Nuclear flask haulage - traction redundancy

[sleepy_hollow]

Yesterday, waiting for a train at Cam & Dursley I saw the shortest goods train in the world. Two class 68's and one nuclear flask wagon, enough power to accelerate into orbit. *** I surmise that two locomotives are used for redundancy reasons rather than, for example as a way of getting one of the locomotives to somewhere else, for tradition, because two class 20s were once used, or because class 68s are under-utilised and need the occasional run. ***

What failure modes does this redundancy cover? Or, putting it the other way, what failure modes does it not cover?


*** Subsequent edit to meet forum standards ***

 

[DarloRich]

Yesterday, waiting for a train at Cam & Dursley I saw the shortest goods train in the world. Two class 68's and one nuclear flask wagon, enough power to accelerate into orbit. Wikipedia says that two locomotives are used for redundancy reasons.

What failure modes does this redundancy cover? Or, putting it the other way, what failure modes does it not cover?

Would you want your train of nuclear goop stuck in the middle of nowhere waiting for a rescue loco? It is a bit of a security nightmare I imagine

I expect the flask wagons are maintained within an inch of thier life to eliminate the risk as far as possible of any of the failures you might find with common freight wagons.

 

[The exile]

Yesterday, waiting for a train at Cam & Dursley I saw the shortest goods train in the world. Two class 68's and one nuclear flask wagon, enough power to accelerate into orbit. Wikipedia says that two locomotives are used for redundancy reasons.

What failure modes does this redundancy cover? Or, putting it the other way, what failure modes does it not cover?

Any fault on the flask wagon itself, I suppose!

 

[sleepy_hollow]

Any fault on the flask wagon itself, I suppose!

Except presumably the brakes or wheelsets seizing, and presumably similar for a locomotive, whereas I assume any fault upstream of the traction motors, for example diesel engine failure, would still allow a train to be moved by the other locomotive. I suppose even for a locomotive welded to the rails having a rescue loco already in the same county could allow the flask to be moved somewhere fairly soon.

 

[skyhigh]

I suppose even for a locomotive welded to the rails having a rescue loco already in the same county could allow the flask to be moved somewhere fairly soon.

Alternatively having a second one on the same train would be even better....

 

[sleepy_hollow]

Alternatively having a second one on the same train would be even better....

That was what I meant by "in the same county", but in fact it could be better if it was not on the train but somewhere where it was easier to reach the other end of the train. In fact yesterday's train had both locos on one end, which presumably means that if the rear loco becomes immobile the front loco might have to run around the county to get to the other end. If the train had been topped and tailed wrong line working might allow the flask to be moved away sooner.

 

[DarloRich]

In fact yesterday's train had both locos on one end, which presumably means that if the rear loco becomes immobile the front loco might have to run around the county to get to the other end. If the train had been topped and tailed wrong line working might allow the flask to be moved away sooner.

if the flask train becomes immobile I suspect the signallers will give priority to getting it moving!

 

[Deepgreen]

I've always found this odd. The waste matter is very low grade and therefore of almost no interest to terrorists, and the flasks themselves are strong enough to withstand massive impacts, so why is it felt so imperative that they be kept on the move no matter what (and what happens if one gets caught up in a line closure and is forced to come to a stand for who knows how long?).

 

[brad465]

I wonder if reversal needs play a part in two locos being used: two locations that come to mind are Dungeness and Bridgwater. At Dungeness, while there appears to be a loop, the crane is beyond it, and the loop is very short (even if the trains are also), so maybe top and tailing is needed there. At Bridgwater the sidings for Hinkley Point trains require a reversing manoeuvre on/off the mainline in at least the northbound direction, and while freight can do reversals with only 1 loco, maybe there is protocol at Bridgwater for a loco needed to see where the move is going (it is a 100mph line if that influences things)?

 

[Class15]

I wonder if reversal needs play a part in two locos being used: two locations that come to mind are Dungeness and Bridgwater. At Dungeness, while there appears to be a loop, the crane is beyond it, and the loop is very short (even if the trains are also), so maybe top and tailing is needed there. At Bridgwater the sidings for Hinkley Point trains require a reversing manoeuvre on/off the mainline in at least the northbound direction, and while freight can do reversals with only 1 loco, maybe there is protocol at Bridgwater for a loco needed to see where the move is going (it is a 100mph line if that influences things)?

But the locos are usually on the same end…

 

[Peter Mugridge]

I've always found this odd. The waste matter is very low grade and therefore of almost no interest to terrorists, and the flasks themselves are strong enough to withstand massive impacts, so why is it felt so imperative that they be kept on the move no matter what (and what happens if one gets caught up in a line closure and is forced to come to a stand for who knows how long?).

For the first part - fear of bad headlines and adverse public image? Most people wouldn't know it's very low grade matter in them.

For the second part - likely nothing unless the press try to make something out of it?

 

[HSTEd]

I've always found this odd. The waste matter is very low grade and therefore of almost no interest to terrorists, and the flasks themselves are strong enough to withstand massive impacts, so why is it felt so imperative that they be kept on the move no matter what (and what happens if one gets caught up in a line closure and is forced to come to a stand for who knows how long?).

The traditional flask operation is of flasks full of spent fuel, which is definitely not "very low grade". Perhaps it is for making a nuclear fission weapon but that is hardly of interest to a terrorist organisation.

Direct contact with that material will result in a fatal dose in seconds, its amazing material for a "dirty bomb" which is a far more reasonable terrorist device.