1999 Blayais Nuclear Power Plant flood

The 1999 Blayais Nuclear Power Plant flood was a flood that took place on the evening of December 27, 1999. It was caused when a combination of the tide and high winds from the extratropical storm Martin led to the seawalls of the Blayais Nuclear Power Plant in France being overwhelmed.[1] The event resulted in the loss of the plant's off-site power supply and knocked out several safety-related systems, resulting in a Level 2 event on the International Nuclear Event Scale.[2] The incident illustrated the potential for flooding to damage multiple items of equipment throughout a plant, weaknesses in safety measures, systems and procedures, and resulted in fundamental changes to the evaluation of flood risk at nuclear power plants and in the precautions taken.[1][3]

Coordinates: 45°15′21″N 0°41′35″W / 45.255833°N 0.693056°W

Location of the Blayais Nuclear Power Plant
Location of the Blayais Nuclear Power Plant


The Blayais plant, equipped with four pressurized water reactors, is located on the Gironde estuary near Blaye, South Western France, operated by Électricité de France. Due to records of over 200 floods along the estuary dating back to 585 AD, some 40 of which had been particularly extensive, the location of the plant was known to be susceptible to flooding, and reports of the 1875 floods mentioned that they were caused by a combination of a high tides and violent winds blowing along the axis of the estuary.[4] The area had also experienced flooding during storms in the recent past, on December 13, 1981 and March 18, 1988.[4] An official report on the 1981 floods, published in 1982,[5] noted that it 'would be dangerous to underestimate' the combined effects of tide and storm, and also noted that the wind had led to 'the formation of real waves on the lower flooded floodplain'.[4]

When the Blayais plant was designed in the 1970s, it was on the basis that a height of 4.0 m (13.1 ft) above NGF level would provide an 'enhanced safety level', and the base on which the plant was built was set at 4.5 m (15 ft) above NGF,[4] although some components were located in basements at lower levels. The protective sea walls around the Blayais plant were originally built to be 5.2 m (17 ft) above NGF level at the front of the site, and 4.75 m (15.6 ft) along the sides.[6] The 1998 annual review of plant safety for the plant identified the need for the sea walls to be raised to 5.7 m (19 ft) above NGF, and envisaged that this would be carried out in 2000, although EDF later postponed the work until 2002.[6] On 29 November 1999, the Regional Directorate for Industry, Research and the Environment sent a letter to EDF asking them to explain this delay.[6]


On December 27, 1999, a combination of the incoming tide and exceptionally high winds produced by Storm Martin caused a sudden rise of water in the estuary, flooding parts of the plant.[1] The flooding began at around 7:30 pm, two hours before high tide, and it was later found that at its height the water had reached between 5.0 m (16.4 ft) and 5.3 m (17 ft) above NGF.[6] The flooding also damaged the sea wall facing the Gironde, with the upper portion of the rock armour being washed away.[1]

Prior to the flooding, units 1, 2 and 4 were at full power, while unit 3 was shut down for refuelling.[1] Starting from 7:30 pm all four units lost their 225 kV power supplies, while units 2 and 4 also lost their 400 kV power supplies.[1][6] The isolator circuits that should have allowed units 2 and 4 to supply themselves with electricity also failed, causing these two reactors to automatically shut down, and diesel backup generators started up, maintaining power to plants 2 and 4 until the 400 kV supply was restored at around 10:20 pm.[1][6] In the pumping room for unit 1, one set of the two pairs of pumps in the Essential Service Water System failed due to flooding; had both sets failed then the safety of plant would have been endangered.[1][6] In both units 1 and 2, flooding in the fuel rooms put the low-head safety injection pumps and the containment spray pumps, part of the Emergency Core Cooling System (a back-up system in case of coolant loss) out of use.[1][6] Over the following days, an estimated 90,000 m3 (3,200,000 cu ft) of water would be pumped out of the flooded buildings.[1]


