IR 05000271/2011010

IR 05000271-11-010, on 05/09/2011 - 08/30/2011, Vermont Yankee Nuclear Power Station, Contaminated Groundwater Monitoring and Effluent Controls Inspection

ML112630475
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	09/20/2011
From:	Christopher Miller Division of Reactor Safety I
To:	Michael Colomb Entergy Nuclear Operations
References
IR-11-010
Download: ML112630475 (26)

Text

{{#Wiki_filter:?z+**ti September 20, ?ALLMr. Michael ColombSite Vice PresidentEntergy Nuclear Operations, Inc.Vermont Yankee Nuclear Power Station185 Old Ferry RoadP.O. Box 500Brattleboro. VT 05302-0500

SUBJECT: VERMONT YANKEE NUCLEAR POWER STATION - GROUNDWATERMoNlToRlNGINSPECTloNREPoRT05000271i2011010

Dear Mr. Colomb:

On August 30,2011, the U.S. Nuclear Regulatory Commission (NRC) completed aground-water monitoring and radioactive effluents inspection at the Vermont Yankee NuclearFower Station. Based on the results of this inspection, no findings were identified. Theenclosed inspection report documents the results of our inspection. The inslcection results werediscussed with you, and other members of your statf, on August 30,2011.- This inspection wasconducted frorn May 9 to August 30, 201 1 and included an office review of your Conceptual SiteModel (CSM) report entitled ;Hydrogeologic lnvestigation of Tritium in Groundwater" (receivedMay 2f)11), and a revised Offsiie Dose Calculation Manual (received July 201 1). The purposeof tlre inspection was to assess your performance relative to the continued monitoring andremediation of residual onsite groundwater contamination of a previous Advanced Off-Gas pipetunnel leak. The inspectors: (1) reviewed your actions to establish a groundwater monitoringprogram and protocols to monitor and assess the residual contaminant plume condition; (2)ieviewed your development of a CSM on which to base your Long-Term GroundwaterMonitoring Program lLfCWUe), including remediation activities; and (3)examined the methodsapplied to assels and calculate the radiological groundwater effluent release and doseconsequence to members of the public.The inspectors examined activities conducted under your license as they relate to safety andcompliance with the Commission's rules and regulations, and with the conditions of yourlicense. The inspection involved field walkdowns; observations of monitoring wells andgroundwater sampling activities; examination of selected procedures, calculations andexamination of records; interviews with station personnel; and detailed technical discussionswith your staff and contractor on the field monitoring data and its analysis including numericalsimulations of the groundwater system and scenarios.NRC inspectors confirmed that Entergy Nuclear-Vermont Yankee (ENVY): effectively evaluatedthe contaminated groundwater with respect to off-site effluent release limits; properly evaluatedthe resultant radiological impact to the public's health and safety; and complied with allapplicable regulatory requirements and standards pertaining to radiological effluent monitoring,dose assessment, and radiological evaluation. Based on completion of these inspectionactivities, the NRC has determined that the exit criteria contained in the April 5, 2010, Deviation Memorandum (ADAMS Accession No. ML100960321) regarding Vermont Yankee groundwaterinspection activities, have been met and our inspection efforts in this area will return to thosedescribed in the Reactor Oversight Process (ROP) baseline inspection program. In addition, inour May 20,2010, inspection (lR No. 0500027112010006, ADAMS Accession No.ML101400040) conducted in accordance with Temporary Instruction (Tl) 25151173, "Review ofthe lmplementation of the lndustry Groundwater Protection Voluntary Initiative," we assessedwhether your groundwater protection program implemented the elements of the voluntaryindustry Groundwater Protection lnitiative (NEl 07-07) and determined that you had notimplemented all of the necessary procedures and processes elements to respond to a leak orspill of radioactive material to groundwater. Since the time of that inspection, we have foundthat you have now installed all of the necessary procedures and process elements, and fullyimplemented the voluntary industry Groundwater Protection Initiative.While it was determined to not be an issue of regulatory import, the inspectors did assess theetficacy and potential benefits of sampling the construction office building (COB) well. This isdiscussed in the report details.In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, itsenclosure, and your response (if any) will be available electronically for the public inspection inthe NRC Public Docket Room or from the Publicly Available Records component of NRC'sdocument system Agencywide Documents Access and Management System (ADAMS).ADAMS is accessible from the NRC Web site at http://www.nrc.qov/readinq*rm/adams.html (thePublic Electronic Reading Room).Docket No. 50-271License No. DPR-28

Enclosure:

lnspection Report 05000271 /201 1 01 0

w/Attachments:

Supplemental lnformationcc wlEncl.: Distribution via ListServ

SUMMARY OF FINDINGS

lR 0500027112011010; 05/0912011 - 081301201 1 ; Vermont Yankee Nuclear Power Station;Contaminated Groundwater Monitoring and Effluent Controls Inspection.The report covers both the event and follow-up activities related to the tritium groundwatercontamination condition at Vermont Yankee Nuclear Power Station that was previously reportedin lR No. 0500027112010010, January 7 , 2011; and the effluent monitoring and controlsprogram. The NRC's program for overseeing the safe operation of commercial nuclear powerreactors is described in NUREG-1649, "Reactor Oversight Process," Revision 4, datedDecember 2006.This report also covers the licensee's follow-up actions to address gaps that were identified intheir implementation of the voluntary lndustry Groundwater Protection Initiative (Nuclear Energylnitiative 07-07).No findings were identified.Enclosure

