ভিভিইআর
ওয়াটার-ওয়াটার পাওয়ার রিঅ্যাক্টর (ডব্লিউডব্লিউভিইআর), অথবা ভিভিইআর (; রূপান্তর ভোদো-ওয়াদিওনি এনারগেটিস্স্কি রিঅ্যাক্তর; ইংরেজি: ওয়াটার-ওয়াটার পাওয়ার রিঅ্যাক্টর) হল প্রাথমিকভাবে বিকশিত চাপযুক্ত জল চুল্লী ডিজাইনের একটি সিরিজ, যা সোভিয়েত ইউনিয়নে (এখন রাশিয়া) ওক্ব গিডরপ্রেস দ্বারা উন্নিত হয়। এর বিদ্যুৎ উৎপাদন ক্ষমতা ৭০ থেকে ১২০০ মেগাওয়াট পর্যন্ত, যা ১৭০০ মেগাওয়াট পর্যন্ত বাড়ানো যায়। ভিভিইআর পাওয়ার স্টেশন ছিল বা দ্বারা ভবিষ্যতে ব্যবহৃত হবে আর্মেনিয়া, বাংলাদেশ, বেলারুশ, বুলগেরিয়া, চীন, চেক প্রজাতন্ত্র, মিশর, ফিনল্যান্ড, জার্মানি, জর্দান, হাঙ্গেরি, ভারত, ইরান, স্লোভাকিয়া, ইউক্রেন, রাশিয়া, তুরস্ক এবং ভিয়েতনাম।
প্রথম ভিভিইআর ১৯৭০ সালে নির্মিত হয়েছিল। ভিভিইআর-৪৪০ মডেল ভি২৩০ সবচেয়ে সাধারণ নকশা ছিল, ৪০০ মেগাওয়াট বৈদ্যুতিক শক্তি উত্‍পন্ন হত। ভি২৩০ একটি অনুভূমিক বাষ্প জেনারেটর সঙ্গে ছয় প্রাথমিক কুল্যান্ট নিয়োগ করে। ভিভিইআর-৪৪০ এর একটি সংশোধিত সংস্করণ, মডেল ভি২১৩, সোভিয়েত ডিজাইনারদের দ্বারা গৃহীত প্রথম পরমাণু সুরক্ষিত পণ্য ছিল। এই মডেল অন্তর্ভুক্ত জরুরী কোর কুলিং এবং অক্জিলিয়ারী খাদ্যে ব্যবস্থা হিসেবে আপগ্রেড দুর্ঘটনা স্থানীয়করণ সিস্টেম।
১৯৭৫ সালের পরে বৃহত্তর ভিভিইআর-১০০০ তৈরি করা হয়েছিল এবং একটি স্প্রে বাষ্প দমন সিস্টেমের সাথে কনট্রেনমেন্ট-টাইপ কাঠামোর মধ্যে একটি চার লুপ সিস্টেম রয়েছে। ভিভিইআর চুল্লী ডিজাইন স্বয়ংক্রিয় নিয়ন্ত্রণ, প্যাসিভ নিরাপত্তা এবং পশ্চিমা তৃতীয় প্রজন্মের পারমাণবিক চুল্লি সঙ্গে যুক্ত প্রতিরোধ সিস্টেম এর সাথে অন্তর্ভুক্ত করা হয়।
ভিভিইআর-১২০০ বর্তমান সংস্করণটি নির্মাণের জন্য প্রস্তাবিত, ভিভিইআর-১০০০ এর বিবর্তন হচ্ছে ক্ষমতা বৃদ্ধি, যার আউটপুট ১২০০ মেগাওয়াট (মোট) এবং অতিরিক্ত প্যাসিভ নিরাপত্তা বৈশিষ্ট্য প্রদান করে।
২০১২ সালে, রোসাটম বলে যে, ভবিষ্যতে এটি ব্রিটিশ এবং মার্কিন নিয়ন্ত্রক কর্তৃপক্ষের সঙ্গে অভিপ্রেত হবে। যদিও, একটি ব্রিটিশ লাইসেন্সের জন্য ২০১৫ এর আগে আবেদন করা অসম্ভাব্য ছিল।
The Russian abbreviation VVER stands for 'water-water energy reactor' (i.e. water-cooled water-moderated energy reactor). The design is a type of pressurised water reactor (PWR). The main distinguishing features of the VVER compared to other PWRs are:Reactor fuel rods are fully immersed in water kept at 15 MPa pressure so that it does not boil at the normal (220 to over 300 °C) operating temperatures. Water in the reactor serves both as a coolant and a moderator which is an important safety feature. Should coolant circulation fail, the neutron moderation effect of the water diminishes, reducing reaction intensity and compensating for loss of cooling, a condition known as negative void coefficient. Later versions of the reactors are encased in massive steel pressure shells. Fuel is low enriched (ca. 2.4–4.4% U) uranium dioxide (UO) or equivalent pressed into pellets and assembled into fuel rods.
