Technical Research Centre

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 26316 Experts worldwide ranked by ideXlab platform

Paterson Mckeough - One of the best experts on this subject based on the ideXlab platform.

  • Research on black-liquor conversion at the Technical Research Centre of Finland
    Bioresource Technology, 1993
    Co-Authors: Paterson Mckeough
    Abstract:

    Abstract A broad programme of Research and development on black-liquor gasification is being undertaken in Finland. The central activity in the programme consists of gasification experiments on a pressurized test facility, designed, built, and operated by the Technical Research Centre of Finland (VTT). The facility has played an important role in the process-development work being carried out in both the public and private sectors. Supporting activities in which VTT has been involved include laboratory-scale experiments, theoretical investigations, and system studies. Through these activities, significant contributions to the over-all process-development effort have been made. In fact, most of the basic data necessary for the present stage of development of black-liquor gasification processes have now been generated.

Mikko Malmivuo - One of the best experts on this subject based on the ideXlab platform.

Ho Cheol Shin - One of the best experts on this subject based on the ideXlab platform.

  • performance evaluation of zircaloy reflector for pressurized water reactors
    International Journal of Energy Research, 2016
    Co-Authors: Jiwon Choe, Deokjung Lee, Jieun Jung, Ho Cheol Shin
    Abstract:

    Summary This paper presents detailed analyses of a pressurized water reactor with a new reflector design using zirconium metal. The optimization of the reflector design has been performed using a two-dimensional fuel assembly reflector model. The three-dimensional core calculation results with the optimized reflector were compared against those with the existing water reflector and iron reflector. The high scattering cross section of zirconium enhances neutron reflections from the reflector to the core, increasing the peripheral assembly powers. From the analysis based on the equilibrium core, it was noted that the cycle length can be extended, and the pin peaks can be decreased when using zirconium reflector. The analysis has been performed for the optimized power reactor 1000 core with combustion engineering type fuel assemblies using the CASMO-4E/SIMULATE-3 (Studsvik Scandpower, Inc., Waltham, MA, USA) code system and SERPENT (VTT Technical Research Centre of Finland, Vuorimiehentie 3, 02150 Espoo, Finland) code, with ENDF/B-VI data. Copyright © 2015 John Wiley & Sons, Ltd.

Kainulainen Erja - One of the best experts on this subject based on the ideXlab platform.

  • Regulatory oversight of nuclear safety in Finland : Annual report 2016
    Säteilyturvakeskus, 2017
    Co-Authors: Kainulainen Erja
    Abstract:

