The same happens to me whenever I just place a regular uranium cell in a reactor.
Minecraft has crashed!
----------------------
Minecraft has stopped running because it encountered a problem; Exception in server tick loop
This error has been saved to D:\Users\Craftme2theMax\Desktop\Minecraft\MultiMC\instances\1.3.2 Mod Testing\.minecraft\crash-reports\crash-2012-09-16_13.59.41-server.txt for your convenience. Please include a copy of this file if you report this crash to anyone.
--- BEGIN ERROR REPORT e3d50331 --------
Generated 9/16/12 1:59 PM
- Minecraft Version: 1.3.2
- Operating System: Windows 7 (amd64) version 6.1
- Java Version: 1.7.0_08-ea, Oracle Corporation
- Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
- Memory: 577519224 bytes (550 MB) / 1087832064 bytes (1037 MB) up to 1908932608 bytes (1820 MB)
- JVM Flags: 2 total; -Xmx2048m -Xms1024m
- FML: FML v3.1.1.368 Minecraft Forge 4.1.2.261 Optifine OptiFine_1.3.2_HD_U_B3 21 mods loaded, 21 mods active
FML [Forge Mod Loader] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
Forge [Minecraft Forge] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
mod_CodeChickenCore [CodeChicken Core] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
mod_NotEnoughItems [Not Enough Items] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
Mystcraft [Mystcraft] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
BuildCraft|Core [BuildCraft] (buildcraft-A-3.2.0pre7.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
BuildCraft|Builders [BC Builders] (buildcraft-A-3.2.0pre7.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
BuildCraft|Energy [BC Energy] (buildcraft-A-3.2.0pre7.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
BuildCraft|Factory [BC Factory] (buildcraft-A-3.2.0pre7.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
BuildCraft|Transport [BC Transport] (buildcraft-A-3.2.0pre7.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
BuildCraft|Silicon [BC Silicon] (buildcraft-A-3.2.0pre7.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
ExtraBees [Extra Bees] (extrabees-1.4.0.16-dev-build.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
FarmCraftory [FarmCraftory 2.0] (FarmCraftory2.0.3_MC1.3.2.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
Forestry [Forestry for Minecraft] (forestry-A-1.5.0.1.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
IC2 [IndustrialCraft 2] (industrialcraft-2_1.106.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
mod_InvTweaks [Inventory Tweaks] (InvTweaks-1.43b-1.3.2.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
IronChest [Iron Chest] (IronChests2-universal-3.7.11.34.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
LogisticsPipes|Main [Logistics Pipes] (LogisticsPipes-0.5.1.pre6.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
mod_PluginsforForestry [Plugins for Forestry] (PluginsForForestry_Dev-MC1.3.2_Mod1.3.28.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
Railcraft [Railcraft] (Railcraft_6.1.1.0.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
silentspy_usefulfood [UsefulFood] (usefulfood_v1.1.0-universal.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
- Is Modded: Definitely; 'forge,fml'
- Profiler Position: N/A (disabled)
- Player Count: 1 / 8; [gu['Craftme2theMax'/522, l='Industrial Revolution', x=299.07, y=73.00, z=-273.62]]
- World Industrial Revolution Entities: 502 total; [nj['item.tile.sapling.oak'/1, l='Industrial Revolution', x=12.18, y=77.13, z=54.66], nj['item.tile.sapling.oak'/2,
- World Industrial Revolution Players: 1 total; [gu['Craftme2theMax'/522, l='Industrial Revolution', x=299.07, y=73.00, z=-273.62]]
- World Industrial Revolution Chunk Stats: ServerChunkCache: 1110 Drop: 0
- Type: Integrated Server
java.lang.NoSuchMethodError: ic2.api.IReactor.produceEnergy()Z
at ic2.common.ItemReactorUranium.processChamber(ItemReactorUranium.java:43)
at ic2.common.TileEntityNuclearReactor.processChambers(TileEntityNuclearReactor.java:345)
at ic2.common.TileEntityNuclearReactor.g(TileEntityNuclearReactor.java:135)
at up.h(World.java:1814)
at gr.h(WorldServer.java:433)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:644)
at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:575)
at axv.p(IntegratedServer.java:105)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:481)
at ep.run(SourceFile:539)
--- END ERROR REPORT 2ff1d8e2 ----------
EDIT:Thanks, Exinferis. Extra Bees did cause it.