ML20122A111

Annual Environmental Operating Report

ML20122A111
Person / Time
Site:	Millstone
Issue date:	04/22/2020
From:	Armstrong L Dominion Energy Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
20-114
Download: ML20122A111 (11)

Text

Dominion Energy Nuclear Connecticut, Inc.

Rt 156, Rope Ferry Road, Waterford, CT 06385 ~ Dominion Dominion Energy.com ~ Energy APR 2 2 2020 U.S. Nuclear Regulatory Commission Serial No.20-114 Attention: Document Control Desk MPS Lie/LO RO Washington, DC 20555-0001 Docket No. 50-423 License No. NPF-49 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 2019 ANNUAL ENVIRONMENTAL OPERATING REPORT In accordance with Section 5.4.1 of the Environmental Protection Plan (EPP), Appendix B to the Millstone Power Station Unit 3 Operating License, Dominion Energy Nuclear Connecticut, Inc. hereby submits the Annual Environmental Operating Report (AEOR),

describing implementation of the EPP for the previous year. Enclosure 1 transmits information for the period of January 1, 2019 to December 31, 2019.

Should you have any questions regarding this report, please contact Mr. Jeffry A. Langan at (860) 444-5544.

Sincerely,

'~~

L. J. Armstrong Director, Nuclear Station Safety and Licensing

Serial No.20-114 2019 Annual Environmental Operating Report Page 2 of 2

Enclosures:

1 Commitments made in this letter: None.

cc: U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 R. V. Guzman NRG Project Manager Millstone Units 2 and 3 U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08 C2 11555 Rockville Pike Rockville, MD 20852-2738 NRG Senior Resident Inspector Millstone Power Station

Serial No.20-114 Docket No. 50-423 License No. NPF-49 Enclosure 1 MILLSTONE POWER STATION UNIT 3 2019 ANNUAL ENVIRONMENTAL OPERATING REPORT JANUARY 1 - DECEMBER 31, 2019 MILLSTONE POWER STATION UNIT 3 DOMINION ENERGY NUCLEAR CONNECTICUT, INC. (DENC}

2019 Annual Environmental Operating Report {AEOR) 1.

Introduction:

This report covers the period January 1, 2019 through December 31, 2019. During 2019, Millstone Power Station Unit 3 (MPS3) concluded fuel cycle 19 in March 2019; MPS3 underwent a refueling outage from April 11, 2019 to May 14, 2019. Fuel cycle 20 began in May 2019 and is expected to continue until Fall 2020.

As required by the MPS3 Environmental Protection Plan (EPP), Appendix B to the MPS3 Operating License, this AEOR includes:

• summaries and analyses of the results of environmental protection activities,

• a list of EPP non-compliances and the corrective actions taken to remedy them,

• a list of all changes in station design or operation, tests, and experiments which involved a potentially significant unreviewed environmental question, and

• a list of non-routine reports submitted in accordance with subsection 5.4.2.

2. Environmental Protection Activities:

2.1 Annual National Pollutant Discharge Elimination System (NPDES) Report of Ecological Monitoring (EPP Section 4.2).

Section 1O(A) of Millstone Power Station's (MPS) NPDES permit (the Permit), as issued to Dominion Nuclear Connecticut, Inc. (DNC; now Dominion Energy Nuclear Connecticut, DENG) by the Connecticut Department of Environmental Protection (DEP; now the Department of Energy and Environmental Protection, or DEEP) on September 1, 2010, requires, among other things, continuation of biological studies of supplying and receiving waters. These studies include analyses of intertidal and subtidal benthic communities, finfish communities, entrained plankton, lobster populations, and winter flounder populations. Section 1O(A)(2) of the Permit requires an annual report of these studies to be sent to the DEEP Commissioner on or before July 31 of each year. The latest report that fulfills these requirements, "Annual Report 2018 - Monitoring the Marine Environment of Long Island Sound at Millstone Power Station, Waterford, Connecticut" (Annual Report), dated July 2019, presents results from studies performed during construction and operation of MPS, emphasizing those of the latest sampling year. Characteristics of and changes to the biological communities noted in these studies are summarized in the Executive Summary section of the Annual Report, which is attached as part of this report.

