Amrollahi: High Security Standards Observed In Bushehr Nuclear Reactor

Beijing, Sept 28, IRNA – Former head of Nuclear Energy Organization of Iran Reza Amrollahi said here Friday in 3rd China New Energy International Forum that Iran has observed the highest international safety standards in construction of the Bushehr Nuclear Reactor. Amrollahi who was speaking in Shian city at the international energy conference as a faculty member of Amir Kabir Technical Engineering University elaborated on the brief history of the BNR from the beginning up to now. He said that the nuclear 1000 mega watt electricity reactor has a 3000 megawatt power for therm o-eclectic production and from the very initial phases of its construction up to now the highest standards have been observed in its construction. He also noted that the security measures observed in BNR prevent the occurrence of any possible radiation hazard from inside of the reactor to its peripheral areas. He said that this reactor’s construction which began in the year 1975 based on a contract sighed between Iran and Germany was halted in 1977 following the victory of the Islamic Revolution, saying, “After that in the year 1994 the government of the time signed another contract with Russia for completion of the project. He said that in the years 2007 and 2008 Iran received the first and second nuclear fuel containers from Russia and the burnt fuel is delivered back to Russia under the supervision of the IAEA in accordance with the signed contracts. The full technical specifications of the BNR, as presented to the 3rd China New Energy International Forum are as follows: Bushehr Nuclear Power Plant From Beginning to Final Stage (Electricity Production) Prepared by: Reza Amrollahi- Amirkabir University of Technology, Tehran, Iran Mohammad Ahmadian- Atomic Energy Organization of Iran (AEOI), Tehran, Iran Abstract Unit-1 of the Bushehr nuclear power plant (BNPP-1) is a WWER-type reactor with 1,000 MW electrical power and 3,000 MW thermal power constructed near Bushehr city at the coast of the Persian Gulf, Iran. The reactor has been recently operational to its full power. Design and construction of Bushehr nuclear power plant from the Beginning to the final stage have been carried out in several stages. All of these stages are in accordance with the nuclear safety regulations of Iran, Standards of the Russian Federation, and the requirements of IAEA. According to standards, assessment of the safety of the nuclear power is essential, and it must be considered. The safety of a nuclear power plant as mandated by IAEA is based on a defense in depth philosophy. The use of defense in depth in nuclear power plant design is the subject of some fundamental principles. Reactor building has a concrete sphere with thickness of 1.7m to 2m at the outside and a metal sphere with diameter of 56m and the thickness of 3Cm at the inside. Concrete Sphere has been designed in order to protect the metal sphere and inside equipment against external natural disasters such as earthquake and specially the aircraft striking. Also the evaluation of the impact of nuclear power plant on public and environment is of the special concern. So in this paper the various stages of design and construction of BNPP-1 and its safety measures are presented and discussed. 1- Introduction The Unit-1 Bushehr Nuclear Power Plant (BNPP-1) has been constructed near Bushehr located at the coastof Persian Gulf, south of Iran. It is a VVER type NPP with1000 MW electrical and 3,000 MW thermal power. Through an agreement with Germany, the BNPP project was started in1975and was stopped in 1979 due to revolution in Iran. The construction project continued with contraction with Russia’s Ministry for Atomic Energy in 1994. The BNPP-1 has been recently commissioned and now is in operational condition. The operation of this nuclear power plant was transferred (Provisional acceptance) to Iran from zero hour September 24, 2013 officially. Design and construction of Bushehr nuclear power plant from the Beginning to the final stage are in accordance with the nuclear safety regulations of Iran, Standards of the Russian Federation, and the requirements of IAEA. According to standards, assessment of the safety of the nuclear power is essential, and it must be considered. The safety of a nuclear power plant as mandated by IAEA is based on a defense in depth philosophy. The history of Bushehr nuclear power plant is reviewed in this paper. In addition the general description of BNPP with more emphasis on safety features and Monitoring systems is considered. Finally the operation status is presented. 