EXECUTIVE SUMMARYBackground:On January 7,2Q10, Entergy Nuclear -Vermont Yankee (ENVY) representatives informed theNRC that tritium was detected in a groundwater monitoring well (GZ-3) at an initial concentrationof approximately 17,000 picocuries per liter (pCi/L). ENVY initiated a prompt investigation toidentify the source of the tritium. The investigation included mapping of the groundwater tritiumplume and investigating potential structures, systems, and components, such as buried pipesand tanks, to determine possible sources and causes of the contamination. As a result of thiseffort, ENVY successfully identified the cause (an underground pipe tunnelthat containedleaking components associated with the Advanced Off-Gas (AOG) system) and subsequentlyterminated the source of the contamination in February 2010.On January 25,2010, Region I initiated an inspection of this abnormal release event to examinethe licensee's performance, and determine if the contaminated groundwater affected, or couldaffect, public health and safety. This inspection included the combined efforts of Region l-basedinspectors, as well as a hydrogeologist from NRC's Office of Nuclear Regulatory Research(RES), and the U.S. Geological Survey's (USGS) New HampshireA/ermont Office. Theinspection included continuing review and assessment of ENW's performance and response tothe groundwater contamination event, including the licensee's actions to monitor and assess theon-site groundwater contamination condition sufficiently to assure public health and safety, andprotection of the environment.Status of ENW's Groundwater Contamination Monitoring:As reported in the licensee's Conceptual Site Model (CSM) "Hydrogeologic Investigation ofTritium in Groundwater at Vermont Yankee Nuclear Power Station" report, analysis of thecharacterization and monitoring data indicate that the direction of groundwater flow is toward theConnecticut River. On-site drinking water sources and off-site drinking water sources inVernon, Vermont are upgradient of the tritium plume and would not be affected. Similarly, off-site drinking water sources in Hinsdale, New Hampshire are upgradient and would not beaffected. Based on review of all available information and data to date, there continues to bereasonable assurance that public health and safety has not been, nor is expected to be,adversely affected by the current on-site groundwater contaminant plume condition.ENW's hydrogeological investigations and groundwater flow and transport measurements andmethods were reasonable and accurate in establishing an estimate of the total groundwatereffluent released to the Connecticut River, and the resulting public dose impacts of thesereleases for 2009 and 2010. The calculational method and estimates have been verified by theNRC to also be reasonable and accurate. Dose calculations were reviewed and independentlyverified by the NRC, and determined to be a small fraction of the "As Low As is ReasonablyAchievable" dose objective specified in 10 CFR Part 50, Appendix I for liquid effluent releases(i.e., significantly less than 3 mrem in a year). NRC verified that ENVY appropriately andaccurately reported the abnormal groundwater effluent releases for 2009 and 2Q10, and thuswas in compliance with applicable NRC regulatory requirements.iiiEnclosure NRC Evaluation of ENW's Groundwater Monitoring Performance:Inspectors determined that there has been no impact to public health and safety due tothe groundwater contamination event. Plant-related radioactivity, including tritium hasnot been detected in any on-site or off-site drinking water well (except in theConstruction Office Building (COB) well, which was removed from use in January 2010when the tritium release was detected in a nearby well GZ-3) or at any off-siteenvironmental monitoring location.Inspectors concluded that ENW is continuing to implement groundwater andenvironmental monitoring protocols to provide on-going radiological oversight andassessment of the on-site contaminated groundwater condition to confirm that publichealth and safety is not, nor is expected to be, adversely affected.lnspectors determined that the licensee implemented actions that conformed to theradiological survey requirements of 10 CFR 20.15011o ensure compliance with doselimits for individual members of the public as specified in 10 CFR 20.1302.Inspectors determined that ENW's May 2011 CSM report "Hydrogeologic Investigationof Tritium in Groundwater at the Vermont Yankee Nuclear Power Station," provides aneffective technical basis for determining groundwater flow and transport parameters tos u p po rt on-s ite g ro undwater effluent release determ inations.lnspectors found that ENW has significantly enhanced its on-site groundwatermonitoring since the initial discovery of the tritium plume. ENVY has completed itsLong-Term Groundwater Monitoring Program (LTGWMP), including updating thelicensing basis in the Final Safety Analysis Report (FSAR); and its revision of the OffsiteDose Calculation Manual (ODCM), to include the current characterization of thehydrologic flow and transport conditions and processes related to tritium migration. TheCSM, LTGWMP, and ODCM provide tools for assessing future abnormal releasesinvolving radionuclide transport, groundwater monitoring locations and samplingfrequencies, and a method for calculating public dose based upon site-specific data.Status of ENW's Response to NEI 07-07:ln a previous inspection (lR No. 0500027112010006) in accordance with T125151173, the NRCidentified a number of gaps in Entergy's implementation of the voluntary Industry GroundwaterProtection Initiative as specified in Nuclear Energy Institute (NEl) 07-07 "lndustry GroundwaterProtection lnitiative - Final Guidance Document" issued August 2007. Since the Springof 2010, ENVY conducted a significant amount of hydrogeologic investigative work and programimprovements to implement NEI 07-07 at the site. The NRC reviewed these actions anddetermined that ENW has now fully implemented the voluntary Industry GroundwaterProtection Initiative.IVEnclosure

REPORT DETAILS

2.