2.2 Effluent Water Quality Monitoring:

Several sections of the Permit require monitoring and recording of various water quality parameters at MPS intakes and at multiple monitoring points within the plant, including outfalls of each unit to the effluent quarry, and outfall of the quarry to Long Island Sound. Section 8 of the Permit requires that a monthly report of this monitoring be submitted to the DEEP. The report that fulfills these requirements, the "Monthly Discharge Monitoring Report" (DMR), includes discharge data from all MPS units. Consistent with prior annual AEOR submissions, water flow, temperature, pH, and chlorine data pertaining to MPS3 are summarized in Table 1.

2019 AEOR Page 1 of 3

Each monthly DMR identifies NPDES permit exceedances (i.e., events where a parameter value was beyond permitted limits) or exceptions (i.e., events where Permit conditions were not met) for the month. However, during 2019, there were no exceedances or exceptions at a discharge associated with MPS3.

2.3 NPDES Permit Renewal By way of background, in 2014 MPS established a team, and scheduled milestones, to ensure that a completed permit renewal application was submitted to the DEEP, in accordance with general requirements, prior to the permit's expiration in August 2015. The permit renewal application was submitted on February 6, 2015, and the DEEP issued a Notice of Sufficiency on March 6, 2015; therefore, the permit is administratively continued and in effect until its reissuance.

3. Environmental Protection Plan (EPP) Non-compliances:

No EPP non-compliances were identified for MPS3 in 2019.

4. Environmentally Significant Changes to Station Design or Operation, Tests, and Experiments:

No MPS3 design change records or system operating procedure changes initiated during 2019 included a determination that a significant unreviewed environmental question existed.

5. Non-Routine Reports of Environmentally Significant Events:

No non-routine reports were submitted in accordance with subsection 5.4.2 of the EPP.

2019 AEOR Page 2 of 3

Table 1. MPS3 NPDES data summary, Jan 1-Dec 31, 2019. Selected water quality parameters for MPS3(1).

Discharge Maximum Discharge pH Average Maximum Temp. Range 2019 Discharge Flow Range(SU)

(OF) Discharge _

Average 11 Maximum Maximum SWS FAC Temp. (°F) FAC (ppm) TRC (ppm)

(10 6 gpd) Temp. (°F) (ppm)

Min Max Min Max January 1360.9 7.8 8.1 54.2 68.0 61.3 19.3 <0.02 <0.02 0.19 February 1360.4 7.9 8.2 55.1 65.9 60.1 21.0 0.05 0.05 0.16 March 1351.1 7.8 8.2 56.2 _ 68.2 62.3 21.1 0.02 0.04 0.19 April 1209.4 6.5 8.1 44.6 74.3 57.3 9.7 <0.02 0.02 0.21 May 1360.4. 6.4 8.2 48.6 90.4 64.2 11.0 0.03 0.03 0.18 June 1360.8 7.6 8.1 72.8 85.2 77.9 16.1 0.05 0.05 0.15 July 1360.7 7.8 8.1 78.9 88.4 84.1 14.4 0.03 0.04 0.15 August 1360.8 7.9 8.2 84.5 89.2 86.3 14.9 0.02 0.04 0.18 September 1360.8 7.9 8.2 84.3 89.0 86.1 15.9 0.05 0.07 0.16 October 1360.8 8.0 8.2 77.7 87.5 81.1 17.0 0.04 0.02 0.19 November 1361.3 7.9 8.2 66.5 91.4 72.5 17.1 0.03 0.04 0.22 December 1360.9 8.0 8.2 41.9 73.2 61.1 14.5 0.06 0.02 0.20 (1) Parameters are measured at MPS3 discharge (DSN 001(), except forTRC (total residual chlorine), which is measured at MPS discharge (quarry cuts; DSN 001-1), and SWS FAC (service water system free available chlorine; DSN 001C-5).

2019 AEOR Page 3 of 3

Attachment to the 2019 Annual Environmental Operating Report January 1 - December 31, 2019 Executive Summary Section of "Annual Report 2018 - Monitoring the Marine Environment of Long Island Sound at Millstone Power Station, Waterford, Connecticut" dated July 2019

Executive Summary This report summarizes results of ongoing environmental occurred less regularly at MP and WP as well, reflecting monitoring programs conducted in relation to the regional temperature increases.

