STUK

Helsinki, Finland
Helsinki, Finland

Time filter

Source Type

Jordan D.,University of Valencia | Algora A.,University of Valencia | Algora A.,Institute of Nuclear Research | Tain J.L.,University of Valencia | And 43 more authors.
Physical Review C - Nuclear Physics | Year: 2013

The β-feeding probabilities for three important contributors to the decay heat in nuclear reactors, namely 102,104,105Tc, have been measured using the total absorption spectroscopy technique. For the measurements, sources of very high isobaric purity have been obtained using a Penning trap (JYFLTRAP). A detailed description of the data analysis is given and the results are compared with high-resolution measurements and theoretical calculations. © 2013 American Physical Society.


Algora A.,University of Valencia | Jordan D.,University of Valencia | Tain J.L.,University of Valencia | Rubio B.,University of Valencia | And 38 more authors.
Physical Review Letters | Year: 2010

The β feeding probability of Tc102,104,105,106,107, Mo105, and Nb101 nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the γ component of the decay heat for Pu239 in the 4-3000s range. © 2010 The American Physical Society.


Yankovich T.,Environment Canada | Beresford N.A.,UK Center for Ecology and Hydrology | Fesenko S.,International Atomic Energy Agency | Fesenko J.,All Russian Research Institute of Agricultural Meteorology | And 9 more authors.
Journal of Environmental Radioactivity | Year: 2013

Environmental assessments to evaluate potentials risks to humans and wildlife often involve modelling to predict contaminant exposure through key pathways. Such models require input of parameter values, including concentration ratios, to estimate contaminant concentrations in biota based on measurements or estimates of concentrations in environmental media, such as water. Due to the diversity of species and the range in physicochemical conditions in natural ecosystems, concentration ratios can vary by orders of magnitude, even within similar species. Therefore, to improve model input parameter values for application in aquatic systems, freshwater concentration ratios were collated or calculated from national grey literature, Russian language publications, and refereed papers. Collated data were then input into an international database that is being established by the International Atomic Energy Agency. The freshwater database enables entry of information for all radionuclides listed in ICRP (1983), in addition tothe corresponding stable elements, and comprises a total of more than 16,500 concentration ratio (CRwo-water) values.Although data were available for all broad wildlife groups (with the exception of birds), data were sparse for many organism types. For example, zooplankton, crustaceans, insects and insect larvae, amphibians, and mammals, for which there were CRwo-water values for less than eight elements. Coverage was most comprehensive for fish, vascular plants, and molluscs. To our knowledge, the freshwater database that has now been established represents the most comprehensive set of CRwo-water values for freshwater species currently available for use in radiological environmental assessments. © 2012 Elsevier Ltd.