    Management review In 2016, all Finnish nuclear power plants operated safely and caused no danger to their surrounding environment or employees. The collective radiation doses of employees were yet again historically low in almost all of the plant units and radioactive releases into the environment very small. The low employee radiation doses were the result of short annual outages and improvements implemented at the nuclear power plants. In spring 2016, three leaking fuel assemblies were replaced at Olkiluoto 1 during an extra refuelling outage, and then three more assemblies were replaced in connection with the annual outage due to subsequent leaks. The fuel leaks were one reason why the employee radiation doses at the plant unit were somewhat higher than in the previous years. Over the course of 2016, Fortum Power and Heat Oy (Fortum) submitted to STUK a total of 20 operational event reports. The operational events did not compromise nuclear or radiation safety. STUK performed an annual outage inspection in compliance with the periodic inspection programme during the annual outage. During the annual outages, Fortum inspected – according to a programme agreed with STUK – that there was no hydrogen flaking in the reactor pressure vessel of the power plant unit 1. Hydrogen flaking could have occurred during manufacture of the pressure vessel. A similar inspection on the pressure vessel of Loviisa 2 was performed in 2014. No hydrogen flaking was detected in either of the pressure vessels. In 2016, STUK focused its regulatory oversight on the Fortum’s organisation, inspecting Fortum’s management, competence, resource and procurement processes. Also in 2016, Fortum completed a major organisational renewal, and STUK oversaw its implementation and initial impact as part of its regulatory oversight. In 2016, Teollisuuden Voima Oyj (TVO) submitted to STUK 11 operational event reports. Some radioactive materials were released into the environment in the case of two of the events. One of the events involved fuel leaks and the other an error during maintenance. The set limits were not exceeded and neither of the events compromised radiation safety of the population. Both events increased the radiation level inside the plant, which was taken into account when planning the work to be done by the employees. STUK performed an annual outage inspection in compliance with the periodic inspection programme during the annual outage. TVO implemented a new organisation and operations model in 2015. Based on inspections by STUK, the new operations model has been largely established, but there are still some challenges pertaining to the atmosphere at the company and the adequacy of resources. STUK will continue to monitor as part of its regulatory oversight the situation and the actions taken by TVO to maintain the organisation’s safety culture during the challenging change. At both Olkiluoto and Loviisa, modifications required for improving safety continued. New main steam line safety valves were installed at Loviisa 1 during the 2016 annual outage. They will also operate in a case where water flows through them in addition to steam. A similar installation was carried out at Loviisa 2 in 2014. New main steam line radiation measuring instruments were also installed and commissioned at Loviisa 1. Of the improvement measures started after the Fukushima accident, further improvements of the flood protection and securing the cooling of the fuel pools are still remaining. Their planning proceeded in 2016. An improvement project of the diesel fuel storage and transfer system was completed in 2016. STUK continued its review of the Loviisa I&C renewal documents and supervised installation work of the renewal’s first phase during the 2016 annual outage. The first phase included a preventive safety function control and indication system as well as modernisation of the I&C status monitoring system. The rest of the I&C renewal installations will be completed during the 2017 and 2018 annual outages. As a result of the Fukushima accident, Olkiluoto will improve, for example, systems used to cool the reactor and add whole new systems for pumping water into the reactor in case of a complete loss of AC power. Another ongoing project at Olkiluoto is an upgrade of the reactor coolant pumps and the emergency diesel generators. In 2016, first of the six reactor coolant pumps in Olkiluoto 1 was replaced. TVO plans to commission the new reactor coolant pumps between 2016 and 2018. STUK continued its review of documents pertaining to the modifications and the supervision of manufacture. The installation and construction work of Olkiluoto 3 are nearing the end, and full-scale testing of the systems and components was started in 2016. Testing of the I&C systems started at the beginning of the year and the first process system tests were performed in April 2016. TVO submitted an operating licence application for the plant unit to the Ministry of Economic Affairs and Employment (MEAE) in April 2016. At the same time, TVO submitted the documents on the plant and its operation required by virtue of the Nuclear Energy Decree to STUK for approval. In 2016, STUK focused its regulatory oversight on review of the operating licence application and on oversight of the remaining installations and the commissioning activities. While reviewing the operating licence application, STUK also prepared implementation decisions for Olkiluoto 3 of the updated YVL Guides that were published in 2013. The new YVL Guides will enter into force for Olkiluoto 3 as soon as the operating licence is granted. Due to suspected product forgeries involving manufacturers in France, STUK required reports from the power companies on whether the suspicions involve manufacture of the components used at Olkiluoto 3 or whether any components from the said manufacturers have been used at the operating nuclear power plants. The report on Olkiluoto 3 must be submitted to STUK by the end of April 2017. No forgeries have been detected at the operating plant units, but the reports on Loviisa will be supplemented in early 2017. In June 2015, Fennovoima submitted to the MEAE a construction licence application for a new nuclear power plant. At the same