Periodic Reporting for period 2 - PIACE (Passive Isolation Condenser)
Periodo di rendicontazione: 2020-12-01 al 2022-11-30
Sustainability and safety improvements are the challenges of the new generations of fission nuclear reactors. Safety involves the largest interest of scientific community, which is pushing to provide technological solutions with high reliability and efficiency. In this framework the project PIACE (Passive Isolation Condenser) will provide a significant contribution to the safety improvement of the present and future technology of nuclear reactors.
The project will demonstrate the feasibility and reliability, shortening the time to market, of an innovative Decay Heat Removal (DHR) system, based on an isolation condenser with non-condensable gases, to manage the variable decay heat in passive way. The innovative concept has the important peculiarity to be completely passive, and the flexibility to be adapted both to the liquid metal and water cooled reactors. Two main branches can be identified in the project, a design assessment, with the support of numerical codes, to analyse the applicability of the concept to the different reactors technologies, and an experimental investigation to test the feasibility and the performance of the system.
The experimental tests will get advantage of the facility SIRIO located in Italy in the SIET laboratories. The facility is conceived for feasibility testing on this new DHR system and it will be easily adaptable for the tests in PIACE.
The ultimate goal is the finalization of specific designs of the innovative DHR concept, ready for industrial implementation on several reactor technologies ranging from currently operating plants (L- and H-WRs) to innovative energy systems (including FRs and ADSs).
The project will demonstrate the feasibility and reliability, shortening the time to market, of an innovative Decay Heat Removal (DHR) system, based on an isolation condenser with non-condensable gases, to manage the variable decay heat in passive way. The innovative concept has the important peculiarity to be completely passive, and the flexibility to be adapted both to the liquid metal and water cooled reactors. Two main branches can be identified in the project, a design assessment, with the support of numerical codes, to analyse the applicability of the concept to the different reactors technologies, and an experimental investigation to test the feasibility and the performance of the system.
The experimental tests will get advantage of the facility SIRIO located in Italy in the SIET laboratories. The facility is conceived for feasibility testing on this new DHR system and it will be easily adaptable for the tests in PIACE.
The ultimate goal is the finalization of specific designs of the innovative DHR concept, ready for industrial implementation on several reactor technologies ranging from currently operating plants (L- and H-WRs) to innovative energy systems (including FRs and ADSs).
In the WP1, the new DHR system was integrated in each reactors technology, the transient enveloping scenarios were defined and the most representative ones, for each reactor, were selected. The system code RELAP5-3D© v.4.3.4. is utilized for the simulations.
The output of the activity reports the description of the systems investigated, the conditions of operation, the enveloping transient scenarios analysed.
In the WP2, on the base of the output of the WP1, the test matrix of each reactor technology relevant for the experimental characterization on SIRIO facility is defined.
For the definition of the test matrix, a steady state has been simulated, in order to guarantee the achievement of the right working conditions corresponding to the nominal conditions of each reactor technology analysed. Then, a transient test has been simulated, in order to evaluate the system response after the actuation of the decay heat removal system, paying attention on the performance of the isolation condenser and the capabilities of non-condensable gases to passively control the coolant temperature, assuring safe long term cooling conditions. The numerical results obtained allow to address that the main phenomena of interest of the safety system for the reactor technologies under investigation can be effectively represented by the SIRIO experimental facility.
The WP3 was devoted to the experimental campaigns needed to verify the system operation and increase its TRL. The available experimental facility SIRIO was used. The facility was however upgraded to fulfil the test to characterized experimentally the innovative decay heat removal systems, both for the LFR (ALFRED) configuration and for additional two reference technologies test cases, which were properly selected to be representative for the wide possible scenarios of the different reactor technologies. The first step of the WP3 was the selection of the two reference cases. The choice of two additional reference test cases, to be experimentally simulated, was based on the amount of investments and related time efforts needed for achieving the SIRIO upgrade, and according to the technological relevance of the proposed tests for any reference systems, according to the feedback received from the WP2. The result of the investigation outlined the PWR and the BWR as reference cases.
The test campaign involved, therefore, the LFR, PWR and BWR reactor technologies. Moreover, it was possible to have a further test on the ADS technology, over the three above tests required in the grant agreement.
