ML21109A282

2020 Annual Environmental Operating Report

ML21109A282
Person / Time
Site:	Millstone
Issue date:	04/19/2021
From:	Armstrong L Dominion Energy Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
21-123
Download: ML21109A282 (11)

Text

Dominion Energy Connecticut, Nuclear Inc. " =

Millstone PowerStation C..s-Energy" 314 Rope Ferry Road, CT06385 Waterford, DominionEnergy.com APR 192021 U.S. Nuclear Regulatory Commission Serial No.21-123 Attention: Document Control Desk MPSLic/LD RO Washington, DC20555-0001 Docket No. 50-423 License No. NPF-49 MILLSTONE POWER STATIONUNIT 3 2020ANNUALENVIRONMENTALOPERATING REPORT Inaccordance with Section5.4.1 oftheEnvironmental Protection Plan (EPP), AppendixB tothe Millstone PowerStation Unit3 Operating License, Dominion Energy Nuclear Inc.

Connecticut, hereby submits theAnnual Environmental Operating Report (AEOR), describingimplementation oftheEPPfor theprevious year. Enclosure 1transmits information for theperiodofJanuary 1, 2020toDecember 31,2020.

Should youhaveanyquestions regarding this report, please contact Mr.Jeffry A.Langan at (860) 444-5544.

Sincerely, sf cg y in Ly L5h c-L.J.Armstrong "

Director, Nuclear Station Safety andLicensing

Serial No.21-123 2020Annual Environmental Operating Report Page2 of2

Enclosures:

1 Commitments made inthisletter: None.

cc: U.S.Nuclear Regulatory Commission Region I 2100Renaissance Blvd, Suite100 King PA 19406-2713 ofPrussia, R.V.Guzman NRCProjectManager Millstone Units 2 and3 U.S. Regulatory Nuclear Commission OneWhite Flint North, Mail Stop08 C2 11555Rockville Pike MD 20852-2738 Rockville, NRCSenior Resident Inspector Millstone PowerStation

No.21-123 Serial Environmental 2020Annual Operating Report 1

Enclosure MILLSTONEPOWERSTATION UNIT3 2020ANNUALENVIRONMENTALOPERATING REPORT MILLSTONEPOWERSTATION UNIT3 DOMINION E NERGYNUCLEARCONNECTICUT, INC.(DENC)

1

Introduction:

This report covers theperiod January 1,2020through December 31,2020.During 2020, Millstone Power Station Unit 3 (MPS3) concluded fuel cycle 20 inOctober 2020;MPS3 underwent a refueling outage from October 1,2020toNovember 12, 2020. Fuel cycle 21began inNovember 2020 and is expectedtocontinue untilSpring 2022.

Asrequired bytheMPS3 Environmental Protection Plan (EPP), Appendix Btothe MPS3Operating License, thisAEORincludes:

= summaries andanalyses ofthe results ofenvironmental protection activities, a a list ofEPPnon-compliances andthe corrective actions taken toremedy them, a a list ofallchanges instation design oroperation, tests, andexperiments which involved a potentially significant unreviewed environmental question, and a a list ofnon-routine reports submitted inaccordance with subsection 5.4.2.

2. Environmental Monitoring Activities:

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

Section 10(A) ofMillstone Power Station's(MPS) NPDES permit (the Permit), asissued to Dominion Nuclear Connecticut, Inc.(DNC; now Dominion Energy Nuclear Connecticut, DENC) bytheConnecticut Department ofEnvironmental Protection (DEP; nowtheDepartment ofEnergy andEnvironmentalProtection, orDEEP) onSeptember 1,2010, requires, amongother things, continuation ofbiological studies ofsupplying and receiving waters. Thesestudies include analyses of intertidal andsubtidal benthic communities, finfishcommunities, entrained plankton, lobster populations, andwinter flounder populations. Section 10(A)(2) ofthePermit requires an annual report ofthese studies tobe,sent totheDEEPCommissioner onorbefore July 31 ofeach year. The latestreport thatfulfillsthese requirements, "Annual Report 2019 Monitoring the Marine Environment ofLongIsland Sound atMillstone Power Station, Waterford, Connecticut" (Annual Report), dated J uly 2 020, presents results from studies performed during construction andoperation ofMPS, emphasizing those ofthelatest sampling year.

