Campus Alert Archive
MIT

4 Rem in One Quarter: The MIT Research Reactor Worker Dose That Triggered an NRC Inspection

MAhazmatadvisorymedium confidence
Confirmed Threat

Between July 1 and September 30, 2007, a nuclear reactor operator at the MIT Nuclear Reactor Laboratory accumulated approximately 4 rem of radiation dose -- more than 80 percent of the annual federal occupational limit of 5 rem in a single quarter. MIT voluntarily reported the anomalous reading to the NRC on October 17, 2007, triggering an inspection that resulted in two Severity Level IV violations and a $5,500 fine. No campus-wide alert was issued; the exposure did not endanger the general campus population.

Alerts
2
Response
—
Killed
0
Injured
0
Institution
Massachusetts Institute of Technology
Private R1 · MA
~11,500 studentsMIT Alert
Confirmed Timeline

Alert Sequence

2 messages in sequence

Some alert texts below are approximate reconstructions from news coverage, not confirmed verbatim transcripts. Reconstructed texts are shown in italic with a dashed border. Verified verbatim texts have a solid border and are marked accordingly.

INITIAL ALERTUnknown
Approximate reconstructionReconstructed from The Tech (MIT student newspaper) October 26, 2007 report on the NRC notification and inspection396 chars
MIT Nuclear Reactor Laboratory is reporting an abnormal radiation dosimetry result. A reactor operator's quarterly dosimeter reading for the period July 1 through September 30, 2007 was approximately 4 rem, which is above normal levels though below the annual NRC occupational limit of 5 rem. MIT is notifying the NRC as a precautionary measure and will fully cooperate with any follow-up review.

This text has been reconstructed from news coverage and may not reflect the exact original wording.

MIT reported the reading voluntarily to the NRC on October 17, 2007 -- the date falls within the quarterly reporting window, not the date of the exposure peak itself
A 4 rem reading in a single quarter was extraordinary: typical quarterly readings for NRL operators were 0.5 rem or less, making this result roughly 8 times above expected
The NRC annual occupational limit is 5 rem; the worker's single-quarter reading was 80% of that full-year limit
UPDATEWebsite
Approximate reconstructionReconstructed from Bellona Foundation December 2007 coverage of the NRC enforcement action against MIT476 chars
The NRC has completed its inspection of the MIT Nuclear Reactor Laboratory following the October dosimetry report. The inspection found two Severity Level IV violations of NRC requirements related to radiation protection program implementation. A civil penalty of $5,500 has been assessed. The NRC noted that MIT's response to the incident was prompt, comprehensive, and technically sophisticated. All other reactor operators had normal dosimetry readings for the same period.

This text has been reconstructed from news coverage and may not reflect the exact original wording.

Severity Level IV is the lowest tier in the NRC's enforcement scale -- reserved for violations of 'very low safety significance'; the exposure was below the federal annual limit
The $5,500 fine was consistent with NRC enforcement norms for Level IV violations at research reactor licensees
The NRC's characterization of MIT's response as 'technically sophisticated' was notable positive language appearing alongside an enforcement action
Context

Background

The MIT Nuclear Reactor Laboratory (NRL) operates the MIT Research Reactor (MITR), a 6-megawatt heavy-water-cooled and moderated research reactor in Building NW12 on the western edge of the MIT campus -- the second-largest university research reactor in the United States, second only to the University of Missouri's MURR. In the third quarter of 2007 (July through September), one of the NRL's licensed reactor operators accumulated a quarterly dosimeter reading of approximately 4 rem -- a result that was roughly eight times higher than the typical reading of 0.5 rem or less for the same period. While the dose was still below the NRC's annual occupational limit of 5 rem, the anomaly was significant enough that MIT voluntarily self-reported the finding to the NRC on October 17, 2007, rather than waiting for the mandatory quarterly report submission. The NRC subsequently conducted an inspection and cited MIT for two Severity Level IV violations -- the agency's lowest category, reserved for incidents of 'very low safety significance' -- related to deficiencies in the radiation protection program that allowed the dose to accumulate undetected until the quarterly dosimetry read. MIT was assessed a $5,500 civil penalty. The NRC noted that MIT's response was 'prompt, comprehensive, and technically sophisticated,' and that readings for all other operators were normal for the same period. The incident was first reported publicly by The Tech, MIT's student newspaper, on October 26, 2007. No campus-wide alert was issued because the exposure was an occupational matter confined to the NRL's licensed work area and posed no threat to the broader campus community. The MITR subsequently operated without further significant enforcement actions related to worker dose management.
Analysis

Key Findings

The 4 rem quarterly reading represented roughly 80% of the annual occupational dose limit in a single quarter, prompting MIT to voluntarily self-report to the NRC
No campus alert was issued -- the incident involved a licensed reactor worker's occupational dose and did not endanger the general campus population
NRC cited two Severity Level IV violations (lowest category) and levied a $5,500 fine; MIT's technical response was praised even as the penalty was applied
All other NRL operators had normal readings for the same period, suggesting the exposure was isolated to one individual's work activities
Outcome
NRC issued two Severity Level IV violations. MIT was assessed a $5,500 civil penalty. The worker suffered no documented ill consequences. MIT's response was described by the NRC as 'prompt, comprehensive, and technically sophisticated.'
Provenance

Sources

  1. Student Paper
    Abnormal Radiation Level Reported (The Tech, October 26, 2007)
    thetech.com
  2. Source
    MIT research reactor incident exposes worker, NRC says (Bellona Foundation, December 2007)
    bellona.org
  3. Official
    MIT Nuclear Reactor Laboratory -- Reactor Safety
    nrl.mit.edu
Tags
nuclear-reactorradiation-overexposureresearch-reactorNRC-violationoccupational-radiationMIT-NRLMITRprivate-r1radiological
Added June 2026Updated June 2026Via ingestion