RADIATION SAFETY

Cornerstone:

Occupational/Public Radiation Safety (PS)2RS6 Radioactive Gaseous and Liquid Effluent Treatment (71124.06)a. Inspection Scope (1 Sample)The licensee's program was evaluated against the requirement to provide adequateprotection of the public from effluent releases resulting from normal operations of theplant by maintaining the dose to the maximally exposed member of the public as farbelow the dose limits in 10 CFR Part20 and 40 CFR Part 190, as is reasonablyachieveable (ALARA). General Design Criterion 60 in 10 CFR Part 50, Appendix A,requires the control and appropriate mitigation of radioactive materials released as planteffluents. In addition, Paragraph 50.34a (and the associated Appendix l) to10 CFR Part 50 provides dose based design criteria to ensure the effectiveness of planteffluent processing systems in maintaining effluent releases to the plant environsALARA.Event Report and Effluent Report ReviewsThe inspector reviewed the ENW 2009 and 2010 Annual Radiological Effluent ReleaseReports. Both of these reports included documentation of groundwater effluent releasesto the Connecticut River and commensurate doses to the "maximally exposed memberof the public" (a child) with comparison to regulatory limits. The inspector determinedthat the reports were submitted as required by the Off-site Dose Calculation Manual(ODCM)/Technical Specifications. The inspector identified radioactive effluent monitoroperability issues reported by the licensee as provided in effluent release reports, anddetermined that the issues were entered into the corrective action program andadequately resolved.ODCM and FSAR ReviewsThe inspector reviewed changes to the ODCM made by the licensee since the lastinspection, against the guidance in NUREG-1301 ,1302, and 0133, and RegulatoryGuides 1

.109 , 1.21 , and 4.1 . The inspector determined that the licensee had notidentified any non-radioactive systems that had become contaminated as disclosedeither through an event report or are documented in the ODCM since the last inspection.The ODCM and Final Safety Analysis Report (FSAR) were revised to includegroundwater pathway effluent calculations and more detailed description of the sitegroundwater flow and transport parameters. Of note, the ODCM Revision 34, (which isdiscussed in detail in Section 4OA3.3 of this report) contains a groundwater, well-specific, groundwater flux calculation methodology that specifies the basis for the currentgroundwater effluent calculations, as well as providing a basis for any future subsurfaceleak from other locations at the plant.Enclosure

2Groundwater Protection Initiative (GPl) ProqramThe inspector reviewed the reported groundwater monitoring results, and changes to thelicensee's written program for identifying and controlling contaminated spills/leaks togroundwater. In a previous inspection (lR No. 0500027112010006)using Temporarylnstruction (Tl) 25151173, the NRC identified a number of gaps in Entergy'simplementation of the voluntary industry GPI as specified in Nuclear Energy Institute(NEl) 07-07 "lndustry Groundwater Protection Initiative - Final Guidance Document"issued August 2007. Since the Spring of 2010, ENVY has conducted a significantamount of hydrogeologic investigative work at the site, including the installation of 29additional monitoring wells, determination of site-specific groundwater flow and transportconditions and parameters, and establishment of a site-specific groundwater monitoringprogram. The licensing basis has recently been revised that includes the ODCM and theFSAR. ln addition, a management oversight group was established to review thesite-specific groundwater monitoring program and procedures. These programimprovements were reviewed during the Spring and Summer of 2Q11, with respect to thecriteria set forth in NEI 07-07. The review determined that ENW has now fullyimplemented the voluntary industry Groundwater Protection lnitiative.Walkdowns and ObservationsThe inspector walked down selected components of the gaseous and liquid dischargesystems to verify that equipment configuration and flow paths align with the FSARdocumented descriptions, and reviewed and assessed equipment material conditions.For equipment or areas associated with the systems cited above that were not readilyaccessible due to radiological conditions, the inspector reviewed the licensee's materialcondition surveillance records. The inspector walked down those filtered ventilationsystems whose test results were reviewed during the inspection. The inspector verifiedthat there were no conditions, such as degraded high efficiency particulate air(HEPA)/charcoal banks, improper alignment, or system installation issues that wouldimpact the performance, or the effluent monitoring capability of the effluent system. Theinspector determined that the licensee had not made any significant changes to theireffluent release points.The inspector observed the routine processing and discharge of effluents (includingsample collection and analysis). The inspector verified that appropriate effluenttreatment equipment was being used and that untreated groundwater effluent wasdesignated as an abnormal liquid effluent, and its discharge into the Connecticut Riverwas appropriately calculated and reported in accordance with ODCM specifications, andin accordance with 10 CFR Part 50, Appendix I regulatory limits.Samplinq and AnalvsesThe inspector selected effluent sampling activities and verified that adequate controlshad been implemented to ensure representative samples are obtained (e.9. provisionsfor sample line flushing, vessel recirculation, composite samplers, etc.). The inspectordetermined that the facility was not routinely relying on the use of compensatoryEnclosure 3sampling, in lieu of adequate system maintenance, based on the frequency ofcompensatory sampling since the last inspection.The inspector reviewed the results of the inter-laboratory comparison program to verifythe quality of the radioactive effluent sample analyses. The inspector verified that theinter-laboratory comparison program include hard-to-detect radioisotopes asappropriate. Groundwater sample measurements included selected back-upmeasurement comparison from an outside commercial laboratory to provide lower limitsof detection than onsite laboratory tritium measurements, and to confirm laboratoryquality control.lnstrumentation and EquipmentEffluent Flow Measuring InstrumentsThe inspector reviewed the methodology that the licensee uses to determine the effluentstack and vent flow rates. The inspector verified that the flow rates are consistent withradiological effluents technical specifications (RETS)iODCM or FSAR values, and thatdifferences between assumed and actual stack and vent flow rates do not affect theresults of the projected public doses.Air Cleaning SystemsThe inspector verified that surveillance test results since the previous inspection forTechnical Specification required that ventilation effluent discharge systems (HighEfficiency Particulate Air (HEPA) and charcoalfiltration) meet Technical Specificationacceptance criteria.Dose CalculationsThe inspector reviewed one gaseous waste discharge permit. The inspector verified thatthe projected dose to members of the public were accurate and based on representativesamples of the discharge path. The inspector evaluated the methods used to determinethe isotopes in the source term to ensure all applicable radionuclides were included,within detectability standards. The inspector reviewed the current 10 CFR Part 61analyses to ensure hardto-detect radionuclides were included in the source term.The inspector reviewed changes in the licensee's offsite dose calculations since the lastinspection. The inspector verified that the changes were consistent with the ODCM andRegulatory Guide 1