Characteristics ofandchanges tothebiological communities noted inthesestudies are summarized intheExecutive Summary section ofthe Annual Report, which isattached aspart ofthis report.

2.2 Effluent Water Quality Monitoring:

Several sections oftheermit require monitoring andrecording ofvarious water quality parameters atMPSintakes andatmultiple monitoring points within theplant, including outfallsofeach unittothe effluent quarry, andoutfall ofthequarry toLongIsland Sound.

Section 8ofthePermit requires that a monthly report ofthis monitoring besubmitted to theDEEP.Thereport that fulfillsthese requirements, the "Monthly Discharge Monitoring Report" (DMR), includes discharge data from allMPSunits. Consistent withprior annual AEORsubmissions, water flow, temperature, pH,andchlorine data pertaining toMPS3 aresummarized inTable 1 Eachmonthly DMR identifies NPDESpermit exceedances (i.e., events wherea parameter valuewasbeyond permitted limits)or exceptions (i.e.,events where Permit conditions werenotmet) for themonth. During 2020, there wasoneexception tothe NPDESpermit. Thedescriptions andcorrective actions aresummarized below from the monthly DMRs.

2020AEORPage1of3

a)MPS3SteamGenerator (DSN 001C-1)

On July 1,2020at01:00 hours, Chemistry Station sampled DSN001C-1 for quarterly parameters inaccordance with Section5,Table P oftheNPDESPermit. Several samples werepreserved andshipped toGEL Laboratories, LLC (GEL)offsite for analysis inaccordance with EPA-approved methods, includingTotal Kjeldahl Nitrogen (TKN). On August 20,2020, DENCidentified that analysis results for TKNonthe July 1st sample had not beenprovided andcontacted GEL.GELnotified DENCthat TKN wasmistakenly omitted from theanalyses performed ontheNPDESsamples. DENC instructed GEL to immediately analyze thesample TKN,eventhough for the28-day hold time hadbeenexceeded. GELcompleted the TKNanalysis on August 24, 2020 at 1445 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.498225e-4 months <br /> andthe result was 0.926 mg/L, which iscomparable with historical sample results andisnota violationof Permit effluent limitations. Thisresultwasincluded inthe July 2020DMRandnotedthat the 28-dayhold time was exceeded inthe"Comments" section. Station Chemistry was alsoinstructedtoobtain another DSN001C-1 sample for TKN,which was sampled on August 24,2020at0140hours andincluded inthe August 2020DMR.This information was also communicated tothe CTDEEPonAugust 24,2020.

GELcompleted thesecond TKNanalysis onAugust 28,2020at0944hours andthe result was0.528 mg/L, which iscomparable with historical sample resultsand isnota violation ofPermit effluent limitations. Thisresult was includedin the August 2020DMR submittal andnoted inthe"Comments" section that thiswasthe second sample for the quarter that wastaken as part ofa correctiveaction for theJuly TKNsample being analyzed outside the 28-day hold time.

2.3 NPDESPermit Renewal Bywayofbackground, in2014MPSestablished a team,andscheduled milestones, to ensure that a completed permit renewal application wassubmitted totheDEEP,in accordance with general requirements, prior tothepermit's expiration inAugust 2015.

Thepermit renewal application was submitted on February 6,2015, and theDEEP issued a Notice ofSufficiency onMarch 6,2015; thepermit therefore, isadministratively continued andineffect until its reissuance.

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

NoEPPnon-compliances wereidentified MPS3in2020.

for

4. Environmentally SignificantChanges toStation Design orOperation,Tests, andExperiments:

NoMPS3design change records orsystem operating procedurechanges initiated during 2020included a determination that a significantunreviewed environmental question existed.

