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Poml P.,European Commission | Burakov B.,Khlopin Radium Institute
Journal of Nuclear Materials | Year: 2017

This paper is dedicated to the 30th anniversary of the severe nuclear accident that occurred at the Chernobyl NPP on 26 April 1986. A detailed study on a Chernobyl “hot” particle collected from contaminated soil was performed. Optical and electron microscopy, as well as quantitative x-ray microbeam analysis methods were used to determine the properties of the sample. The results show that the particle (≈240 x 165 μm) consists of a metallic Zr matrix containing 2–3 wt. % U and bearing veins of an U,Nb admixture. The metallic Zr matrix contains two phases with different amounts of O with the atomic proportions (U,Zr,Nb)0.73O0.27 and (U,Zr,Nb)0.61O0.39. The results confirm the interaction between UO2 fuel and zircaloy cladding in the reactor core. To explain the process of formation of the particle, its properties are compared to laboratory experiments. Because of the metallic nature of the particle it is concluded that it must have formed during a very high temperature (>2400∘C) process that lasted for only a very short time (few microseconds or less); otherwise the particle should have been oxidised. Such a rapid very high temperature process indicates that at least part of the reactor core could have been supercritical prior to an explosion as it was previously suggested in the literature. © 2017 The Authors


News Article | November 14, 2016
Site: www.theenergycollective.com

The development of new nuclear fuels is crucial to the success of new fast reactor designs. Examples include TRISO fuel for HTGRs and Molten Salt fuel for 21st century iterations of the work done at Oak Ridge in the 1960s. (WNN) Russia has started testing its new type of nuclear fuel, REMIX, at the MIR research reactor at the Research Institute of Atomic Reactors in Dimitrovgrad, which is in the Ulyanovsk region. Rostaom said on 11/3 that REMIX fuel rods manufactured in July had been “immersed in the active zone” of MIR. Development of REMIX (from Regenerated Mixture) fuel is part of state nuclear corporation Rosatom’s strategy to enable better use of recycled uranium and plutonium on an industrial scale in pressurized water reactors. Some of the plutonium may come from nuclear weapons decommissioned as part of international treaties. Russia is also using this inventory of surplus plutonium to make MOX fuel for its BN-800 fast reactor which was recently connected to the grid to generate electricity. A loop-type research reactor, MIR is designed mainly for testing fuel elements, fuel assemblies and other core components of different types of operating and promising nuclear power reactors. The first data from testing the fuel in MIR will include the “swelling, gassing and distribution of fission products and, of course, the isotopic composition of the used fuel rods,” the head of innovation at the Khlopin Radium Institute, Andrey Belozub, said in the Rosatom statement. Use of the MIR research reactor is an “extremely important step”, Rosatom said, towards full implementation of the project to introduce REMIX into the Russian fuel cycle. According to World Nuclear News, REMIX fuel is produced directly from a non-separated mix of recycled uranium and plutonium from reprocessing used fuel, with a low-enriched uranium (LEU, up to 17% U-235) make-up comprising about 20% of the mix. This gives fuel initially with about 1% Pu-239 and 4% U-235 which can sustain burn-up of 50 GWd/t over four years. REMIX fuel can be repeatedly recycled with 100% core load in current VVER-1000 reactors, and correspondingly reprocessed many times – up to five times according to Russian nuclear fuel manufacturer Tenex, so that with less than three fuel loads in circulation a reactor could run for 60 years using the same fuel, with LEU recharge and waste removal on each cycle. (WNN) Canadian reactor designer StarCore Nuclear has applied to the Canadian Nuclear Safety Commission (CNSC) to begin the vendor design review process for its Generation IV high temperature gas reactor (HTGR). The CNSC’s pre-licensing vendor review process is an optional service to provide an assessment of a nuclear power plant design based on a vendor’s reactor technology. The three-phase review is not a required part of the licensing process for a new nuclear power plant, but aims to verify the acceptability of a nuclear power plant design with respect to Canadian nuclear regulatory requirements and expectations. Earlier this year the CNSC agreed to conduct a phase 1 vendor design review for Terrestrial Energy’s integral molten salt reactor design concept. StarCore CEO David Dabney said the company’s application to the CNSC, lodged on 24 October, marked the culmination of eight years’ work. “We are confident that our plant size and technology will enable us to bring safe, clean energy to the many remote sites in Northern Canada that currently have no choice other than to use costly, unreliable and polluting carbon-based fuels,” he said. Montréal-based StarCore, founded in 2008, is focused on developing small modular reactors (SMRs) to provide power and potable water to remote communities in Canada. Its standard HTGR unit would produce 20 MWe (36 MWth), expandable to 100 MWe, from a unit small enough to be delivered by truck. The helium-cooled reactor uses Triso fuel, – spherical particles of uranium fuel coated by carbon which effectively gives each tiny particle its own primary containment system, manufactured by BWXT Technologies. Each reactor would require refueling at five-yearly intervals. StarCore describes its reactor as “inherently safe.” The use of helium, which does not become radioactive, as a coolant means that any loss of coolant would be “inconsequential”, the company says. The reactors would be embedded 50 metres underground in concrete silos sealed with ten-tonne caps. DOE Inks Deal with GE-Hitachi for Laser Enrichment Plant at Paducah The Department of Energy (DOE) has agreed to sell depleted uranium to GE-Hitachi Global Laser Enrichment, LLC (GLE) over a 40-year period which would be enriched at a proposed GLE state-of-the-art facility. DOE has agreed to sell 300,000 tonnes of depleted uranium hexafluoride (UF6) to GE Hitachi Global Laser Enrichment (GLE) for re-enrichment at a proposed plant to be built near DOE’s Paducah site in Kentucky. The agreement paves the way for commercialization of Silex laser enrichment technology. The proposed new facility would use depleted uranium to produce natural uranium which is used for production of fuel for civil nuclear reactors. The facility would be built near DOE’s Paducah Gaseous Diffusion Plant in western Kentucky. The construction and operation of the billion-dollar facility at Paducah could to bring approximately 800 to 1,200 jobs to the local