The WP4 was devoted to the comparison of the experimental data with the pre-test analyses to solve any difference or scaling distortions, as well as to validate the computational tools and provide “best practices” guidance to capture the main underlying phenomena. Moreover, a technical specification of the innovative safety system was developed for each of the nuclear technologies under study, covering aspects like, but not limited to, system functions, system criteria, interface requirements, system performances, validation basis. The analyses of the benefits of the innovation in terms of plant robustness, traded off with the impacts deriving from its implementation (in terms of layout, civil structures, instrumentation and control, etc.), was assessed for both existing NPPs, potentially benefitting from the technology, as well as for next generation reactors. The activities outcome represents a perspective improvement in terms of TRL and bring the innovative system closer-to-the-market.
In the WP5 the PIACE dissemination, education and training activities were carried over, to create synergies with the platforms and networks of research organizations, industry, technology and engineering centres, utilities, regulatory bodies to widen the outreach of their offer by covering aspects related to the challenges and opportunities of the technological innovation in the nuclear industry.
The project got advantage by the Horizon Results Booster, a support system available in EC, to addresses projects eager to go beyond their Dissemination and Exploitation (D&E) obligations under Horizon 2020.
The output of the activity reports the description of the systems investigated, the conditions of operation, the enveloping transient scenarios analysed.
In the WP2, on the base of the output of the WP1, the test matrix of each reactor technology relevant for the experimental characterization on SIRIO facility is defined.
For the definition of the test matrix, a steady state has been simulated, in order to guarantee the achievement of the right working conditions corresponding to the nominal conditions of each reactor technology analysed. Then, a transient test has been simulated, in order to evaluate the system response after the actuation of the decay heat removal system, paying attention on the performance of the isolation condenser and the capabilities of non-condensable gases to passively control the coolant temperature, assuring safe long term cooling conditions. The numerical results obtained allow to address that the main phenomena of interest of the safety system for the reactor technologies under investigation can be effectively represented by the SIRIO experimental facility.
The WP3 was devoted to the experimental campaigns needed to verify the system operation and increase its TRL. The available experimental facility SIRIO was used. The facility was however upgraded to fulfil the test to characterized experimentally the innovative decay heat removal systems, both for the LFR (ALFRED) configuration and for additional two reference technologies test cases, which were properly selected to be representative for the wide possible scenarios of the different reactor technologies. The first step of the WP3 was the selection of the two reference cases. The choice of two additional reference test cases, to be experimentally simulated, was based on the amount of investments and related time efforts needed for achieving the SIRIO upgrade, and according to the technological relevance of the proposed tests for any reference systems, according to the feedback received from the WP2. The result of the investigation outlined the PWR and the BWR as reference cases.
The test campaign involved, therefore, the LFR, PWR and BWR reactor technologies. Moreover, it was possible to have a further test on the ADS technology, over the three above tests required in the grant agreement.
The WP4 was devoted to the comparison of the experimental data with the pre-test analyses to solve any difference or scaling distortions, as well as to validate the computational tools and provide “best practices” guidance to capture the main underlying phenomena. Moreover, a technical specification of the innovative safety system was developed for each of the nuclear technologies under study, covering aspects like, but not limited to, system functions, system criteria, interface requirements, system performances, validation basis. The analyses of the benefits of the innovation in terms of plant robustness, traded off with the impacts deriving from its implementation (in terms of layout, civil structures, instrumentation and control, etc.), was assessed for both existing NPPs, potentially benefitting from the technology, as well as for next generation reactors. The activities outcome represents a perspective improvement in terms of TRL and bring the innovative system closer-to-the-market.
In the WP5 the PIACE dissemination, education and training activities were carried over, to create synergies with the platforms and networks of research organizations, industry, technology and engineering centres, utilities, regulatory bodies to widen the outreach of their offer by covering aspects related to the challenges and opportunities of the technological innovation in the nuclear industry.
The project got advantage by the Horizon Results Booster, a support system available in EC, to addresses projects eager to go beyond their Dissemination and Exploitation (D&E) obligations under Horizon 2020.
The PIACE project has provided a series of outputs of scientific relevance. An experimental validation of the innovative safety system was demonstrated for different types of reactor technologies investigated in the project in a wide range of operating conditions. The tests were used also for the qualification of the calculation codes used in the nuclear field for the study of the safety system and of highly relevant phenomena such as natural circulation and two-phase heat transfer, including condensation in the presence of non-condensable gases. And as outcome of the entire project technical documents with the technical details of the innovative safety system for the integration on existing and innovative power plants, was issued.