News Article | October 22, 2016
Site: www.theenergycollective.com

Five years after announcing that it had chosen Pyhäjoki, in northern Finland, as the site for a new Russian-designed 1200 MW nuclear reactor, Finnish company Fennovoima is within sight of a 2018 construction start date. No, this is not the notorious Olkiluoto-3 EPR being builty by Areva– this is Hanhikivi 1, to be built by Rosatom. Journalist Eric Marx travelled to Finland to find out why Fennovoima is succeeding where other new nuclear projects in Europe are struggling. The largest construction site in Finland juts out into the Bay of Bothnia, a rocky outcrop that is known as the Hanhikivi Peninsula. Busy with large earthmoving diggers, and replete with concrete batching plants and a steep embankment rising 4.6 meters above sea level, in ten years’ time this open patch of land will be home to Finland’s third nuclear power plant and sixth reactor. Roughly 700,000 cubic tons of rock have been excavated, explains Jouni Sipiläinen, the construction director of Fennovoima, the company owned by a consortium of Finnish companies and municipalities that aims to build and operate the VVER-1200 reactor designed and supplied by Rosatom, the Russian nuclear energy company. Electric and waste water lines have been laid and over a thousand workers have already passed the required training for project construction. The Russian company Titan-2, which is the main building contractor, has its offices in the area. A two-meter high security fence now rings the entire 555-hectare site, while over there, says Sipiläinen, pointing to two large craters filled with muddy water, is where the reactor and turbine halls will sit. All that’s needed now is a construction license. “Hanhikivi will be the most modern, the safest and best plant there is in the world,” proclaims Matti Soronen. The mayor of Pyhäjoki, a municipality of 3,207 inhabitants, Soronen views nuclear power in terms of economic growth. He believes in the technology and is proud of the strong safety record of the country’s four existing nuclear reactors. If all goes according to plan, Hanhikivi 1 could start producing electricity from 2024. That is welcomed by the industry and energy companies as well as small municipalities across the country, like Pyhäjoki, which are susceptible to sharp increases in electricity prices as a result of costly imports. One of the chief benefits of the plant for Fennovoima’s owners will be the opportunity to purchase dependable and competitively priced energy. Pyhäjoki is one of 57 Finnish owners which comprise of municipalities, industrial companies and power companies that own a piece of the power plant as shareholders in Voimaosakeyhtiö SF, which owns 66% of Fennovoima. The shares don’t equal dividends, but resemble a cooperative, or what’s referred to in Finland as the “mankala” business model. The shareholders finance the project. In turn, they are entitled to tax-free power at producer prices, in proportion to their holdings. The rest of the shares (34%) are owned by Rosatom through its Finnish subsidiary RAOS Voima. As several dozen municipal utilities are included among the Fennovoima shareholders, this has made for wide-ranging dialogue in town councils across Finland about their participation in the project. Notably, in 2014 the project’s home municipality of Pyhäjoki voted 18 to 3 to host the project. In Finland, the support of the host municipality is indispensable for a nuclear power plant, because the local municipality has the right of veto. “The problem in northern Finland is we have been losing inhabitants,” says Soronen. The nuclear power plant will employ an estimated 450 to 500 people after it’s built. Some 3,000 to 4,000 will be involved during construction. In Raahe, a town some 20 kilometres up the coast, the leadership of the SSAB Ruukki steel plant also supports the plans. With 2,800 employees the plant is hungry for cheap electricity. Its iron and steel production consumes one percent of all electricity in Finland. It relies partly upon wind power, but cannot at present expand without more predictable energy flows, especially in winter during peak usage periods. Along with forestry and farming in the dairy and pork industries, the steel plant is one of Pyhäjoki’s big employers. The Hanhikivi 1 project will change the landscape of the municipality. “We want to build residential buildings and provide new services,” says the mayor. “It’s only natural that we want growth.” According to a poll held in December 2015, two-thirds of the residents of Pyhäjoki are in favour of the project. The Fennovoima board compared several potential plant suppliers and chose Rosatom because of two deciding factors: familiarity with VVER technology and attractive commercial terms. “The people of Finland have not lost belief in nuclear itself as we have four good reactors which are all still running today,” says Jussi Lehto, head of Kerava Energy and also the CEO of Voimaosakeyhtiö SF. Of the four existing reactors in Finland, the two power plant units in Loviisa (to the east of Helsinki) are of the VVER-type. In operation since 1977 and 1980, the units have since been modernized, with their operating permits extended through to the end of the next decade. Currently some 18 VVER units from Russia operate safely in five EU countries. Another deciding factor was the attractive turnkey agreement that Rosatom offered. This obliges the Russian supplier to take on the risk of any budgetary overruns or timetable delays. Rosatom also bought into the deal, becoming a 34 percent owner after German energy company Eon, one of the original shareholders in the project, decided to pull out of nuclear power in 2013. According to Lehto, owners’ equity will cover €1.7 billion of the estimated €6.5 billion to €7 billion cost of the reactor, with the rest coming from loans which Rosatom is responsible for securing. The ultimate cost of the electricity to be supplied by the new plant will be around €50/MWh. That is much cheaper than, for example, the £97.50/MWh strike price (for 35 years, inflation-proof) guaranteed by the UK government to the owners of the proposed Hinkley Point C nuclear power plant, which is to be built by EDF of France. According to Lehto, the project terms contributed to the wide buy-in from Finnish society at all levels. In late 2014 the Parliament in Helsinki approved the deal by a wide 115-74 vote. The Parliament enacted the condition that owners from Finland or the European Economic Area must always hold a majority ownership of at least 60% in the project. As part of the plant supply contract, Rosatom is obliged to deliver nuclear fuel for at least the first ten years. After that the fuel can be freely tendered. The deal also makes sense for Finland from a macro-viewpoint. The country imports about 20% of its electricity annually and the government and Finnish industry want to reduce that amount. In January this year, during a cold spell, “we were just lucky to cover peak [electricity] demand and avoid a catastrophe,” says Lehto. Estimates are for Hanhikivi 1 to produce about 9 TWh of electricity annually, which is half the total amount of electricity Finland imported in 2014. “All the companies that are shareholders are now 100 percent behind the project,” says Lehto. “We will build this,” he continues. “We will try to make a profit, but we also want to be responsible for Finland and the global environment.” Currently Fennovoima’s main priority is the licensing process.  There are roughly 8000 regulatory guidance protocols involving design specs for the plant’s safety, construction and operation, as well as requirements for detailed management plans of the organizations of both Fennovoima and the plant supplier. It is a demanding process even for the most experienced technical oganisation, in keeping with the reputation of the Finnish regulator STUK as one of the strictest nuclear supervisory authorities in the world. Of course, safety is key and the company is committed to taking all the time and making all the efforts needed to fulfill all the required criteria. Finland’s regulatory process involves a single approval for the construction licence application, unlike the multiple steps found in some other jurisdictions. According to Fennovoima CEO Toni Hemminki, the licensing phase needs the full attention of the whole project organisation. Fennovoima is working on tackling all challenges and is confident to receive the construction license in 2018. Before even a single design plan can be submitted, STUK requires that the design development and management are according to requirements and reviewed in detail. “In this respect the requirement level of STUK has increased,” says Project Director Minna Forsström. It means the plant supplier Rosatom has to align these procedures into a management system and supply chain that already includes 300 companies. The Fukushima disaster in Japan in 2011 has led to additional safeguards being implemented across the nuclear industry. “Greater efforts to ensure safety in the wake of Fukushima are an absolute priority”, says Janne Nevalainen, the STUK manager of the Hanhikivi project. As part of its standard procedures, STUK is currently reviewing the reactor’s double containment silos, passive cooling systems and core catcher. The catcher is a special design feature of the VVER that traps and retains molten core material in case of a meltdown. Passive cooling works via a gravity wall tripwire that functions without the use of any electrical power. Concrete silos at Hanhikivi will be of a thickness ratio that prevents possible radiation leakage, but which will also be strong enough to withstand an outside force such as an airplane crash. Nevalainen says one of the lessons learned from Olkiluoto 3 is that all aspects need to be verified down to the smallest supplier. Rosatom will “have to show who is doing what and when, and they have to show they have certified the quality assurance and quality control. When those are ready and good, Fennovoima then has to audit the supply chain. And when those audits are complete, and we can see that all work is being done according to instructions, then we will have assurance that things are being done in proper order.” In Russia at the Leningrad II nuclear plant site a VVER-1200 reactor is currently being built, which is scheduled to become operational in 2018, and serves as a useful reference for Hanhikivi 1. One of the strengths of Rosatom is its experience: it has produced more than 50 VVER family reactors. Fennovoima now employs about 300, and over half of them in Forsström’s project department: she has eight teams of engineers and technicians, of which some have more than 35 years experience in working with VVER technology. “I’m really proud of our team,” says Forsström. “Collectively, my supporting team has more than 200 years expertise working on large scale projects. I can really say nobody has ever before brought together that kind of team in Finland.” This article was first published inWorld Energy Focus 2016, a magazine produced by Energy Post for theWorld Energy Congress in Istanbul.


