A Decade of REMS
This is a 10-year summary of data collected by DOE’s Radiation Exposure Monitoring System (REMS). Data were analyzed over a ten-year period from CY 2010 – 2019. During this time period, more than 884,000 annual monitoring records representing over 222,000 unique individuals from 42 sites were monitored. Of those individuals, over 50,000 individuals (22 percent) received measurable radiation dose.
The goal of this summary is to provide a broad description of occupational radiation exposure data collected across the DOE Complex over the past 10 years through the use of interactive graphics, and to offer explanations for trends seen in these data. The information that follows is divided into different areas that help illustrate the complex nature of the DOE mission and the relationship to occupational radiation dose.
Certain key indicators are useful when evaluating occupational radiation exposures received at DOE facilities. The key indicators are analyzed to identify and correlate parameters having an impact on radiation dose at DOE.Definitions
The Total Effective Dose (TED) is comprised of external and internal dose. The penetrating (deep) photon dose represents the majority of the TED.
The Committed Effective Dose (CED) has generally fluctuated over the last 10 years (with a notable exception for CY 2010) and is 46 percent lower than in CY 2010.
Average Measurable TED
Average measurable TED has been at a consistent level within the DOE over the past 10 years.
Doses In Excess of Limits
There was one dose limit exceedance over the 10 year period. This exceedance was the result of a puncture wound. There was an additional administrative control limit exceedance as the result of a puncture wound in 2018.
From CY 2010 to 2019, the collective internal dose fluctuated around the 10 year average of 58.6 rem. CED increased in CY 2010, primarily due to a substantial internal dose of 32 rem at SRS, which accounted for one-third of the collective internal dose that year. Internal dose decreased from CY 2011 to 2013. In CY 2014, the CED increased overall by 21 percent. This was caused by a 25 percent increase in CED at Y-12 due to an increase in work activities after the CY 2013 response to a government sequestration. Since CY 2017, CED has remained fairly stable, averaging 58 rem. The majority of all internal dose every year (greater than 90 percent) can be attributed to uranium enrichment at the Y-12 National Security Complex in Oak Ridge. CED was the smallest component of total dose (6.0-10.1 percent) throughout the 10-year period.
Deep dose (photon) was the largest component of collective TED (71.9-80.7 percent) from CY 2010 to 2019. The trend in deep dose mirrored that of total collective dose; deep dose increased in CY 2010, then decreased again from CY 2011 to 2013, with a slight increase in CY 2014. There was a 29 percent increase in deep dose from CY 2014 to 2015 due to waste management activities at the Idaho Site. Increases and decreases in the deep dose therefore, are the overall drivers in the increase and decrease in the collective TED. Deep dose has fluctuated in the past 10 years in accordance with increases and decreases in demolition and decontamination (D&D) activities, production work, and safety practices. A main reason of the decrease since CY 2006 has been the shutdown of facilities that had contributed significantly to the collective deep dose in the past. Deep dose increased in CY 2017, likely attributed to the resumption of programmatic activities at WIPP and LANL and increased radiological work at ORNL and SRS, but has remained fairly stable since. More details are found under the Historical Overview tab of this report.
Neutron dose fluctuated over the past 10 years in relation to activities at large plutonium processing facilities, primarily LANL, Hanford, and SRS. There was an upswing in the neutron component in CY 2010, attributable to ARRA-funded projects and some sites claim as a direct result of new reporting requirements from the amendment to 10 CFR 835. Neutron dose increased by 19 percent from CY 2018 to 2019. Neutron dose from CY 2010 to 2019 comprised 12-21 percent of total dose.
The collective internal dose has generally remained the same across the DOE Complex from CY 2010 to 2019, with the exception of CY 2010. The number of individuals with measurable CED increased in CY 2010, decreased through the end of CY 2015, and gradually increased each following year. There was a 5 percent increase in the number of individuals with measurable CED in CY 2019. Typically, over 90 percent of all internal doses are attributable to uranium operations at Y-12 in Oak Ridge.
Similarly, the collective Committed Effective Dose (CED) has generally fluctuated over the past 10 years with one notable exception. In CY 2010, a major incident at SRS caused a significant increase in CED. The collective Committed Effective Dose (CED) has remained within 23% of the 10-year average over the past 10 years with one notable exception. In CY 2010, an incident at SRS resulted in a significant intake and CED to one individual. (See Occurrence Report EM-SR—SRNS-CPWM-2010-0008.) The CED decreased by 26% from 59.6 person-rem in CY 2018 to 51.2 person-rem in CY 2019.