operation of Millstone Power Station (MPS). MPS can Thermal effects on dominant species' abundance and affect local marine biota in the following ways: large distribution patterns were also evident at FI in 2018, and organisms may be impinged on the traveling screens that most apparent in the low intertidal zone. Seasonally high protect the condenser cooling and service water systems; abundance of Hypnea musciformis, a species observed smaller ones may be entrained through the condenser for the first time in 2001, and expanded populations of cooling-water system, which subjects them to various Sargassum filipendula, Corallina officinalis, and mechanical, thermal, and chemical effects; and marine Gelidium pusillum now characterize the lower shore communities in the discharge area may also be subjected community at FI. Melanothamnus (previously to mechanical, thermaL and chemical effects resulting Neosiphonia) han,eyi has maintained a perennial from the outflow of the cooling water. population at FI in 2018, but occurred mainly as a This report contains a separate section for each major summer annual at sites unaffected by MPS.

biological monitoring program, some of which have been Ascophyllum nodosum growth, represented as the most conducted without interruption since 1976. These long- recent internodal length, was greatest at FI in 2018, term studies have provided the representative data and significantly higher than both MP and WP. Although scientific bases necessary to assess potential biological growth was slightly lower at WP, with all sites combined, impacts as a result of MPS construction and operation. growth in 2018 was lower than 2017, and continued a In addition to sections related to the biological declining trend observed since 2011, but showing no monitoring program, this report includes a section correlation to annual mean water temperature. This providing a complete and thorough description of all continues to demonstrate no clear relationships among National Pollutant Discharge Elimination System monitoring sites, or correlation with station operating (NPDES) pennit compliance work undertaken for the conditions, indicating that the thermal plume from MPS implementation of flow reduction and/or entrainment has had little effect on local populations. Natural mitigation technologies, operational methods or other influences of other factors, such as ambient temperature measures undertaken in 2018, and a section which conditions, stonns and wave action, nutrients and light, provides a comprehensive summary of activities and play the dominant role in determining Ascophyllum accomplishments of Dominion Energy Nuclear growing conditions in tl1e Millstone area.

Connecticut (DENC) in the Niantic River Nitrogen Work The rocky intertidal monitoring program has also Group effort. documented regional patterns and modifications to shore communities umelated to MPS operation. These include Rocky Intertidal Studies the introduction to the region of three exotic red algae (Antithamnion pectinatum in 1986, Grateloupia tun1tunt Rocky intertidal habitats are extensive in the Millstone in 2004, and Dasysiphoniajaponica in 2010), decreases area, and support rich and diverse communities of attached in barnacle abundance in recent years, and long-term algae and animals. Rocky intertidal studies at MPS are increases in abundance of the common seaweeds Fucus designed and implemented to characterize these vesiculosus and Chondnts crispus.

communities. Analyses of rocky shore data to date indicate that changes attributed to MPS operation are Eelgrass minor, transient, and restricted to a small area along 150 meters of shoreline in the immediate vicinity of the Eelgrass (Zostera marina L.) was monitored at three discharge. locations in the vicinity ofMPS. Data from 2018 surveys As in previous years, seasonal shifts in occurrence of indicated that tl1e two study sites nearest to the MPS annual algal species were noted at FI during 2018. These thermal plume (Jordan Cove (JC) and White Point(WP))

shifts included absence or abbreviated season for cold- supported healthy and expansive eelgrass populations, water species (e.g., Monostroma grevillei, consistent with results since the study began in 1985.

Protomonostroma undulatum, Spongomorpha arcta, and While there has been moderate variability in abundance Dumontia contorta) and extended season for warm-water and distribution over the entire study period at these two species (e.g., Grinnellia americana, Antithamnion sites, this variability was not related to MPS operation.

pectinatwn, and Grateloupia tun1turu). Similar shifts Both predicted and measured thermal input to these sites have been observed in most years included in this time- from the cooling water discharge is at most minimal (<

senes However, some species with cold-water affinity 1°C above ambient conditions) and well below levels (e.g., Protomonospora, Dumontia) have recently considered stressful to eelgrass.