Decay heat illustration2
It takes several days for all the decay heat to subside after a reactor is SCRAMed, during which the heat must be removed by cooling systems

Around two and a half hours after the flooding began, a high-tide alarm for the estuary was triggered in the observation room of plant 4, although those in the other plants failed to activate. This should have caused the control room operators to launch a 'Level 2 Internal Emergency Plan', however this was not done as the requirement had been omitted from the operation room manual;[1] instead they continued to follow the procedure for the loss of the off-site power supply, so failing to shut down the operating reactors at the earliest opportunity to allow the decay heat to start to dissipate.[6] At 3:00 am on December 28, the power plant's emergency teams were called to reinforce the staff already on site; at 6:30 the management of the Institute for Nuclear Protection and Safety (now part of the Radioprotection and Nuclear Safety Institute) were informed, and a meeting of experts was convened at the IPSN at 7:45 am.[6] At 9:00 am the Level 2 Internal Emergency Plan was finally activated by the Directorate of Nuclear Installation Safety (now the Nuclear Safety Authority) and a full emergency management team of 25 people was formed, working in shifts around the clock.[6] At noon on December 28, the incident was provisionally rated at 'level 1' on the International Nuclear Event Scale[7] before being reclassified at 'level 2' the following day.[8] The team was scaled back during December 30, and stood down around 6 pm the same day.[6]

During the morning of December 28, the Institute for Nuclear Protection and Safety estimated that, if the emergency cooling water supply failed, there would have been over 10 hours in which to act before core meltdown started.[6]

On 5 January, the regional newspaper Sud-Ouest ran the following headline without being contradicted: "Very close to a major accident", explaining that a catastrophe had been narrowly avoided.[9]

A report on a number of samples taken after the flooding on January 8 and 9 found that the event had had no quantifiable effect on radiation levels.[10]


The Institute for Nuclear Protection and Safety issued a report on January 17, 2000, calling for a review of the data used to calculate the height of the surface on which nuclear power stations are built. It suggested that two criteria should be met: that buildings containing equipment important for safety should be built on a surface at least as high as the highest water level plus a safety margin (the cote majorée de sécurité or 'enhanced safety height'), and that any such buildings below this level should be sealed to prevent water ingress.[6] It also contained an initial analysis which found that, in addition to Blayais, the plants as Belleville, Chinon, Dampierre, Gravelines and Saint-Laurent were all below the 'enhanced safety height' and that their safety measures should be re-examined.[6] It also found that although the plants at Bugey, Cruas, Flamanville, Golfech, Nogent, Paluel, Penly and Saint-Alban met the first criterion, the second should be verified; and called for the plants at Fessenheim and Tricastin to be re-examined since they were below the level of major adjacent canals.[6] The consequent upgrading work, implemented over the following years, is estimated to have cost approximately 110,000,000 euro.[3]

In Germany, the flooding prompted the Federal Ministry for Environment, Nature Conservation and Nuclear Safety to order an evaluation of the German nuclear power plants.[1]

Following the events at Blayais, a new method of evaluating flood risk was developed. Instead of evaluating only the five factors required by Rule RFS I.2.e (river flood, dam failure, tide, storm surge and tsunami), a further eight factors are now also evaluated: waves caused by wind on the sea; waves caused by wind on river or channel; swelling due to the operation of valves or pumps; deterioration of water retaining structures (other than dams); circuit or equipment failure; brief and intense rainfall on site; regular and continuous rainfall on site; and rises in groundwater. In addition, realistic combinations of such factors are taken into account.[3]

Among the remedial actions taken at Blayais itself, the sea walls were raised to 8.0 m (26.2 ft) above NFG,[4] – up to 3.25 m (10.7 ft) higher than before – and openings have been sealed to prevent water ingress.[3]


Twelve days prior to the floods, a local anti-nuclear group was formed by Stéphane Lhomme under the TchernoBlaye banner (a portmanteau of the French spelling of Chernobyl and Blaye, the nearest town).[11] The group gained support following the flood and their first protest march of between 1,000 and 1,500 people took place on April 23, but was blocked from reaching the plant by police using tear gas.[11][12] The group continue their opposition to the plant, still under the presidency of Stéphane Lhomme.