The 10-year average measurable CED across the Complex was 0.044 rem. The major event in CY 2010 was an outlier that resulted in an above-average value for that year. Internal doses ranged between 0.033 and 0.038 for the years CY 2011 through 2013, and increased to 0.045 for both CY 2014 and 2015. In CY 2016 and 2017, the internal dose continued to increase above the 10-year average to 0.050 and 0.051 respectively. However, in CY 2018, the average measurable CED decreased by 13.7 percent to 0.044 rem. In CY 2019, the average measurable CED decreased by 18.6 percent to 0.036 rem.
Average measurable TED is calculated by dividing the collective TED by the number of individuals with a measurable TED. It is considered to be a good measure of the dose accrued by workers at DOE. However, it should be noted that it does not paint an exact picture of dose distribution across the worker population. Overall, average measurable TED has been fairly consistent over the past 10 years within the DOE. An exception can be seen in CY 2010 and 2015. The CY 2010 increases correlates with a major incident and was largely attributable to an unusually high internal exposure (see Doses in Excess of Limits and Internal Dose sections of the Overview). The CY 2015 increase correlates with an overall increase in radioactive work at four of the five largest sites (i.e., increases at Idaho Site, Hanford, LANL, and SRS). The average measurable TED has been fairly stable around 0.058 rem since CY 2016.
The average measurable TED has decreased overall by over 26 percent from CY 2010 to 2019.
Two specific TED limits are considered as a measure of high individual doses. The RadCon Manual [Ref. 1] established a maximum 2 rem Administrative Control Levels, and 10 CFR 835 establishes a regulatory TED limit of 5 rem per year. There was 1 dose in excess of the TED regulatory limit (5 rem [50 mSv]) in the period CY 2010 – 2019; in CY 2010, a puncture wound involving Pu-238 at SRS led to the highest internal dose (CED) in the DOE Complex over the past 10 years (31.6 rem). No individual was reported to have exceeded the TED regulatory limit since this incident. In CY 2018, one individual was reported to have exceeded the 10 CFR 835.202 Total Organ Dose (TOD) limit of 50 rem; this individual also exceeded the 2 rem Administrative Control Level, but not the regulatory TED limit. This incident occurred when a worker's glovebox glove was punctured by a frayed wire cable.
 DOE-STD-1098-2017, "DOE Radiological Control Manual," U.S. Department of Energy, January 2017
Over the past 10 years (CY 2010 – 2019), there have been minor changes in reporting requirements and radiation dose limits. In fact, the current DOE dose limits were implemented in CY 1989. It is worth noting, however, that the regulation regarding radiation protection standards and program requirements (10 CFR 835) has been amended four times (CY 1998, 2007, 2011, and 2017). Recent requirements of 10 CFR 835 include the adoption of ICRP 60 neutron weighting factors and the revision of ICRP dose conversion factors. Some sites noted that these new recommendations caused a reported increase in neutron dose but the extent of the increase is not possible to determine from the data in REMS.
DOE Order (O) 231.1A, which outlined the annual reporting requirements for REMS, was issued in CY 2003 and replaced with DOE O 231.1B in CY 2011. DOE Manual (M) 231.1-1A, Environment, Safety, and Health Reporting Manual, was approved in CY 2004 but has since been replaced by the online REMS Reporting Guide in CY 2012.
DOE Order (O) 5480.11, Radiation Protection for Occupational Workers (CY 1988), and 10 CFR 835 require that each DOE facility have an ALARA (as low as reasonably achievable) program as part of its overall radiation protection program. According to the ALARA principle, resources spent to reduce dose need to be balanced against the risks avoided. This has been one of the fundamental pillars in radiation protection for DOE since the 1970’s. While some sites have reported that the use of ALARA has helped to reduce dose, it is not possible to measure the overall impact from ALARA improvement as there are many other confounding factors such as the closure of facilities, reductions in production, and D&D efforts.