.109 . The inspector reviewed meteorological dispersion anddeposition factors used in the ODCM and effluent dose calculations to ensureappropriate factors were being used for public dose calculations. The inspectorreviewed the latest Land Use Census and verified that changes have been factored intothe dose calculations.Enclosure

b.4GPI lmplementationThe inspector reviewed the identified leakage or spill events, and the ENVY entriesrecorded in their decommissioning file as required by paragraph 50.75 (g) in10 CFR Part 50. The inspector verified that the January 7, 2010, Advanced Off-Gas(AOG) leak event was documented in the decommissioning file, which also includedrecords of trace contaminants besides tritium, that were detected in soil around the priorAOG leak location and in soil samples taken during on-site well drilling operations.The inspector verified that on-site groundwater sample results and a description of anysignificant on-site leaks/spills into groundwater for each calendar year were documentedin the Annual Radiological Environmental Operating Report (AREOR) for radiologicalenvironmental monitoring program (REMP) or the Annual Radiological Effluent ReleaseReport (ARERR) for the RETS.Problem ldentification and ResolutionThe inspector verified that problems associated with the effluent monitoring and controlprogram were being identified by the licensee at an appropriate threshold and wereproperly addressed for resolution in the licensee corrective action program.Findinqs and ObservationsNo findings were identified.OTHER ACTIVITIESProblem ldentification and ResolutionBackgroundIn January 2010, following the licensee's detection of on-site groundwater tritiumcontamination, the NRC inspection team determined that the licensee's subsurfaceConceptual Site Model (CSM) of the Vermont Yankee (W) site, which had beendeveloped in response to the NEI 07-07 GPl, was not sufficiently detailed. The NRCteam found the initial CSM did not: (1) provide sufficient specificity to identify the sourcearea for the H-3 (tritium) leak; (2) include fundamental definition of the groundwater flowand transport units (e.g., depths and extents); and (3) include the hydraulic and transportrelationships and parameters. Based upon hydrogeologic investigations begun inresponse to the tritium leak, ENW significantly updated the CSM to account for site-specific groundwater flow and transport processes, properties and conditions asdocumented in their May 2011 report "Hydrogeologic lnvestigation of Tritium inGroundwater."The initial detection of the. tritium leak was in monitoring well GZ-3 (see Attachment A,Figure 1) located on the Connecticut River bank. The source of the contamination wasnot readily discernable due to an absence of monitoring wells adjacent to the plantsystems, structures and components (SSC) that contain radioactive fluids, asEnclosure4.4c42 b.5recommended in the NEI 07-07 Groundwater Protection Initiative. Subsequently, ENWexamined numerous candidate SSCs for possible sources of the leak, and then installeda series of groundwater monitoring wells to aid in identifying the tritium leak source. ByFebruary 6,2010, monitoring well GZ-10 was installed next to the AOG building wheresubsurface pipes within a pipe tunnel conveyed fluids carrying radionuclides. The GZ-10monitoring data was instrumental in determining the specific leak location which was theunderground concrete pipe tunnel associated with the AOG system. The initial tritiumconcentration at GZ-10 was approximately 2.5 million pCi/L. By November 15, 2010, thelicensee completed installation of 29 new groundwater monitoring wells to identify theextent of the tritium plume and its behavior (i.e., flow directions and rates).Inspection ScopeThe licensee initiated Condition Report, CR-WY-2010-0541, on February 8, 2010, toassess and correct gaps in their implementation of the NEI Industry GroundwaterProtection Initiative, NEI 07-07, based on findings from an NEI peer review onJanuary 25,2010; and the subsequent identification of deficiencies by an NRCinspection conducted in accordance with Tl2515-173. The status of this condition reportwas previously reviewed and documented in Inspection Report No. 05000271/2UAA06issued on May 20,2010 (ADAMS Accession No. M1101400040).During the current inspection, the NRC inspection team reviewed the remaininggroundwater monitoring program elements which were incomplete at the time of theearlier inspection. The NRC inspection focus was to confirm and assess ENW's actionsrelative to the establishment, implementation, and maintenance of a Long-TermGroundwater Monitoring Program (LTGWMP). The LTGWMP was designed to overseeand assess the current groundwater contamination conditions, and have the capability todetect new or changed groundwater conditions and potential future releases.Findinqs and ObservationsNo findings were identified.The NRC team determined that the licensee did establish a set of site-specificg roundwater monitoring program procedures. Ad ministrative Procedure PP-G PP-7605,"Groundwater Protection Program," established a station management review group, fheGroundwater Protection Expert Panel(GPEP), to oversee and approve the groundwatermonitoring program processes and procedures to include: (1) contamination risk profile,including the assessment of station work practices that may adversely affectgroundwater contamination; (2) site-specific groundwater monitoring plan; and (3) theupdating of the groundwater-related licensing documents, such as the FSAR, to reflectcurrent hydrogeology information and analyses, and the ODCM, to indicate groundwatermonitoring locations and frequencies, and a groundwater effluent pathway dosecalculation methodology.The GPEP approved the current set of groundwater monitoring procedures; thegroundwater monitoring plan; a revision to FSAR Section 2.4 to update the hydrogeologydescription of the site; and Revision No. 34 of the ODCM, which captures theEnclosure 40A3.1a.6groundwater effluent release calculation methodology. NRC has determined that ENVYhas satisfactorily completed the previous outstanding items in CR-WY-2010-0541.Event Follow-up (lP 71153 - 1 sample)Groundwater Tritium ContaminationInspection ScopeThe scope of this inspection included a continuing review of ENW's groundwatermonitoring program to assess the residual on-site groundwater tritium contaminationconditions and ENW's remediation efforts, as well as the licensee's actions to completetheir LTGWMP to effectively assess the current groundwater conditions, and their abilityto detect any future leaks that may impact the groundwater both onsite and offsite. Inaddition to NRC health physics specialists and NRC hydrogeologists, a U.S. GeologicalSurvey (USGS) supervisory hydrogeologist from the USGS New HampshireA/ermontOffice also participated in this inspection.During this inspection effort, the inspectors met and discussed groundwater, geophysicalsurvey, and tritium migration issues with ENW technical and management personneland contractors; reviewed data, records, technical drawings, and procedures; observedmonitoring well activities including remedial extractions and processing; and conducteddirect inspection and observed the licensee's and their contractor's performance overthe course of several on-site visits. NRC inspectors also reviewed ENW's remedialactions to extract contaminated groundwater from the highest concentration center of theplume, which began on March 25,2010.NRC inspectors reviewed ENW's investigations; numerous site hydrogeology,geophysical and radionuclide survey activities; measurement of groundwater gradientsin the overburden and bedrock hydrogeologic units; estimates of hydraulic and transportparameters; numerical simulation studies of groundwater flow at the site for a variety ofpumping well scenarios; and ENW's determination of the extent of radionuclide release.The inspectors also reviewed the use of this information to support the calculation ofradiological liquid effluent releases from the previous AOG tunnel leakage via thegroundwater pathway, and calculation of the corresponding safety impact of radiationdose to the public due to this abnormal groundwater effluent release.Findinqs and ObservationsNo findings were identified.Tritium Contamination MeasurementAfter the AOG pipe leak was terminated on February 15,2010, the monitoring wellsample results tracked the tritium contamination movement east across the site towardsthe Connecticut River. Based on ENW's hydrogeologic investigations which includedwell hydraulic tests, soils closest to the AOG pipe leak were more porous with higherhydraulic conductivity that allowed for more rapid groundwater flow and subsequentEnclosureb.