Ongoing concerns

Due to the remedial works the plant is now believed to be adequately protected from flooding, however the access roadway remains low-lying and vulnerable. Due to this, particularly since the 2011 Fukushima I nuclear accidents in Japan, concerns have been raised over the potential difficulty of getting help to the plant in an emergency.[13][14]

The seawalls at Blayais are now higher than the tsunami that hit Japan, knocking out the cooling systems at Fukushima Dai-ichi. The adequacy of the sea walls has, however, been disputed by Professor Jean-Noël Salomon, head of the Laboratory of Applied Physical Geography at Michel de Montaigne University Bordeaux 3, who believes that, due to the potential harm and economic cost that would result from a future flood-related disaster, the sea walls should be designed to withstand simultaneous extreme events, rather than simultaneous major events.[4]

See also


  1. ^ a b c d e f g h i j k l Generic Results and Conclusions of Re-evaluating the Flooding in French and German Nuclear Power Plants Archived 2011-10-06 at the Wayback Machine J. M. Mattéi, E. Vial, V. Rebour, H. Liemersdorf, M. Türschmann, Eurosafe Forum 2001, published 2001, accessed 2011-03-21
  2. ^ COMMUNIQUE N°7 - INCIDENT SUR LE SITE DU BLAYAIS Archived 2013-05-27 at the Wayback Machine ASN, published 1999-12-30, accessed 2011-03-22
  3. ^ a b c d Lessons Learned from 1999 Blayais Flood: Overview of the EDF Flood Risk Management Plan, Eric de Fraguier, EDF, published 2010-03-11, accessed 2011-03-22
  4. ^ a b c d e f L'inondation dans la basse vallée de la Garonne et l'estuaire de la Gironde lors de la "tempête du siècle" (27-28 décembre 1999) / Flooding in the Garonne valley and the Gironde estuary caused by the "storm of the century" (27-28 December 1999) Salomon Jean-Noël, Géomorphologie : relief, processus, environnement, Avril-juin, vol. 8, n°2. pp. 127-134, doi : 10.3406/morfo.2002.1134, accessed 2011-03-25
  5. ^ Crue de la Garonne, décembre 1981 : éléments pour une analyse, A Dalmolin, Délégation régionale à l'architecture et à l'environnement d'Aquitaine, published 1982
  6. ^ a b c d e f g h i j k l m n o p Rapport sur l'inondation du site du Blayais survenue le 27 décembre 1999 Institute for Nuclear Protection and Safety, published 2000-01-17, accessed 2011-03-21
  7. ^ COMMUNIQUE N° 2 - INCIDENT SUR LE SITE DU BLAYAIS Archived 2011-07-22 at the Wayback Machine ASN, published 1999-12-28, accessed 2011-03-22
  8. ^ COMMUNIQUE N° 4 - INCIDENT SUR LE SITE DU BLAYAIS Archived 2011-07-22 at the Wayback Machine ASN, published 1999-12-29, accessed 2011-03-22
  9. ^ Sud-Ouest, 5 janvier 2000 - Centrale de Blaye : Très près de l'accident majeur
  10. ^ Point radioécologique de l'estuaire de la Gironde immédiatement après l'inondation du 27 décembre 1999 (Prélèvements des 8 et 9 janvier 2000) Institute for Nuclear Protection and Safety, published 2000-01-17, accessed 2011-03-21
  11. ^ a b L'histoire de TchernoBlaye TchernoBlaye, accessed 2011-03-29
  12. ^ In brief Archived 2012-03-26 at the Wayback Machine WISE, accessed 2011-03-29
  13. ^ Inquiétudes sur la centrale du Blayais Sud-Ouest, published 2011-03-14, accessed 2011-03-22
  14. ^ La centrale nucléaire du Blayais suscite l'inquiétude, actualité Reuters Le Point, published 2011-03-21, accessed 2011-03-22
Bristol Channel floods, 1607

The Bristol Channel floods, 30 January 1607, drowned many people and destroyed a large amount of farmland and livestock. Recent research has suggested that the cause may have been a tsunami.

