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What are the risks of nuclear power plants in wartime?

Karine Herviou
Karine Herviou
Deputy Director General in charge of the Nuclear Safety Division of the Institute for Radiation Protection and Nuclear Safety (IRSN)
Najmedin Meshkati
Najmedin Meshkati
Professor of Civil/Environmental Engineering at the University of Southern California (USC)
Veronika Ustohalova
Veronika Ustohalova
Senior Researcher, Nuclear Engineering & Facility Safety at Öko-Institut e.V.
ASN_0037728_A4
Olivier Gupta
Director General of the ASN and President of the Western European Nuclear Regulators Association (WENRA)
Key takeaways
  • The conflict between Russia and Ukraine is unprecedented in terms of nuclear safety. It is the first armed conflict in a country with a major nuclear programme: Ukraine derives about 50% of its energy from fission.
  • A plant can be damaged in a number of ways: breaching missiles, a power cut leading to core meltdowns, etc. This can have serious consequences for the environment and the health of the population. This can have serious consequences for the population and the surrounding nature.
  • Moreover, no specific treaty exists to deal with this threat. However, Protocol I and II of the Geneva Convention allow for “norms” of behaviour in wartime that should be respected.
  • One of the most effective ways to minimise the risks would be to create a demilitarised zone around nuclear power plants to protect the population.

The recent occu­pa­tion of two nuclear sites in Ukraine by Russ­ian forces has high­light­ed the impor­tance of mon­i­tor­ing such facil­i­ties in wartime. This is the first armed con­flict in a coun­try with a major nuclear pro­gramme: Ukraine derives about 50% of its ener­gy from fission.

The world’s nuclear pow­er plants were built in peace­time and were not designed to with­stand all types of bomb­ing. In times of con­flict, the radi­a­tion mon­i­tor­ing devices of these facil­i­ties can be dis­con­nect­ed by the attack­er, mak­ing it dif­fi­cult to mon­i­tor the lev­els of radi­a­tion in the sur­round­ing envi­ron­ment in real time in case of a problem.

In Ukraine, the coun­try’s nuclear reg­u­la­tor informed the Inter­na­tion­al Atom­ic Ener­gy Agency (IAEA) of its dif­fi­cul­ties in com­mu­ni­cat­ing with staff at the Zapor­izhzhia plant (one of the sites that is occu­pied), fol­low­ing the deac­ti­va­tion of some mobile net­works and because Russ­ian forces blocked the inter­net1. The IAEA con­sid­ers that this sit­u­a­tion is con­trary to one of the sev­en pil­lars2 of nuclear safe­ty3.

The dangers of spent fuel

A nuclear pow­er plant can be dam­aged in a num­ber of ways dur­ing a war: mis­siles can hit safe­ty-crit­i­cal reac­tor equip­ment – for exam­ple, breach the reac­tor con­tain­ment and impact the core cool­ing sys­tems, caus­ing radioac­tive mate­r­i­al to be dis­persed over a wide geo­graph­i­cal area; the pow­er or water sup­ply to a nuclear reac­tor can be dis­abled, lead­ing to core melt­downs (as hap­pened in the Fukushi­ma acci­dent)4. How­ev­er, the Zapor­izhzhia reac­tors are of rel­a­tive­ly mod­ern design and, unlike the Cher­nobyl reac­tor, are enclosed in a pres­surised steel ves­sel, which is itself housed in a mas­sive pre-stressed con­crete con­tain­ment struc­ture. Such a struc­ture is very robust.

Any dam­age to spent fuel assem­blies – as a result of bomb­ing, for exam­ple – could lead to a radi­o­log­i­cal emergency.

Nuclear reac­tors con­tain spent fuel dur­ing oper­a­tion. Spent fuel con­tains an accu­mu­la­tion of high­ly radioac­tive fis­sion prod­ucts, includ­ing iodine, cae­sium and stron­tium. Any dam­age to spent fuel assem­blies – as a result of bomb­ing, for exam­ple – could lead to a radi­o­log­i­cal emer­gency (defined as a sit­u­a­tion in which there is a risk of abnor­mal expo­sure to work­ers and the pop­u­la­tion liv­ing nearby).

Nuclear reac­tors are housed in build­ings made of robust mate­ri­als. They also boast a num­ber of safe­ty sys­tems to ensure that the core remains cool, even if some of the sys­tems are destroyed. That said, they were pri­mar­i­ly designed to with­stand a falling air­craft, for exam­ple, but not high-inten­si­ty pro­jec­tiles, such as those used in warfare.

