| 1. |
- Ambrozova, I., et al.
(author)
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Measurement of target fragments produced by 160 MeV proton beam in aluminum and polyethylene with CR-39 plastic nuclear track detectors
- 2014
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In: Radiation Measurements. - : Elsevier BV. - 1350-4487. ; 64, s. 29-34
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Journal article (peer-reviewed)abstract
- Production of target fragments from reactions of 160 MeV proton beams in aluminum and polyethylene was measured with CR-39 plastic nuclear track detectors (PNTD). Due to the detection limit of PNTD, primary protons cannot be detected; only low-energy short-range target fragments are registered. As a feasibility study, a so called "two step etching method" was employed to get the linear energy transfer (LET) spectra, absorbed dose, and dose equivalent. This method is discussed in this paper, together with the measured results. (C) 2014 Elsevier Ltd. All rights reserved.
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| 2. |
- El-Jaby, S., et al.
(author)
-
ISSCREM: International Space Station cosmic radiation exposure model
- 2013
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In: IEEE Aerospace Conference Proceedings. - 1095-323X. - 9781467318112
-
Conference paper (peer-reviewed)abstract
- A semi-empirical model is derived from operational data collected aboard the International Space Station (ISS) with the U.S. tissue equivalent proportional counter (TEPC). The model provides daily and cumulative mission predictions of the operational dose equivalent that space-crew may receive from galactic cosmic radiation (GCR) and trapped radiation (TR) sources as a function of the ISS orbit. The parametric model for GCR exposure correlates the TEPC dose equivalent rate to the cutoff rigidity at ISS altitudes while the TR parametric model relates this quantity to the mean atmospheric density at the crossing of the South Atlantic Anomaly (SAA). The influences of solar activity, flux asymmetry inside the SAA, detector orientation, and position aboard the ISS on the dose equivalent have been examined. The model has been successfully benchmarked against measured data for GCR and TR exposures to within ±10% and ±20%, respectively, over periods of time ranging from a single day to a full mission. In addition, preliminary estimates of the protection quantity of effective dose equivalent have been simulated using the PHITS Monte Carlo transport code. These simulations indicate that the TEPC dose equivalent is a conservative estimate of the effective dose equivalent.
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| 3. |
- El-Jaby, S., et al.
(author)
-
Method for the prediction of the effective dose equivalent to the crew of the International Space Station
- 2014
-
In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 53:5, s. 810-817
-
Journal article (peer-reviewed)abstract
- This paper describes a methodology for assessing the pre-mission exposure of space crew aboard the International Space Station (ISS) in terms of an effective dose equivalent. In this approach, the PHITS Monte Carlo code was used to assess the particle transport of galactic cosmic radiation (GCR) and trapped radiation for solar maximum and minimum conditions through an aluminum shield thickness. From these predicted spectra, and using fluence-to-dose conversion factors, a scaling ratio of the effective dose equivalent rate to the ICRU ambient dose equivalent rate at a 10 mm depth was determined. Only contributions from secondary neutrons, protons, and alpha particles were considered in this analysis. Measurements made with a tissue equivalent proportional counter (TEPC) located at Service Module panel 327, as captured through a semi-empirical correlation in the ISSCREM code, where then scaled using this conversion factor for prediction of the effective dose equivalent. This analysis shows that at this location within the service module, the total effective dose equivalent is 10-30% less than the total TEPC dose equivalent. Approximately 75-85% of the effective dose equivalent is derived from the OCR. This methodology provides an opportunity for pre-flight predictions of the effective dose equivalent and therefore offers a means to assess the health risks of radiation exposure on ISS flight crew. Crown copyright (C) 2014 Published by Elsevier Ltd. on behalf of COSPAR. All rights reserved.
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| 4. |
- Golovchenko, A. N., et al.
(author)
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Fragmentation of 370 MeV/n Ne-20 and 470 MeV/n Mg-24 in light targets
- 2010
-
In: Radiation Measurements. - : Elsevier BV. - 1350-4487. ; 45:7, s. 856-860
-
Journal article (peer-reviewed)abstract
- Total charge-changing cross sections and cross sections for the production of projectile-like fragments were determined for fragmentation reactions induced by 370 MeV/n Ne-20 ions in water and lucite, and 490 MeV/n Mg-24 ions in polyethylene, carbon and aluminum targets sandwiched with CR-39 plastic nuclear track detectors. An automated microscope system and a track-to-track matching algorithm were used to count and recognize the primary and secondary particles. The measured cross sections were then compared with published cross sections and predictions of different models. Two models and the three-dimensional Monte Carlo Particle Heavy Ion Transport Code System (PHITS) were used to calculate total charge-changing cross sections. Both models agreed within a few percent for the system Mg-24 + CH2, however a deviation up to 20% was observed for the systems Ne-20 + H2O and C5H8O2, when using one of the models. For all the studied systems, PHITS systematically underestimated the total charge-changing cross section. It was also found that the partial fragmentation cross sections for Mg-24 + CH2 measured in present and earlier works deviated up to 20% for Z = 6-11. Measured cross sections for the production of fragments (Z = 4-9) for Ne-20 + H2O and C5H8O2 were compared with predictions of three different semi-empirical models and JQMD which is used in the PHITS code. The calculated cross sections differed from the measured data by 10-90% depending on which fragment and charge was studied, and which model was used. (C) 2010 Elsevier Ltd. All rights reserved.
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| 5. |
- Gustafsson, Katarina, 1980, et al.
