations are made in the frame of first-order perturbation theory. The solution is investigated for a different frequencies and system sizes. The limits of point-kinetic and space-dependent behaviour were investigated. An interesting interference phenomenon was found between the point kinetic and the pure space dependent components of the noise for certain combinations of the frequency and system size. The results bear a significance for the dynamics of Molten Salt Reactors (MSR), which will be reported on in a companion paper.
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| 2. |
- Fernandez-Ordonez, M., et al.
(författare)
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Reactivity determination techniques in ads systems for the incineration of radioactive wastes
- 2010
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Ingår i: International Conference on the Physics of Reactors 2010, PHYSOR 2010. - 9781617820014 ; , s. 2933-2945
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Konferensbidrag (refereegranskat)abstract
- The Subcritical Accelerator Driven Systems (ADS) have been proposed as one of the strategies for reducing the inventory and radiotoxicity of the spent nuclear fuel. The reactivity monitoring of ADS has been found to play a key role in the development of this technology. Although the current-to-power technique has been proposed as the main reactivity monitoring technique, it is necessary to periodically calibrate it using additional techniques. In this work, the standard reactivity monitoring techniques using Pulsed Neutron Source experiments have been evaluated in the coupled fast-thermal subcritical assembly YALINA-Booster. In addition, a new method to measure the absolute value of the system reactivity is proposed by using micro-interruptions of the continuous external neutron source (beam-trips). This technique, used for the first time in a subcritical core, provided results compatible with the standard PNS methods and can be used in future power ADS. Even more, to allow instantaneous reactivity checks, we have developed and tested the necessary electronic chains and data acquisition system to determine the system reactivity during a single beam trip, thus allowing the determination of the reactivity within a second.
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| 3. |
- Larsson, Viktor, 1984, et al.
(författare)
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Neutron Noise Calculations Using the Analytical Nodal Method
- 2010
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Ingår i: Proc of PHYSOR 2010 - Advances in Reactor Physics to Power the Nuclear Renaissance, Pittsburgh May 9-14 2010. - 9781617820014 ; 2, s. 939-950
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Konferensbidrag (refereegranskat)abstract
- In this study, the neutron noise, i.e. the stationary fluctuations of the neutron flux around its mean value, is calculated in 2-group diffusion theory using the Analytical Nodal Method. A brief description of the calculation of the static flux is also included. The static solution is benchmarked against a reference solution in the case of a homogeneous core. The same calculational scheme for the neutron noise as for the static flux is used. As a dynamical benchmark, the calculated neutron noise for a 2D fully homogeneous reactor is compared with the analytical solution, which can easily be determined for homogeneous reactors, at different frequencies. The result of the benchmarks is that the numerical calculations using ANM accurately match the analytical solutions.
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| 4. |
- Pazsit, Imre, 1948, et al.
(författare)
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Reactor kinetics, dynamic response and neutron noise in molten salt reactors
- 2010
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Ingår i: International Conference on the Physics of Reactors 2010, PHYSOR 2010. - 9781617820014 ; 2, s. 979-999
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The dynamic space- and frequency dependent response of a Molten Salt Reactor (MSR) to stationary perturbations is investigated in a simple analytical model. The Green's function of the system is investigated in the general case of arbitrary fuel recirculation velocity and in the limiting case of infinite fuel velocity which permits closed form solutions both in the static and dynamic case. It is found that the amplitude of the induced noise is generally higher and the domain of the point kinetic behaviour valid up to higher frequencies than in a corresponding traditional system. This is due to the differing behaviour of the delayed neutron precursors as compared to the traditional case. The MSR equations are not self-adjoint and the adjoint equation and adjoint function have to be constructed, which is also done here. Finally the space-dependent neutron noise, induced by propagating perturbations of the absorption cross section is calculated. A number of interesting properties that are relevant to full size MSRs are found and interpreted. The results are consistent with those in traditional systems but the domains of various behaviour regimes (point kinetic, space dependent etc.) is shifted to higher frequencies or system sizes.
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| 5. |
- Sandberg, Urban, et al.
(författare)
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Shielding fuel assemblies used to protect the beltline weld of the reactor pressure vessel from fast neutron radiation in Ringhals unit 3 and 4
- 2010
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Ingår i: International Conference on the Physics of Reactors 2010, PHYSOR 2010. - LaGrange Park : American Nuclear Society. - 9781617820014 ; , s. 1534-1540
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Konferensbidrag (refereegranskat)abstract
- The beltline weld on the reactor pressure vessel of Ringhals units 3 and 4 has a lifetime estimate of 40 years under the current operating conditions. In the event of power up rates and lifetime extension the irradiation embrittlement of the beltline weld may be a limiting condition. One way to solve this problem is to limit the fast neutron radiation on the reactor pressure vessel. This paper will focus on a solution with specially designed assemblies for the positions that have the highest influence on the fast neutron dose for the beltline weld.
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| 6. |
- Sehgal, Bal Raj
(författare)
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Feasibility and desirability of employing the thorium fuel cycle for power generation
- 2010
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Ingår i: International Conference on the Physics of Reactors 2010, PHYSOR 2010. - 9781617820014 ; , s. 1951-1973
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Konferensbidrag (refereegranskat)abstract
- Thorium fuel cycle for nuclear power generation has been considered since the very start of the nuclear power era. In spite of a very large amount of research, experimentation, pilot scale and prototypic scale installations, the thorium fuel was not adopted for large scale power generation [1,2]. This paper reviews the developments over the years on the front and the back-end of the thorium fuel cycle and describes the pros and cons of employing the thorium fuel cycle for large generation of nuclear power. It examines the feasibility and desirability of employing the thorium fuel cycle in concert with the uranium fuel cycle for power generation.
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