5. Non-Routine Reports ofEnvironmentally Significant Events:

Nonon-routine reportsweresubmitted inaccordance with subsection 5.4.2 oftheEPP.

2020AEORPage2of3

3 o

3 Pag 019 AE SWS 019020018017 M

015 018018 017019 M M M M 019020 me is 00202 DSN TRCppm Maximum <002 003007005003 003006 006004 007006004 whi ch cho ppm M M M M M 004 av M

MPS31.FACppm forMaximum

<002 002002 003004 007005 005004 009003 res free Ma sys tota FA parameters Average A

Temp.

0F 196199197158221 155167 157161 39 153159TRC wat M M M M E M M E M M M for quaity 630625645636746 784 M

868 685670 654exc ser water 0F M M M M 885873 M M 001C FAC Seected 680680 852866 880926 920 M

DSNSWS Avera 705 Disch Discharge Temp F

Ma 933 864832783 and 2020.Temp.

Range Min542577579443659 720808 865834 561530441 disch 0011, 31, E E M E M M E E E M M M DSN an1Dec pH SU Max Discharge Range 81 83 82 83 82 82 82 81 82 83 84 81 MPS3 at cuts;

summary, Fow datagpd 78 80 80 78 79 79 79 78 79 76 78 78 mea are quarr disch NPDES 13609 13608 13609 12686 13609 13600 13515 13602 13620 13603 13605 13605 ParMPS at MPS3anuary Marchi February May Apri uneuy AugustiOctobe Septembe 1.

Tabe Decem NovembNote 1

Attachment tothe 2020Annual Environmental Operating Report January 1 December 31,2020 Executive Summary Section of "Annual Report theMarineEnvironment 2019 Monitoring ofLongIsland Soundat Power Millstone Station,Waterford, Connecticut" dated July 2020

Executive Summary toa small areaalong 150meters ofshoreline intheimmediate vicinityofthe discharge.

This report summarizes results ofongoing As inprevious years, seasonal shifts in environmental monitoring programs occurrence ofannual algal species were conducted in relation to theoperation of noted at FIduring 2019. Theseshifts Millstone Power Station (MPS). MPS can included absence orabbreviated season for affect local marine biota in thefollowing ways:cold-water species (e.g. Protomonostroma large organisms may be impingedon the undulatum, Spongomorpha arcta) and traveling screens that protect thecondenser extended seasonforwarm-water species cooling andservicewater systems; smaller (e.g., Antithamnion pectinatum and onesmaybeentrained through the condenser Grateloupia turuturu). Similar shifts have cooling-water system, which subjects them to beenobserved inmostyears included inthis various mechanical, thermal, and chemical time-series However, some species with effects; and marine communities inthe cold-water (e.g.,

affinity Protomonospora, discharge areamay alsobe subjected to Dumontia) occurred less regularly atMPand mechanical, thermal, andchemical effects WP aswell, reflecting regional temperature resulting from theoutflow ofthe coolingwater. increases compared toearlier study years.

This report contains a separate sectionfor Thermal effects on dominant species' eachmajor biological monitoring program, abundance and distribution patterns were someofwhich havebeenconducted without also evident atFIin 2019, andmostapparent interruption since 1976.Theselong-term in the lowintertidal zone.Seasonally high studies have provided therepresentative data abundance ofHypneamusciformis, aspecies and scientific basesnecessary to assessobserved for thefirst timein2001,and potential biological impacts asa result ofMPS expanded populations ofCorallinaofficinalis construction andoperation. andGelidiumpusillum nowcharacterize the In addition to sections related to the lower shore community at Fl.

biological monitoring program, this report Melanothamnus (previously Neosiphonia) includes a section providing a complete and hanteyi maintaineda perennial populationat thorough description ofall National Pollutant all three sitesin2019.

