How to randomly place signal portions to a time series in python?

I have 100 signal portions, which I want to sum them randomly to a time series which is a white noise. i want to finally create a 24 hours time series which these 100 portions is randomly distributed over it. I create white noise for 24 hours as below:

dt=1/100
nt = 86400 / dt   
t=np.arange(dt,nt*dt,dt)
noise= np.random.randn(len(t))

each signal portion is 12 seconds. I do not know how to distribute these 100 portions randomly in created white noise. Also I need to know the exact second which each 100 portion is added to the noise.