Reactivity is controlled by control rods that can be inserted into the reactor from above. These rods are made from a neutron absorbing material and, depending on depth of insertion, hinder the chain reaction. If there is an emergency, a reactor shutdown can be performed by full insertion of the control rods into the core.
As stated above, the water in the primary circuits is kept under a constant elevated pressure to avoid its boiling. Since the water transfers all the heat from the core and is irradiated, the integrity of this circuit is crucial. Four main components can be distinguished:To provide for the continued cooling of the reactor core in emergency situations the primary cooling is designed with redundancy.
The secondary circuit also consists of different subsystems:To increase efficiency of the process, steam from the turbine is taken to reheat coolant before the deaerator and the steam generator. Water in this circuit is not supposed to be radioactive.
The tertiary cooling circuit is an open circuit diverting water from an outside reservoir such as a lake or river. Evaporative cooling towers, cooling basins or ponds transfer the waste heat from the generation circuit into the environment.
In most VVERs this heat can also be further used for residential and industrial heating. Operational examples of such systems are Bohunice NPP (Slovakia) supplying heat to the towns of Trnava (12 km away), Leopoldov (9.5 km away), and Hlohovec (13 km away), and Temelín NPP (Czech Republic) supplying heat to a nearby town 5 km away. Plans are made to supply heat from the Dukovany NPP to Brno (the second-largest city in the Czech Republic), covering two-thirds of its heat needs.
A typical design feature of nuclear reactors is layered safety barriers preventing escape of radioactive material. VVER reactors have four layers:Compared to the RBMK reactors – the type involved in the Chernobyl disaster – the VVER uses an inherently safer design. It does not have the graphite-moderated RBMK's risk of a power surge transient or criticality accident. Also the RBMK power stations were constructed without containment structures on grounds of cost as well as the relative ease of re-fueling. (Fuel elements in an RBMK can be replaced while the reactor is running at its nominal output, allowing the continuous operation and plutonium extraction compared to pressurized water reactors like the VVER which need to be shut down to exchange fuel rod assemblies.)
When first built the VVER design was intended to be operational for 35 years. A mid-life major overhaul including a complete replacement of critical parts such as fuel and control rod channels was thought necessary after that. Since RBMK reactors specified a major replacement programme at 35 years designers originally decided this needed to happen in the VVER type as well, although they are of more robust design than the RBMK type. Most of Russia's VVER plants are now reaching and passing the 35 year mark. More recent design studies have allowed for an extension of lifetime up to 50 years with replacement of equipment. New VVERs will be nameplated with the extended lifetime.
In 2010 the oldest VVER-1000, at Novovoronezh, was shut down for modernization to extend its operating life for an additional 20 years; the first to undergo such an operating life extension. The work includes the modernization of management, protection and emergency systems, and improvement of security and radiation safety systems.
The VVER-1200 (or NPP-2006 or AES-2006)
is an evolution of the VVER-1000 being offered for domestic and export use.
The reactor design has been refined to optimize fuel efficiency.
Specifications include a $1,200 per kW electric capital cost, 54 month planned construction time, and expected 60 year lifetime at 90% capacity factor. The VVER-1200 has a gross and net thermal efficiency of 37.5% and 34.8%. The VVER 1200 will produce 1,198 MWe of power.