7tritium migration over a few months (e.9., GZ-10, GZ-20, and GZ-15), while the lessporous soils to the east, were less conductive (lower hydraulic conductivity) togroundwater flow and subsequently, the tritium contamination transport slowed as theplume progressed further east to the river bank, with a migration time interval on theorder of one to two years (e.9., GZ-14, GZ-3, and GZ-4). Trend plots of the tritiumplume migration demonstrating this response are included in Attachment A of this report.The groundwater monitoring well data continues to support the CSM of predictedgroundwater flow in the overburden and shallow water table units.Near the end of 2010, monitoring well GZ-24 indicated measurable tritium contaminationwhich peaked in early 2011 at about 9,000 pCi/L (below the Environmental ProtectionAgency (EPA) drinking water standard for tritium of 20,000 pCi/L). Subsequently,another nearby monitoring well, GZ-6, also revealed trace levels of tritium (plots of theseresults are provided in Attachment A). The CSM does not account for this discoverybased on the existing tritium plume migration, and ENW promptly initiated aninvestigation to identify its source. The monitoring frequency of these two wells wasincreased to several times per week. Weekly status calls with the NRC and the State ofVermont were held to discuss these investigation results. Five subsurface pipe lineswere identified in the immediate area of these two wells. One of these was an AOGpassive drain line which was determined by ENVY to be unnecessary for continued plantoperations. This line was subsequently permanently removed from service. Otherparallel efforts, that are ongoing at the time of this inspection report, include tracer gasinjection and leak detection monitoring of the other four subsurface pipe lines. Based onthe prompt retiring of the AOG drain line, samples from monitoring wells GZ-24 and GZ-6 since early April 2011, have returned to less than detectable radioactivity thusexhibiting no indication of a continuing leak to groundwater. Although the original causeof the tritium activity has not been concluded at this time, the actions taken by ENW torespond to the tritium activity detected in GZ-24 and GZ-6, by initiating an investigationto address the potential leak, was a practical demonstration of the recently completedLTGWMP (groundwater monitoring program) in action, and appears to have successfullyminimized a groundwater effluent release.Hvd roqeoloqv Assessment1.0 Conceptual Site Model (CSM)ENW's "Hydrogeologic lnvestigation of Tritium in Groundwater at Vermont YankeeNuclear Power Station" (CSM) was completed in May 2011. The development andtesting of the CSM was reviewed during this inspection. Although not an NRC regulatoryrequirement, the development and testing of a CSM was identified in NEI-07-07,"lndustry Groundwater Protection Initiative - Final Guidance Document," dated August2007, which directs nuclear plant operators to: "Perform hydrogeologic and geologicstudies to determine predominant groundwater flow characteristics and gradients." TheCSM provides detailed information derived from site and regional groundwater studiesconducted between January and December 2010. This study included a review ofprevious site hydrogeological information; the installation of 29 additional onsitegroundwater monitoring wells outfitted with pressure transducers to determinegroundwater gradients and flow directions; and down-hole geophysical surveys andEnclosure Imeasurements conducted in six onsite and offsite bedrock aquifer drinking water wells.This work followed an iterative investigative approach to determine the location andextent of the tritium plume and its behavior including well specific concentrations andgradients. The study further investigated the vertical depth of the tritium plume in theoverburden (soil overlaying the bedrock), and limited investigation of the bedrockaquifer. The CSM provided effective horizontal definition and spatial relationships in theoverburden but did not determine the depth of tritium plume penetration into the bedrockaquifer down gradient of the plant.To investigate the vertical extent of the tritium plume, ENVY developed six deepoverburden monitoring wells that terminated just above the bedrock interface(specifically wells GZ-12D, GZ-13D, GZ-1 4D, GZ'18D, GZ-19D, and GZ-22D)'Subsequent groundwater samples showed a wide range of tritium concentrations withsome of these wells indicating less than 2,000 pCi/L. This range along with groundwatertransducer data indicating an upward and horizontalflow to the Connecticut River,implies the potential for very little downward migration to the underlying bedrockinterface. However, sample results from two wells (GZ-12D and GZ-22D), indicatedconcentrations of 65,000 and 500,000 pCi/L respectively, suggesting the potential fordownward migration to the underlying bedrock aquifer if local groundwater gradients anddiffusion favor it. Limited packer testing was conducted in the COB well using a series ofpacked off intervals corresponding to interpreted fracture locations from the down-holegeophysical surveys. Sampling only was conducted in the lowest two intervals of thewell. lnitially, ENW expressed concern that there may be a vertical leak path from theoverlying tritium plume in the overburden unit to the bedrock aquifer by way of the COBwell annulus and around the bottom of the steel well casing. Therefore ENVY directedthat further testing and sampling cease. Since that time, ENVY refurbished the COBwell to prevent potential leakage past the well casing, and to establish the COB well as apotential environmental monitoring well. ENVY has indicated that there are technicalreasons why low-flow sampling would not be feasible to collect representative samples,and that sampling may create downward migration of the tritium into the bedrock aquifer.However, inclusion of the COB wetl in ENW's LTGWMP could serve as a sentinelwellto provide an early indicator of contaminant migration to the bedrock aquifer, anddetailed information for consideration in remediation decisions.NRC and USGS scientists are confident that there are existing methods to collectsufficient volumes at appropriate well depth locations for water sampling in theretrofitted COB well. Based upon details provided on the COB retrofitting in the ENWCSM report, sampling in the present COB well would not lead to vertical migrationaround the well casing into the bedrock aquifer. The sand pack around the inside PVCmay well attenuate tritium emanating from one of the contributing fractures but wouldnot preclude confidence in detecting tritium in high concentrations (above the LowerLimit of Detection) in the retrofitted COB well. There are existing industry methods thatwould be suitable for sampling the COB wellfor hydraulic gradients and the presence oftritium.Enclosure 92.0 Remediation ProgramENVY implemented a remediation program on March 25,2010, to extract contaminatedgroundwater in the highest concentration center of the plume using well EW-1A. Thisactivity was suspended on November 8, 2010, after removal of the targeted 307,000gallons of tritiated groundwater. Following discussions with Vermont State officials, thisremedial activity was restarted on December 30,2010, from GZ-14 and GZ-22D, whichat that time represented the groundwater well locations with the highest tritiumconcentrations. The initial extraction activity removed approximately 300 mCi orapproximately 10 percent of the total tritium activity, and assisted in decreasing theplume's concentration and extent in and around the AOG concrete pipe tunnel. Theobjective of the licensee's remediation program is to minimize releases of tritium to theConnecticut River. Based on the very low radiation dose hazard associated with theresidual groundwater tritium plume, there are no NRC requirements for activeremediation.3.0 Long-Term Groundwater Monitoring ProgramThe "Vermont Yankee Groundwater Monitoring Plan" was approved by the GPEP onJune 28, 2011. In this document, each monitoring well is described, categorizing eachas either a sentinel or perimeter well. These well categories are related to the"streamtube groundwater model" in the ODCM. The perimeter wells are close to the"perimete/' (boundary) of the Vermont Yankee site, and are located near the shorelineof the Connecticut River bank, where the sampled tritium concentrations are used asrepresentative values for each defined "stream tube" in effluent release calculations.Sentinel wells are close to potential subsurface sources of radioactivity such asunderground pipes or tanks, and are designated for monthly sampling