Discharge Elimination System(NPDES) Ascophyllumnodosumgrowth, represented permit compliance workundertaken forthe as themostrecent internodal length, was implementation of flowreduction and/or greatest atFIin 2019,significantly higher than entrainment mitigation technologies, both MP andWP. Withall sites combined, operational methodsor other measuresgrowth in2019washigher than 2018, and was undertaken in2019,anda section whichthethird highest mean growth since this provides a comprehensive summaryof methodology began in2011This continues to activities andaccomplishments ofDominion demonstrate no clear relationships among Energy Nuclear Connecticut (DENC) inthe monitoring sites, or correlation with station Niantic River Nitrogen WorkGroup effort. operating conditions, indicating thatthe thermal plume fromMPShashadlittle effect RockyIntertidal Studies on local populations. Natural influences of other factors, suchas ambient temperature Rocky intertidal habitats areextensive inthe conditions, storms andwaveaction, nutrients Millstone andsupport area, rich anddiverse andlight, playthe dominant role indetermining communities ofattached algae andanimals. Ascophyllum growing conditions in the Rocky intertidal studies atMPSaredesigned Millstone area.

and implemented to characterize these Therocky intertidal monitoring program has communities. Analyses ofrocky shore data to alsodocumented regional patterns and date indicate that changes attributed toMPS modifications toshore communities unrelated operation are minor, transient, and restricted to MPS operation. Theseinclude the introduction totheregion ofthree exotic red Executive Summaryi

algae (Antithamnion Grateloupia turuturu pectinatum in1986, atall in 2004, and At theeffluent thesubtidal sites inthevicinity sampling site ofMPS.

(EF), the Dasysiphonia japonicain2010), decreases in sedimentary environment remains coarse, barnacle abundance inmorerecent years,with lowsilt/clay which isrelated todischarge andlong-term increases inabundance ofthe ofcooling water intoLongIsland Sound(LIS) commonseaweeds Fucusvesiculosus and attheQuarry cuts. Sediments attheintake Chondrus crispus. site (IN) were generally consistent with sediment characteristics prior to dredging Eelgrass during MPSMPS3construction. Sediments atJordan Cove(JC) continued tohavethe Eelgrass (zostera marina L.)wasmonitored smallest meangrain size andhighest silt/ciay atthree locations inthe vicinity of MPS.Data content ofall four stations, attributed tothe from2019surveys indicated that thetwo discharge areascouring and fines ediment study sites nearest totheMPSthermal plume deposition inthevicinity oftheJC site.

(Jordan Cove(JC) andWhitePoint(WP)) Sedimentary characteristics atthereference supported healthy andexpansiveeelgrass site atGiants Neck(GN) weresimilar to populations, consistent with results since the previous years' observations andcontinued study began in1985. While therehasbeen toreflectnatural variabilityunrelated toMPS.

moderate variability in abundance a nd The 2019infaunal communities at all distribution overtheentire study period at sampling sites continued to respond to these twosites, this variability wasnotrelated sedimentary environments. Dominant taxa at to MPS operation. Bothpredicted and all sites were reflective of climax communities measured thermal input tothese sites from that have undergone long-term successional thecooling waterdischarge isat most development in response to increased andwell

(<

minimal 10Caboveambient below levels considered conditions) stressful stability oftheir sedimentary environments.

to Multidimensional scaling showeddistinct eelgrass. separation of communities affected by Bycomparison, high eelgrass population construction andinitial operation ofMPS3, variability hasbeenobserved intheNiantic but also illustrated regional temporal River, wherecomplete and often sudden community shifts unrelated to MPS operation.

eelgrass bedlosses weredocumented onsix Changesin community structure and separate occasions prior to2019. Data from functional groupdominance at subtidal the2019survey showcontinued recovery of benthic infaunal stations during the period someeelgrass bedsintheNiantic River.1980-2019 reflect notonly effectsrelated to Because theNiantic River islocated wellconstruction andinitial operation ofMPS3, awayfrom anyinfluence oftheMPSthermalbutother regional and/or local bioticand plume, eelgrass population fluctuations thereabiotic factors. Community changes atthe mustberelated toenvironmental factors such reference site(GN) during theperiod 1980-as increasing ambient seawater2019wereattributed solely tothese latter temperatures, disease, increased turbidity, factors, andnottooperation ofMPS.

andwaterfowl grazing. Results fromthis monitoring therefore suggest thatfluctuations Lobster Studies ineelgrass populations observed atsites in theNiantic River areduetochanges inlocal Impacts associated withrecent MPS andregional environmental conditions and operations onthe local lobsterpopulation were not toMPSoperation. assessed bycomparing results ofthe2019 study year todata collectedfrom 1978 through Benthic Infauna 2018. Emphasis has been placed on assessing long-term trends intheabundance Benthic infaunal monitoring documented and population characteristics oflobsters long-term trends insediment characteristics collected inthe Millstone Point area.