The first two units are being built at Leningrad Nuclear Power Plant II and Novovoronezh Nuclear Power Plant II. More reactors with a VVER-1200/491 like the Leningrad-II-design are planned (Kaliningrad and Nizhny Novgorod NPP) and under construction. The type VVER-1200/392M
as installed at the Novovoronezh NPP-II has also been selected for the Seversk, Zentral and South-Urals NPP. A standard version was developed as VVER-1200/513 and based on the VVER-TOI (VVER-1300/510) design.
In July 2012 a contract was agreed to build two AES-2006 in Belarus at Ostrovets for a cost of about $10 billion (Note that this price equates to $4,200 per kW capital cost as opposed to the $1,200 per kW initially cited above).
An AES-2006 is being bid for the Hanhikivi Nuclear Power Plant in Finland. On 30 November 2017, concrete was poured for the nuclear island basemat for first of two V-392M units at Rooppur in Bangladesh.
In August 2016 the first VVER-1200, Novovoronezh II-1, was connected to the grid and started commercial operation on 27 February 2017.
From 2015 to 2017 Egypt and Russia came to an agreement for the construction of four VVER-1200 units at El Dabaa Nuclear Power Plant.
The nuclear part of the plant is housed in a single building acting as containment and missile shield. Besides the reactor and steam generators this includes an improved refueling machine, and the computerized reactor control systems. Likewise protected in the same building are the emergency systems, including an emergency core cooling system, emergency backup diesel power supply, and backup feed water supply,
A passive heat removal system had been added to the existing active systems in the AES-92 version of the VVER-1000 used for the Kudankulam Nuclear Power Plant in India. This has been retained for the newer VVER-1200 and future designs. The system is based on a cooling system and water tanks built on top of the containment dome.
The passive systems handle all safety functions for 24 hours, and core safety for 72 hours.
Other new safety systems include aircraft crash protection, hydrogen recombiners, and a core catcher to contain the molten reactor core in the event of a severe accident. The core catcher will be deployed in the El Dabaa Nuclear Power Plant build.
A number of designs for future versions of the VVER have been made:Russia recently installed two nuclear reactors in China at the Tianwan Nuclear Power Plant, and an extension consisting of a further two reactors was just approved. This is the first time the two countries have co-operated on a nuclear power project. The reactors are the VVER 1000 type, which Russia has improved incrementally while retaining the basic design. These VVER 1000 reactors are housed in a confinement shell capable of being hit by an aircraft weighing 20 tonnes and suffering no expected damage. Other important safety features include an emergency core cooling system and core confinement system. Russia delivered initial fuel loads for the Tianwan reactors. China planned to begin indigenous fuel fabrication for the Tianwan plant in 2010, using technology transferred from Russian nuclear fuel producer TVEL.
The Tianwan Nuclear Power Plant uses many third party parts. While the reactor and turbo-generators are of Russian design, the control room was designed and built by an international consortium. In this way the plant was brought to meet widely recognised safety standards; safety systems were already mostly in place but the previous monitoring of these systems did not meet international safety standards. The new VVER 1000 plant built in China has 94% of its systems automated, meaning the plant can control itself under most situations. Refueling procedures require little human intervention. Five operators are still needed in the control room.
In May 2010 Russia secured an agreement with the Turkish government to build a power plant with four VVER-1200 reactors at Akkuyu, Turkey. However, due to the accident experienced in Fukushima, anti-nuclear environmentalist groups heavily protested the proposed reactor at Akkuyu.
On 11 October 2011 an agreement was signed to build Belarus’ first nuclear power plant at Astravyets, using two VVER-1200/491 (AES-2006) reactors with active and passive safety systems. In July 2016, the reactor vessel for unit 1 has hit the ground during transportation, and though no damage was sustained it was decided to be replaced to allay public fears, delaying the project by a year. Unit 1 is now planned to commence operation in 2019.
In October 2013 the VVER-1000 (AES-92) design was selected by the Jordan Atomic Energy Commission in a competitive tender for Jordan's first twin reactor nuclear power station.
In November 2015 and March 2017 Egypt signed preliminary agreements with Russian nuclear company Rosatom for a first VVER-1200 unit at El Dabaa to start operations in 2024. Discussions continue for final approval.