Chernobyl Nuclear Power Plant

Chernobyl Nuclear Power Plant
Chernobyl Nuclear Power Station, viewed from the roof of a building in Prypiat, Ukraine.
Chernobyl Nuclear Power Station, viewed from the roof of a building in Prypiat, Ukraine.
Data
Country Ukraine
Start of commercial operation 1977
Ceased operation 2000
Reactors
Reactors active 0 (0 MW)
Reactors shut down 4
Reactors canceled 2 (2,000 MW)
Power
Capacity 4,000 MW
Total power generation in 2008 0 GW·h
Average annual generation (last 5 yrs) 0 GW·h
Net generation 0 GW·h
Other details
Website
http://www.chnpp.gov.ua/

The Chernobyl Nuclear Power Plant (Ukrainian: Державне спецiалiзоване пiдприємство "Чорнобильська АЕС", Russian: Чернобыльская АЭС) is a nuclear power plant near the city of Prypiat, Ukraine, 18 km northwest of the city of Chernobyl, 16 km from the border of Ukraine and Belarus, and about 110 km north of Kiev. It was the site of the Chernobyl disaster in 1986, but due to high power demand, continued to operate until December 2000. Workers remain at the site as the remaining three reactors at the Chernobyl plant, although no longer in operation, still contain nuclear fuel which needs to be monitored around the clock.

Contents

Construction

The V.I. Lenin Nuclear Power Station (Russian: Чернобыльская АЭС им. В.И.Ленина) as it was known during the Soviet times, consisted of four reactors of type RBMK-1000, each capable of producing 1000 megawatts of electric power (3.2 GW of thermal power).

Location.

Construction of the plant and the city of Pripyat to house workers and their families began in 1970, with reactor no. 1 commissioned in 1977. It was the third nuclear power station in the USSR of RBMK type (after Leningrad and Kursk), and the first ever nuclear power plant on Ukrainian soil. The completion of the first reactor in 1977 was followed by reactor no. 2 (1978), no. 3 (1981), and no. 4 (1983). Two more reactors, nos. 5 and 6, capable of producing 1000 MW each, were under construction at the time of the accident. Reactor no. 5 was almost complete at the time of the accident and was scheduled to start operating in the fall of 1986. However, it has since been abandoned; construction cranes still stand next to it to this day.

The structure of units 1 and 2 at the Chernobyl Nuclear Power Plant was very different from units 3 and 4, in the sense that they had a more robust accident localisation system. The control rooms in units 3 and 4 were to the side of the reactor, with no extra concrete or steel wall. But the control rooms of units 1 and 2 were at the back of the reactor, with a thick concrete wall between the two. Many nuclear structure experts claim that if the same accident happened in unit 1 or 2, the accident would have been more contained within the building, and the top (roof) of the reactor building could have simply been repaired after the accident, instead of building a sarcophagus. All units at the complex were of the RBMK type, a Soviet Union nuclear reactor that was used only in USSR and never exported. These reactors were originally designed for making nuclear material, but were changed slightly for making power.

Accidents

1982

In 1982, a partial core meltdown occurred in reactor no. 1 at the Chernobyl plant. Due to the secret policy of the Soviet Union, the extent of the accident was not made public until years later. The reactor was repaired and put back into operation within months.

1986

Reactor #4 with its enclosing sarcophagus.
See Chernobyl disaster, Chernobyl disaster effects

On April 26, 1986, a disaster occurred at reactor no. 4, which has been widely regarded as the worst accident in the history of nuclear power. As a result, reactor no. 4 was completely destroyed and has since been enclosed in a concrete sarcophagus to prevent further escape of radiation. The population of nearby areas were evacuated. Large areas of Europe were affected by the accident, but increased radiation exposure outside of Ukraine, Belarus and the Russian Federation "are comparable to an annual dose from natural background radiation and are, therefore, of little radiological significance" according to the United Nations Scientific Committee on the Effects of Atomic Radiation.[1] The construction of a new reactor no. 4 sarcophagus is under way.

1991

In 1991, during a scheduled shutdown, a fire broke out in reactor no. 2's turbine, causing severe damage to the reactor building. It was then decided that reactor no. 2 would not be returned to operation because of the severity of the damage.

Decommissioning

From 1991, Western nations pushed Ukraine to shut down the Chernobyl plant. After the fire at reactor 2, it was decided that the plant would be taken out of service in two stages, with one of the two remaining reactors being shut down by the year 1996 and another by the year 2000. It was decided that reactor 1 would be shut down first for two reasons, the first being that it is the older of the two, the other being that so much labour and money was invested into making reactor 3 operational four years prior to the fire, that to shut it down so soon would be uneconomical.

Unit 3 was the last reactor to be operated at the Chernobyl plant. To meet the year 2000 deadline, the reactor was shut down on 15 December 2000 during the official ceremony of the power plant shut-down with Ukrainian President Kuchma present in the control room during the event. At about 1:17 PM local time, the reactor team pressed AZ5, Rapid Emergency Defence, within seconds the power readout meter was reading zero. The shutdown went as planned.

Even after the last reactor shutdown, people continue to work at the Chernobyl plant until reactor units 1, 2, and 3 are totally decommissioned, which is expected to take years. The first stage of decommissioning is the removal of highly radioactive spent nuclear fuel, which is placed in deep water cooling ponds. However, storage facilities for this are not suitable for long term containment, and those on site do not have the capacity for all the spent fuel from units 1, 2 and 3. A second facility is planned for construction that will use dry storage technology suitable for long term storage and have the required capacity.[2]

Removal of uncontaminated equipment has begun at unit 1 and this work could be complete by 2020-2022.[3]

The remains of the reactor unit 4 will remain radioactive for some time. The isotope responsible for the majority of the external gamma radiation dose at the site is Cs-137 which has a half life of about 30 years. It is likely that with no further decontamination work, in 300 years the gamma ray dosage at the site will be close to the background level. However, as most of the alpha emitters are longer lived, the soil and many surfaces in and around the plant are likely to be contaminated with transuranic metals such as plutonium and americium, which have much longer half lives. It is planned that the reactor buildings will be disassembled as soon as it is radiologically safe to do so.

Sarcophagus replacement

Main article: New Safe Confinement

On 17 September 2007 it was announced that a new steel containment structure would be built to replace the aging and hastily built sarcophagus that currently protects reactor core #4. The project, financed by an international fund managed by the European Bank for Reconstruction and Development, will be designed and built by the French-led consortium Novarka, which includes the companies Bouygues and Vinci. Novarka will build a giant arch-shaped structure out of steel, 190 m wide and 200 m long to cover the old crumbling concrete dome that is currently in use.

It is expected to take a year to design the new building and another two years to build it. The steel casing project is expected to cost $1.4 bn (£700 m). A separate deal has also been made with the U.S. firm Holtec to build a storage facility within the exclusion zone for nuclear waste which has been produced by Chernobyl.

See also

Other Chernobyl articles

Other accidents

Nuclear safety

Other

References

  1. ↑ UNSCEAR assessments of the Chernobyl accident
  2. ↑ Dry storage progress at Chernobyl
  3. ↑ Decommissioning at Chernobyl

External links