Changes in Mission
The Department of Energy (DOE) was officially created in CY 1977 with the Department of Energy Organization Act. The mission of the Department was focused on two major areas: defense activities related to nuclear weapons production and testing, and the consolidation of energy-related programs. The mission of DOE began to change significantly in the late 1980’s as the focus became less oriented around weapons production. Several facilities that historically had produced weapons and related components were no longer in operation by the end of CY 2014.
ARRA Funded Sites
From CY 2006 to 2008, collective dose was steadily decreasing across the DOE complex largely due to diminishing production and remediation activities; however, in CY 2009, the American Recovery and Reinvestment Act (ARRA) was passed, and almost $38.3 billion was allotted to DOE for CY 2009 and CY 2010. Over $5 billion was used to support remediation efforts at several sites and created almost 8,000 jobs. The largest portion of funding went to Hanford, Idaho, Savannah River, and Oak Ridge. An increase in activities and personnel led directly to an increase in collective dose from CY 2009 to 2012. As ARRA funding decreased, so did projects, resulting in a decrease in dose after CY 2013. Over the last 10 years, collective TED has averaged 400 rem.
DOE has been in the process of remediating many sites, and several major ones were closed in the recent past including Fernald (CY 2004). Additionally, the gaseous diffusion plants at Portsmouth were placed in cold shutdown status in CY 2005. Cleanup was officially declared complete at Rocky Flats (CY 2005), and remediation began at Moab, UT (UMTRA) in CY 2008. Some decisions made in CY 2002 set the tone for the ten-year period of this report. DOE, EPA, and the State of Washington agreed to accelerate the cleanup at Hanford. In addition, operations at Idaho were transferred from the Office of Environmental Management to the Office of Nuclear Energy, although remediation still remained a priority. Environmental remediation continues at other large sites including Savannah River and Oak Ridge.
In addition to cleanup activities, DOE has also allocated more funds to non-nuclear research, including nanotechnology, renewable energy, and advanced materials. This shift in research priority has continued to lessen the radiation exposure that workers receive. ALARA continues to be a pillar of radiation worker protection in DOE, but the combination of safer work practices along with diminished weapons production, site closures, and shrinking environmental footprints for remediation have all contributed to an overall downward trend in dose for the past 10 years.
Collective TED has been decreasing for this group of sites since CY 2015. There was a 35 percent increase in collective TED from CY 2014 to 2015. This increase was primarily due to increased cleanup activities at SPRU. Collective TED in CY 2016 decreased by 8 percent as SPRU finished the removal of the more significant source term activity.
CY 2019 saw a 1 percent increase in collective TED from the previous year.
The five sites shown contribute the majority of the collective radiation dose at DOE. The examination of these sites and the changes in dose experienced at these sites is instructive due to the contribution of these sites to the overall DOE collective dose.
Los Alamos National Laboratory
The DOE Idaho Site, located at Idaho Falls, Idaho, consists of four facilities: Idaho National Laboratory (INL), the Advanced Mixed Waste Treatment Project (AMWTP), the Idaho Cleanup Project (ICP), and the DOE Idaho Operations Office. From CY 2010 to 2019, over 69,000 annual monitoring records were submitted. Total collective dose was generally low from CY 2012 to 2014, as well as from CY 2016 to 2019. The composition of dose at Idaho Site is consistent with most DOE sites, in that the greatest component of dose is deep dose.
Collective dose increased in CY 2010 and 2011 related to increased D&D activities under ARRA in CY 2010 and an incident in CY 2011, which led to internal exposure of 16 workers at the Materials and Fuels Complex Zero Power Physics Reactor (ZPPR) Facility. Dose decreased significantly in CY 2012, to a level comparable to CY 2003. This decrease was due to a shutdown of the Materials and Fuel Complex, continuing safety enhancements at AMWTP, and the completion of some high-dose jobs related to cleanup activities. In CY 2013 and 2015, dose increased due to increased Department of Homeland Security training exercises and accelerated waste processing operations to meet contractual obligations. In addition to the increased waste processing, the waste processed had a higher average exposure rate than processed waste in CY 2012. Collective dose in CY 2017 decreased by 15 percent from CY 2016 as the result of decreased decontamination activities, along with decreased level of radioactivity of the waste that was handled. In CY 2018, collective dose increased by 9% from CY 2017 as upgrade and maintenance activities were conducted. In CY 2019, overall collective dose decreased 12 percent to 76.5 rem, but the neutron dose component increased 188 percent from 1.6 rem in CY 2018 to 4.6 rem in CY 2019.
