Decay-in-storage planning
Sizing decay storage is the first practical waste decision. Programs that size to the 9.9-day Ac-225 parent half-life alone will run out of capacity within the first quarter. Plan against the full decay chain hold time, peak weekly volume, and ramp trajectory — not the launch month's average.
Sizing the room
Capacity calculation
Estimate weekly waste volume by dose count and stream, then multiply by your chain-driven hold time (see Hold-time calculation). Add headroom for an audit cycle or two. Running at 100% capacity leaves no margin for inventory growth or a missed release survey.
Segregation by stream and activity
Separate sharps, soft waste, and liquids. Separate by approximate activity at point of generation — do not mix high-activity dose-draw waste with low-activity post-administration consumables. Mixed streams default to the longest hold time and largest waste class.
Labeling and inventory
Every container labeled with isotope, date generated, expected release date, and responsible AU. Inventory log updated at generation, not at release — late entries break the audit trail.
Access & ventilation
Restricted-access room per 10 CFR §20.1902 posting requirements. Continuous ventilation, ideally negatively pressured relative to surrounding spaces. Spill kit and alpha-capable survey instrument staged at the door.
Design decisions to lock in early
Get right at design
Room sized for 2–3× steady-state, not launch month. FIFO staging with date-visible labeling. Survey station inside the room, not down the hall. Drainage plan if liquid streams are anticipated.
Costly to retrofit later
Adding ventilation or negative pressure post-build. Re-segregating mixed streams already in storage. Reclassifying inventory after a manifest template change. Moving the decay room mid-program.
Storage capacity is often the rate-limiting factor when ramping a new targeted alpha therapy program. It can help to start the facilities conversation with chain hold time and peak weekly volume rather than square footage.
- 10 CFR §35.92 — Decay-in-storage.
- 10 CFR §20.1902 — Posting requirements.