Decay heat

Decay heat is the heat released as a result of radioactive decay. This heat is produced as an effect of radiation on materials: the energy of the alpha, beta or gamma radiation is converted into the thermal movement of atoms.

Decay heat occurs naturally from decay of long-lived radioisotopes that are primordially present from the Earth's formation.

In nuclear reactor engineering, decay heat continues to be generated after the reactor has been shut down (see SCRAM), and nuclear chain reactions have been suspended. The decay of the short-lived radioisotopes created in fission continues at high power, for a time after shut down. The major source of heat production in a newly shut down reactor is due to the beta decay of new radioactive elements recently produced from fission fragments in the fission process.

Quantitatively, at the moment of reactor shutdown, decay heat from these radioactive sources is still 6.5% of the previous core power, if the reactor has had a long and steady power history. About 1 hour after shutdown, the decay heat will be about 1.5% of the previous core power. After a day, the decay heat falls to 0.4%, and after a week it will be only 0.2%. Because radioisotopes of all half life lengths are present in nuclear waste, enough decay heat continues to be produced in spent fuel rods to require them to spend a minimum of one year, and more typically 10 to 20 years, in a spent fuel pool of water, before being further processed. However, the heat produced during this time is still only a small fraction (less than 10%) of the heat produced in the first week after shutdown.If no cooling system is working to remove the decay heat from a crippled and newly shut down reactor, the decay heat may cause the core of the reactor to reach unsafe temperatures within a few hours or days, depending upon the type of core. These extreme temperatures can lead to minor fuel damage (e.g. a few fuel particle failures (0.1 to 0.5%) in a graphite moderated gas-cooled design) or even major core structural damage (meltdown) in a light water reactor or liquid metal fast reactor. Chemical species released from the damaged core material may lead to further explosive reactions (steam or hydrogen) which may further damage the reactor.

December 1981 windstorm

The December 1981 windstorm was a severe storm that particularly affected southern England, Wales and south west France during December 13, 1981. The storm formed as a secondary low.In England, the storm started with violent winds and snow, which reached Cornwall during the morning. Prior its arrival a number of record low temperatures were reached for December, with -25.2C at RAF Shawbury in Shropshire, -5.5C in Southampton, while in Wales a record of -22.7C was recorded at Corwen in Denbighshire.

In the evening spring tides combined with a 1.45 m (4.8 ft) storm surge resulted in the highest water levels recorded in the Bristol Channel since the start of the 20th century. Water from melting snow, caused by milder weather accompanying the depression, added to the flooding. The maximum surge at Hinkley Point was measured at 1.3 metres (4 ft 3 in) above the 7.4 metres (24 ft) tidal level Ordnance Datum (OD) at 2025 hours, and 1.3 metres (4 ft 3 in) measured at Avonmouth. The wind was measured at 40 knots (74 km/h; 46 mph) from the west. Over topping of the sea defences along a 7 miles (11 km) stretch of the North Somerset coast at 22 locations from Clevedon to Porlock began after 19:30, and continued until about 21:30 when the wind speed had reached 50 knots (93 km/h; 58 mph) from the west. Although there was no loss of life, the resultant flooding covered 12,500 acres (5,100 ha) of land, affecting 1072 houses and commercial properties, with £150,000 worth of livestock killed and £50,000 of feed and grain destroyed. Wessex Water Authority estimated the total cost of the damage caused at £6m, resulting in a three-year programme of sea defence assessment, repair and improvement.In France, the storm caused widespread flooding in the south west, causing considerable damage in the river basins of the Garonne and Adour and flooding the city of Bordeaux.The MV Bonita, an 8000 tonne Ecuadorian cargo ship sailing from Hamburg to Panama was caught in the storm in the English Channel. 29 were rescued from the ship, 4 by helicopter until the storm was too strong for the helicopter to operate. The remaining crew were rescued by the Guernsey lifeboat, however there were 2 fatalities.Water entered the cooling water pump house of Hinkley Point nuclear power station, causing a shut-down for weeks after the storm.