Hanford, located near Richland, Washington, consists of the Hanford Site, the Office of River Protection (ORP), and the Pacific Northwest National Laboratories (PNNL). From CY 2010 to 2019, over 96,000 annual monitoring records were submitted. While collective dose fluctuated over the ten-year period, the general trend was a 60 percent decrease in dose over the past 10 years.
Cleanout and removal of gloves boxes at the Plutonium finishing Plant (PFP) activities were funded by ARRA, and neutron dose steadily decreased from CY 2010 to 2012 as these glovebox activities decreased along with ARRA funds. Since CY 2012, neutron dose has continued to decrease. In CY 2018, neutron dose contributed to less than 3.1 percent of the collective TED, in comparison to CY 2012 when neutron dose comprised nearly 22 percent of the collective TED. Total collective dose increased until CY 2010 due to increased D&D activities related to ARRA-funded work; however, dose decreased again through CY 2012 due to a decrease in ARRA-related D&D activities. In CY 2013, dose decreased due to reductions in work regarding budgetary constraints. In CY 2014, the primary reasons for the decrease in collective TED was a change in the work scope at DOE-RL to include more work involving heavy equipment which increased the distance between workers and source terms and the implementation of long-length tools at DOE-ORP. Increases in CY 2015 were primarily related to work at the plutonium finishing plant facility, including the dismantlement of two large glove boxes in the process lines and the cleanout of the plutonium recovery facility canyon. Decreases in CY 2017 were associated with a transition in work activities from source term removal to facility demolition at the Plutonium Finishing Plant (PFP) facility and the continued operation of several projects at minimal level due to changes in funding. The collective dose has remained around 65 rem since CY 2017.
Los Alamos National Laboratory (LANL) is located 35 miles northwest of Santa Fe, New Mexico, includes more than 2,000 individual facilities and currently employs over 10,000 individuals. From CY 2010 to 2019, nearly 127,000 annual monitoring records were submitted. While there is no clear trend from CY 2010-2016, the total dose has been trending upwards since CY 2017. The composition of dose at LANL is unusual because the largest component is neutron dose, which accounted for 41.8 – 57.4 percent of total dose in the 10-year period. This is the only site out of the top five contributors that has this characteristic; this is explainable by the fact that LANL processes plutonium in gloveboxes, which can result in a neutron dose from the alpha/neutron reaction and from spontaneous fission of the plutonium.
Work with solid waste was curtailed early in CY 2014 due to the radioactive material release event at the Waste Isolation Pilot Plant and its relation to LANL waste packaging. (See Occurrence Report EM-CBFO-NWP-WIPP.) This caused a 31 percent decrease in collective TED in CY 2014. Starting in CY 2016, programmatic work resumed. This has resulted in increasing dose since the resumption of work. The majority of dose at LANL is attributable to increased operations at TA-55 (Plutonium Processing Facility). Within the 10-year period, the highest collective dose (224 person-rem) occurred in CY 2019.
Oak Ridge includes operations from Y-12 National Security Complex (Y-12), Oak Ridge National Laboratory (ORNL), the Oak Ridge Institute for Science and Education (ORISE), and the East Tennessee Technology Park (ETTP), formerly known as the K-25 Site. Over 131,000 annual monitoring records were received from Oak Ridge during the last 10 years (CY 2010 – 2019). Collective dose at Oak Ridge fluctuated around the 10-year average (136.5 person-rem), but from CY 2016 - 2018, the collective dose has been above average, primarily due to maintenance and waste handling activities at neutron research and radiochemistry facilities, and increased project work activities at hot cell and radiochemistry facilities.
Overall, there is no clear trend over the past 10 years at Oak Ridge regarding total collective dose with the exception that isotope production at ORNL is the primary driver behind the total collective dose for Oak Ridge. It is clear that Oak Ridge is unique in that the largest component of dose has consistently been internal dose (ranging from 31 – 45 percent). No other site in the top five contributors to dose has this characteristic as typically over 90 percent of all internal dose throughout the complex originates at Y-12 during uranium processing. Usually, one-third of all internal dose measurements taken are through air sampling.