frequency, whilethe perimeter wells are designated for quarterly sampling frequency. Based on thegroundwater transport conditions as described in the CSM, these sampling frequenciesappear reasonable and support the required quarterly effluent release calculations.Annual licensee review of the groundwater monitoring program, and continued ongoingreview of water table measurement results to confirm the validity of the CSM providereasonable assurance of the efficacy of the established groundwater monitoringprogram. As mentioned previously in this report, any change in the groundwater flowconditions, such as cessation of extraction well activities, may trigger a need for morefrequent monitoring and hydrogeologic evaluation to reestablish baseline conditions.ENVY continues to implement groundwater and environmental monitoring protocols thatprovide on-going radiological oversight and assessment of the onsite residualcontaminated groundwater sufficient to confirm that public health and safety has notbeen affected.Off-site Dose Calculation ManualThe revised ODCM includes listing of site-specific hydrologic parameters taken from theCSM report, and a simplified "stream tube" mathematical model based on Darcy's law,to calculate and evaluate current and future groundwater pathway liquid effluentreleases. These estimates assess potential impacts to the public and environment in aEnclosure 10clear and simple manner. The revised ODCM (Revision 34 dated July 8, 2011)documents the W groundwater release model which uses the "stream tube" concept toidentify and partition the groundwater pathways in the overburden units, and estimateradionuclide fluxes to the accessible environment at each of the perimeter well locationsalong the Connecticut River. This calculation method establishes a specific hydraulicconductivity at each perimeter well and uses actualwater table data to determinehydraulic gradients in the calculation of groundwater flux through each stream tube.The resulting groundwater flow is multiplied by the quarterly sampled tritiumconcentration from the applicable groundwater monitoring well (i.e., perimeter well) toestimate the tritium flux. These stream tube estimates are then totaled to determine thecumulative groundwater radioactive effluent release to the environment for eachcalendar quarter, as well as calculation of the dose impact to the public, as previouslyestablished in the ODCM.The revised ODCM also identifies the groundwater potable wells to be sampled andtheir sampling frequency as part of the REMP. The revised ODCM indicates that theSouthwest Well will be sampled quarterly for gamma isotopic and tritium analyses.Inspectors observed that the COB well, which is directly below the observed andmonitored tritium contaminant plume, is not identified for sampling in the REMP portionof the ODCM. Tritium concentrations exceeding background levels but well below theEPA drinking water standard (i.e., 20,000 pCi/L) were observed in the lower portion ofthe COB well during an earlier source characterization campaign prior to itsrefurbishment. At the interface between the bedrock aquifer used for service water atW, and the overlying "deep overburden" unit, tritium was sampled in GZ-22D with aconcentration exceeding 500,000 pCi/L. Subsequently, ENW agreed to use GZ-22Das an extraction well to minimize the groundwater effluent release. The COB well hasbeen retrofitted as an environmental monitoring well, however, the licensee has noplans to use it as such at this time. lf used as a sentinel well it could provide an earlyindicator of migration of radionuclides into and within the bedrock aquifer.The revised ODCM identifies the minimum sampling frequency and radionuclideanalyses. All the sentinel wells are specified with monthly sampling frequency, which isappropriate since the "stream tube" analysis uses monthly concentration data. Theperimeter wells are to be sampled quarterly. Due to possible episodic changes ingroundwater recharge and hydraulic gradients, some of the perimeter wells couldencounter significant changes in concentrations within the quarterly period, which maynot be detected. This may be especially relevant if the extraction well pumpage ceasesin wells, GZ-145 and GZ-22D. lnspectors determined that monitoring perimeter wellson a monthly basis within the tritium plume, at least initially following cessation ofextraction activities until the groundwater flow conditions become re-established, wouldensure sufficient groundwater monitoring to capture this transient condition and the newequilibrium of monitored natural attenuation.The analysis of "subsurface Groundwater Pathways to the Connecticut River" section ofthe ODCM uses a "stream tube" approach. This approach provides for horizontalflowand transport for the "shallow Overburden" and "Deep Overburden" hydrogeologic units.It fails to mention or consider the "Bedrock Potable Aquife/' hydrogeologic unit. There issignificant uncertainty in whether there has been or could be tritium migration into orEnclosure 11future radionuclide transport to and within this unit. The CSM mentions the bedrockpotable aquifer but relies upon the assumption that there are "constant upwardgradients" from this unit to the overlying "Deep Overburden" unit. Limited monitoringdata in the past supports this assumption. However, without monitoring in the COB weltfor hydraulic gradients there is no opportunity to confirm tritium migration to or within thebedrock potable aquifer. Therefore some uncertainty remains.Radiolooical AssessmentNotwithstanding some of the remaining uncertainties in the licensee's CSM and NRC'sobservations referenced above, the groundwater gradient and flow direction at W inboth the overburden and bedrock aquifers is towards the Connecticut River. There is nocurrent direct drinking water ingestion pathway to any member of the public in thecurrent tritium plume flow path. ENW's original calculation estimated a total tritiumgroundwater release for this event of approximately 2.79 Ci. The original estimateassumed a shallow plume without a vertical dispersion. Based on additionalinvestigations that included installation of six deep overburden wells, a verticalbroadening of the plume was observed prior to its entering the Connecticut River. Thisadditional groundwater flux area contributed to a slight increase in the effluent releasecalculation to approximately 4.2 Ci. The perimeter monitoring wells along theConnecticut River shoreline peaked during November of 2010 and have been decliningsince that time. Therefore the additional tritium being released into the river during 2011is expected to decrease from the 2010 values.The revised ODCM specifies individual stream tube measurement calculations thatinclude each monitoring well that borders the Connecticut River (i.e., perimeter wells).Based on this approach, the Vermont Yankee groundwater liquid effluent releasesreported in the 2009 and 2010 Annual Radioactive Effluent Release Reports indicated0.4 Ci of tritium was released in 2009 resulting in 0.00005 mrem per year to a maximallyexposed member of the public (child), and 3.84 Ci of tritium was released in 2010resulting in a maximally exposed dose of 0.00056 mrem per year to a child. The doseassessment provided a detailed ingestion pathway and age-group specific doseassessment, as specified in the ODCM. The calculations were reviewed and verified toadhere to the specifications of the ODCM, and the dose assessment methodologyreflected in Regulatory Guide 1.109, "Calculation of Annual Doses to Man from RoutineReleases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFRPart 50, Appendix 1." These calculations are in accordance with NRC regulatoryrequirements, and represent a very smallfraction of NRC liquid effluent annual pubticexposure limit of 3 mrem per year.4OAO Meetinqs. includinq ExitThe inspectors presented the preliminary inspection results to Mr. M. Colomb, and othermembers of ENW staff, at an exit meeting on August 30, 2011. The inspectors verifiedthat none of the information in this report is proprietary. One Entergy drawing depictingthe onsite groundwater monitoring well map is provided in Attachment A to this report.Enclosure A-1Attachment AFigure 1, Vermont Yankee Groundwater Monitoring Well Map** lndicates a drawing obtained from ENW for purposes of inspection review and assessment.Attachment A Vermont Yankee Groundwater Monitoring Well TritiumDataAttachment AVY Monitoring Well Results.<tGZ-t +-GZ-z +-GZ-3 +GZ-4 +GZ-5 <-GZ-6 +GZ-7-cz_g -cz_Lo -aFcz_I! +Gz_12 .*-Gz_L3 +GZ_13D +GZ_L <DGZ-L4D-tsGZ-15 aGZ-t6 -GZ-17 +GZ-19 {-GZ-19D -*-GZ-2O-r<- GZ-ZL +lFGZ-12D -.&"- GZ-18 "-** GZ-18D

