ExplosiveForce Strange effects.

Hello i am attempting to make a rather realistic-ish explosion with a blast wave, I got it working but i am having some strange effects such as…

The force of the blast seem to be stronger when there are more rigid-body objects around
But if it blows up with just 1 object it has little effect.

It is like its drawing energy from the surrounding objects to output a bigger blastwave.

Any ideas? here is my code.
I have been doing tests in a 0 gravity space like environment. Thanks.
Here is a web demo, Hopefully it will explain a little better

Webplayer

    var expandRate = 10.0;
	var radius = 0.0;
    var power = 500.0;
    var losePower = 250.0;
	
	function Update () {
		radius += expandRate * Time.deltaTime;
		collider.radius = radius;
		power -= losePower*Time.deltaTime;
	}
	
     function OnTriggerEnter (other : Collider) {
         var explosionPos : Vector3 = transform.position;
         var colliders : Collider[] = Physics.OverlapSphere (explosionPos, radius);
         
         for (var hit : Collider in colliders) {
             if (!hit)
                 continue;
             
             if (hit.rigidbody && other.tag != "Bullet")
                 hit.rigidbody.AddExplosionForce(power, explosionPos, radius, 3.0);
         }
     }

The problem is that you will deliver one application of force for every OnTriggerEnter(). The more objects, the more times OnTriggerEnter() is called. And your Update() function is also strange. It means the more time has passed since this object is created, the greater the range and the less the force. I’m not sure why you want this.

My suggestion is to get rid of the Update() code, and have the OnTriggerEnter() code either disable the script or destroy the object the script is attached to after it applies the explosive force once.