In light of the murder of a security guard at a nuclear power plant allegedly by ISIS, I had a conversation with someone this weekend on that subject.  A brief synopsis of it follows.

Person A: So can ISIS do anything to a nuclear power plant?

Me: Do you really want to have this conversation?

Person A: Yes.

Me: Okay.  So be it.  No, ISIS can’t do anything.

Person A: But what about Chernobyl?

Me:  At Chernobyl, which is an RBMK-1000 design, it was neutronically a loosely couple reactor in order to allow refueling on line because it was producing weapons grade material.  It’s neutron moderator was graphite, not water.  The water was both the coolant and a neutron poison.  Thus, on lose of coolant, the neutron population rapidly increased.  That fateful night an electrical engineer was running a test on the reactor, and the reactor operators were operating under his procedure.  He put the plant in a condition in which safety systems and automatic reactor trips were bypassed, forced a plant transient, and voided the core of water.

When he did this, reactor power increased by a factor of 100 within one second.  Shortly after the accident a lot of multidimensional analysis work was performed to ascertain whether it was a nuclear explosion or a steam explosion.  The answer was pretty clear, it was a steam explosion.  Commercial nuclear reactors cannot explode like a bomb.  It’s impossible.  But it dispersed the coolant channels in such a manner that the core could no longer be cooled.  It melted.

This Russian design had what we call a positive void coefficient, leading to an overall positive power coefficient.  Reactor transients with increasing power further increase power.  In America, the code of federal regulations dictates that reactors be designed with overall negative power coefficients.  In Europe too, I believe.  The RBMK only exists in Russia and the Ukraine.

I’m sorry, I asked you if you really wanted to have this conversation.

Person A: So the plant is intrinsically safe, but can ISIS do anything with the security badge?

Me: No.  Entry into the plant requires biometric screening, like palm prints.  If someone tried to force their way into the plant, they would be shot within seconds (not to mention the fact that the turnstiles would never open).  The only real threat to safety and security would be an inside job, where engineers who had extensive knowledge of the safety analysis of the plant went into the plant to area terminal cabinets and opened sliding links, lifted leads, and so on, disabling safety systems.  In other words, malicious tampering.  Engineers are very non-fertile ground for that sort of thing, having worked their entire careers trying to baby the machine into working right to begin with.  No engineer wants to see his life’s work go away in ignominy.  Besides, engineers are boring people.

Person A: So why all the hype?

Me: Soccer moms will do anything, give over any amount of privacy, give up virtually anything, in order to maintain a level of safety and security.  ISIS and nuclear power plants is the latest incarnation of the whole ISIS thing generically.  The government gets a chance to say, “Hey, listen to us, we’ll protect you if you’ll only give us access to your iPhone, all of your records, bank accounts, medical data, tell us whether you have any guns in the home, let us listen to and record your phone calls and all of your text messages, and in short be your protector.  We’ll take care of you, we promise!  We won’t let the mean bad men make the big bad thingy go BOOM and hurt your precious little babies!  Let me have the keys to your life, sweetie!”