Rocky Flats Plant, Source Calibration Laboratory
HAER No. CO-83-AE
(Rocky Flats Plant, Building 126)
Rocky Flats Environmental Technology Site, Highway 93, Golden, Jefferson County, Colorado. Building 126 is
located between Second and Third streets (to the west and east) and between Central and
Cedar avenues (to the north and south).
This building is a secondary contributor to the Rocky Flats
Plant historic district. It is associated with the U.S. strategy of
nuclear military deterrence during the Cold War, a strategy considered of major importance
in preventing Soviet nuclear attack. Building 126 was part of the radiation protection
program and used to calibrate dosimeters worn by employees to measure radiation exposure.
Building 126 was constructed during the transition period from film dosimeters to
The Source Calibration Laboratory (Building 126) is a small,
flat-roofed, rectangular building, measuring 28 feet north-south by 16 feet east-west (448
square feet). The building is divided into two rooms with a common hallway on the south
side (at the entrance). The structure is built on a concrete slab-on-grade and is one
story high. Ceiling heights are approximately 12 feet. The roof is flat and is constructed
of 24-gauge rock deck. Exterior walls are constructed of 12-foot-thick concrete. Interior
design elements include a series of seven small-diameter neutron source storage wells
along the east wall. Three small-diameter neutron source storage units are located along
the north side of the interior-shielding wall (in the east room).
The structure contains no windows, except for a small window in the metal door, located
on the south side of the building. Site utilities include a heating, ventilation, and air conditioning system located on
the roof. Various vents and utility boxes exist on the top of the roof.
Building 126 was part of the radiation protection
program. Other buildings within this complex include Building 123, the Health Physics/Analytical
Laboratory; and Building 125, the Standards Laboratory. In the past, this facility was used to
expose and calibrate radiation detection devices worn by employees to detect radiation
exposure. This building, constructed during the transition period from film dosimeters to
thermoluminescent dosimeters, was used to calibrate both types of dosimeters. Film dosimeters were calibrated by exposing the film within the dosimeter to gamma and
neutron radiation, which darkened the film. Employee exposure was calculated by comparing
the amount of darkening between the calibrated dosimeter and that worn by the employee.
Thermoluminescent dosimeters were calibrated by exposing the crystal within the
dosimeter to gamma and neutron radiation. The exposed crystal was then heated to release
stored energy in the form of light. The amount of light emitted was then measured.
Employee exposure was calculated by comparing the amount of light emitted between the
calibrated dosimeter and that worn by the employee. At the present time, the building is inactive although sealed radioactive sources are
stored in the facility.
Building 126 was constructed between 1968 and 1969.
Falk, Roger, employed at the plant since 1966 by the site
contractor. Personal communication,
United States Department of Energy. Historical Release Report (HRR) (1994), by
EG&G. Rocky Flats Plant Repository. Golden, Colorado, 1994.
United States Department of Energy. Final Cultural Resources Survey Report (1995), by Science Applications International Corporation. Rocky Flats Repository. Golden,
D. Jayne Aaron, Environmental Designer, engineering-environmental
Management, Inc. (e²M), 1997. Judith Berryman, Ph.D., Archaeologist, e²M, 1997.
Index to Photographs
Located between Second and Third streets and Central and Cedar avenues, Golden Vicinity, Jefferson County, Colorado.
Photograph CO-83-AE-1 taken by Timothy McGrath and Katherine T. Abeya, Source One, site
CO-83-AE-1 – View of Building 126, looking north. Building 126, the Source Calibration Laboratory, was used to expose and calibrate radiation detection devices, including thermoluminescent dosimeters, worn by employees to measure radiation exposure.