community. “This agreement furthers the Energy Department’s environmental cleanup mission while reducing cleanup costs, creating good local jobs, and supporting an economical enrichment enterprise for our energy needs,” said Energy Secretary Ernest Moniz. GLE will finance, construct, own and operate the Paducah Laser Enrichment Facility (PLEF) adjacent to the Energy Department site. The facility will be a commercial uranium enrichment production facility under a Nuclear Regulatory Commission (NRC) license. DOE’s inventory of depleted uranium is safely stored in approximately 65,000 specialized storage cylinders at the Department’s Paducah and Portsmouth (Ohio) sites. The Paducah plant was constructed in the 1950s to enrich uranium for national security applications, and later enriched uranium for commercial nuclear power generation. The Energy Department resumed control of the plant enrichment facilities in 2014 after the operator ceased gaseous-diffusion enrichment operations in 2013. GLE is a joint business venture of GE (51%), Hitachi (25%) and Cameco (24%). Earlier this year GE Hitachi announced its desire to reduce its equity interest in GLE and in April signed a term sheet with Silex giving the Australian company an exclusive option to acquire GE Hitachi’s entire 76% interest in GLE. In 2012, the US NRC granted GLE a combined construction and operating licence for a laser enrichment plant of up to 6 million separative work units at Wilmington, North Carolina. GLE has successfully demonstrated the concept in a test loop at Global Nuclear Fuel’s Wilmington fuel fabrication facility but has not yet decided whether to proceed with a full-scale commercial plant there. (NucNet): Russia is considering asking foreign partners to join its development of the Generation IV SVBR 100 reactor design, but has denied reports that the cost of the project has more than doubled. The original cost of the project was put at 15bn rubles (€209m, $226m) and this has not changed, Rosatom said. The SVBR 100 is one of six designs chosen by the Generation IV International Forum (GIF) for its program of research and development into the next generation nuclear energy systems. GIF said the SVBR 100 is a lead-cooled fast reactor which features a fast neutron spectrum, high temperature operation, and cooling by molten lead or lead-bismuth. It would have multiple applications including production of electricity, hydrogen and process heat. Molten Salt Reactors: IAEA to Establish New Platform for Collaboration Experts from 17 countries laid the foundations last week for enhanced international cooperation on a technology that promises to deliver nuclear power with a lower risk of severe accidents, helping to decrease the world’s dependence on fossil fuels and mitigate climate change. “It is the first time a comprehensive IAEA international meeting on molten salt reactors has ever taken place,” said Stefano Monti, Head of the Nuclear Power Development Section at the IAEA. “Given the interest of Member States, the IAEA could provide a platform for international cooperation and information exchange on the development of these advanced nuclear systems.” Molten salt reactor technology has attracted private funding over the last few years, and several reactor concepts are under development. One area under research is the compatibility between the salt coolant and the structural materials and, for some designs, the chemical processes related to the associated fuel cycle, Monti said. The challenges are not only technical. Nuclear regulators will need to review existing safety regulations to see how these can be modified, if necessary, to fit molten salt reactors, since they differ significantly from reactors in use today, said Stewart Magruder, senior nuclear safety officer at the IAEA. Participants, including researchers, designers and industry representatives, emphasized the need for an international platform for information exchange. “While the United States is actively developing both technology and safety regulations for molten salt reactors, the meeting is an important platform to exchange knowledge and information with Member States not engaged in the existing forums,” said David Holcomb from the Oak Ridge National Laboratory. Molten salt reactors, nuclear power reactors that use liquid salt as primary coolant or a molten salt mixture as fuel, have many favorable characteristics for nuclear safety and sustainability. The concept was developed in the 1960s, but put aside in favor of what has become mainstream nuclear technology since. In recent years, however, technological advances have led to growing interest in molten salt technology and to the launch of new initiatives. The technology needs at least a decade of further intensive research, validation and qualification before commercialization. Molten salt reactors operate at higher temperatures, making them more efficient in generating electricity. In addition, their low operating pressure can reduce the risk of coolant loss, which could otherwise result in an accident. Molten salt reactors can run on various types of nuclear fuel and use different fuel cycles. This conserves fuel resources and reduces the volume, radiotoxicity and lifetime of high-level radioactive waste. To help speed up research, it is essential to move from bilateral to multilateral cooperation, said Chen Kun from the Shanghai Institute of Applied Physics of the Chinese Academy of Sciences. “It is the first time China has the opportunity to share knowledge with India, Indonesia and Turkey on this technology.” Indonesia is considering building its first nuclear power plant with molten salt reactor design, said Bob Soelaiman Effendi from Indonesia Thorium Energy Community. (WNN) China and the UK have signed a joint R&D agreement which created their Joint Research and Innovation Centre (JRIC) to be opened soon in Manchester, England. Initial work is expected to include developing advanced manufacturing methods. JRIC will support innovation in nuclear research and development through UK-China collaboration. This will develop, it said, “leading-edge research and innovative technologies which will support safe and reliable nuclear energy around the globe.” With NNL and CNNC each owning a 50% share, they will jointly pay for the centre’s research and development expenses and plan to invest 422 million yuan ($65.1 million) over a five-year period, CNNC said. (WNN) The UK’s Nuclear Advanced Manufacturing Research Centre (AMRC) said it has signed a new agreement with the US Nuclear Infrastructure Council (USNIC) to work together on research and development to support the UK’s civil nuclear program. The memorandum of understanding was signed by Jay Shaw, senior business development manager for the Nuclear AMRC, and David Blee, executive director of USNIC, during a visit to the Nuclear AMRC on 10/26.