Total collective dose gradually increased from CY 2010 through 2012. The reasons for the increase are: an increase in cleanup activities at ETTP and Y-12, an increase in production at Y-12, and also an increase in waste operation and isotope production at ORNL. Above average doses from CY 2010 to 2012 are attributed to activities funded by ARRA. The primary reason for collective dose decrease in CY 2013 was an approximate 2-month decrease in production work at Y-12 in preparation for the government shutdown during sequestration in October 2013. Likewise, the slight increase in CY 2014 dose was caused by the increased activity required to recover from the actions associated with the CY 2013 government sequestration. A 10 percent decrease in CY 2015 was the result of intermittent work stoppages throughout the year at Y-12 from weather and other factors and a decrease in collective TED at the transuranic waste processing center. A 21 percent increase in CY 2016 was the result of increased activities at the radiochemistry facilities in addition to increased maintenance and waste handling activities. A 13 percent increase in CY 2017 was attributed to maintenance and waste handling activities at neutron research and radiochemistry facilities, and increased project work activities at hot cell and radiochemistry facilities. In CY 2018, collective dose decreased 13 percent from CY 2017 levels from decreased work activities at hot cell and radiochemistry facilities. CY 2019 collective dose decreased 7 percent from the previous year.
Savannah River (SR) is a 310 square mile DOE site located near Aiken, South Carolina. It includes multiple organizations, including DOE Savannah River Operations Office, the NNSA Savannah River Site Office, and the Savannah River National Laboratory (SRNL). Over 69,000 annual monitoring records were submitted from CY 2010 to 2019 at SR. SR received $1.6 billion in ARRA funding to accelerate the cleanup of legacy waste, which led to an increase in total dose from CY 2010 - 2012. In CY 2010, one individual received an internal dose of 32 rem. Total collective dose remained below the 10 year average (131.5 person-rem) from CY 2013 to 2016.
As mentioned previously, collective dose increased significantly in CY 2010 due to an increase in ARRA-funded D&D activities. A major contributor to this increase was a large internal exposure (32 rem) from an intake of plutonium in one individual, which contributed to 18.1 percent of collective TED for CY 2010. Collective dose then decreased and remained steady in CY 2011 and 2012 (between 145 and 150 person-rem). This reduction in dose is attributable to the implementation of a variety of tools and techniques to reduce dose and the reduction in ARRA-funded activities. The collective dose decreased significantly in CY 2013 due to a host of budget issues that arose during the year and many ALARA initiatives that were employed. In CY 2014, a slight increase in collective dose was attributed to completing projects like the SRNL Cell Window replacements. Increases in CY 2016 were attributed to the remediation of 1950s era storage tanks and resuming process operations in portion of the H Canyon. The 35 percent increase in collective dose from CY 2016 to 2017 can be attributed to more workers engaging in activities with a high potential for exposure such as the 3H evaporator pot repair and the Defense Waste Processing Facility Melter 2 removal and replacement. The collective dose increased by 7 percent from CY 2018 to 2019, but remained lower than CY 2017 levels.
Collective dose in the DOE Complex decreased by nearly 21 percent from CY 2010 to 2019. Many factors led to this including CY 2010 being a year that involved an overexposure, which raised the collective TED compared to other years.
Beginning in CY 2009, dose increased as ARRA-related funding helped secure additional sources of funding for D&D activities at multiple DOE sites, primarily Hanford and Idaho, and for increased production work at Oak Ridge, LANL, and Pantex. In CY 2010, collective dose rose to its highest level since CY 2005 due to the additional work funded by ARRA. However, as ARRA-related funding began to diminish, so did work activities and dose, as collective TED decreased from CY 2010 to 2014. Since CY 2015, collective dose has remained fairly steady, averaging around 744 person-rem from CY 2015 to 2019.
While DOE Order 231.1A (2003) and 231.1B (2011) were implemented in regards to reporting, no significant changes were seen. The amendments to 10 CFR 835 appear to have had minimal impact on the collective dose as operational changes in mission were more significant. There does appear to be some dose reduction from CY 2011 to 2012 due to better ALARA awareness and use of safety technology, but this is confounded by a reduction in ARRA activities as well. In CY 2013, the overall decrease in collective TED was attributed to preparation for government shutdown during October sequestration and work reductions due to budget constraints. The slight collective TED decrease in CY 2014 was attributed to curtailing work with solid waste and changes in work scope to incorporate ALARA processes.