Well, since you're using an ICE CASUC, I would just switch to the RP tubes. No spillage and you just set a Transposer or Filter to stuff the tube with as much ice as you can per .2 seconds (on the RP timer). Should keep you're reactor SO supplied with ice you can potentially run OUT of ice and have to deal with increasing your production! I almost never see any leakage from RP tubes. If you stick too much in one, it just backstuffs the sending Trans/Filter, which is no big deal, since it'll just clear out when the Reactor has room for more ice.
I have been experimenting with the RP2-PR4 machines, and I must agree with the previous poster, it's going to become MUCH easier to set up CASUC designs. Unlike the last poster, I don't think this is a BAD thing at all! It feels MUCH more 'Reactor' like. I never did like the 'One Box to Power Them ALL' style reactors and making them work better with BC/RP pipes/tubes only brings the more complicated (and dangerous) designs into the realm of the conceivable for the rest of us!
What i am saying is that RP2's tubes are free to use. Whereas Buildcraft, unless you use redstone engines, cost resources to operate. And the Retriever (in my eyes) is a one does it all machine that is using no resources to operate. (I don't consider solar panels from RP2 to be a resource consuming process either)
As for leakage in BC pipes, there are many ways to stop leakage. There is even the great addon "additional pipes" that lets you have advanced insertion pipes to reduce the leakage.
Though you can't use the advanced insertion pipe on a 5 chamber, bucket cooled reactor, you instead need the advanced extraction pipe (configured to pull empty buckets) so there is going to be leakage at the reactor.
For any leaks we have the obsidian pipe, which can be powered by Buildcraft energy to suck leaked items in from up to 5 blocks away.
The problem with just BC and Additional Pipes is the flow rate. And without RP2 you need a good way to fill buckets (if you are doing a bucket CASUC) and for that we have a very good bucket filler addon for BC.
Another problem with just BC and those two mods is retrieving empty buckets from the reactor core at the rate we need them to be extracted. For that i am using power crystals power conversion addon since it's energy link is capable of sending Buildcraft energy once per tick. Thus allowing a flow rate of 20 buckets per second using a single wooden transport pipe.
The thing with Buildcraft though is that it's wooden pipes is very lossy, you can feed them up to 256 Buildcraft energy and they will consume it all! Since our smallest voltage in IC (after an energy storage) is 32 EU we need to be clever to split that power down into 1 EU packets. You do this by using cable intersections (8 of them makes the remaining power reach 1 EU) and this power is sent to the energy link to act on the wooden pipe. So you are extracting up to 20 items from a chest per second using 1 EU per item.
Either way, point is that i have designed a reactor that can reach 1740 EU/t using buckets as a cooling system. I don't need to use RP2 and i am consuming 14 EU/t for the bucket delivery system. I could make it using RP2 PR4 using retrievers and save myself that 14 EU/t but IMHO, any mechanical work should cost something. RP2's mechanical work is FREE in all intents and purposes.
As for an ICE CASUC, you don't need to worry about leakage at the reactor since you can just use the advanced insertion pipe and make a feedback loop at the reactor. And if the rate of ice arriving at the reactor is a problem then either use the energy linker from the addon i suggested or use a combustion engine since that will pull one ice stack every .625 seconds. Doubling the number of engines (and entrance pipes) obviously doubles the rate of delivery into the system.
For that one doesn't need to use RP2 either! And the delivery system has it's costs assigned to it. Thus you want to reduce said costs as much as you possibly can (which is part of the challenge, part of the fun) to give you an as high net gain as you possibly can.
As soon as Finite Liquid (water being finite, only replenished by rain) is updated to be forge compatible i am going to install it to make myself a CASUC. Not because finite liquid makes it easier to design a reactor or makes the net gain from such an reactor any higher... But because it makes it more challenging (and thus more fun) designing one.