atw - International Journal for Nuclear Power | 06.2021

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atw Vol. 66 (2021) | Issue 6 ı November RESEARCH AND INNOVATION 56 performed. The wall condensation models were incorporated into the SPACE code heat transfer package. For pure steam condensation, like the problem addressed in this paper, the same model used in RELAP5/MOD3.3 was selected as a default model. The maximum value among Nusselt’s [14], Shah’s [15], and Chato’s [16] correlations is used to consider the geometric and turbulent effects. The experimental correlation for PAFS is also included in the wall condensation model as an option in SPACE code [17]. Based on the calculation results mentioned in chapter 3.2.1, this model was applied. In this section, the default model and experiment correlation model for PAFS were compared to confirm the prediction ability of SPACE code for PCHX cooling performance. Chen’s model, which is the default option in SPACE code, is applied to the outside of PCHX [18]. The fluid temperature after PAFS operation is shown in Figure 12. The calculation result shows that the fluid temperature on the return water line is higher than the experiment, and that the default option case is highest. That means that the calculation results which were obtained using the default option and the PAFS model underestimated cooling performance. However, the calculation using the PAFS model was more accurate than the default option. 4 Conclusions In this study, a MSGTR experiment with the PAFS operation performed by KAERI was simulated using the SPACE code. This study focused on verifying the prediction capability of the SPACE code for MSGTR accidents, which is one of the multiple failure accidents, and to evaluate the cooling capacity of the PAFS during such an accident. The calculation results showed that the overall system transient results using the SPACE code showed comparatively similar trends with the experimental results in terms of the system pressure, mass flow rate, and collapsed water level in components. Therefore, it was concluded that the SPACE code reasonably predicted the experiment. And, the default model, which uses the maximum value among Nusselt’s, Shah’s, and Chato’s and the experiment correlation model for PAFS in SPACE code were compared to confirm the prediction ability of SPACE code for PCHX cooling performance. The calculation result using the PAFS model was more accurately estimated than the default option. Based on the present calculation results, the following conclusions were obtained in this study. First, the experiment and calculation results showed that the cooling capability of PAFS is sufficient to replace the active auxiliary feedwater system during MSGTR transient. Additionally, it is recommended that the PAFS model in SPACE code be applied for more accurate prediction results for PAFS operation by performing a safety analysis of an APR+ nuclear power plant. Acknowledgements This work was performed within the program of the fifth ATLAS Domestic Standard Problem (DSP-05), which was organized by the Korea Atomic Energy Research Institute (KAERI) in collaboration with the Korea Institute of Nuclear Safety (KINS) under the national nuclear R&D program funded by the Ministry of Education (MOE) of the Korean government. The authors are also grateful to the fifth ATLAS DSP-05 program participants: KAERI for the experimental data and to the council of the fifth DSP- 05 program for providing the opportunity to publish the results. Acronyms and Abbreviations NPP HSGL LPP MSIV MFIV Nuclear Power Plant High Steam Generator Level Low Pressurizer Pressure Main Steam Isolation Valve Main Feed-water Isolation Valve MSSV Main Steam Safety Valve SIP PAFS PCCT Safety Injection Pump Passive Auxiliary Feedwater System Passive Condensate Cooling Tank PCHX Passive Condensation Heat Exchanger HL CL IL SG Hot Leg Cold Leg Intermediate Leg Steam Generator References [1] Korean NSSC, Regulations on the Scope of Accident Management and the detailed criteria of Accident Management Capability Evaluation, Notification No. 2017- 34 of the Nuclear Safety and Security Commission in Korea, Rev.1 (2017). [2] IAEA, Safety of Nuclear Power Plants: Design, IAEA Specific Safety Requirements No. SSR-2/1, Rev.1 (2016). [3] J.H. Koh et al., Current status of design extension conditions technology development for prevention of severe accident in nuclear power plants, 13th International Conference on probabilistic Safety Assessment and Management (PSAM 13) (2016). [4] KAERI, Experimental Study on the Multiple Steam Generator Tube Rupture with Passive Auxiliary Feedwater System Operation, KAERI/TR-8010/2020 (2020). [5] J. Cheon