Occupational Radiation Exposure at Commercial Nuclear Power Reactors and Other Facilities 2018: Fifty-First Annual Report (NUREG-0713, Volume 40)
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Manuscript Completed: December 2019
Date Published: March 2020
1299 Bethel Valley Road, SC-200, MS-21
Oak Ridge, TN 37830
M.N. Nguyen, NRC Project Manager
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001
This report summarizes the occupational exposure data that are maintained in the U.S. Nuclear Regulatory Commission (NRC) Radiation Exposure Information and Reporting System (REIRS) database. The bulk of the information contained in this report was compiled from the 2018 annual reports submitted by five of the seven categories 1 of NRC licensees subject to the reporting requirements of Title 10 of the Code of Federal Regulations (10 CFR) 20.2206, Reports of Individual Monitoring. Because there are no geologic repositories for high-level waste currently licensed and no NRC-licensed low-level waste disposal facilities currently in operation, only five categories are considered in this report. The annual reports submitted by these licensees consist of radiation exposure records for each monitored individual. These records are analyzed for trends and presented in this report in terms of collective dose and the distribution of dose among the monitored individuals.
Annual reports for 2018 were received from a total of 182 NRC licensees from the five categories included in this report. The summation of reports submitted by the 182 licensees indicated that 159,988 individuals were monitored, 67,835 of whom received a measurable dose (Table 3.1). When adjusted for transient individuals, there were actually 110,861 unique individuals that were monitored, 49,445 of whom received a measurable dose (see Section 5).
The collective dose incurred by these individuals was 8,165 person-rem (81,650 person-millisieverts [mSv]), which represents a 1 percent increase from the 2017 value. The 2018 collective dose is 4 percent lower than the 5-year average of 8,506 person-rem (2013 – 2017), which is not a statistically significant change.2 The increase in collective dose in 2018 was small due to decreases in three categories offsetting increases in the remaining two reporting categories; spent fuel storage licensees (176 percent increase) and industrial radiographers (15 percent increase). Three reporting categories reported decreases; manufacturing and distribution (M&D) licensees (2 percent decrease), fuel cycle licensees (10 percent decrease), and commercial nuclear power reactor licensees (9 percent decrease). When compared to the 5-year average of collective dose for each category, fuel cycle licensees had a statistically significant decrease, and industrial radiographers had a statistically significant increase. The increases or decreases for the remaining three categories were not statistically significant.
The number of individuals receiving a measurable dose decreased by 4 percent from 2017, but was still 7 percent below the 5-year average and not statistically significant. When adjusted for transients, the average measurable dose of 0.17 rem (1.7 mSv) was slightly higher in 2018, compared to 0.16 rem (1.6 mSv) in 2017, and is not statistically significant when compared to the 5-year average. The average measurable dose is defined as the total effective dose equivalent (TEDE) divided by the number of individuals receiving a measurable dose. In 2018, one individual exceeded 5 rem (50 mSv) TEDE at an industrial radiography licensee (see Section 6).
In calendar year 2018, the average annual collective dose per reactor for light-water reactor (LWR) licensees was 59 person-rem (590 person-mSv). This is a 9 percent decrease from the value reported for 2017 (Table 4.3) but is not statistically significant when compared to the 5-year average. The total outage hours at commercial nuclear power plants decreased 4 percent from 2017 to 2018 [Ref. 1]. The collective dose for the LWR licensee category decreased 587 person-rem (5,870 person-mSv) from 6,416 person-rem (64,160 person-mSv) in 2017 to 5,829 personrem (58,290 person-mSv). The average annual collective dose per reactor was 111 person-rem (1,110 person-mSv) for the 33 boiling-water reactors (BWRs) and 34 person-rem (340 person-mSv) for 65 pressurized-water reactors (PWRs). The BWR 2018 value is 3 percent lower than the 5-year average annual collective dose per BWR reactor. The 2018 value for PWR licensees is 15 percent below the 5-year average annual collective dose per PWR reactor. Neither of these differences is statistically significant. The primary driver for the decrease in collective dose was the closure of Oyster Creek (BWR).
There were 26,395 individuals that were monitored at two or more licensees during the monitoring year. The assessment of the average measurable dose per individual is adjusted each year to account for the reporting of a measurable dose for transient individuals by multiple licensees. The adjustment to account for transient individuals has been specifically noted in footnotes in the figures and tables for commercial nuclear power reactors.
1 Commercial nuclear power reactors and test reactor facilities; industrial radiographers; fuel processors (including uranium enrichment facilities), fabricators, and reprocessors; manufacturing and distribution of byproduct material; independent spent fuel storage installations; facilities for land disposal of low-level waste; and geologic repositories for high-level waste. There are currently no NRC licensees involved in low-level waste disposal or geologic repositories for high-level waste.
2 This report presents additional Statistical Comparisons in Section 2.2.
Page Last Reviewed/Updated Wednesday, March 24, 2021