2- History The BNPP project was initiated in 1975 through a bilateral agreement with Germany, but work only continued through 1979, when the revolution ousted the Shah and construction stopped. Iran signed a contract with Russia’s Ministry for Atomic Energy in 1994, but the project continued to face technical and financial obstacles. Russia also provides the nuclear fuel for the plant, and spent fuel is sent back to Russia. The IAEA has arranged to verify and seal the fresh fuel shipments, and all of the fuel assemblies imported from Russia for use at the Bushehr plant remained under Agency seal before being loaded into the reactor. In a series of shipments between December 2007 and January 2008, Iran received a total of 82 tons of fuel from Russia for the initial fuel loading of the BNPP. On 20 January 2008 a fourth Russian shipment of nuclear fuel arrived. On 22 September 2009, it was reported that the first reactor was 96% complete and final testing would begin in the near future. Indicating that the plant was nearing completion, engineers conducted a series of pre-start tests in 2009 and 2010. The plant first reached criticality in May 2011, and officially came online in September 2011. The plant started adding electricity to the national grid on 3 September 2011, and was officially opened in a ceremony on 12 September 2011, attended by Russian Energy Minister Sergei and head of the Rosatom Sergei Kiriyenko. 3- Unit- 1BNPP general description The reactor consists of 163 fuel assemblies. Each assembly contains 311 pressurized fuel rods. Length of Each fuel assembly is 4570 mm and has an average weight of about 720 kg (490 kg fuel (uranium dioxide). There are three separate systems(Cooling loops) used to transfer and exchange the heat generated by the nuclear fission process, thereby keeping the reactor operating at a safe temperature. Primary loop has been formed of four same loop including primary loop pipes with inner diameter of 850 mm, reactor cooling pump and steam generator. Pressurizer vessel is located at the center of these four loop Generated vapor at steam generators at 58 atm is sent to the turbine building through four 600 mm nominal diameter pipeline. Steam directly is sent to the high pressure turbine and then conduct to three low pressure turbines. Technical specifications of bushehr nuclear power plant Technical Specifications of Bushehr nuclear power plant power plant type (PWR) thermal electerical power 3000 MW electerical power 1000 MW number Of the reactor coolant loop 4 first loop pressure 157 bar reactor Inlet temperature 290 reactor outlet temperature 321 water in circulation 84000 m3/hr The amount of produced steam 5900 ton/hr The amount of third loop cooling water 60 m3/s power plant fuel Uranium oxide primary fuel enrichment 1.6%, 2.4%, 3.62%, 4.02% number of fuel assembly 163 (each assembly contain 311 rod) total fuel weight 115 ton (80 ton Uranium oxide) As steam leaves the turbine, it passes over hundreds of pipes carrying cooler water from the tertiary system. As the water cools, it condenses from steam back to water for reuse in the steam generator. Water from each system is physically separated from water in the other systems. In order to ensure the functioning of safety system in the earthquake, The Bushehr atomic power plant has been designed based on the most advanced and toughest international standards, adding that the facility can withstand earthquakes of at least 8.0 on the Richter scale near the plant. All buildings, structures and equipment in terms of the maximum acceleration of the 0.4 g are designed. Turbine system (Unit-1 BNPP third loop) 4- Reactor technical safety features The Bushehr atomic power plant has entered the operational phase for safe and sustainable generation of electricity. In routine operation, there are some physical barriers to prevent the radioactivity from the reactor core escaping into the environment: • The fuel cladding: The uranium fuel pellets are sealed in Zircaloy fuel rods. The fuel rods are placed in assemblies. • The Reactor vessel: The reactor core is enclosed in a huge containment shell of steel known as the reactor vessel. • The reactor containment building: This building is a sealed containment of pre-stressed concrete. • The cooling loops: There are three separate systems (Primary loop, Secondary loop or steam water cycle and Third loop or cooling loop) Multiple layers of safety are as follow: • Containment Vessel: 1.5-inch thick steel • Shield Building Wall: 3 to 4 foot thick steel reinforced concrete • Dry Well Wall: 5 foot thick reinforced concrete • Bio Shield: 4 foot thick leaded concrete with 1.5-inch thick steel lining inside and out • Reactor Vessel:4 to 8 inches thick steel • Reactor Fuel Weir Wall 1.5 foot thick concrete Unit-1 BNPP reactor building has a concrete sphere with thickness of 1.7m to 2m at the outside and a metal sphere with diameter of 56m and the thickness of 3Cm at the inside. There are three separate systems (Primary loop, Secondary loop or steam water cycle and Third loop or cooling loop) used to transfer and exchange the heat generated by the nuclear fission process, thereby keeping the reactor operating at a safe temperature. 