ExecutiveSummaryii

Throughout LIS, thelobster population was lowadult lobster abundance andlowlarval stable orincreasing from1978through 1999.densities throughout LIS. Impacts associated Commercial lobster catchesin LIS with impingement oflobsters atMPS have precipitously declined from 2000to2013and beengreatly reduced bytheuseofaquatic havestabilized atrecord lowlevels through organism return systems atboth units, which 2019.Inthis study, lobstersintheMPSarea return impinged lobsters toNiantic Baywith haveshowna similar trend, with abundance documented very high survival rates.

indices (total catch and catch perunit effort (CPUE)) nearly 70% lower inresearch pots FishEcology Studies and98%lower intrawls during thepast eight years (2012-2019), compared tohighest levelsResults fromtheFish Ecology monitoring inthe1990s. Declines in pot andintrawl program suggest MPS operation has nothad catches wereunrelated toMPS operations a discernible effect onlocal fish assemblages and attributed toan increase in mortality based on analysis ofchanges incommunity associated with ambient seawater composition and long-term abundance temperature rise andtemperature mediated trends.No significant long-term trendsin stressors that include a shell disease affecting abundance were identified forAnchovy, lobster populations fromeastern LIStothe Cunner andTautog eggs, Grubby or larvae, Gulf ofMaine.Egg-bearing females have juvenile and adult Silversides. Atlantic been disproportionately and negatively Menhaden larvae showeda significantly impacted byshell disease incomparison to increasing trend in abundance, as did other lobsters. Inaddition, predation bythe juveniles collected inseines. A significant highnumberof Tautog caught intrapsdecreasing trend wasexhibited for American contributed torecord highlobster mortality SandLance larvae andGrubby collected at during 2015 2019. Declines inthe theIntake,Jordan Cove,andNiantic River abundance of legal-size lobsters were trawl samplingsites. Overthepast 44years, attributed inparttotheoutbreak ofshellCunner andTautog larval abundances have disease andtoa nearly 5 mm increase inthe significantly increased. Juvenile andadult minimumlegal-size since 1978. Recenttrawl catches ofCunner increased atthe reductions inlandings oflegal-size lobsters Niantic River (NR) station and decreased at harvested by commercial lobstermen in theJordan Cove(JC) trawl stations. Trawl eastern LIScoincided with declines observed catches ofjuvenile andadult Tautog have inthis study, andlobster catches remained significantly increased attheNRstation. No severely depressed inother areas ofLIS sincetrends intheabundance ofjuvenileand adult the Iobster die-off observed in1999. Cunner andTautog wereobserved at IN Long-term trends observed in lobster following theremoval oftheMPS3 intake population characteristics during thepast four cofferdam in1983.

decades (molting, female size atmaturity, Themagnitude ofentrainment isdependent abundance andsize characteristics ofegg- uponeggandlarval densities andcondenser bearing females) appear related towarmer cooling water flows during their periods of ambient seawater temperatures and/or the occurrence. Reductions incooling-water recent outbreak ofshell disease, andnot flows havebeenimplemented atMPSwith MPS operation. Increased ambient water theuseofVFDsduring thepeakperiod of temperature may be responsible forthe Winter Flounder annual spawning. Inaddition increased susceptibility andtransmission of to theUnit 3 fish return, whichwas in diseases affecting lobsters inLIS, which isat operation at unitstart-up in 1986, thesouthern boundary oftheir rangeof impingement impacts werefurther reduced at distribution innearshore waters. MPSwith theinstallation ofa fish return at The numberoflobster larvae entrained Unit 2 inearly 2000.Theimplementation of through theMPScooling water systems was these mitigation measures serve tominimize highly variable andlowinrecent years, dueto Executive Summaryiii

entrainment and impingement impacts at Summerjuvenile abundance fromthe2019 MPS. Niantic River beamtrawl survey waslowfor Annual variations in ichthyoplankton thetime-series and reflected lowlarval entrainment likelyreflected differences in abundance.