Grudzevich O.T.,RAS Institute of Physics and Power Engineering | Yavshits S.G.,Khlopin Radium Institute
Physics of Atomic Nuclei | Year: 2013

The cross sections for the fission of 232Th, 235,238U, 237Np, and 239Pu target nuclei that was induced by 20- to 1000-MeV neutrons and protons were calculated. The respective calculations were based on the multiconfiguration-fission (MCFx) model, which was used to describe three basic stages of the interaction of high-energy nucleons with nuclei: direct processes (intranuclear cascade), equilibration of the emerging compound system, and the decay of the compound nucleus (statistical model). Fission barriers were calculated within the microscopic approach for isotopic chains formed by 15 to 20 nuclei of the required elements. The calculated fission cross sections were compared with available experimental data. It was shown that the input data set and the theoretical model used made it possible to predict satisfactorily cross section for nuclear fission induced by 20- to 1000-MeV nucleons. © 2013 Pleiades Publishing, Ltd.


Badikov S.A.,National Research Nuclear University MEPhI | Chechev V.P.,Khlopin Radium Institute
Applied Radiation and Isotopes | Year: 2014

As a rule the evaluated decay data and their uncertainties reflect the current level of consistency of the experimental data as well as its shortage. However, if we assume a priori that the structure of the decay scheme is precisely established, the inclusion of the exact balance relationships in the evaluation procedure leads to lower uncertainties of the recommended data and strong correlations between some of the evaluated parameters. Such a self-consistent decay data evaluation was carried out using the 242Cm alpha decay as an example. © 2013 Elsevier Ltd.