time, Fennovoima submitted to STUK for review documents required by the Nuclear Energy Decree. Fennovoima has supplemented and will supplement the construction licence application in stages between 2015 and 2018. Delivery of documents has been delayed from the schedule of the first licensing plan due to slower organisation than expected of the project and its supply chain and due to a lack of resources in the design organisation. STUK monitored the development of Fennovoima’s management system and quality management, and assessed the company’s organisational resources to begin construction of a nuclear power plant. In September 2015, STUK launched the inspections included in the regulatory inspection programme, and a total of 15 inspections of Fennovoima and key organisations of the plant supplier were carried out in 2016. Furthermore, STUK’s experts participated as observers in audits of the plant supplier and its subcontractors, arranged by Fennovoima. The handling and storage of spent nuclear fuel and operational waste and the disposal of operational waste were implemented safely, and no events compromising safety were detected at the Loviisa or Olkiluoto nuclear power plants. Due to the successful planning of operations, the plants accumulated clearly less operational waste than nuclear power plants on average. An important positive development in the waste management of the plants was the fact that operation of a solidification facility for liquid radioactive waste at the Loviisa nuclear power plant started on 15 February 2016 after STUK had approved the related application. Fortum continued the planning of repairs of the damage observed in the outer surface of the concrete vault in the solidified waste disposal facility, which is why the disposal of solidified waste could not be started yet. The operating licence for the Research reactor FiR 1 of VTT Technical Research Centre of Finland is valid until the end of 2023. VTT shut down the Research reactor for financial reasons in June 2015 and has been preparing decommissioning of the Research reactor ever since. STUK has conducted all the measures necessary for the oversight of the reactor that was shut down and prepared for the review of the application on the decommissioning of the reactor. VTT submitted a nuclear waste management plan for the Research reactor to the Ministry of Economic Affairs and Employment in September 2016. The report described all measures since the 2015 report and all planned measures up until 2022. STUK stated in its statement to the MEAE that VTT had clearly progressed with the planning of the Research reactor’s decommissioning over the course of the past year. The most important open issues regarding the decommissioning of the Research reactor involve the return of spent fuel to the United States and the storage and disposal of dismantling waste. After Posiva Oy received a construction licence from the Government on 12 November 2015, STUK’s oversight has focused on the construction of the encapsulation and disposal facility. The regulatory oversight during the construction stage covers design, manufacture, construction and installation of the nuclear waste facility and its safety-classified systems, structures and components. This stage also includes the nuclear waste facility’s commissioning stage, at which time STUK will oversee Posiva’s operations, review testing programmes and results, and perform commissioning inspections. In 2016, STUK’s oversight focused particularly on the assessment of Posiva’s readiness for construction after the submission of the construction licence. STUK continued to oversee construction of the underground Research facility by Posiva, Posiva’s system design, activities of the Posiva organisation and development of Posiva’s safety analyses. An important stage in 2016 was the start of the construction of the disposal facility according to the construction licence. STUK comprehensively assessed Posiva’s readiness for construction before the construction work was started. In June 2016, Fennovoima submitted to the MEAE its environmental impact assessment programme on the disposal of spent nuclear fuel as required in the 2010 decision-inprinciple. The submission of the EIA programme started Fennovoima’s spent fuel disposal project and the selection process of the disposal facility site. Fennovoima has proposed Sydänneva in Pyhäjoki and Eurajoki as the potential sites. The more exact Research area in Eurajoki has not been determined as of yet. In its statement on the EIA programme, STUK emphasised the fact that the proposed process would last a long time, the need to regularly assess the programme to ensure that it is up to date and the fact that the exact Research area in Eurajoki must be determined as soon as possible. In addition to the operation and construction of a nuclear facility, the use of nuclear energy as laid down in section 2 of the Nuclear Energy Act includes the possession, manufacture, production, transfer, handling, use, storage, transport, export and import of nuclear material. Furthermore, components, systems and information required by nuclear facilities are subject to licensing and oversight by virtue of the Nuclear Energy Act. In 2016, STUK became aware of two cases of import without the proper licence. Nuclear safeguards in Finland were implemented in compliance with the international treaties. Nuclear safeguards ensure that nuclear materials and other nuclear items remain in peaceful use in compliance with the relevant licences and declarations and that nuclear facilities and related technologies are only utilised for peaceful purposes. STUK maintains a national control system which aim is to take care of the necessary oversight of use of nuclear energy for the non-proliferation of nuclear weapons. STUK processed reports and declarations on nuclear materials and performed safeguards inspections together with the International Atomic Energy Agency (IAEA) and the European Commission. STUK actively promoted with the IAEA and the European Commission the development of nuclear safeguards for the disposal of spent fuel. Key issues in this development work were the development of a new oversight model and a new fuel measuring technology.1. paino