Environmental impact of nuclear power

The environmental impact of nuclear power results from the nuclear fuel cycle, operation, and the effects of nuclear accidents.

The greenhouse gas emissions from nuclear fission power are much smaller than those associated with coal, oil and gas, and the routine health risks are much smaller than those associated with coal. However, there is a "catastrophic risk" potential if containment fails, which in nuclear reactors can be brought about by overheated fuels melting and releasing large quantities of fission products into the environment. This potential risk could wipe out the benefits. The most long-lived radioactive wastes, including spent nuclear fuel, must be contained and isolated from the environment for a long period of time. On the other side, spent nuclear fuel could be reused, yielding even more energy, and reducing the amount of waste to be contained. The public has been made sensitive to these risks and there has been considerable public opposition to nuclear power.

The 1979 Three Mile Island accident and 1986 Chernobyl disaster, along with high construction costs, also compounded by delays resulting from a steady schedule of demonstrations, injunctions and political actions, caused by the anti-nuclear opposition, ended the rapid growth of global nuclear power capacity. A release of radioactive materials followed the 2011 Japanese tsunami which damaged the Fukushima I Nuclear Power Plant, resulting in hydrogen gas explosions and partial meltdowns classified as a Level 7 event. The large-scale release of radioactivity resulted in people being evacuated from a 20 km exclusion zone set up around the power plant, similar to the 30 km radius Chernobyl Exclusion Zone still in effect. But published works suggest that the radioactivity levels have lowered enough to now have only a limited impact on wildlife. In Japan, in July 2016, Fukushima Prefecture announced that the number of evacuees following the Great East Japan earthquake events, had fallen below 90,000, in part following the lifting of evacuation orders issued in some municipalities.

Fessenheim Nuclear Power Plant

The Fessenheim Nuclear Power Plant is located in the Fessenheim commune in the Haut-Rhin department in Grand Est in north-eastern France, 15 km (9.3 mi) north east of the Mulhouse urban area, within 1.5 km (0.93 mi) of the border with Germany, and approximately 40 km (25 mi) from Switzerland. The plant is located in the thirteenth most densely populated region in Metropolitan France and in the centre of the European Backbone. It is the oldest operational nuclear power plant in France since the Superphénix, a fast breeder reactor, was closed in 1996/97.There have been ongoing concerns about the seismic safety of the plant and, following the 2011 Fukushima I nuclear accidents, on March 21 the local Information and Oversight Commission for the plant called for the seismic risk to be re-evaluated based on a 7.2 magnitude earthquake; the plant was originally designed for a 6.7 magnitude earthquake. The Swiss cantons of Basel-Stadt, Basel-Landschaft and Jura have also said that they are going to ask the French government to suspend the operation of Fessenheim while undertaking a safety review based on the lessons learned from Japan. The German state of Baden-Württemberg has called for a temporary closure in line with the 3-month shutdown of pre-1981 plants ordered in Germany. On March 29 the Franche-Comté Regional Council went further and voted for the plant to be closed, the first time a French Regional Council has passed such a vote. On April 6 the Grand Council of Basel-Stadt also voted for the plant to be closed as did the council of the Urban Community of Strasbourg on April 12. The European Parliament's Green members are also supporting the closure demands and are referring the matter to the European Commission. Around 3,800 people demonstrated near the plant on April 8; a larger demonstration is expected on April 25. The group Stop Fessenheim have collected over 63,000 signatures through an online petition calling for Fessenheim's closure, and, on April 18, began a 366-day 'fasting relay' outside the préfecture office in Colmar.In November 2018, President Macron announced that both units will close in spring 2020.