et al., The Development of a Passive Auxiliary Feedwater System in APR+, ICAPP2010, San Diego, USA (2010). [6] S.J. Ha et al., Development of the SPACE code for nuclear power plants, Nuclear Engineering and Technology 43, (2011) 45-62. [7] IAEA, Safety Assessment for Facilities and Activities, IAEA Safety Standards Series No. GSR Part 4, Rev.1 (2016). [8] Petruzzi, A., D’Auria, F., Thermal-Hydraulic System Codes in Nuclear Reactor Safety and Qualification Procedures, Science and Technology of Nuclear Installations, Vol. 2008, Article ID 460795, (2008) p.16. [9] KAERI, Description report of ATLAS facility and instrumentation, KAERI/TR-7218/2018 (2018). [10] Y.S. Kim et al., Commissioning of the ATLAS thermalhydraulic integral test facility, Annals of Nuclear Energy, Vol. 35, (2008) pp. 1791-1799. [11] K.H. Kang et al., Separate and integral effect tests for validation of cooling and operational performance of the APR+ Passive Auxiliary Feedwater System, Nuclear Engineering and Technology 44, No.6, (2012). [12] KAERI, Description report of ATLAS-PAFS Facility and Instrumentation, KAERI/TR-5545/2014 (2014). [13] B.U. Bae et al., Design of condensation heat exchanger for the PAFS(Passive Auxiliary Feedwater System) of APR+ ( Advanced Power Reactor Plus)”, Annals of Nuclear Energy, Vol.46, (2012) 134-143. [14] Nusselt, W.A., The surface Condensation of Water Vapor, Zieschrift Ver. Deut. Ing., 60, (1916) p.541. [15] Shah, M.M., A general correlation for heat transfer during film condensation inside pipes, Int. J. Heat Mass Transfer, 22, (1979) p.547. [16] Chato, J.C., Laminar Condensation inside Horizontal and Inclined Tubes, American society of heating, refrigeration and air conditioning engineering journal, 4, (1962) p.52. [17] B.U. Bae et al., Evaluation of mechanistic wall condensation models for horizontal heat exchanger in PAFS (Passive Auxiliary Feedwater System), Annals of Nuclear Energy, Vol.107, (2017) 53-61. [18] K.Y. Choi et al., Development of a wall-to-fluid heat transfer package for the SPACE code, Nuclear Engineering and Technology, Vol.41, No.9 (2009). Author Kyungho Nam Associate research engineer Korea Hydro & Nuclear Power Co., LTD. Central Research Institute Safety Analysis Group Deajeon, Republic of Korea Kyungho Nam. Associate research engineer at Korea Hydro & Nuclear Power Central Research Institute (KHNP CRI). Majored in nuclear engineering and have a master’s degree 4 years of experience in nuclear safety analysis, and the current work is also safety analysis using safety analysis code and containment P/T analysis. Research and Innovation Study on Verification of SPACE Code Based on an MSGTR Experiment at the ATLAS-PAFS Facility ı Kyungho Nam
atw Vol. 66 (2021) | Issue 6 ı November Top IAEA Presents New Platform on Small Modular Reactors and Their Applications (iaea) The IAEA presented its newly established Platform on Small Modular Reactors (SMRs) and their Applications, aimed at supporting countries worldwide in the development and deployment of this emerging nuclear power technology, during an event on the margins of the of the 65 th IAEA General Conference. With more than 70 SMR designs under development in 17 countries and the first SMR units already in operation in Russia, SMRs and their smaller cousins, microreactors (MRs), are forecast to play an increasingly important role in helping the global energy transition to net zero. Still, the technology, its safety and economic competitiveness must be de monstrated before SMRs can be more widely deployed, panellists agreed. The IAEA’s new Platform on SMRs and their Applications will assist countries in addressing these and related challenges. Using as a reference the Nuclear Energy Series publication, Technology Roadmap for Small Modular Reactor Deployment, the Platform provides experts with a one-stop shop to access the IAEA’s full array of support and expertise on SMRs, from technology development and deployment (including nonelectric applications) to nuclear safety, security and safeguards. “High standards of nuclear safety, security and non-proliferation must be ensured for SMR deployment,” Mikhail Chudakov, IAEA Deputy Director General and Head of the Department of Nuclear Energy said in his opening remarks. “But beyond this, it is generally recognized that if SMRs are going to be successful, they will need to be economically com petitive with respect to other clean energy alternatives. Achieving that will require accelerating their technological development and readiness level.” The IAEA has in place several activities related to SMRs to support its Member States through cooperation in SMR design, development and deployment and to serve as a hub for sharing SMR