  • Regulatory oversight of nuclear safety in Finland : Annual report 2014
    Säteilyturvakeskus, 2015
    Co-Authors: Kainulainen Erja
    Abstract:

    Management review In 2014, all Finnish nuclear power plants operated safely and caused no danger to their surrounding environment or employees. The collective radiation doses of employees were yet again historically low and the radioactive releases into the environment very small. The low employee radiation doses were the result of short annual outages and improvements implemented by the NPPs. Radioactive waste generated in the operational processes of the NPPs accumulated as anticipated. Its processing and final disposal in underground facilities took place in a controlled manner. An emergency preparedness drill was arranged at the Loviisa NPP in November to practice, for the first time in Finland, a simultaneous emergency at two plant units. In 2014, six events warranting a special report were reported by Loviisa NPP. These events did not influence the safety of the employees or the area surrounding the plant. Fortum Power and Heat Oy (hereinafter referred to as “Fortum”) has several pending long-term nuclear safety development projects that involve development of the management system, processing of operational events, as well as maintenance of the operational limits and conditions. STUK will monitor their progress and assess effectiveness of the measures. As part of the oversight of the organisation, STUK ordered a study to assess the nuclear safety culture of Fortum and the functionality of related procedures. The report states that safety is appreciated at Loviisa NPP and the safety culture in general is at an acceptable level. However, the NPP must continue active development of the safety culture. In 2014, three events warranting a special report were reported by the operating units at Olkiluoto. These events did not influence the safety of the employees or the area surrounding the plant. STUK performed an annual outage inspection in compliance with the inspection programme during the annual outage. Good operations and examples of continuous improvement were observed during the inspection. During inservice inspections carried out during the annual outage, Teollisuuden Voima Oyj (hereinafter “TVO”) detected cracks in the feedwater lines of both plant units. The cracked mixing points will be replaced during the next annual outage. In 2014, STUK focused its regulatory oversight on the plant’s management, modification and procurement processes. A reformed modification work process was introduced in 2014. At both Olkiluoto and Loviisa, modifications required for improving safety continued regarding plant systems, structures and components as well as operating procedures. An expansion project of the interim storage facility for spent nuclear fuel at Olkiluoto proceeded as planned in 2014. System modifications have been completed. A decision on an application to increase the capacity of the interim storage facility for spent nuclear fuel is being processed by STUK. An upgrade project regarding the reactor coolant pumps, their control and the frequency converters needed to supply power to the pumps has been started at Olkiluoto. STUK approved the project’s conceptual design plans in 2014. As a result of the Fukushima accident, Olkiluoto will improve, for example, systems used to cool the reactor and add whole new systems for pumping water into the reactor in case of a complete loss of AC power. In 2014, a modification of an auxiliary feedwater system recirculation line was implemented at Olkiluoto 1. It reduces the system’s dependence on seawater cooling. The purpose of an I&C renewal project launched at Loviisa NPP in 2005 was to digitalise almost the entire I&C system of the plant. In 2014, Fortum announced that the supplier of the modernisation had been changed and the scope of the renewal project had been significantly cut back, which is why the project would not be completed until by the end of 2018. Modifications implemented in 2014 included improving reliability of the reactor coolant system’s pressure control system at Loviisa 2 and installing qualified safety valves for the secondary side water and water/steam flow. As a result of the Fukushima accident, four air-cooled heat exchangers have been installed that will ensure cooling of the fuel in the reactor and the fuel pools in case heat transfer to the sea is lost. Furthermore, separate flood protection components have been installed in some systems important to safety. The protection elements take into account exceptionally high seawater levels during a storm. Most of the detailed design of the Olkiluoto 3 plant unit has been approved by STUK, and the volumes of construction work and component manufacture have decreased. Installation activity at the Olkiluoto 3 construction site has also slowed down starting in early 2014. Manufacture and installation of the emergency diesel generator auxiliary system pipelines were almost the only works still ongoing in 2014. Pressure and leak tightness tests of the containment took place at the nuclear island in February. STUK inspected the plant site before testing and oversaw the testing. Results of the tests clearly met the acceptance criteria. The most important open issue regarding plant design at Olkiluoto 3 is the I&C systems. In 2014, the licensing of I&C proceeded well as STUK approved the overall I&C plan, i.e. architecture, and found that the analysis of I&C active failures were acceptable. Next, STUK started reviewing the Technical I&C materials. In 2014, STUK ordered a preliminary report on the safety culture during commissioning of Olkiluoto 3. Challenges highlighted in the report included the highly complex stage during the lifecycle of the plant and the fact that open items and deviations from the construction stage tend to cumulate. Issues that were deemed especially challenging included potential slow processing of unexpected events and people focusing only on their own work in a very narrow sector. The results will assist STUK in targeting its regulatory oversight to the key issues and challenges during the commissioning stage. In 2014, STUK drafted preliminary safety assessments on supplementary applications for the decisions-in-principle on Fennovoima’s Hanhikivi 1 and TVO’s Olkiluoto 4. In its preliminary safety assessment on Fennovoima’s