Rounds & format
IRCHO consists of two rounds: a free, open screening and a fully online Final under webcam supervision, with a US$10 entry fee. Top performers receive cash prizes and physical certificates signed by our Scientific Advisor.
Round 1 — Open Screening (free)
Window: 1 month · Format: PDF submission · Fee: free
Round 1 opens for one full month. You work on the problems independently, at your own pace, and upload a single PDF before the deadline — there is no fixed “exam slot”. Expect around 6–10 hours of focused work to complete all three parts.
- Part A — Multiple choice (10 questions): types of radioactive decay (α, β, γ), nuclear reactions and Q-values, units (Bq, Gy, Sv), equilibria and radiochemical dating.
- Part B — Three extended problems: decay-chain calculations, activity / half-life problems, nuclear equation balancing and dosimetry scenarios.
- Part C — Three real experimental data tasks: participants analyse decay curves and a gamma-ray detector spectrum, as in environmental monitoring and nuclear medicine. This part is unique to IRCHO.
Round 2 — Final (US$10 entry fee)
Access: top scorers from Round 1 · Length: 120 min · Monitoring: webcam · Fee: US$10
Qualifiers receive an invitation by email confirming their place in the Final. On the scheduled day, you join a single live online session under webcam supervision and solve the Final problem set. There is no entry fee.
- Live session — Final problem set (120 min). Advanced problems plus a data-interpretation task on a real radiochemical measurement (γ-spectrum, decay curve, or yield analysis).
- Webcam supervision throughout. Quiet room, single screen, no third parties present.
Awards: top-performing finalists receive prizes recognised by IRCHO. Finalists placing in the top 30% by Final-round score receive a physical certificate signed by our Scientific Advisor, mailed worldwide. All finalists receive a certificate of participation.
Edition I · 2026 — schedule
All times are UTC. Session times for the Final are confirmed in the invitation email.
- R1 Round 1 opens — registration & problems
- R1 Round 1 submission deadline
- R1 Round 1 results announced
- R2 Round 2 registration window
- R2 Round 2 — Final
- R2 Final results & awards announcement
- ✉ Physical certificates dispatched worldwide
Schedule is subject to minor changes. Registered participants are notified by email before any update takes effect.
The first step is free.
Round 1 is open to all students worldwide. No selection required.