Flamanville Nuclear Power Plant

The Flamanville Nuclear Power Plant is located at Flamanville, Manche, France on the Cotentin Peninsula. The power plant houses two pressurized water reactors (PWRs) that produce 1.3 GWe each and came into service in 1986 and 1987, respectively. It produced 18.9 TWh in 2005, which amounted to 4% of the electricity production in France. In 2006 this figure was about 3.3%.

A third reactor at the site, a EPR unit, is currently under construction.

As of July 2016, the project was three times over budget and years behind schedule.

Various safety problems have been raised, including weakness in the steel used in the reactor.

In 2006, before the start of construction of the EPR (unit 3), there were 671 workers regularly working at the two operational reactors.

List of floods in Europe

This is a list of notable recorded floods that have occurred in Europe.

Nuclear reactor safety system

This article covers the technical aspects of active nuclear safety systems in the United States. For a general approach to nuclear safety, see nuclear safety.The three primary objectives of nuclear reactor safety systems as defined by the U.S. Nuclear Regulatory Commission are to shut down the reactor, maintain it in a shutdown condition and prevent the release of radioactive material.

Nuclear safety and security

Nuclear safety is defined by the International Atomic Energy Agency (IAEA) as "The achievement of proper operating conditions, prevention of accidents or mitigation of accident consequences, resulting in protection of workers, the public and the environment from undue radiation hazards". The IAEA defines nuclear security as "The prevention and detection of and response to, theft, sabotage, unauthorized access, illegal transfer or other malicious acts involving nuclear material, other radioactive substances or their associated facilities".This covers nuclear power plants and all other nuclear facilities, the transportation of nuclear materials, and the use and storage of nuclear materials for medical, power, industry, and military uses.

The nuclear power industry has improved the safety and performance of reactors, and has proposed new and safer reactor designs. However, a perfect safety cannot be guaranteed. Potential sources of problems include human errors and external events that have a greater impact than anticipated: The designers of reactors at Fukushima in Japan did not anticipate that a tsunami generated by an earthquake would disable the backup systems that were supposed to stabilize the reactor after the earthquake.

Catastrophic scenarios involving terrorist attacks, insider sabotage, and cyberattacks are also conceivable.

Nuclear weapon safety, as well as the safety of military research involving nuclear materials, is generally handled by agencies different from those that oversee civilian safety, for various reasons, including secrecy. There are ongoing concerns about terrorist groups acquiring nuclear bomb-making material.

Saint-Laurent Nuclear Power Plant

The Saint-Laurent Nuclear Power Station is located in the commune of Saint-Laurent-Nouan in Loir-et-Cher on the Loire – 28 km upstream from Blois and 30 km downstream from Orléans.

The site includes two operating pressurized water reactors (each 900MWe), which began operation in 1983. They are cooled by the water of the Loire River.

Two other UNGG reactors used to exist at the site, which were brought into service in 1969 and 1971 and were retired in April 1990 and June 1992.The site employs approximately 670 regular workers.

Tricastin Nuclear Power Plant

The Tricastin Nuclear Power Plant (French: Centrale Nucléaire du Tricastin) is a nuclear power plant consisting of 4 pressurized water reactors (PWRs) of CP1 type with 915 MW electrical power output each. The power plant is located in the south of France (Drôme and Vaucluse Department) at the Canal de Donzère-Mondragon near the Donzère-Mondragon Dam and the commune Pierrelatte.

The power plant is part of the widespread Tricastin Nuclear Site (see below), which was named after the historic Tricastin region. Three out of the four reactors on the site had been used until 2012 to power the Eurodif Uranium enrichment plant, which had been located on the site.

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