Two glow-in-the-dark exit signs holding 15 curies of tritium went missing from a Boulder body shop

Caliber Collision in Boulder, Colorado, lost two tritium exit signs that together held 15 curies of the radioactive gas, each sign carrying 7.5 curies. The Colorado Department of Health reported the loss to the U.S. Nuclear Regulatory Commission, which logged it as Event Number 58488 on October 9, 2026, six days after the signs were determined to be missing.

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Exit signs like these glow without wiring or batteries, because the light comes from the tritium itself. The report does not say where the Boulder signs went, and the notice is the only public record of the loss.

What Event 58488 records

The NRC event notification lists the licensee as Caliber Collision at a Boulder location, the reporting organization as the Colorado Department of Health, and the event date as October 3, 2026. Its text states that two exit signs, each containing 7.5 curies of tritium for 15 curies in total, were determined to be lost by the licensee. The signs are Isolite Corporation model SLX60, and Colorado filed the matter under its own report identifier, CO260024. The event was classed as non-emergency, the state licence number is GL002508, and the NRC received the call at 5:15 p.m. Eastern time on October 9 from staff member Kathryn Kirk, with Kerby Scales as the headquarters operations officer.

Colorado is an Agreement State, meaning it regulates this kind of radioactive material in place of the federal agency under an agreement between the governor and the NRC chairman, as the NRC’s Agreement States page explains. That is why the first report came from a state health department. The NRC still publishes the event in its daily listing so that headquarters, and the public through the NRC’s index of event notification reports, can see it.

Tritium gas sealed inside a glowing tube

According to the NRC backgrounder on tritium exit signs, the signs contain tritium gas sealed in glass tubes lined with a light-emitting compound. The tritium emits low-energy beta radiation that makes the lining glow, so no electricity is needed. The agency says the signs pose little or no threat to public health, safety or security, because the beta radiation cannot pass through paper or clothing and inhaled tritium leaves the body relatively quickly.

The Colorado report classifies the material as “Less than Cat 3.” Per the report’s own explanation, sources in that band are very unlikely to cause permanent injury, though unshielded material that is not securely managed could possibly cause temporary injury to someone in close contact with it for many weeks. The NRC’s own wording is more reassuring for sealed signs, and the hazard the report describes depends on material being unshielded and unmanaged, which is why a missing pair is tracked even when the public risk is small.

The 15-curie total comes from two identical signs, and the report makes no claim that either was damaged. Because the notice records only that the licensee determined them lost, the open questions are practical ones that the event text does not answer: whether the signs left the building with a fixture, whether they were discarded, and whether anyone has been told to look for them.

The timeline is short. The event date is October 3, the Colorado notification reached the NRC on October 9, and the entry was current in the NRC’s daily report as of October 19. Nothing in the record indicates a recovery or an update to the original text, so the status of the two Isolite signs remains lost as far as the public record shows.

The rules that make a lost sign reportable

Facilities that use these signs are general licensees in the NRC’s terms. Under the backgrounder, they must not remove the labels or the radiation symbol, must not abandon a sign, and must not throw one in ordinary trash. A sign that is no longer wanted goes to a specifically licensed recipient such as a manufacturer, distributor or licensed waste broker, and any lost, stolen or broken sign must be reported to the NRC or the relevant Agreement State. A sign may not be sold or given away unless it stays in use at its original location, and a disposal or transfer has to be reported within 30 days.

The federal rule behind that sits in 10 CFR 31.5. Paragraph (c)(6) says a licensee “shall not abandon the device,” paragraph (c)(8) limits disposal to authorised routes such as transfer to a specific licensee, and paragraph (c)(10) requires compliance with the NRC’s rules for reporting theft or loss of licensed material. Whether the Boulder signs were thrown out during a renovation, removed with a fixture or mislaid is not stated, and the licensee’s explanation does not appear in the event text.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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