Something to Talk About: Missile Threats against East Asian Reactors 


As Washington's strained relations with Beijing and Pyongyang continue to frazzle, it's unclear how bad things might get. The prospects of war with North Korea or China are still quite distant. It's certainly very difficult to imagine how a war with either might begin and what might be hit. To deter future conflict, however, requires imagining all possibilities.  

In this regard, one target set that deserves more attention is nuclear plants in South Korea, Taiwan, and Japan. At a recent NPEC workshop on what new security threats Washington should work more closely with Seoul and Tokyo on, the increasing vulnerability of nuclear plants in the region was examined. A summary of the workshop's key findings is attached along with short video excerpts, selected graphics, and draft commissioned research.

The workshop's key takeaways are that North Korean and Chinese missiles are now lethal and accurate enough to disable a variety of nuclear plant subsystems. China and North Korea can deter and shape U.S. and allied military resistance in a variety of ways by targeting these points. The good news is there are a number of steps South Korea, Taiwan, and Japan might take to mitigate these threats. Holding discussions clarifying how may have to be done in private but it's not too early to begin.


Jun 04, 2020
Understanding and Reducing Military Vulnerabilities of Civilian Nuclea.... (PDF) 3,391.13 KB

Something to Talk About:  Missile Threats against East Asian Reactors

By Henry Sokolski


Middle Eastern nuclear plants’ vulnerability to military aerial attacks have a long history. Yet, the vulnerability of East Asian plants to such attacks have rarely, if at all, been discussed.  Googling the topic, one can find but a single mention — a brief South Korean news piece on how inadequate reactor containment buildings are in protecting against ballistic missile strikes.  Otherwise, all that is available analyses of how much damage terrorists might inflict against nuclear facilities.

It is unclear what explains this analytic omission.  Perhaps it is just history:  Middle Eastern nuclear plants have been targeted by states with aerial and missile strikes some 13 times.  China, Russia, the United States, North Korea, South Korea, and Japan have yet to even threaten such attacks in East Asia

That, however, may change. Until the 1970s, in the most militarily disputed region in Asia—Korea—the only way Pyongyang could attack targets in South Korea or Japan was with commandos, artillery barrages, or air attacks. The same would be true of South Korea against the North.  Such non-missile attacks, however, could be risky as they might precipitate all-out war or be deflected by air defenses or repulsed by domestic forces.  Over the last decade, however, both North and South Korea and China have acquired missiles with sufficient range and accuracy to not just target, but to hit specific subsystems at civilian nuclear sites.

In the 1990s, this was not the case.  Then, North Korea’s and China’s missile accuracies were measured in kilometers or hundreds of meters. Today, they are measured in meters.    

Targeting East Asian Nuclear Plants: Why and How

It’s unlikely North Korea or China would target South Korea, Japanese, or Taiwanese nuclear plants in the opening round of any shooting war.  Given the size and high accuracies of their missile arsenals, though, Pyongyang or Beijing might well threaten such strikes either in the ramp up to hostilities or in the midst of conflict to deter further resistance or shape the character of battle. 

Consider the following 2025 scenario. North Korean troops exchange small arms fire, as they recently did, at the Demilitarized Zone (DMZ).  This time, however, a newly elected conservative South Korean government is less quick to dismiss the shots as accidents as one ROK serviceman is killed and another wounded. Washington, to show solidarity with Seoul and to deter further North Korean provocations, flies “deterrence” B-2 sorties from bases in the United States into the North’s declared air defense zones. 

The North, undeterred, again fires small arms shots against DMZ personnel. Eager to show its independence, the South Korean government shows its stuff: It fires one of its Hyunmoo 2c missiles in a demonstration shot intended to fall harmlessly off the coast near the North Korea naval and missile base at Mayans-do.  It misses its mark and instead hits land.  The North Koreans mistakenly assume the missile was aimed at the nearby Simpo reactors.

Pyongyang considers retaliating by targeting a nuclear plant in the South.  It could threaten to do so to extract some concession from Washington or Seoul. Or, to prove the seriousness of its intent, it could conduct a demonstration shot, firing one of its accurate KN-23 ballistic missiles from its missile base at Chiha-ri at a parking lot just outside one of South Korea’s nuclear power plants.  Pyongyang decides to go for the demonstration shot. This spooks Seoul, which takes the precautionary measure of shutting down all of its nuclear power plants. This powers down over 20 percent of the country’s electrical supply. Brownouts and blackouts ensue.

At this point, there could be a break in hostilities or things could escalate with more missile exchanges. In the latter case, the North could up its game by targeting either the electrical grid wires feeding into a South Korean nuclear plant or, alternatively, targeting the plant’s emergency generating diesel station.  Neither, if destroyed, would prompt a loss of coolant accident, core meltdown or a radiological release. 

Any such strike, however, would clearly raise fears that the North might up its game in yet another follow-on strike.  This could be accomplished by knocking out the emergency generating diesel station or the nuclear control room or the reactor containment building itself.  Fears of such follow-on attacks would likely prompt massive voluntary or state-mandated evacuations of millions of South Koreans, who would flood the public roads. This alone could distract South Korea from engaging any further military or defensive operations against the North.   

Finally, if the conflict continued to escalate, the North might, at some point, threaten to target the spent fuel ponds at one or more of South Korea’s nuclear plants.  Depending on the prevailing winds (see below), the massive amounts of radioactivity such an attack would release would force the evacuation of between roughly 10 and 100 million South Korean and Japanese civilians. 

This scenario is for Korea. Similar results could be induced if China or North Korea targeted nuclear plants in Japan or Taiwan. In the case of possible attacks against Japan’s reprocessing plant at Rokkasho, the releases and evacuations would range between roughly nine and 90 million citizens.