5-Environmental impacts of BNPP Nuclear power plants emit small amount quantities of radioactive gases and liquids to the environment under controlled and monitored conditions during normal plant operations. These radioactive discharges can have environmental impacts on humans, animals, plants, and sea life. Monitor the discharges and analyze environmental samples to ensure that the impacts of plant operations are minimized is vital. Radioactive release from Unit-1 BNPP and Its monitoring equipment is considered. 5-1- Radioactive Releases The unit-1 BNPP gaseous and liquid radiological effluent release into the environment in normal operation is controlled. Gaseous released into the atmosphere through various filters from 100m smokestacks after required controls. Liquid is then controlled via an open channel with a length of 400 m then followed by four tunnels 1,200 m about 25 m below the sea level. Liquid and gaseous discharge during normal operation 2-5- Environmental Monitoring The BNPP-1 Radiation Monitoring System consists of following subsystems: • System Monitoring • Area Monitoring • Personnel Monitoring • Activity Release Monitoring, and • Environmental Monitoring The environmental monitoring is paid in this paper. Main elements of environmental monitoring for Unit-1 BNPP are specified as below: • Meteorological Monitoring • Persian Gulf Monitoring • Ground water Monitoring • Surface Water Monitoring • Demographic Monitoring • Ecological Monitoring • Land and Water Use Monitoring The Environmental Monitoring System comprises of: • Stations for monitoring and measurement of the level of ambient equivalent dose rate of gamma radiation at the site; • Posts for monitoring and measurement volumetric activities of aerosols, iodine vapors and radioactive inert gases through vent stack release; • Post to monitor and measure the liquid discharge as the result of personnel decontamination; • Post to monitor the liquid discharge as the result of automobile decontamination; • Posts for monitoring and measurement of volumetric activities of liquid discharges in the discharge channel of the plant; • control panel to provide radiation monitoring and measurement information for use by Radiation Monitoring System of the plant and BNPP personnel; • the center of data and information related to monitoring systems; • Stations for monitoring and measurement of the level of ambient equivalent dose rate of gamma radiation around the site as well as monitoring of meteorological parameters. Due to the need for controlling plant safety and protection of people and the environment, off-site laboratory is designed and built. 5- Operation Unit-1 BNPP is delivered electricity to the national grid from 25 June 2013. Until August 5, 2013 It has delivered about two and a half million megawatt hours electricity to the national grid. Generated Power by the generator convert from 27 kV to 400 kV through two transformer set and then finally be sent to the grid by a 400 kV gas-post. BNPP generator is three phases synchronous that its stator coils are cooled with water. Coolant of the rotor and the stator core is hydrogen. It has the output power of about1000 MW and has two poles and its industrial brand is TBB - 1000 - 27/2 - T3. Output stator voltage is also 27 Kv. BNPP has two 230 kV and 400 kV posts. 6- Conclusion Unit-1 of the Bushehr nuclear power plant located near Bushehr city at the coast of the Persian Gulf, Iran has been recently operating to its full power and is delivered electricity to the national grid from 25 June 2013. The operation of this nuclear power plant was transferred (Provisional acceptance) to Iran from zero hour September 24, 2013 officially. Unit-1 BNPP is equipped with reliable safety systems and has entered the operational phase for safe and sustainable generation of electricity. Monitoring the discharges and analyzing the environmental samples are carried out to ensure that the impacts of plant operations are considered and also due to the need for controlling plant safety and protection of people and the environment, off-site laboratory is designed and built. 7- References Final safety analysis report (FSAR), Moscow, 2007. Bushehr Nuclear Power plant Environmental report (BNPP-ER), Tehran, Iran, 2004/end