Executive Summary ii

By comparison, high eelgrass population variability has Impacts associated with recent MPS operations on the been observed in the Niantic River, where complete and local lobster population were assessed by comparing often sudden eelgrass bed losses were documented on six results of the 2018 study year to data collected from 1978 separate occasions prior to 2018. Data from the 2018 through 2017. Emphasis has been placed on assessing survey show continued recovery of some eelgrass beds in long-term trends in the abundance and population the Niantic River, with some expansion into Smith Cove. characteristics of lobsters collected in the Millstone Point Because the Niantic River is located well away from any area.

influence of the MPS thermal plume, eelgrass population Throughout LIS, the lobster population was stable or fluctuations there must be related to environmental increasing from 1978 through 1999. Commercial lobster factors such as increasing ambient seawater catches in LIS precipitously declined from 2000 to 2013 temperatures, disease, increased turbidity, and waterfowl and have stabilized at record low levels through 2018. In grazing. Results from this monitoring therefore suggest th.is study, lobsters in the MPS area have shown a similar that fluctuations in eelgrass populations observed at sites trend, with abundance indices (total catch and catch per in the Niantic River are due to changes in local and unit effort (CPUE)) nearly 70% lower in research. pots and regional environmental conditions and not to MPS 98% lower in trawls during the past seven years (2012-operation. 2018), compared to highest levels in the 1990s. Declines in pot and in trawl catch.es were unrelated to MPS Benthic Infauna operations and attributed to an increase in mortality associated with ambient seawater temperature rise and Benthic infauna! monitoring documented long-term temperature mediated stressors that include a shell disease trends in sediment characteristics at all the subtidal sites affecting lobster populations from eastern LIS to the Gulf in the vicinity of MPS. At the effluent sampling site (EF), of Maine. Egg-bearing females have been the sedimentary environment remains coarse, with low disproportionately and negatively impacted by shell silt/clay which is related to discharge of cooling water disease in comparison to other lobsters. In addition, into Long Island Sound (LIS) at the Quarry cuts. predation by the high number of Tautog caught in traps Sediments at the intake site (IN) were consistent with contributed to record high lobster mortality during 2015 -

sediment characteristics prior to dredging during MPS 2018. Declines in the abundance of legal-size lobsters MPS3 construction. Sediments at Jordan Cove (JC) were attributed in part to the outbreak of shell disease and continued to have the smallest mean grain size and to a nearly 5 mm increase in the minimum legal-size since highest silt/clay content of all four stations, attributed to 1978. Recent reductions in landings oflegal-size lobsters the discharge area scouring and fine sediment deposition harvested by commercial lo bstennen in eastern LIS in the vicinity of the JC site. Sedimentary characteristics coincided with declines observed in this study, and lobster at the reference site at Giants Neck (GN) were similar to catches remained severely depressed in other areas of LIS previous years' observations and continued to reflect since the lobster die-off observed in 1999.

• natural variability umelated to MPS. Long-term trends observed in lobster population The 2018 infauna! communities at all sampling sites characteristics during the past four decades (molting, continued to respond to sedimentary environments. female size at maturity, abundance and size Dominant taxa at all sites were reflective of climax characteristics of egg-bearing females) appear related to communities that have undergone long-term successional warmer ambient seawater temperatures and/or the recent development in response to increased stability of their outbreak of shell disease, and not MPS operation.

sedimentary environments. Multidimensional scaling Increased ambient water temperature may be responsible showed distinct separation of communities affected by for the increased susceptibility and transmission of construction and initial operation of MPS3, but also diseases affecting lobsters in LIS, which is at the southern illustrated regional temporal community shifts umelated boundary of their range of distribution in nearshore to MPS operation. Changes in community structure and waters.

functional group dominance at subtidal benthic infauna! The number oflobster larvae entrained through the MPS stations during the period 1980-2018 reflect not only cooling water systems was highly variable and low in effects related to construction and initial operation of recent years, due to low adult lobster abundance and low MPS3, but other regional and/or local biotic and abiotic larval densities throughout LIS. Impacts associated with factors. Community changes at the reference site (GN) impingement oflobsters at MPS have been greatly reduced during the period 1980-2018 were attributed solely to by the use of aquatic organism return systems at both units, these latter factors, and not to operation of MPS. which return impinged lobsters to Niantic Bay with documented very high survival rates.

Lobster Studies Fish Ecology Studies Executive Summary 111

Results from the Fish Ecology monitoring studies Protection (CTDEEP). During the same time pe1iod, during 2018 indicate that no long-term abundance trends adult Winter Flounder abundance in the Niantic River has for various life stages of seven selected species could be remained low. Reflecting the continued trend of low directly related to MPS operation. No significant long- abundance, The .6.-mean Catch Per Unit Effort (CPUE) tenn trends in abundance were identified for Anchovy, for adult fish(> 15cm) captured in the year-round Trawl Cunner and Tautog eggs, American Sand Lance and Monitoring Program (TMP) in 2018 was tied with 2016 Grubby larvae, or juvenile and adult Silversides. Atlantic as the lowest (0.6) value since 1976.

