Summary Report for Conduct of Kozloduy NPP Stress Tests

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“Kozloduy NPP” PLC SUMMARY REPORT for Conduct of Kozloduy NPP Stress Tests Information system of the AMC (IS of AMC) is set of hardware and software (firmware) means for information support (ensuring information and data exchange) between the management team of the emergency activities and the emergency personnel in the AMC. IS of AMC receives input data from these systems for monitoring of safety-related parameters, automated radiation monitoring systems of the NPP and meteorological observation system. Generated input data is used for assessment of the condition of facilities, radioactive releases and dose rates to public, and is required for decision-making and application of protection measures. 8. Means for annunciation and communication means: «Kozloduy NPP» plc - in case of initiation of the Emergency Plan - has available the advanced annunciation system which is intended to assure qualitative and reliable annunciation at the NPP site, as well as for settlements within 12 km area. If required all other process means are used (pager, radiostation, office telephone, home telephone, mobile telephone) for information, telephone and radio exchange and loudspeakers, with which it is possible to announce the personnel, managing authorities and public. 6.1.3 Evaluation of factors which can prevent management of accident and not envisioned circumstances 6.1.3.1 Factors impacting all nuclear structures at the site 6.1.3.1.1 Significant damages on infrastructure or flooding in vicinity of the plant which may prevent access to it On the basis of assessments done in relation with „Earthquakes” within the range of seismic impacts 0,26 < PGA ≤ 0,36g which is significantly beyond design 0,2 g, significant failures and damages are expected to seismically non-qualified structures and structures at the site. At the site, at this level of seismic impacts it is probable that all administrative buildings designed according to general industrial regulations (Administrative Building, Engineering Laboratory Building, medical centre) will be severely damaged and not available, and it is probable that seismically non-qualified process trestles will fail. There is a probability of failure to the bridges above the cold channel, and in this case direct connection between Electric production 1 and Electric production 2 may fail. Such damages shall be expected also to buildings and infrastructure in vicinity of the site. Due to beyond design basis seismic impacts it is highly probable that the hospital and fire protection building in the town won’t function normally. These secondary effects from the combined impact of the earthquake and sequential flooding shall be considered at planning of Emergency actions and at diversification of evacuation routes, delivery of required fuel and materials to the plant, at assessment of access of the shift personnel. 175/202
“Kozloduy NPP” PLC SUMMARY REPORT for Conduct of Kozloduy NPP Stress Tests At seismic acceleration within the range of 0,26 < PGA ≤ 0,36g surely the upper part of ventilation stack of the special building SB2 will destruct. At its destruction the top one the third of the chimney (about 50 m) may affect partially the neighbouring site infrastructure (ways) that will cause difficulties in accessing SFS via these ways for the emergency teams or heavy machinery. In the considered range of seismic acceleration, the SFS maintains capability to perform its functions of safe storage of the spent fuel. Analyses of „Off-site flooding” show that even volley discharge of entire volume of Shimamov val dam cannot increase water level in the valley in vicinity of the plant more than elevation +29.00, therefore there is no hazard of flooding at the site and direct impact on safety functions. At assessment of response capabilities, it is required to consider possible flooding of the part of Kozloduy town and correspondingly possible difficulties in accessing the plant. All scenarios of combination of the beyond design basis earthquake with flooding lead to loss of ShPS due to flooding. With their loss emergency make-up of the spray pools of Units 5 and 6 is also lost, i.e. time for ensuring of ultimate heat sink will be limited. More important weaknesses were found at studying of flooding of the plant with MWL = 32,93 m, and may be divided as follows: · termination to electric production and transfer of electric power supply sources to DGS – due to possible loss of the part of electric lines, connecting Kozloduy NPP with the power grid; · termination to water supply in cold channel - loss of BPS and unavailability of access to the BPS overland; · loss of emergency make-up of the spray pools of unit 5 and 6– loss of shaft pump station (ShPS); · flooding of the part of town infrastructure and access from Kozloduy town to the plant via bypass way. · flooding of the part of underground communications below elevation 32,93 m – drainage of the rainwater sewerage and leaks in its channels. Potential external impacst due to flooding including failure to personnel access, equipment and material delivery to the site are discussed in item 3.2.4. of this report. 6.1.3.1.2 Loss of communication structures/systems At complete loss of power supply to the plant, margin for restoration of the power supply to communication structures/systems is as follows: · Availability of these systems from the UPS up 8 hours; · Availability of these systems from DG-1 and DG-2 in AMC, more than 4 days. 6.1.3.1.3 Impact on various buildings and premises which are used by the crisis teams or to which access will be required for accident management 176/202
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Summary Report for Conduct of Kozloduy NPP Stress Tests

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