International regimes and treaties

The pos­si­bil­i­ty of a nuclear risk in Ukraine is of con­cern to the Unit­ed Nations Secu­ri­ty Coun­cil, which held an emer­gency meet­ing in ear­ly March. The US ambas­sador said at that ses­sion that the attack on the Zapor­izhzhia nuclear pow­er plant “pos­es a seri­ous threat to the world5”. In addi­tion, the IAEA Board of Gov­er­nors adopt­ed a res­o­lu­tion con­demn­ing the Russ­ian inva­sion and call­ing for Ukraine to regain con­trol of its nuclear facil­i­ties. This res­o­lu­tion was in line with an ear­li­er UN Gen­er­al Assem­bly res­o­lu­tion6.

The risk of nuclear reac­tor facil­i­ties being attacked in wartime has long been of con­cern7 and the inter­na­tion­al regime relat­ing to attacks on nuclear reac­tors and asso­ci­at­ed facil­i­ties8 includes a num­ber of treaties, agree­ments and “stan­dards of conduct”.

No specific treaty

There is, how­ev­er, no spe­cif­ic treaty, even though there have been a num­ber of attacks on reac­tors in recent decades91011. How­ev­er, as ear­ly as 1956, the Inter­na­tion­al Red Cross pro­posed “immu­ni­ty from attack for instal­la­tions”, includ­ing nuclear pow­er plants, where the attack might endan­ger civil­ian pop­u­la­tions. This pro­pos­al even­tu­al­ly led to an amend­ment to Pro­to­col I of the Gene­va Con­ven­tion12. Thus, even in the absence of treaties, this pro­to­col and Pro­to­col II13, as well as the oth­er rules men­tioned above, pro­hib­it such attacks because they have cre­at­ed “norms” of inter­na­tion­al behav­iour that should be respected.

The IAEA, for its part, has long recog­nised the need to pro­hib­it armed attacks on nuclear facil­i­ties. In 1987, the Agen­cy’s Gen­er­al Con­fer­ence adopt­ed a res­o­lu­tion con­cern­ing the pro­tec­tion of such facil­i­ties. It stressed that the con­se­quences of a radioac­tive release would be wide­spread – lit­er­al­ly – as it would affect ter­ri­to­ries with­in and beyond the bor­ders of the attacked coun­try. The Agency also high­light­ed the need to reach an inter­na­tion­al agree­ment on this issue14.

Demilitarised zones?

Although many experts do not want to be too alarmist15, wars are, by nature, unpre­dictable. Accord­ing to Najmedin Meshkati16 of the Uni­ver­si­ty of South­ern Cal­i­for­nia, the only way to avoid a cat­a­stro­phe is to estab­lish demil­i­tarised zones around nuclear pow­er plants. “The IAEA, for exam­ple, should ask the attack­ing coun­try to declare a no-fight zone around these facil­i­ties and, most impor­tant­ly, allow plant oper­a­tors to rotate their crews so that they can rest because human error is a major fac­tor in such a sit­u­a­tion,” he says. “The oper­a­tors, who are the first and last line of defence in these facil­i­ties, work under con­di­tions of intense wartime stress while wor­ry­ing about their fam­i­lies and loved ones and the gen­er­al con­se­quences of war”17.

Zapor­izhzhia nuclear pow­er sta­tion, Ukraine (CC: Ralph1969)

Veroni­ka Usto­halo­va18 of the Öko-Insti­tut in Ger­many adds that the pow­er sup­ply to a reac­tor must be main­tained in the event of an attack, some­thing that could be dif­fi­cult to do in wartime, to ensure the reac­tor con­tin­ues to be cooled and so avoid core melt­down. “Dur­ing a con­flict the safest solu­tion is to shut down all nuclear reac­tors,” she says. “The prob­lem is that in dis­cus­sions on nuclear safe­ty, vio­lent con­flicts or wars have so far been con­sid­ered unlike­ly or not addressed at all,” she points out. “There is no inter­na­tion­al set of rules defin­ing the cri­te­ria by which nuclear reac­tors in war zones should be shut down.”

More­over, inter­na­tion­al norms may be dif­fi­cult to enforce when the vio­lat­ing par­ty is a major power.