Beresford N.A.,UK Center for Ecology and Hydrology | Yankovich T.L.,Environment Canada | Wood M.D.,University of Salford | Fesenko S.,International Atomic Energy Agency | And 3 more authors.
Science of the Total Environment | Year: 2013

The application of the concentration ratio (CR) to predict radionuclide activity concentrations in wildlife from those in soil or water has become the widely accepted approach for environmental assessments. Recently both the ICRP and IAEA have produced compilations of CR values for application in environmental assessment. However, the CR approach has many limitations, most notably, that the transfer of most radionuclides is largely determined by site-specific factors (e.g. water or soil chemistry). Furthermore, there are few, if any, CR values for many radionuclide-organism combinations. In this paper, we propose an alternative approach and, as an example, demonstrate and test this for caesium and freshwater fish. Using a Residual Maximum Likelihood (REML) mixed-model regression we analysed a dataset comprising 597 entries for 53 freshwater fish species from 67 sites. The REML analysis generated a mean value for each species on a common scale after REML adjustment taking account of the effect of the inter-site variation. Using an independent dataset, we subsequently test the hypothesis that the REML model outputs can be used to predict radionuclide, in this case radiocaesium, activity concentrations in unknown species from the results of a species which has been sampled at a specific site. The outputs of the REML analysis accurately predicted 137Cs activity concentrations in different species of fish from 27 Finnish lakes; these data had not been used in our initial analyses. We recommend that this alternative approach be further investigated for other radionuclides and ecosystems. © 2013 Elsevier B.V.


Brown J.E.,Norwegian Radiation Protection Authority | Gjelsvik R.,Norwegian Radiation Protection Authority | Roos P.,Technical University of Denmark | Kalas J.A.,Norwegian Institute for Nature Research | And 2 more authors.
Journal of Environmental Radioactivity | Year: 2011

Recent developments regarding environmental impact assessment methodologies for radioactivity have precipitated the need for information on levels of naturally occurring radionuclides within and transfer to wild flora and fauna. The objectives of this study were therefore to determine activity concentrations of the main dose forming radionuclides 210Po and 210Pb in biota from terrestrial ecosystems thus providing insight into the behaviour of these radioisotopes. Samples of soil, plants and animals were collected at Dovrefjell, Central Norway and Olkiluoto, Finland. Soil profiles from Dovrefjell exhibited an approximately exponential fall in 210Pb activity concentrations from elevated levels in humus/surface soils to " supported" levels at depth. Activity concentrations of 210Po in fauna (invertebrates, mammals, birds) ranged between 2 and 123Bqkg-1d.w. and in plants and lichens between 20 and 138Bqkg-1d.w. The results showed that soil humus is an important reservoir for 210Po and 210Pb and that fauna in close contact with this media may also exhibit elevated levels of 210Po. Concentration ratios appear to have limited applicability with regards to prediction of activity concentrations of 210Po in invertebrates and vertebrates. Biokinetic models may provide a tool to explore in a more mechanistic way the behaviour of 210Po in this system. © 2010 Elsevier Ltd.


