Would an EMP in the US Cause all of our active Nuclear Power Plants to melt down and explode?

Question

In an article from the National Journal released and linked to from the Drudge Report today(28MAR2014), Peter Pry, "a former CIA officer and head of a congressional advisory board on national security" claimed that a single EMP that is large enough to take out the power grid in the US would result in(among other things):

One hundred four nuclear reactors going Fukushima, spreading toxic clouds everywhere.

Due to US NRC standards, all Nuclear Power Plants include a containment vessel so the only way for them to spew toxic clouds would be for them to explode much like happened in Fukushima.

So In the event of an EMP would we have nearly all of the active plants melting down and exploding?

Answer 1

Could a single EMP cause nearly all USA reactors to "go Fukushima" - melt-down and explode? (paraphrased)

In brief

No because

• NRC policies have taken into account EMP since the late 1970s
• The USA has no nuclear reactors of the old design type used at Fukushima.

EMP

The Nuclear Regulatory Commission (NRC) have been studying the effect of EMP on nuclear power plants since the 1970s to ensure that these plants can shutdown safely after an EMP.

See Keeping U.S. Reactors Safe from Power Pulses

The NRC requires U.S. nuclear power plants to be able to shut down safely in the face of many extreme events – tornados, hurricanes and earthquakes. But the NRC also takes into account far more unusual events, like solar flares and electromagnetic pulse (EMP) caused by a certain type of nuclear weapon.

Here's an example study: Interaction of electromagnetic pulse with commercial nuclear-power-plant systems

it was concluded that: (1) Diffuse fields inside Seismic Class I buildings are negligible; (2) EMP signal entry points are identifi- able; (3) Interior signal attenuation can be reasonably modeled; (4) Damage thresholds, even for equipment containing solid state components are high; (5) EMP induced signals at the critical equipment in the example plant are much less than nominal operating levels, but plant topology and cabling practice have a strong influence on responses; (6) The likelihood that individual com- ponents examined will fail is small; therefore, it is unlikely that an EMP event would fail sufficient equipment so as to prevent safe shutdown

EMP from high altitude nuclear tests in the 1960s did cause significant damage to some sections of street lighting and other equipment at long range.

Since the continental USA is a large country, it would take an extraordinarily large nuclear explosion to create a single EMP pulse that affects both west and east coasts.

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Fukushima

The containment failures at Fukushima were due to a combination of factors:

• The Tsunami knocked out the power grid in the region.
• The Tsunami flooded the standby generators at the power plant.
• The Reactors did not have a purely passive system for reaching cold-shutdown.

The Fukushima reactors are Boiling Water Reactors (BWR) designed by GE in the 1960s and now designated, by some people, as Generation-1 reactors. According to Wikipedia there are no Generation-1 reactors operating in the USA (they've all been decommissioned - the last was Big Rock Point in 1997). However this system of classification is not universally used.

Answer 2

There is no reason to think this is the case. The effect of high altitude electromagnetic pulses has been studied by a scientific commission for the US government and they released a long, in-depth result. It's a 168-page book, full of physical models and engineering assessments -- hard to summarize in its entirety, but from a quick look it seems to me to be solid evidence.

Their conclusion is that there would certainly be some level of damage, some of which could take years to recover from. They end with the following paragraph:

As a final note, the bottom line for predicting E1 HEMP effects is that our modern world has never experienced such as assault. We can try to predict effects and draw upon similar effects and experimentation, but there is always the possibility of some surprise. Often even somewhat minor issues have lead to extensive problems in the past, which would not have been predicted. It is also not known how American society in general would react if massive infrastructure failures occur over a large region and for a long time.

This is to say: obviously it would be a very negative event, with consequences. That said, there's no evidential support for an apocalyptic scenario such as the one presented by the claimants.

In fact, they have an appendix dedicated to "E1 HEMP Myths" and they openly call out apocalyptic scenarios as "not very believable":

Some general emphasis of comments fall into either “the world as we know it will come to an end” if there is a high altitude nuclear burst, or the other extreme: “it’s not a big deal, nothing much will happen”. Since we really have never had a nuclear burst over anything like our current modern infrastructure, no one really knows for sure what would happen, but both extremes are not very believable.