• GZ-22D .-. "*".. GZ-23 *** GZ-24--, GZ-25GZ-26 GZ-27300000025000002000000B lsoooooo.1000000500000O) Ol O O O O O O O O O O O O rl e{ ri rl Fl r'{ FlO O r.t F.{ t-{ r'{ r{ r{ Fl r{ F{ rl r{ r{ r'{ el ri r'{ F { r{ F{oo o oo oo oo o oo oo o oo oo ooN N N NN N N N N N N N (\I (\ N NN N N N N\. \. \- \. \. \- \. \- \. \. \- \- \. \. \. \. \- \. \. \.F N N I\ F I\ I\ N N I\ T\ F N T\ T\ N N N N F T\t-{ r-l el r{ -l e{ Fl r'{ r-t rl rl r{ Fl r{ Fl Fl r'{ -l Fl ri ii\. \. \. \ \. \- \. \. \- \- \ \- \- \. \- \. \. \- \. \-F{ N rl N m + lJ1 (o F 6 Ol O t{ N r'{ N (r1 <f lJ) r.O t\t-l r-l rl F{ Fl qto3ofpci/rtstsNoqnooooooooooooooooLL/!712009L2lt7/2009Llt7/20LO2/t7120!03/L7/20!04177/20L0sl!7l2OLO6/L7/20LO7/L7lzot08lL7/20t0s/t7/20!oL0/77/2010tL/L7l2OLOL2/L7/20t0tlLT/2O!!2/L7/207L3/77/20tL4/!7/20LtslL7/2OL!6/L7lzOt!7/L7/20!Lr++tlooo6)oryNryryrytsPNJN'IJAurtsO()J3!.c3!c3oa)o5FToa=o VY Perimeter Well Tritium Trend500000J 400000IcL 3ooooo2000001000000-+-GZ-3+GZ-4+GZ-L AA'clooF.t el F\. \ F.{riN\-Fl e.l r.{FF{NNNt-{ rlmsf::::;:::::i:::iN N N F l\ el r{ F.{ N N N F F t\ f\r-{ rl Fl r{ Fl \ \ \ F{ Fi F{ r{ d Fl F{\. \- \- \- \. O rl (\ \. \- \ \. \ \ \iLn l.o F
• Ol t{ r'l Fl Fl (\l m sf ln (o FA-4Attachment A Vermont Yankee GZ-24, GZ-6"f"o'rrun* "td*^C*-GZ-6t"-. "fd"ud,t*"-GZ-2420000 t18000 l16000 I14ooo I12000 l.loooo I8000 l6000 l4ooo I2000 l0L.*p',^9\"*.Attachment A B-1ATTACHMENT B