Hanhikivi 1 plant unit, STUK stated that an AES-2006 nuclear power plant of Rosatom can be constructed in a manner that meets the Finnish safety requirements. However, STUK raised some issues where meeting of the Finnish safety requirements would require changing of the NPP design, such as provisions for an airplane crash, internal floods, fires and severe accidents. STUK also stated that Fennovoima must improve its expertise and develop its management system in order to be capable to assess and ensure the safety of a new NPP, as well as to draft the construction license materials to be submitted to STUK. In its supplementary application, TVO applied for an extension of five years to the deadline for submitting a construction license application for the new nuclear power plant unit at Olkiluoto in compliance with the 2010 decision-in-principle. STUK stated that there are no nuclear safety issues that would prevent the extending of the deadline. The Government approved Fennovoima’s supplementary application for the decision-in-principle and the Parliament ratified it. The Government refused TVO’s application on an extension to the deadline for the construction license application. In 2014, STUK continued its preparations for the processing of the construction license applications. The processing and storage of nuclear waste and spent nuclear fuel, as well as the nuclear fuel repository project, proceeded safely, and no problems were detected at Loviisa or Olkiluoto. Due to the successful planning of operations, the plants accumulated clearly less nuclear waste than NPPs on average. At Loviisa NPP, STUK supervised the commissioning of a liquid waste solidification facility. Damage was observed in concrete containers used in solidification at the end of 2013. Trial runs were discontinued to study their cause. STUK deemed the conclusions made based on reports correct. Loviisa NPP continued its activities and studies pertaining to the commissioning of the solidification facility, and the trial runs should be completed by the end of 2015. STUK reviewed and approved a periodic safety assessment of the Loviisa low- and intermediate-level operational waste repository and stated that the safety level of the repository is good and its operation can be safely continued. VTT Technical Research Centre of Finland is preparing the decommissioning of a Research reactor at Otaniemi. STUK issued statements on the environmental impact assessment program for the decommissioning and a related report. The project by Posiva Oy (hereinafter referred to as “Posiva”) on final disposal of spent nuclear fuel has proceeded: Posiva submitted a construction license application for the encapsulation plant and disposal facility to the Government in late 2012. Posiva submitted to STUK the safety documentation required by the Nuclear Energy Decree and STUK started reviewing the materials in early 2013. The fact that some of the application materials were submitted to STUK late and the need for additional information to some documents was postponed the review process, which was completed in late 2014. A statement by the Advisory Committee on Nuclear Safety on the Posiva construction license application and the preliminary safety assessment by STUK, as well as STUK’s statement, could not be submitted to the Ministry of Employment and the Economy until in early 2015. The process was very demanding because it was the first preliminary safety assessment for a repository of this type in the world. STUK used a team of Finnish and international experts from a variety of Technical sectors as an aid in its review. In addition to reviewing the documents, STUK conducted inspections of Posiva’s management system and organisation. STUK was able to determine that the encapsulation plant and disposal facility can be constructed in such a manner that it will be safe. In separate decisions on documents by virtue of section 35 of the Nuclear Energy Act, STUK presented specific requirements regarding the construction stage. The requirements included supplementing the system design of the encapsulation plant in compliance with the construction stages, further studies on the performance of the barriers of the repository and development of the long-term safety case for the operating license application. The construction of the underground Research facility (Onkalo) was completed for the most part by the end of 2012. In 2014, Posiva excavated facilities to be used to test the final disposal method, as well as the last of the shafts and tunnels, and completed structural engineering works. STUK supervised the construction of the underground Research facility, the operations of Posiva’s organisation and the Research carried out at Onkalo. The safeguards of nuclear materials in Finland was implemented in compliance with the international agreements. Annual verifications of design information were implemented for the nuclear power plant units under construction and the physical inventories of nuclear materials of the operating NPPs were verified. STUK verified the correctness of stored fuel data by means of spent fuel measurements. Furthermore, STUK inspected the operations of other nuclear material holders and physical inventory results. As a summary of the inspections and oversight in 2014, STUK could state that nuclear energy was used in compliance with the reports and no unannounced activities took place. Inspection results submitted by the IAEA and the European Commission as well as conclusions made based on the inspection activities also support STUK’s observations. In 2014, the IAEA and the Commission started electronic transfer of surveillance data from Loviisa NPP directly to the Commission and further to the IAEA. Enabling the electronic transfer of monitoring data is an obligation laid down in the Additional Protocol of the Safeguards Agreement between Finland and the IAEA. STUK’s duty was to support the NPPs and international organisations when they ensure that the electronic data transfer complies with all requirements pertaining to nuclear security and information security. In 2014, STUK participated in a laser scanning campaign of the Onkalo facility carried out by the Commission and the IAEA where it was verified that Onkalo has been constructed as reported. The results of the campaign can be used as reference data in future inspections of Onkalo.1. paino

