SEISMIC QUALIFICATION OF THE EQUIPMENT FOR LOVIISA PLANT AUTOMATION RENEWAL PROJECT

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Cornelius Glenn
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1 SEISMIC QUALIFICATION OF THE EQUIPMENT FOR LOVIISA PLANT AUTOMATION RENEWAL PROJECT P. Varpasuo Fortum Nuclear Services Ltd., Espoo, Finland ABSTRACT This paper describes the seismic qualification methods used for the equipment qualification in the automation renewal project of Loviisa Nuclear Power Plant. The main aim of the qualification program is to ensure the sufficient strength of the equipment and their supports. For the new buildings in the renewal project the appropriate floor response spectra have been developed and the equipment located in these has been qualified according to the rules and stipulation of the code []: Guide YVL.6, Seismic events at nuclear power plants. INTRODUCTION The paper studies the design methods and specific seismic qualification methods for digital automation equipment for Loviisa nuclear power plant. The excitation in the free field is defined by the acceleration response spectrum described in the YVL Guide.6. The spectral shape to be used to define this motion corresponds to a median (50 percentile) spectrum developed for hard rock sited. For the Loviisa plant upgrading projects, the horizontal peak ground acceleration will be assumed equal to 0.g.. QUALIFICATION OF THE EQUIPMENT TO BE RENEWED THAT IS LOCATED IN THE EXISTING PLANT BUILDINGS For the new equipment that is located in the existing plant buildings mixed methods of qualification have been adopted. The floor response spectra for the existing buildings of the Loviisa plant have been calculated in the task of carrying out the seismic probabilistic risk analysis (SPSA). The floor response spectra have been calculated for the reactor building and for the turbine building. The calculated response spectra have presented in reference []. The highest applicable amplification found in the response spectra is 0. Consequently the equipment should be qualified with the maximum spectral acceleration of.5 g and with the shape given in Fig.. Design ground response spectrum for values PGA = g and ζ = 0.05 Spectral acceleration (g) Frequency (Hz) Fig.. Design ground response spectrum for values PGA = g and ζ = 0.05

2 THE TYPE TESTS OF ELECTRICAL AND I & C COMPONENTS The type tests of electrical and I & C components include sufficient requirements for the duration of mechanical stress against the design basis earthquake. The durability of inter-component cabling and connections is demonstrated by analyses or tests. In the following Table are listed the types of equipment to be seismically qualified in the Loviisa NPP automation renewal project. Table Safety classified Instrumentation & Control equipment to be renewed BUILDING ROOM LEVEL APP. EQUIPMENT NOTE Desalination plant (control room of ventilation systems, lift floors +8.95/+0.0) Y I&C cabinet Only I/Ocabinets Auxiliary building (I &C cabinet room, lift floors +7.00/+7.40) Diesel building (control room) A I&C cabinet Only I/Ocabinets D0303 D033 D033 D I&C cabinet Turbine hall T P/DPtransmitters Turbine hall (feed-water level) T P/DPtransmitters Reactor building R P/DPtransmitters Reactor building (transmitter rooms, socalled "sheet metal rooms") R0509 R059 R05 R P/DPtransmitters Diesel building (diesel rooms) Turbine building (control room) D030 D03 D03 D033 Control room FLOOR RESPONSE SPECTRA P/DPtransmitters Large image display Pressure switches will replace transmitters As an example of the floor response spectra used in the analytical qualification the response spectra for main operation elevation +5 for the reactor building and for the elevation + for turbine building are given in the following two figures. The reactor building is a concrete structure whereas the turbine/control building is a steel framed structure. For both buildings a three dimensional structural model was set up. For reactor building the spectra were determined for five different levels The damping ratio for which the spectrum is generated is %. For turbine/control building the spectra were computed for five different floor levels. Also in this case, the damping ratio of the spectrum is %.

3 Fig.. Reactor building, the horizontal response spectrum of the acceleration on the floor level of 5 m at % damping in the y-direction Fig. 3. Turbine Hall, the horizontal response spectrum of the acceleration on the floor level of m at % damping in the x-direction. 3

4 EXAMPLE OF THE QUALIFICATION BY ANALYSIS FOR LARGE IMAGE DISPLAY- PEDESTAL IN THE CONTROL ROOM The pedestal structure of the display is modeled using beam elements. The columns are assumed to be clamped to the floor. The finite element model used in the qualification is depicted in the Figure 4. And the widened floor spectrum for analysis is given in Figure 5. Fig. 4. Finite element model of the large image display pedestal structure in the control room Kiihtyvyys [m/s^] Taajuus [Hz] Verhokäyrä Levitetty käyrä Fig. 5. Widened floor response spectra used for qualification of large image display pedestal 4

5 The own weight of the display is insignificant. The first mode of the display-pedestal structure is over 40 Hz meaning that the structure is stiff compared to dominating excitation frequencies. The obtained displacements are insignificant and largest stresses very small. The analysis shows that display-pedestal structure is well able to carry the seismic loads. CONCLUSIONS The paper explained the seismic qualification methodology for the equipment to be renewed during the Loviisa NPP automation renewal project. The equipment is located in the existing plant buildings. The structural response used in the qualification effort of the equipment has been developed during the seismic probabilistic risk assessment carried out for the plant during the year 99. REFERENCES Guide YVL.6 /9..00 Guide YVL.6 Seismic events and nuclear power plants, STUK, Centre for radiation protection, ISBN , Helsinki, 00. Loviisa, Probabilistic safety assessment Final report. Section 8. External initiating events. Subsection 8.. Seismic safety assessment. Folders 5 and 6. Imatran Voima Oy

SEISMIC DESIGN CHARACTERISTICS OF THE NEW BUILDING FOR DIGITAL AUTOMATION EQUIPMENT FOR LOVIISA NUCLEAR POWER PLANT

13 th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 2004 Paper No. 2803 SEISMIC DESIGN CHARACTERISTICS OF THE NEW BUILDING FOR DIGITAL AUTOMATION EQUIPMENT FOR LOVIISA