SUPPLEMENTAL INFORMATION

KEY POINTS OF CONTACT

Licensee Personnel

S. Skibniowsky, Environmental and Effluents Chemistry Specialist

J. Hardy, Chemistry Manager

M. Shaw, Principal Hydrogeologist, GZA GeoEnvironmental, Inc.

LIST OF ITEMS

OPENED, CLOSED AND DISCUSSEDOpened and ClosedNone.

LIST OF DOCUMENTS REVIEWED

Procedures:CHRP-LWD-2610-01, Rev. 1, "liquid Waste Disposal"OP 2611, Rev. 50, "Stack Effluent Sampling and Analysis"OP 2612, Rev. 9, "Burning of Radioactively Contaminated Used Oil"EN-CY-1 1 1, "Groundwater Monitoring"EN-CY-109, Rev. 2, "sampling and Analysis of Groundwater Monitoring Wells"EN-CY-108, Rev. 3, "Monitoring of Non-radioactive Systems"EN-RP-113, Rev. 4, "Response to Contaminated Spills/Leaks"OP 4605, Rev. 45, "Environmental Radiation Sampling and Analysis"CHAD-7605-01, "Groundwater Monitoring Plan"PP-GPP-7605, "Groundwater Protection Program"EGAD-7605-01, "Groundwater Contamination Risk Profile""Hydrogeologic lnvestigation of Tritium in Groundwater at Vermont Yankee Nuclear PowerStation" (CSM report) May 2011Condition Reports:cR-wY-2009-2317cR-wY-z009-2889cR-wY-2010-4181cR-vrY-2011-1483cR-wY-2o11-2545Attachment B

B-2Other DocuTentsVermont Yankee Groundwater Monitoring Plan, Revision 1Final Safety Analysis Report, Section 2.4Off-Site Dose Calculation Manual, Revision 34Mack, T.J., Belaval, Marcel, Degnan, J.R., Roy, S.J., and Ayotte, J.D.,2011, Geophysical andflow-weighted natural-contaminant characterization of three water-supply wells in NewHampshire: U.S. Geological Survey Open-File Report 2011-1019, 20 p., athttp://pubs. usgs. gov/of l 201 1 l 1 01 I l .ALARAAOGAREORARERRCFRciCOBCRCSMCSTENVYEPAFSARGPEPGPIgpmHEPALTGWMPMNAmremNEINRCNRRODCMPSPSBRCAREMPRESRETSODCMpCi/LSSCUSGSVY

LIST OF ACRONYMS

As Low As Reasonably AchievableAdvanced Off-GasAnnual Radiological Environmental Operating ReportAnnual Radiological Effluent Release ReportCode of Federal RegulationsCuriesConstruction Office BuildingCondition ReportConceptual Site ModelCondensate Storage TankEntergy Nuclear Vermont YankeeEnvironmental Protection AgencyFinal Safety Analysis ReportGroundwater Protection Expert PanelGroundwater Protection Initiativegallons per minuteHigh Efficiency Particulate AirLong Term Groundwater Monitoring ProgramMonitored Natural AttenuationmilliremNuclear Energy Institute, Inc.Nuclear Regulatory CommissionNuclear Reactor RegulationOffsite Dose Calculation ManualPublic Radiation SafetyPlant Services BuildingRoot cause analysisRadiological Environmental Monitoring ProgramNuclear Regulatory ResearchRadiological Effluents Technical SpecificationsOff-site Dose Calculation Manualpico-Curies per LiterSystems, Structures, and ComponentsUnited States Geological SurveYVermont YankeeAttachment B }}