Two Texas sites reported radioactive sources that failed, one stuck open and one leaking

A Covestro LLC chemical plant in Baytown, Texas, discovered on September 17 that a radiation gauge’s shutter had jammed open, exposing a 100-millicurie Cesium-137 source it was supposed to keep shielded. The same day, roughly 200 miles away at Fort Sam Houston in San Antonio, a laboratory instrument belonging to the Defense Health Agency tested positive for contamination from a leaking Nickel-63 source. Both failures reached the Nuclear Regulatory Commission within a day of each other, logged as separate entries in the agency’s September 25 event notification report.

Neither company nor agency has reported any exposure to workers or the public. The two events involve different isotopes, different equipment, and different regulatory chains, but they landed in the same federal document because both, for a few days at least, put sealed radioactive material somewhere it was not supposed to be.

A Cesium-137 gauge stuck open at a Baytown chemical plant

The Baytown device was a Texas Nuclear model 5205 gauge containing a 100 millicurie Cesium-137 sealed source, the kind of fixed industrial instrument that measures material levels or density by beaming gamma radiation through a pipe or vessel wall. The gauge was discovered with the source shutter stuck in the open position, meaning the mechanism meant to block the radiation beam when the gauge is not in active use had failed to close.

Covestro told regulators that “there is no risk of additional radiation exposure to members of the public or radiation workers” from the stuck shutter, and the company said it had already contacted a service provider to repair the mechanism. Cesium-137 is a byproduct of nuclear fission commonly used in exactly this kind of industrial gauge, according to the CDC’s fact sheet on the isotope, which notes it also shows up in medical radiation therapy and thickness-measurement devices for materials like paper and metal, and that the general public already carries trace, harmless amounts of Cs-137 in the body from decades-old weapons testing fallout.

A stuck shutter on a fixed gauge is a containment and shielding problem, not automatically an exposure event. The shutter’s job is to physically block the gamma beam whenever the gauge is not actively taking a measurement, so a mechanism jammed open means the source keeps emitting in that direction continuously rather than only during a reading. That is a maintenance failure with a defined fix, which is why the report describes a repair order and a waiting service technician rather than an evacuation or a public health advisory.

A leaking Nickel-63 source inside a gas chromatograph in San Antonio

At Fort Sam Houston, the source in question was a 13.6 millicurie Nickel-63 sealed source built into an Agilent Technologies model 7890A gas chromatograph, a laboratory instrument that uses low-level radiation from the sealed source to help detect trace chemical compounds as they pass through the machine. Routine wipe testing, the standard swab-and-count procedure licensees use to check for contamination on a sealed source’s surface, came back positive on September 17.

The Defense Health Agency’s radiation safety officer was still awaiting formal leak-test results when the report reached the NRC, and the notification states plainly that “there were no reported exposures.” A positive wipe does not by itself confirm how much material has escaped or where it went; it confirms only that some measurable contamination was present on the wipe, which is why the full leak-test results remained the open question at the time of filing.

Two failures, two different regulators, one shared federal filing

Texas is one of dozens of states that regulate most radioactive material use directly, under what the NRC calls Agreement State status. The Texas Department of State Health Services holds primary regulatory authority over licensees like Covestro under that arrangement, with the NRC’s Region IV office in Arlington reviewing the state program’s performance rather than issuing the day-to-day licenses itself. The Fort Sam Houston chromatograph, by contrast, belongs to a federal defense agency, which is why its event still routed to the NRC’s own notification system even though DSHS’s Radiation Control Program licenses most other radioactive material users across the state.

Both events entered the same document anyway, because the NRC’s event notification reports compile licensee-reported incidents from across the country into a single running index regardless of which regulator normally oversees a given facility. A stuck gauge shutter in a chemical plant and a leaking gas chromatograph in a military hospital complex have almost nothing in common mechanically. They ended up on the same page because both organizations judged the failures serious enough to report the same week, within a few hundred miles of each other, without waiting to see whether the pending test results would make the picture better or worse.

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