Menhaden larvae showed a significantly increasing trend In 2018, overall combined larval abundances in Niantic in abundance, as did juveniles collected in seines. A Bay (sampling sites EN and NB) and Niantic River (sites significant decreasing trend was exhibited for Grubby A, B, and C) were below average for their respective collected at the Intake, Jordan Cove, and Niantic River time-series. Stages 1 and 2 larval abundances in the trawl sampling sites. Over the past 43 years, Cunner and River stations were below time-series means, while Tautog larval abundances have significantly increased. Stages 3 and 4 larval abundances were above time-series Juvenile and adult trawl catches of Cunner increased at means. All stages of larval abundances in the Niantic the Niantic River (NR) station and decreased at the Bay Stations were below time-series means. Relative to Jordan Cove (JC) trawl stations. Trawl catches of the Niantic River, larval abundance in Niantic Bay has juvenile and adult Tautog have significantly increased at increased in recent years, suggesting higher production in the NR station. No trends in the abundance of juvenile LIS rather than in estuaries such as the Niantic River.

and adult Cunner and Tautog were observed at 1N Summer juvenile abundance from the 2018 Niantic River following the removal of the MPS3 intake cofferdam in beam trawl survey was low for the time-series and 1983. reflected low larval abundance.

The magnitude of entrainment is dependent upon egg The number oflarvae entrained at MPS is a measure of and larval densities and condenser cooling water flows potential impact to Winter Flounder. Annual estimates during their periods of occurrence. Reductions in of entrainment are related to both larval densities in cooling-water flows have been implemented at MPS with Niantic Bay and MPS cooling-water volume. The 2018 the use of VFDs during the peak period of Winter entrainment estimate of 51 million reflected slightly Flounder annual spawning. In addition to the Unit 3 fish lower than average Niantic Bay larval densities. An return, which was in operation at unit start-up in 1986, entrainment reduction of 33.12% (based on maximum impingement impacts were further reduced at MPS with permitted flow) in 2018 can be attributed to the use of the the installation of a fish return at Unit 2 in early 2000. variable frequency drives (VFDs) during the "Interval" The implementation of these mitigation measures serve from April 4 to May 23 (defined in the MPS NPDES to minimize entrainment and impingement impacts at permit as the period "from April 4 to May 14 or the first MPS. day after May 14 when the intake water temperature Annual variations in ichthyoplankton entrainment reaches 52 °F, whichever is later, but no later than June likely reflected differences in spawning and transport of 5").

eggs and larvae within LIS. Other factors, such as Processes that are unrelated to MPS operation and extremes in seasonal water temperature, may also affect which occur after juvenile Winter Flounder leave shallow larval growth and development. A number of temporal nursery waters during the fall of their first year of life and spatial changes were identified in the community of seem to be operating to account for fewer adults. A fishes and macroinvertebrates collected in the MPS trawl bottleneck in recruitment may occur during the late monitoring program. These changes were unrelated to juvenile life stage (ages-1 and 2), probably from the operations of MPS, but rather were associated with predation. Environmental effects, including changes to shifts in the dmninance of individual taxa from changes the Niantic River habitat (e.g., widely fluctuating in habitat, range extensions or contractions related to a eelgrass abundance), a warming trend in regional warming trend in ambient seawater temperature, and seawater temperature, and interactions witl1 other species changes in fishing rates and fishing regulations. (e.g., predation), especially during early life history, are also important processes affecting Winter Flounder Winter Flounder Studies population dynamics.

Results from Winter Flounder studies through 2018 Various life history stages of Winter Flounder have suggest that MPS operations have had minimal effects on been monitored since 1976 to determine what effect, if Winter Flounder biomass in the Niantic River. Declines any, MPS may have on the local Niantic River in stock size have been greatly evident on a regional population, particularly through the entrainment of basis, including LIS, Rhode Island and all other Southern larvae. Over the past two decades, low Winter Flounder New England waters. Entrainment during the larval life abundance levels have been found throughout LIS by the stages of Winter Flounder occurs, however there has Connecticut Department of Energy and Environmental been large variation in the amount oflarval mortality and Executive Surnmary iv

recruitment in recent years, both occuning independently of MPS operations.

Executive Summary v