| 1. |
- Abbondanno, U, et al.
(författare)
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The data acquisition system of the neutron time-of-flight facility n_TOF at CERN
- 2005
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 538:1-3, s. 692-702
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Tidskriftsartikel (refereegranskat)abstract
- The n_TOF facility at CERN has been designed for the measurement of neutron capture, fission and (n, xn) cross-sections with high accuracy. This requires a flexible and-due to the high instantaneous neutron flux-almost dead time free data acquisition system. A scalable and versatile data solution has been designed based on 8-bit flash-ADCs with sampling rates up to 2 GHz and 8 Mbyte memory buffer. The software is written in C and C++ and is running on PCs equipped with RedHat Linux.
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| 2. |
- Bécares-Palacios, V., et al.
(författare)
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Reactivity monitoring with imposed beam trips and pulsed mode detectors in the subcritical experiment YALINA-Booster
- 2009
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Ingår i: Proceedings of International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators. - : International Atomic Energy Agency. - 9789201504104
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Konferensbidrag (refereegranskat)abstract
- Reactivity monitoring is one of the urgent problems that require a solution in order to achieve a license for a future full-scale ADS. As a part of the EUROTRANS experiments at the YALINA-Booster facility, presented in this conference, a set of measurements with imposed beam-trips has been performed. Traditionally, the source jerk method has been used in subcritical systems to obtain the reactivity by comparing the total neutron flux before the neutron source removal to the semi-stable delayed neutron flux after the source removal. The deuterium-tritium neutron source of the YALINA-Booster facility can, in addition to pulsed mode operation, operate with continuous beam with short imposed millisecond-scale interruptions, thus providing the possibility to monitor the reactivity at each beam trip in the source jerk manner. In order to test the validity of the beam-trip reactivity values determined by using detectors operating in current-mode (also presented in this conference), the reactivity values of the YALINA-Booster assembly obtained through the beam-trip technique using pulsed-mode detectors is presented in this work. In these experiments, a beam-trip frequency of 1 Hz and an interruption time of ∼20 ms have been chosen and two different core loadings with effective multiplication factor around 0.95 have been investigated. These two different loadings with close to equal reactivity but different source multiplication characteristics make it possible to explore the effect of the different source multiplications. In addition, the response of the imposed beam-trip reactivity monitoring technique to reactivity insertions and removals has been studied through control rod movements. Experimental data from fission chambers have been acquired from all three zones of the core: the fast booster zone, the thermal zone and the reflector.
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| 3. |
- Becares, V., et al.
(författare)
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Evaluation of the criticality constant from Pulsed Neutron Source measurements in the Yalina-Booster subcritical assembly
- 2013
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Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 53, s. 40-49
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Tidskriftsartikel (refereegranskat)abstract
- The prompt decay constant method and the area-ratio (Sjostrand) method constitute the reference techniques for measuring the reactivity of a subcritical system using Pulsed Neutron Source experiments (PNS). However, different experiments have shown that in many cases it is necessary to apply corrections to the experimental results in order to take into account spectral and spatial effects. In these cases, the approach usually followed is to develop different specific correction procedures for each method. In this work we discuss the validity of prompt decay constant method and the area-ratio method in the Yalina-Booster subcritical assembly and propose a general correction procedure based on Monte Carlo simulations.
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| 4. |
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| 5. |
- Becares, V., et al.
(författare)
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Validation of ADS reactivity monitoring techniques in the Yalina-Booster subcritical assembly
- 2013
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Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 53, s. 331-341
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Tidskriftsartikel (refereegranskat)abstract
- The development of a reactivity monitoring system for subcritical reactors is a major task prior to industrial scale accelerator driven system (ADS) construction. Within the 6th European Framework Program, the IP-EUROTRANS project has performed a series of experiments at the Yalina-Booster subcritical assembly located at the Joint Institute for Power and Nuclear Research (JIPNR) of the National Academy of Sciences of Belarus, using a continuous (D, T) (fusion) neutron source in pulsed and continuous mode with short interruptions (beam trips). In this paper, the implementation and results of three different monitoring techniques intended to operate with continuous neutron sources will be presented, namely the source-jerk technique, the prompt decay constant technique and the current-to-flux technique. The results will be compared with the values of the reactivity obtained using the pulsed source in PNS experiments, discussed in detail in another paper.
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| 6. |
- Berglöf, Carl, et al.
