[1.42] Unexpected exception

2011-12-21 23:15:36 [SEVERE] Unexpected exception
java.lang.NullPointerException
at jb.a(SourceFile:181)
at ic2.common.TileEntityNuclearReactor.generateEnergy(TileEntityNuclearReactor.java:614)
at ic2.common.TileEntityNuclearReactor.processChamber(TileEntityNuclearReactor.java:488)
at ic2.common.TileEntityNuclearReactor.processChambers(TileEntityNuclearReactor.java:419)
at ic2.common.TileEntityNuclearReactor.l_(TileEntityNuclearReactor.java:131)
at fi.f(World.java:1204)
at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:446)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:353)
at cu.run(SourceFile:457)

This bug is probably caused by nuclearpowers getting low on thier uranium cell.