regulatory knowledge and experience. Although the IAEA safety standards can generally be applied to SMRs, global experts from the SMR Regulators’ Forum are working on a tailor-made solution to help national authorities regulate this new class of nuclear power reactors, which are expected to generate up to 300 megawatts (electrical) (MW(e)) of power depending on their design. Participants spoke about challenges facing SMR development and deployment and how the new Platform could be used to help countries address them. “Potential topics for medium to long term activities include supply chain development, the development of industrial codes and standards, and suitable deployment strategies,” said Marco Ricotti, a professor of nuclear engineering at Italy’s Politecnico di Milano, who chairs the IAEA’s Technical Working Group for Small and Medium-sized or Modular Reactors (TWG-SMR). “Based on discussions within the (SMR Regulators’) Forum and also within our own regulatory forums at work, we feel strongly that it is not realistic in the near term to develop detailed guidance for every technology,” said Marcel de Vos, who works on new reactor licensing at the Canadian Nuclear Safety Commission. “The pragmatic approach in our view is that we need to work with what we have and make calculated improvements as experiences are gathered and gained.” “There is a lot of work ahead of us, but we are working efficiently and in the right direction with Member States,” said Lydie Evrad, Deputy Director General and Head of the Department of Nuclear Safety and Nuclear Security. “The Platform is a very powerful interdepartmental mechanism, bringing together expertise from across the organization on SMRs,” said Stefano Monti, Chair of the Platform Implementation Team and Head of the IAEA’s Nuclear Power Technology Development Section. | www.iaea.org Foratom: Limited Attention to Nuclear in Commission’s Energy Price Communication (foratom) FORATOM would have liked to see today’s communication from the Commission pay closer attention to the role which low-carbon and dispatchable nuclear can play in mitigating the current energy crisis. By including European nuclear in its toolkit of measures to tackle energy prices, it would have a unique opportunity of limiting its dependence on carbon intensive natural gas imports, thereby reducing its exposure to wholesale price fluctuations and its carbon footprint. “As highlighted in the communication, the current price increases are being driven by higher natural gas prices on the global market”, states Yves Desbazeille, FORATOM Director General. “Therefore, as the EU moves to increase its share of variable renewables, it is essential that EU policy supports other low-carbon European sources to ensure reduced dependency on imports.” The Communication also highlights the effects which lower availability of renewables has had on the market, leading to supply constraints. Because nuclear can provide both baseload and dispatchable electricity, it acts as a perfect counterbalance at times when renewables are unavailable. As noted in the Communication, nuclear currently accounts for around 25% of the electricity mix in the EU. With industrial activity ramping up post COVID, this has led to an increase in demand for energy. “It would be a mistake to treat this as a short-term issue. It is clear that demand for electricity is expected to increase dramatically in the push to decarbonise Europe’s economy” adds Mr. Desbazeille. “Therefore, the EU needs to already be putting solutions in place today to ensure that it is able to generate enough low-carbon electricity in Europe to meet growing demand. This means supporting the development of nuclear energy”. The Communication also makes reference to the sustainable finance taxonomy, reiterating the point that a complementary Delegated Act (CDA) ‘will cover nuclear energy subject to and consistent with the results of the specific review process underway in accordance with the EU Taxonomy Regulation’. As this review is now complete, and the experts have overall concluded that nuclear is taxonomy compliant, we urge the Commission to urgently publish the CDA to avoid nuclear being unfairly penalised. | www.foratom.org NEI’s New Ad Campaign “See the Light” Embraces a Carbon-Free Future (nei) What’s New? The Nuclear Energy Institute launched its “See the Light” ad campaign, which speaks to the critical role nuclear energy plays in our carbon-free future. With eye-catching bursts of light illumi nating a dark room, the ad emphasizes that a brighter future must be powered by a diverse energy system championed by wind, solar and nuclear. 57 NEWS News
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