(författare)
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Auto-correlation and variance-to-mean measurements in a subcritical core obeying multiple alpha-modes
- 2011
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Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 38:2-3, s. 194-202
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Tidskriftsartikel (refereegranskat)abstract
- Neutron noise measurements based on the Rossi-alpha and Feynman-alpha methodologies have been performed in a heterogeneous subcritical system. It is shown that the traditional single alpha-mode formulations of the Rossi-alpha and Feynman-alpha methods are not applicable due to the presence of higher alpha-modes. Formalisms taking into account multiple alpha-modes are applied resulting in satisfactory results. Three alpha-modes could be identified using the Rossi-alpha method, whereas only two could be obtained using the Feynman-alpha method. In the Feynman-alpha case, the possibility to obtain the fastest decaying alpha-mode was diminished due to detector dead time effects. It was found that the slowest decaying alpha-mode does not exactly correspond to the prompt decay found in pulsed neutron source measurements, which confirms the results of previous studies. Strengths and weaknesses of the multiple alpha-mode Rossi-alpha and Feynman-alpha methods observed in this study are pointed out.
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| 7. |
- Berglöf, Carl, et al.
(författare)
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Neutron noise measurements in the YALINA-Booster experiments
- 2009
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Ingår i: Proceedings of International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators. - : International Atomic Energy Agency. - 9789201504104
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Konferensbidrag (refereegranskat)abstract
- In addition to the pulsed neutron source measurements and the continuous source beam-trip and current-to-flux measurements performed in the YALINA-Booster facility, also presented in this conference, a set of neutron noise measurements has been performed to achieve a complete characterization of the core. The neutron noise measurements have been performed in three different configurations covering a subcriticality range from 0.85 to 0.977. The Rossi-α neutron noise technique has been applied to detector counts from two channels in the thermal part of the core. The Rossi-α results are compared to the experimental prompt neutron decay constants obtained from the pulsed neutron source measurements. A first approach fitting procedure reveals a need of three exponentials to describe the Rossi-α histograms. It has been found that at deep subcriticality, the fundamental mode decay may coincide with or be close to a higher eigenmode, thus making it difficult to determine the prompt neutron decay constant correctly.
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| 8. |
- Berglöf, Carl, et al.
(författare)
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Pulsed neutron source reference measurements in the subcritical experiment YALINA-Booster
- 2009
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Ingår i: Proceedings of International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators. - : International Atomic Energy Agency. - 9789201504104
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Konferensbidrag (refereegranskat)abstract
- In support of an online reactivity monitoring experiment, also presented in this conference, this work presents the reactivity calibration measurements performed with a pulsed neutron source in the coupled fast-thermal subcritical facility YALINA-Booster. These experiments reveal the complexity of experimentally obtaining a global reactivity from a highly heterogeneous core. Moreover, the effect of varying the source multiplication at constant reactivity on the area ratio technique is explored. It is found that the reactivity obtained with the area ratio technique carry strong spatial dependence, but it can be handled by calculated correction factors. On the other hand the method is showed not to be sensitive to changes in the source multiplication. It is also shown that the prompt neutron decay constant does not vary strongly over the core except at deep subcritical states.
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| 9. |
- Berglöf, Carl, et al.
(författare)
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Spatial and Source Multiplication Effects on the Area Ratio Reactivity Determination Method in a Strongly Heterogeneous Subcritical System
- 2010
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Ingår i: Nuclear science and engineering. - 0029-5639 .- 1943-748X. ; 166:2, s. 134-144
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Tidskriftsartikel (refereegranskat)abstract
- The area ratio method of Sjostrand is generally considered one of the most reliable reactivity determination methods and thus is a major candidate for off-line calibration purposes in future accelerator-driven systems for high-level waste incineration. In this work, the Sjostrand area ratio method has been evaluated experimentally under thorough conditions in the strongly heterogeneous subcritical facility YALINA-Booster. Both strengths and weaknesses of the method have been identified. Most surprisingly, it has been found that the area ratio reactivity estimates may differ a factor of 2 depending on detector position. It is also shown that this strong spatial dependence can be explained based on a simple two-region point-kinetics model and corrected by means of correction factors obtained through Monte Carlo simulations. A new Monte Carlo correction method is proposed that includes, at the same time, the spatial disturbance and the effective delayed neutron fraction. In that way, the value of the effective multiplication factor is obtained from the measured dollar reactivity without the need of calculating the effective delayed neutron fraction explicitly, and thereby, the delayed neutron transport is performed only once. Further, it has been found that the Sjostrand area ratio method is not sensitive to perturbations of the source multiplication factor.
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| 10. |
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