(author)
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PHITS simulations of the Matroshka experiment
- 2010
-
In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 46:10, s. 1266-1272
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Journal article (peer-reviewed)abstract
- The radiation environment in space is very different from the one encountered on Earth. In addition to the sparsely ionizing radiation, there are particles of different Z with energies ranging from keV up to hundreds of GeV which can cause severe damage to both electronics and humans. It is therefore important to understand the interactions of these highly ionizing particles with different materials such as the hull of space vehicles, human organs and electronics. We have used the Particle and Heavy-Ion Transport code System (PHITS), which is a three-dimensional Monte Carlo code able to calculate interactions and transport of particles and heavy ions with energies up to 100 GeV/nucleon in most matter. PHITS is developed and maintained by a collaboration between RIST (Research Organization for Information Science & Technology), JAEA (Japan Atomic Energy Agency), KEK (High Energy Accelerator Research Organization), Japan and Chalmers University of Technology, Sweden. For the purpose of examining the applicability of PHITS to the shielding design we have simulated the ESA facility Matroshka (MTR) designed and lead by the German Aerospace Center (DLR). Preliminary results are presented and discussed in this paper.
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| 6. |
- Hayatsu, K., et al.
(author)
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Lunar radiation dose due to cosmic rays and their secondary particles
- 2010
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In: 61st International Astronautical Congress 2010, IAC 2010.Prague, 27 September-1 October 2010. - 9781617823688 ; 5, s. 4084-4088
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Conference paper (peer-reviewed)abstract
- To be able to safely perform human activities on the lunar surface, it is very important to assess the radiation environment, including the dose from galactic cosmic Rays (GCRs) and large Solar Energetic Particles (SEPs). Especially, large SPEs are highly hazardous to lunar habitants. In this paper, several SPEs have been evaluated in order to estimate the effective dose equivalent on the lunar surface. Several events give more than 1 Sv without any shield.
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| 7. |
- Koliskova, Z., et al.
(author)
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Simulations of absorbed dose on the phantom surface of MATROSHKA-R experiment at the ISS
- 2012
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In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 49:2, s. 230-236
-
Journal article (peer-reviewed)abstract
- The health risks associated with exposure to various components of space radiation are of great concern when planning manned long-term interplanetary missions, such as future missions to Mars. Since it is not possible to measure the radiation environment inside of human organs in deep space, simulations based on radiation transport/interaction codes coupled to phantoms of tissue equivalent materials are used. However, the calculated results depend on the models used in the codes, and it is therefore necessary to verify their validity by comparison with measured data. The goal of this paper is to compare absorbed doses obtained in the MATROSHKA-R experiment performed at the International Space Station (ISS) with simulations performed with the three-dimensional Monte Carlo Particle and Heavy-Ion Transport code System (PHITS). The absorbed dose was measured using passive detectors (packages of thermoluminescent and plastic nuclear track detectors) placed on the surface of the spherical tissue equivalent phantom MATROSHKA-R, which was exposed aboard the ISS in the Service Zvezda Module from December 2005 to September 2006. The data calculated by PHITS assuming an ISS shielding of 3 g/cm(2) and 5 g/cm(2) aluminum mass thickness were in good agreement with the measurements. Using a simplified geometrical model of the ISS, the influence of variations in altitude and wall mass thickness of the ISS on the calculated absorbed dose was estimated. The uncertainties of the calculated data are also discussed; the relative expanded uncertainty of absorbed dose in phantom was estimated to be 44% at a 95% confidence level.
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| 8. |
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| 9. |
- Larsson, Irina, 1975, et al.
(author)
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Factors influencing helium measurements for detection of control rod failures in BWR
- 2012
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In: International Conference on the Physics of Reactors 2012: Advances in Reactor Physics (PHYSOR 2012), Knoxville, TN;15- 20 April 2012. - 9781622763894 ; 4, s. 3092-3099
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Conference paper (peer-reviewed)abstract
- Much effort has been made to minimize the number and consequences of fuel failures at nuclear power plants. The consequences of control rod failures have also gained an increased attention. In this paper we introduce a system for on-line surveillance of control rod integrity which has several advantages comparing to the surveillance methods available today in boiling water reactors (BWRs). This system measures the helium released from failed control rods containing boron carbide (B4C). However, there are a number of factors that might influence measurements, which have to be taken into consideration when evaluating the measured data. These factors can be separated into two groups: 1) local adjustments, made on the sampling line connecting the detector to the off-gas system, and 2) plant operational parameters. The adjustments of the sample line conditions include variation of gas flow rate and gas pressure in the line. Plant operational factors that may influence helium measurements can vary from plant to plant. The factors studied at Leibstadt nuclear power plant (KKL) were helium impurities in injected hydrogen gas, variation of the total off-gas flow and regular water refill. In this paper we discuss these factors and their significance and present experimental results of measurements at KKL.
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| 10. |
- Larsson, Irina, 1975, et al.
(author)
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Improvements of fuel failure detection in boiling water reactors using helium measurements
- 2012
-
In: International Congress on Advances in Nuclear Power Plants 2012, ICAPP 2012. - 9781622762101 ; 4, s. 2401-2406
-
Conference paper (peer-reviewed)abstract
- To certify a continuous and safe operation of a boiling water reactor, careful surveillance of fuel integrity is of high importance. The detection of fuel failures can be performed by off-line gamma spectroscopy of off-gas samples and/or by on-line nuclide specific monitoring of gamma emitting noble gases. To establish the location of a leaking fuel rod, power suppression testing can be used. The accuracy of power suppression testing is dependent on the information of the delay time and the spreading of the released fission gases through the systems before reaching the sampling point. This paper presents a method to improve the accuracy of power suppression testing by determining the delay time and gas spreading profile. To estimate the delay time and examine the spreading of the gas in case of a fuel failure, helium was injected in the feed water system at Forsmark 3 nuclear power plant. The measurements were performed by using a helium detector system based on a mass spectrometer installed in the off-gas system. The helium detection system and the results of the experiment are presented in this paper.
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