The safety of French nuclear power plants

In terms of nuclear safe­ty, Olivi­er Gup­ta, Direc­tor Gen­er­al of the French Nuclear Safe­ty Author­i­ty (ASN) and Pres­i­dent of the West­ern Euro­pean Nuclear Reg­u­la­tors Asso­ci­a­tion (WENRA) explains in an arti­cle pub­lished in Les Echos on 13 March that “WENRA and oth­er inter­na­tion­al bod­ies have pro­posed sup­port for the Ukrain­ian Nuclear Safe­ty Author­i­ty, but it is not easy to imple­ment”19.

In the event of a seri­ous acci­dent, there are actions to pro­tect the pop­u­la­tion that could be imple­ment­ed: “What could lead to the most severe acci­dent, with the most releas­es into the envi­ron­ment, is a sce­nario with a core melt­down in an active plant. Based on the work car­ried out in 2014 fol­low­ing the Fukushi­ma acci­dent, it can be esti­mat­ed that in the event of a very seri­ous acci­dent, with­out dam­age to the reac­tor build­ing, it might be nec­es­sary to evac­u­ate the pop­u­la­tion with­in a five-kilo­me­tre radius and to shel­ter those liv­ing with­in a 20-kilo­me­tre radius. If, on the oth­er hand, we imag­ine an acci­dent with loss of the reac­tor con­tain­ment, we would have to extend these zones to 20 kilo­me­tres and 100 kilometres.”

An exclu­sion zone ensures that no one is exposed in the first few hours in the event of a core melt.

Karine Hervi­ou, Deputy Direc­tor Gen­er­al in charge of the Nuclear Safe­ty Unit at the IRSN (Insti­tut de Radio­pro­tec­tion et de Sureté Nucléaire) adds, “most of the world’s reac­tors were rein­forced [fol­low­ing the Fukushi­ma acci­dent] in the event of a loss of elec­tric­i­ty. There are sev­er­al lines of defence before core melt­down occurs. A reac­tor can self-pow­er for a cer­tain peri­od of time and there are emer­gency gen­er­a­tors with an auton­o­my of about ten days. Some of them are bunkered – that is, they are pro­tect­ed from the out­side. These gen­er­a­tors require fuel to oper­ate; the sites have reserves to oper­ate for about ten days.”

“Obvi­ous­ly, if exter­nal pow­er can­not be restored and the site can­not be refu­elled, there is a risk of core melt­down. How­ev­er, some Ukrain­ian plants have an advan­tage over Fukushi­ma: they boast sys­tems that fil­ter out radioac­tive releas­es – such as the radioiso­tope cae­sium, for exam­ple – in the event of a core melt­down. The loss of pow­er sup­plies is a risk in a war sit­u­a­tion that can­not be exclud­ed. Indeed, this is one of the most impor­tant risks for us: the loss of power.”

What about the time it takes to cool down the plant in case of a grid fail­ure, to remove the rods and allow the units to be shut down? “It takes months, even years. The proof is that the dis­charged assem­blies, at cycle end, must be cooled for three years before they can be trans­port­ed. They are then stored again in the pools at La Hague, where they are cooled once more.” The threat is there­fore serious.

“An exclu­sion zone ensures that no one is exposed in the first few hours in the event of a core melt. Depend­ing on the ele­ments released and the radius of the exclu­sion zone, it may be nec­es­sary to take pro­tec­tive actions beyond this zone. There will be restric­tions on the con­sump­tion and mar­ket­ing of food­stuffs at least.”

“The pow­er plant oper­at­ing con­di­tions are also impor­tant: the teams in place need peace of mind to work. In a war sit­u­a­tion this is obvi­ous­ly not the case. This is anoth­er major risk for a reac­tor in a coun­try at war.”

The con­clu­sion is not a hap­py one: nuclear pow­er plants are not com­pat­i­ble with war. As things stand, that the attack­ing pow­er does not tar­get nuclear facil­i­ties is per­haps all we can hope for. How­ev­er, a site like Zapor­izhzhia can also be con­sid­ered unat­tack­able for this very rea­son: the risk of a major nuclear acci­dent. Indeed, after tak­ing con­trol in ear­ly March, the Rus­sians imme­di­ate­ly installed tanks and ammu­ni­tion depots inside the plant because they were con­vinced that the Ukrain­ian army would nev­er dare attack the site with heavy weapons20.

Isabelle Dumé
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