Niemela I.,STUK
11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012, PSAM11 ESREL 2012 | Year: 2012

This article presents an isolation of I&C model from PRA model as implemented in FinPSA software. The I&C system is modeled using communication vectors, which are suitable for modeling large distributed control systems. The modeling is compact and allows convenient expression of large systems. On top of the I&C system, control tasks are defined, and fault trees link to control tasks. The I&C model can link to fault trees to introduce dependencies, for example electric power or room cooling. Thus, the interface between system fault trees and I&C model is twofold: fault refer to I&C tasks, and I&C model refers to fault trees of its support systems.


Ahonen E.,STUK
11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012, PSAM11 ESREL 2012 | Year: 2012

This presentation is based on the master's thesis: Studying of the Failure Tolerance with the Probabilistic Risk Assessment, which examines the new YVL guides' requirements for the failure tolerance analysis. In addition, a new method for examining the possibility to accomplish these requirements with the probabilistic risk assessment (PRA) has been developed. The nuclear power plant safety arrangements are based on the requirement that no user error or equipment malfunction can cause any serious accident. Furthermore, the critical safety systems must be able to function if any given device in the system is incapacitated and if any given safety-related device is unavailable due to repairs or maintenance, even in several simultaneous occurrences. To ensure the failure tolerance of the most important safety functions, the operational principles behind different safety systems need to be as diverse and independent as possible. The developed method and the new value-adding measure of failure tolerance can be used to identify the dependency between various system factors. These can also be used in examining the implementation of the required safety factors.


Niemela I.,STUK
11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012, PSAM11 ESREL 2012 | Year: 2012

This article describes accurate quantification method MCA (MinCut Accurate) for minimal cut sets originating from event tree/fault tree systems. The method is intended primarily for cases where conditional failure probability is high and the rare event approximation is very inaccurate. The article shows that a single quantification method cannot be used, but a combination of two methods is required. This is because a minimal cut set file derived from several event tree sequences contains two types of cut sets: 1. Minimal cut sets derived from different accident sequences are mutually exclusive, since event tree sequences are mutually exclusive. 2. Minimal cut sets belonging to one accident sequence are mutually independent. It is also shown by an example that when minimal cut sets originate from several accident sequences with probabilistic success, Mincut Upper Bound (MCU) quantification can produce optimistic results. In theory, MCA requires calculation of a huge number of cross-products. In practical implementation, thresholds are defined to select cut sets for different quantification methods. Typically, it takes much less than one minute to quantify one million minimal cut sets.


Prat O.,CEA Marcoule Nuclear Site | Ansoborlo E.,CEA Marcoule Nuclear Site | Sage N.,CEA Marcoule Nuclear Site | Cavadore D.,CEA Marcoule Nuclear Site | And 3 more authors.
Environment International | Year: 2011

Ore workers are conventionally monitored for exposure by measuring the uranium in their urine, but specific biomarkers of kidney damage still remain to be discovered. A recent toxicogenomics study allowed us to focus on osteopontin (OSTP) normally excreted in human urine and linked to mineral metabolism. Objectives: We examined the association between osteopontin and uranium exposure both in vitro, in a human kidney cell model, and in the urine of exposed individuals. Methods: OSTP was measured in supernatants of uranium-exposed HK2 cells to establish a dose-response curve and a time course experiment. Its role was studied through a gene extinction experiment. Uranium and OSTP were then monitored in the urine of exposed nuclear fuel industry workers and a chronically exposed population. These levels were compared with those found in a non-exposed population. Results: The study of HK2 cells indicated that OSTP secretion decreased after uranium exposure in a concentration and time dependent manner, but its suppression does not affect cell sensitivity to uranium. In spite of wide inter-individual variability, this parameter decreases also in human urine when urinary uranium exceeds 30. μg/L after an acute exposure, a value considered to be critical for kidney damage. Conclusion: This study reports how toxicogenomics can highlight putative toxicity biomarkers in an easy to access biological fluid. The decrease of urinary osteopontin in response to uranium exposure suggests kidney damage and would thus be complementary to current markers. © 2011 Elsevier Ltd.

Loading STUK collaborators
Loading STUK collaborators