Huge concentrations of + singular or plural noun?

I'm reading George Orwell's You and the Atomic Bomb, and I'm wondering why he says 'huge concentrations of industrial plant'. I expected 'industrial plants'.

Here's the sentence:

The one thing that might reverse it is the discovery of a weapon — or, to put it more broadly, of a method of fighting — not dependent on huge concentrations of industrial plant.

Thanks!

Solution 1:

From Lexico:

plant

[mass noun]

Machinery used in an industrial or manufacturing process.

‘inadequate investment in new plant’

He's not referring to the place or facility where production takes place but the machinery.

huge concentrations of industrial machinery