The forum discussion centers on the MCNP error message "the new source has overrun the old source," which occurs when the user sets 5000 source histories per cycle on the KCODE card. The error consistently appears at source particle number 5688 during the first inactive cycle. Reducing the source histories to 1000 resolves the issue, indicating a potential misconfiguration in the input file. A solution provided suggests adjusting the fifth entry in the KCODE card to a value of 10000 or 15000 to accommodate the number of particles.
PREREQUISITESBeginners in MCNP, simulation analysts, and researchers working with Monte Carlo methods who are troubleshooting source history configurations and error messages.
dear, you just put a fifth entry in kcode. if your number of particles is 5000, then put 5000*2 = 10000 or 15000 as fifth entry in your kcode. then see how it works...gsyou said:And the error is really tricky. When I set 5000 source histories per cycle on KCODE card, the error appeared every time at source particle no. 5688, and only one inactive cycle has run. But when I set 1000 source histories per cycle, the error disappeared, and MCNP seems run well. This really makes me confused. Does it imply any error in my input file?