spawning and transport ofeggsandlarvae Thenumber oflarvae entrained atMPSisa within LIS. Other factors, suchasextremes measureof potential impact to Winter inseasonalwater temperature, may alsoFlounder. Annual estimates ofentrainment affect larval growth and development. A arerelated toboth larval densities inNiantic number oftemporal and spatial changes were BayandMPScooling-water volume. The identified inthecommunity offishes and 2019entrainment estimate of40 million macroinvertebrates collected intheMPS reflected lower thanaverage Niantic Bay trawl monitoring program. These changes larval densities. An entrainment reduction of wereunrelated totheoperations ofMPS, but 58.6% (based onmaximum permitted flow) in rather wereassociated withshifts inthe 2019canbeattributed totheuseofthe dominance ofindividual taxa fromchanges in variable frequency drives (VFDs) during the habitat, rangeextensions or contractions "Interval"from April 4 toMay19(defined in related warming to a trend in ambient theMPSNPDESpermit astheperiod "from seawater temperature, andchanges infishing April 4 toMay14orthe first dayafter May14 rates andfishing regulations. when theintake water temperature reaches 52 0F, whichever islater, butno later than Winter Flounder Studies June 5") and the Unit 3 refueling outage, which lasted from April 11toMay14.

Various life history stagesof Winter Processes thatareunrelated to MPS Flounder havebeenmonitored since 1976to operation and which occurafter juvenile determine what effect, if any, MPSmayhave Winter Flounder leave shallownursery waters on thelocal Niantic Riverpopulation, during the fall of their first year oflife seemto particularly through theentrainment oflarvae. beoperating toaccount for fewer adults. A Overthepasttwo decades, lowWinterbottleneck inrecruitment may occurduring Flounder abundance levels havebeen foundthelate juvenile life stage (ages-1 and2),

throughout LlS by the Connecticut probably frompredation. Environmental Department ofEnergy andEnvironmental effects, including changes tothe Niantic River Protection (CTDEEP). During the same time habitat (e.g., widely fluctuating eelgrass period, adult Winter Flounder abundance in abundance), a warming trendin regional the Niantic Riverhas remained low.seawater temperature, andinteractions with Reflecting the continued trend of low other (e.g.,

species predation), especially abundance, The A-meanCatchPer Unitduring early life history, arealso important Effort (CPUE) for adult fish (>15cm) captured processes affecting Winter Flounder intheyear-round Trawl Monitoring Programpopulation dynamics.

(TMP) in 2019 was tied with 2 016 and 2018 Results fromWinter Flounder studies asthe lowest (0.6) value since 1976. through 2019 suggest that MPS operations In 2019, overall combinedlarval havehadminimal effects onWinter Flounder abundances inNiantic Bay(sampling sitesbiomass intheNiantic River. Declines in ENandNB) andNiantic River (sites A,B,and stock size havebeengreatly evident on a C)werebelow average for theirrespective regional basis, including LIS,RhodeIsland time-series. All abundances oflarval stagesandall other Southern NewEngland waters.

(Stages 1 4)intheRiver andBaystations Entrainment during thelarval lifestages of werebelow time-series means.Relative to Winter Flounder occurs, however there has theNiantic River, larval abundance inNiantic beenlarge variation intheamount oflarval Bayhasslightly increased inrecent years,mortality andrecruitment inrecent years, both suggesting higher production inLISrather occurring independently ofMPSoperations.

than inestuaries suchastheNiantic River.

Executive Summaryiv