Maria Pusa - One of the best experts on this subject based on the ideXlab platform.

  • The Numerical Multi-Physics project (NUMPS) at VTT Technical Research Centre of Finland
    Annals of Nuclear Energy, 2015
    Co-Authors: Jaakko Leppänen, Ville Hovi, Timo Ikonen, Joona Kurki, Maria Pusa, Ville Valtavirta, Tuomas Viitanen
    Abstract:

    Abstract The four-year Numerical Multi-Physics (NUMPS) project funded by the Academy of Finland was initiated at VTT Technical Research Centre of Finland in September 2012, for the purpose of studying and developing high-fidelity computational methods for nuclear reactor analysis. The project is built around calculation codes developed at VTT, and it aims at the coupled three-dimensional modeling of neutronics, thermal hydraulics and fuel behavior of nuclear reactors. The work involves the continuous-energy Monte Carlo code Serpent and CFD code PORFLO, together with two light-weight solvers, COSY and FINIX, coupled to Serpent at source code level. This paper is a review on the current status and development activities, reflecting the status of the NUMPS project at the beginning of its second complete year.

  • The Serpent Monte Carlo code: Status, development and applications in 2013
    Annals of Nuclear Energy, 2015
    Co-Authors: Jaakko Leppänen, Maria Pusa, Ville Valtavirta, Tuomas Viitanen, Toni Kaltiaisenaho
    Abstract:

    Abstract The Serpent Monte Carlo reactor physics burnup calculation code has been developed at VTT Technical Research Centre of Finland since 2004, and is currently used in over 100 universities and Research organizations around the world. This paper presents the brief history of the project, together with the currently available methods and capabilities and plans for future work. Typical user applications are introduced in the form of a summary review on Serpent-related publications over the past few years.

  • burnup calculation capability in the psg2 serpent monte carlo reactor physics code
    2009
    Co-Authors: Jaakko Lepp, Maria Pusa
    Abstract:

    The PSG continuous-energy Monte Carlo reactor physics code has been developed at VTT Technical Research Centre of Finland since 2004. The code is mainly intended for group constant generation for coupled reactor simulator calculations and other tasks traditionally handled using deterministic lattices physics codes. The name was recently changed from acronym PSG to “Serpent”, and the capabilities have been extended by implementing built-in burnup calculation routines that enable the code to be used for fuel cycle studie s and the modelling of irradiated fuels. This paper presents the methodology used for burnup calculation. Serpent has two fundamentally different options for solving the Bateman depletion equations: 1) the Transmutation Trajectory Analysis method (TTA), based on the analytical solution of linearized depletion chains and 2) the Chebyshev Rational Approximation Method (CRAM), an advanced matrix exponential solution developed at VTT. The first validation results are compared t o deterministic CASMO-4E calculations. It is also shown that the overall running time in Monte Carlo burnup calculation can be significantly reduced using specialized calculation tec hniques, and that the continuous-energy Monte Carlo method is becoming a viable alternative to deterministic assembly burnup codes.