1/2 watt 150KOhm will drop the residual voltage to about 15% of 240 in 30 seconds. That's two RC time constants of 150kOhm x 94uF. That gives us a peak of about 240*1.4 * 0.15 (50 volts) after 28 or so seconds, assuming the caps were charged just before the peak of the 240 volt cycle.
since power is (I^2)/R, we get 240 * 240 or 57600/150000 which is 0.384 watts.
You may need to adjust these for variations in line voltage and capacitor tolerance. The 30 seconds to a "safe" voltage I made is arbitrary. 30 seconds seems like a safe amount of time to shut of a project, unplug it and start playing with the insides.
Just for fun, utility company power factor caps are designed to discharge to 50 volts or less after 5 minutes of disconnect.