How Destructive Might the Incoming Missiles Be

The accuracies of the latest generation of cruise and ballistic missiles assure a very high probability of kill against a variety of nuclear plant aim points.  These include electrical power feed-in supply lines, emergency electrical diesel generator buildings, nuclear control rooms, reactor containment buildings, and spent reactor fuel pond buildings.  All of these nuclear plant subsystems are nearly as large at the circle of error probable of the missiles North Korea or China might fire against them:  One or two missiles should be sufficient to knock out any single aim point.

As for the targets themselves, most can be dispatched either with unitary or, if necessary, with tandem-charged munitions.  The later use shaped charges are designed to penetrate metal armor and concrete.  The thickest concrete structures at a reactor site are rarely more than one and a half meters thick.  Reactor containment structures are designed to keep several hundred pounds per square inches of internal pressure from escaping into the atmosphere after a loss of coolant or fuel melt-down from an accident.  They are not designed to deflect missile attacks, much less tandem charged munitions. The roofs of the nuclear control rooms, the diesel generator buildings, and the spent fuel storage ponds are generally much thinner than the reactor’s main containment walls.

What Might Be Done

Structurally, the roofs of the spent fuel ponds, the nuclear control room, and the diesel generator buildings could be strengthened by using ultra high performance concrete.  This advanced material can sustain compressions of 35,000 psi or more—a several hundred-fold increase over existing plant roof structures.  This could be done at modest cost.

In addition, slat armor structures could be built to prevent tandem charged munitions from properly coupling with their aim points.  This also could be accomplished at a modest cost around the spent fuel pond, diesel generating building, and the nuclear control room.

The National Research Council made a series of additional recommendations in a 2006 report on nuclear plant vulnerabilities to Congress.  First among these, was to remove as much of the older spent fuel from reactor storage ponds as possible and to space out the remaining hotter, newer spent fuel so as to reduce the amount of radiation that might otherwise be released if the storage pond was ever hit.  The report also recommended that sprinkler cooling systems be installed over the spent fuel ponds and coolant level monitors so if a pond was hit and the coolant level dipped, the sprinklers would be set off to keep the spent fuel from overheating. 

Another suggestion that Japan has already acted on to limit the harm a possible terrorist attack might inflict against its nuclear reactors is to build additional, remote reactor control rooms. Finally, active and passive defenses can be installed.  These include covering potential reactor aim points with bird-cage like slats, which would set off incoming missiles and dual-charged munitions before they could have a chance to couple physically with the target.  And finally, air and missile defenses could be deployed to fend off possible attacks.  Belarus has done this in the case of its Astravets nuclear plant.  Of all the nuclear plant mitigation strategies, active defenses are the most expensive.

Talking the Talk

This brief memo should get the ball rolling. Nuclear security forums already exist internationally and regionally to discuss how best to protect against terrorist attacks.  These should be expanded to include the topic of military aerial and massive attacks.  At these forums, best practices in defending and responding to military attacks against nuclear plants should be established as a routine topic.

Taking on this topic may prove challenging. South Korean politicians and diplomats, still eager to improve relations with the North, may be loath to publicly discuss war scenarios involving Pyongyang. Nor will they want to suggest that China might attack them. The Japanese government, still committed to opening up scores of reactors, also will be reluctant to discuss its nuclear plants' military vulnerabilities in public.  Taiwan authorities, who have yet to determine how they intend to fully replace the nuclear plants they intend to close in 2025, may be squeamish about identifying new immediate vulnerabilities that could require additional spending of any sort.  

As for the United States, it, luckily, is not yet vulnerable to conventional missile attacks.  Yet, the nuclear industry and the Energy Department have persistently promoted working with South Korea and Japan on advanced reactor and nuclear fuel cycles and have extolled the virtues of making nuclear power great again. Asking Washington to take the lead in opening discussions on military vulnerabilities to nuclear plants won’t be easy. 

Unfortunately, not discussing these vulnerabilities would only make matters far worse.  In that there ought to be some solace for all parties sufficient to encourage private talks, at the very least.


Videos from New Frontiers for U.S. Alliance Cooperation with Japan and the ROK


Selected Radiological Release Maps: Taiwan


Selected Radiological Release Maps: South Korea and Japan




Draft (May 24, 2020)

Understanding and Reducing Military Vulnerabilities of Civilian Nuclear Plants: The Case for the Northeast Asia

Jungmin Kang, Independent Consultant
Former Chairman of the ROK Nuclear Safety and Security Commission

The following is an excerpt. To read the entire research paper, CLICK HERE. 

1. Introduction

A Fukushima-like nuclear accident does not have to be caused by nature. Similar results could be wrought by military attack that disabled its safety systems, including cooling and power systems of nuclear power plants (NPPs).

This study shows hypothetical releases from a core meltdown or spent fuel pool fire of NPPs occurred by military attack such as missile attacks in some of Northeast Asia countries, with atmospheric dispersion and deposition calculations using the HYSPLIT code with historical meteorological data for the region.

2. Nuclear Power Reactors in Some Northeast Asia Countries

2.1 Japan
As of March 2020, of the 33 reactors that are operable, nine reactors are actually operating and 18 are in the process of restart approval due to the aftermath of the 2011 Fukushima accident. Japan also has 27 power reactors that are permanently shut-downed.

Fig. 1 shows the status of nuclear power plants in Japan as of October 2017. Table 1 and 2 show operable power reactors and power reactors under construction, respectively, in Japan.

Despite of the relatively small numbers of reactors in operation, the Japanese government is about to commence operating the Rokkasho reprocessing plant in early 2022. The Rokkasho reprocessing plant is capable of separating annually about eight tons of plutonium from the reprocessing of 800 tons of spent fuel. The plant has a pool that currently holds approximately 3,000 tons of spent fuel from PWRs and BWRs.