Dubasov Y.V.,Khlopin Radium Institute
Pure and Applied Geophysics | Year: 2010

Over a period in 1961-1990 496 underground nuclear tests and explosions of different purpose and in different rocks were conducted in the Soviet Union at Semipalatinsk and anovaya Zemlya Test Sites. A total of 340 underground nuclear tests were conducted at the Semipalatinsk Test Site. One hundred seventy-nine explosions (52. 6%) among them were classified as these of complete containment, 145 explosions (42.6%) as explosions with weak release of radioactive noble gases (RNG), 12 explosions (3.5%) as explosions with nonstandard radiation situation, and four excavation explosions with ground ejection (1.1%). Thirty-nine nuclear tests had been conducted at the Novaya Zemlya Test Site; six of them - in shafts. In 14 tests (36%) there were no RNG release. Twenty-three tests have been accompanied by RNG release into the atmosphere without sedimental contamination. Nonstandard radiation situation occurred in two tests. In incomplete containment explosions both early-time RNG release (up to ~1 h) and late-time release from 1 to 28 h after the explosion were observed. Sometimes gas release took place for several days, and it occurred either through tunnel portal or epicentral zone, depending on atmospheric air temperature. © 2009 Birkhäuser Verlag Basel/Switzerland.


Chechev V.P.,Khlopin Radium Institute
Physics of Atomic Nuclei | Year: 2011

The current status of some decay data used in nuclear astrophysics and cosmochronology is presented. The half-life of 79Se has been evaluated as 3. 6(3) × 105 yr. The total energy of non-neutrino radiation released in act of 37Ar decay has been obtained being 2. 709 (16) keV per disintegration. The recommended half-life values of the long-lived radionuclides (T1/2 ≳ 106 yr) of 26Al, 40K, 53Mn, 60Fe, 87Rb, 93Zr, 98Tc, 107Pd, 129I, 135Cs, 146Sm, 176Lu, 182Hf, 187Re, 205Pb, 232Th, 235U, 238U, 244Pu, and 247Cm are given based on the evaluations published until 2010. © 2011 Pleiades Publishing, Ltd.


Tyurin G.P.,Khlopin Radium Institute
AIP Conference Proceedings | Year: 2010

An improved LCP identification method based on Pulse shape analyses has been designed, the module "Dual Pulse-Shape Analyzer" has been built and tested and resent experimental results of instrument utilizing have been presented. © 2010 American Institute of Physics.


Be M.-M.,CEA Saclay Nuclear Research Center | Chechev V.P.,Khlopin Radium Institute
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2013

Gamma ray data are used in more and more areas of application, and so over the years the demand for recommended gamma ray energies and intensities has increased. This paper proposes a list of gamma rays whose intensity is sufficiently well-known and they can be used for the calibration of gamma ray spectrometers and other applications; it is based on studies carried out by an international group of evaluators: The Decay Data Evaluation Project. One goal of this paper is to gather this set of data together in order to facilitate and generalize their use. In the first part, a brief description of the methodology followed throughout the evaluations is given, different methods of gamma ray intensity evaluation are presented, some typical examples of evaluations are shown; in the second part, the list of chosen nuclides is given along with their applications, and finally a list of recommended gamma ray intensities is presented. © 2013 Elsevier B.V.


Chechev V.P.,Khlopin Radium Institute | Huang X.,China Institute of Atomic Energy
Applied Radiation and Isotopes | Year: 2015

Several directions of the demand for decay data in nuclear astrophysics are discussed for radionuclides near the valley of nuclear stability. The current half-life and gamma-ray intensity evaluation results are presented for some radionuclides of astrophysical interest. An extended list of such nuclides is offered for their nuclear characteristics to be further evaluated by the Decay Data Evaluation Project collaboration participants. © 2015 Elsevier Ltd.


Chechev V.P.,Khlopin Radium Institute
Applied Radiation and Isotopes | Year: 2012

The results of new decay data evaluations are presented for 243Cm (α) decay to nuclear levels in 239Pu and 245Cm (α) decay to nuclear levels in 241Pu. These evaluated data have been obtained within the Decay Data Evaluation Project using information published up to 2011. © 2012 Elsevier Ltd.

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