AND SEISMOLOGICAL OBSERVATIONS OF THE BALTIC SEA REGION EEEXXXCCCUUURRRSSSIIIOOONNN G GGUUUIIIDDDEEE SEISMICITY AND ADJACENT TERRITORIES September 10–12, 2007, Lithuania EEXXCCUURRSSIIOONN GGUUIIDDEE Contributors: V. Gregorauskienė R. Kanopienė J. Lazauskienė A. Pačėsa J. Satkūnas I. Virbickienė AND SEISMOLOGICAL OBSERVATIONS OF THE BALTIC SEA REGION EEEXXXCCCUUURRRSSSIIIOOONNN G GGUUUIIIDDDEEE SEISMICITY AND ADJACENT TERRITORIES September 10–12, 2007, Lithuania CONTENT VILNIUS TOUR PROGRAMME 1. Location of the Vilnius tour excursion sites 82 2. Lithuania: some historical facts 84 3. Vilnius City: the trace of a history 85 4. Pučkoriai outcrop 86 5. Trakai City: the ancient ducal residence 87 6. Kernavė: the first capital of Lithuania? 88 EXCURSION TO IGNALINA NUCLEAR POWER PLANT 111... Programme of the excursion to Ignalina NPP 90 222... Scheme of the excursion route and stops 91 333... Stop No 1. Ignalina Nuclear Power Plant 92 444... Stop No 2. Ignalina seismic monitoring station site 94 555... Stops No 3–4. Ladakalnis hill and Aukštaitija National park 98 666... Annex. Geology of Ignalina NPP region 100 (V. Marcinkevičius et al., 1995) 83 AND SEISMOLOGICAL OBSERVATIONS OF THE BALTIC SEA REGION EEEXXXCCCUUURRRSSSIIIOOONNN G GGUUUIIIDDDEEE SEISMICITY AND ADJACENT TERRITORIES September 10–12, 2007, Lithuania PPPrrrooogggrrraaammmmmmeee ooofff ttthhheee eeexxxcccuuurrrsssiiiooonnn tttooo IIIgggnnnaallliiinnnaaa NNNPPPPPP September 12, 2007, Wednesday 7.30 Departure from the E-Guesthouse Hotel. (Ševčenkos 16, Vilnius) 10.00 Arrival to Ignalina NPP. 10.00–12.30 Stop No 1.1 Visit to Ignalina NPP. 12.30–13.30 Lunch at Ignalina NPP. (Participants leaving this day departure to Vilnius). 13.30–15.30 Stop No 2. Ignalina seismic monitoring station. Cold snacks. 15.30–16.30 Site seeing trip in Aukštaitija National Park. 16.30–17.00 Stop No 3. Ladakalnis hill. 17.30–18.30 Stop No 4. Lūšiai Lake and Palūšė village 19.00–21.00 Departure to Vilnius 90 AND SEISMOLOGICAL OBSERVATIONS OF THE BALTIC SEA REGION EEEXXXCCCUUURRRSSSIIIOOONNN G GGUUUIIIDDDEEE SEISMICITY AND ADJACENT TERRITORIES September 10–12, 2007, Lithuania Scheme of the Excursion route and stops 1. Ignalina Nuclear Power Plant (Ignalina NPP). 2. Ignalina seismic monitoring station. 3. Ladakalnis hill (Aukštaitija National Park). 4. Lake Lūšiai and Palūšė village (Aukštaitija National Park). 91 AND SEISMOLOGICAL OBSERVATIONS OF THE BALTIC SEA REGION EEEXXXCCCUUURRRSSSIIIOOONNN G GGUUUIIIDDDEEE SEISMICITY AND ADJACENT TERRITORIES September 10–12, 2007, Lithuania SSStttoooppp NNNooo 111 Ignalina Nuclear Power Plant The Power Plant is constructed on the southern coast Drūkšiai Lake. The area of Drūkšiai Lake is 44.8 sq. km (Fig. 1). The nearest to the Power Plant large cities are Vilnius, located in 130 kms (575 000 inhabitants), and Daugavpils in Latvia, located in 30 kms (126 000 inhabitants). Fig. 1. Location of Ignalina NPP Design and engineering geological investigations prior to construction started and in 1974 on December 31, 1983 unit 1 commissioned. Originally, unit 2 was to be launched in 1986, but commissioning postponed to the year 1987 because of the Chernobyl accident. On April 26, 1986, following the Chernobyl accident, at the request of the government of Lithuania, the government of the USSR suspended the construction of unit 3. In 1989 the construction of unit 3 discontinued altogether. It took 11 years to build the world’s most Powerful Nuclear Plant. The construction of the Ignalina NPP necessitated: 142 km of roads, 50 km of railway, 390 km communication lines, 334 km of electricity lines, 133 km of sewerage lines, 164 km of thermal lines. Three million 544,00 m3 of concrete and reinforced concrete and 76 480 tonnes of reinforcement were used for the construction. The INPP contains RBMK – 1500 water – cooled graphite – moderated channel – type power reactors. The RBMK – 1500 reactor is the largest power reactor in the world. The thermal power output of one unit is 4800MW; the electrical power capacity is 1500 MW. Ignalina NPP generates about 80% of electricity consumed in Lithuania. 92 AND SEISMOLOGICAL OBSERVATIONS OF THE BALTIC SEA REGION EEEXXXCCCUUURRRSSSIIIOOONNN G GGUUUIIIDDDEEE SEISMICITY AND ADJACENT TERRITORIES September 10–12, 2007, Lithuania The important area of a nuclear power plant safety is storage of the spent nuclear fuel. From the beginning of Ignalina NPP operation the spent nuclear fuel is stored under a layer of water in special pools placed in the same buildings, as reactors. It is a temporary way of storage, therefore the international competition for the spent nuclear fuel storage was announced, the German company GNB gained the victory in which. In 1993 Ignalina NPP and the German company GNB signed the contract on the delivery of 20 CASTOR and 40 CONSTOR steel containers for the storage of the spent nuclear fuel. The total cost of the contract was about 30 mln DM. The first container CASTOR was sent to the storage site constructed nearby Ignalina NPP on May 12, 1999. Some part of the spent nuclear fuel has already been placed in all