A worker at the Savannah River National Laboratory was restricted from radiological work for the rest of 2019 after receiving a dose of radiation somewhere off site that put him well above a key exposure threshold at the Aiken, S.C. site, a spokesperson for site contractor Savannah River Nuclear Solutions said Wednesday.
The employee took the dose some time before July 19, when the independent federal Defense Nuclear Facilities Safety Board (DNFSB) reported the exposure. Congress created the DNFSB to protect the public from possible hazards at DOE nuclear weapon sites. Savannah River Nuclear Solutions (SRNS) did not quantify the dose the researcher received, or specify the type of radiation to which he was exposed.
The Fluor-led contractor did acknowledge, as a DNFSB site inspector wrote in a weekly report, that the dose put the employee well above the site’s administrative control limit of 500 millirem: the level that triggers a response by SRNS. The contractor discovered the dose during a routine quarterly scan of the employee’s thermoluminescent dosimeter: a wearable radiation monitor.
DNFSB said the researcher got a “high energy gamma ray” dose that was both “much greater than what he would be expected to receive from his work and offsite activities” and “inconsistent with an extensive list of potential accidental exposure scenarios.”
“SRNS has conducted an extensive investigation regarding the dose recorded on a SRNL Researcher’s Thermoluminescent Dosimeter (TLD),” a company spokesperson wrote Wednesday in an email. “Based on extensive evaluation of the worker’s job location and radiological surveys and dosimetry results of coworkers, SRNS is confident that the SRNL Researcher did not receive an occupational dose at the Savannah River Site but will assign the dose to the employee.”
A spokesperson for the DNFSB declined to elaborate on the board’s July 19 report. The board spokesperson said DNFSB “has not specifically sent correspondence to DOE” about the incident.
Under agency regulations, the maximum annual dose limit for federal and contract workers at DOE sites is 5 rem: many times the administrative threshold that prompted SRNL to restrict the dosed research from further radiological work this year.