available containers of CASTOR type (20 containers) and was taken to the spent nuclear fuel storage site. The container is located on a special platform at the site. One of the important works related with the future decommissioning of INPP Unit 1 is the unloading and location of the spent nuclear fuel in the storages. The Ignalina NPP experts affirm that the available number of the containers will not solve the problem of the spent nuclear fuel, basing on the evaluation that in the case of Unit 1 shutdown at the end of year 2004, and Unit 2 shutdown in year 2010, 350 containers in addition would be required. The spent nuclear fuel can be stored in containers CASTOR and CONSTOR for 50 years, then it is necessary to take it out to the final burial place, but in Lithuania such place is not stipulated yet. Under the pressing of EU Lithuania made a commitment to prepare for the decommissioning first unit of Ignalina NPP by 2004 and the second unit has to be ready for decommissioning by 2009 under the sufficient financing support. Both units of Ignalina NPP are of the same type as Chernobyl one e.g. according the western standards is considered as unsafe. 93 AND SEISMOLOGICAL OBSERVATIONS OF THE BALTIC SEA REGION EEEXXXCCCUUURRRSSSIIIOOONNN G GGUUUIIIDDDEEE SEISMICITY AND ADJACENT TERRITORIES September 10–12, 2007, Lithuania SSStttoooppp NNNooo 222 Stations of seismological monitoring system (“Ignalina” seismic monitoring station) The territory of Lithuania and adjacent areas in the Baltic Region feature a low seismic activity due to the Earth crust of Early Precambrian consolidation and significant distances to the active tectonic zones. Nevertheless, according to historical and instrumental data, 45 local earthquakes of small and moderate size ruptured since 1616 to 1987. Local earthquakes of maximum expected magnitudes (more than 5) can generate shaking of the Earth surface with intensity VII or even VIII. The first instrumental seismological observations in Lithuania were initiated in 1970 when Vilnius seismic station (VIL) was founded (Fig. 2). Three analog long period (T=25 s) and three short period (T=1.5 s) seismometers were installed at Vilnius station. Collected data were processed and stored in Moscow University until 1992. Later on, maintenance of station and routine data processing was undertaken by Institute of Physics of Lithuania. 450 distant and regional seismic events were reported in seismic bulletin of Vilnius seismic station during the period 1991–1995. Phase readings, amplitudes and periods were defined in routine processing. Distances from the epicentres to Vilnius station were calculated and reported in the bulletin. No local events were registered in Vilnius seismic station. Probably, high‐level background noise at this site reduced resolution of short period seismometers inhibiting detection of small local events. Operation of Vilnius seismic station was suspended in the beginning of 1999. (SLTR) Fig. 2. Seismic station’s network in Lithuania. Bounded triangles – four existing seismic stations of Ignalina NPP, red squares – two new GEOFON network broad bend seismic stations foreseen to be installed in 2008–2010 94 AND SEISMOLOGICAL OBSERVATIONS OF THE BALTIC SEA REGION EEEXXXCCCUUURRRSSSIIIOOONNN G GGUUUIIIDDDEEE SEISMICITY AND ADJACENT TERRITORIES September 10–12, 2007, Lithuania The fist comprehensive study of seismic activity of Lithuania was carried out in 1988 as a part of re‐examination of safety of Ignalina Nuclear Power Plant (INPP). Twenty two outstanding experts of the Soviet Union came to conclusion that seismic hazard was assessed not enougth when designing INPP despite local and international regulations insisted on it. In order to improve the situation the experts proposed to install seismic network and monitor local seismicity. The group of industrialised states G‐7 approved the plan of actions improving safety of Soviet nuclear reactors in 1992. Fund named ʺAccount of Nuclear Safetyʺ provided irrevocable loan for Lithuania to renovate safety systems of INPP in 1994. One of the projects considered installation of a Seismic Alarm System, SAS. This system was designed to issue alarm when damaging seismic wave approaches the INPP. The SAS was complemented with the Seismic Monitoring System, SMS. The SMS was designed to collect data of local seismicity and dynamic behaviour of structures of INPP. The SMS consists of number of accelerometers deployed inside buildings of INPP (Fig. 3) and four vertical short period seismometers installed in boreholes with at the depth of 30 m located at a distance of ~30 km to the INPP (Fig. 4). Fig. 3. Deploymet of accelerometers of SMS at INPP The signals of the seismometers are transformed to digital form and telemetered continuously to the control center in INPP. The control center records data of seismometers if local or teleseismic event is detected. SAS and SMS including four outside seismic stations on territory of Lithunia were installed in June of 1999 (Figs. 1, 2). Two more seismic stations had to be installed on the territory of Latvia and Belarus.