ML13119A083

Requests for Additional Information for the Environmental Review of the Sequoyah Nuclear Plant License Renewal Application

ML13119A083
Person / Time
Site:	Sequoyah
Issue date:	05/10/2013
From:	David Drucker License Renewal Projects Branch 2
To:	James Shea Tennessee Valley Authority
Drucker D 415-6223
References
Download: ML13119A083 (22)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 May 10, 2013 Mr. Joe W. Shea Vice President, Nuclear licensing Tennessee Valley Authority P.O. Box 2000 Soddy-Daisy, TN 37384

SUBJECT:

REQUESTS FOR ADDITIONAL INFORMATION FOR THE ENVIRONMENTAL REVIEW OF THE SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION

Dear Mr. Shea:

By letter dated January 7,2013, Tennessee Valley Authority, submitted an application pursuant to Title 10 of the Code of Federal Regulations (CFR) Part 54, to renew the operating licenses DPR-77 and DPR-79 for Sequoyah Nuclear Plant, Unit 1 and 2, for review by the U.S. Nuclear Regulatory Commission (NRC or the staff). The staff is reviewing the information contained in the license renewal application and has identified areas where additional information is needed to complete the review. The enclosure lists the environmental requests for additional information (RAls), and the Severe Accident Mitigation Alternatives (SAMA) RAls.

These RAls were discussed with Mr. Henry Lee, and a mutually agreeable date for the response is within 60 days from the date of this letter for the environmental RAls and 30 days for the SAMA RAls. If you have any questions, please contact me at 301-415-6223 or bye-mail at david.drucker@nrc.gov.

Sincerely, Cj;)Jo Ji<.

David M. Drucker, Sr. Project Manager Projects Branch 2 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328

Enclosure:

Requests for Additional Information cc w/encl: Listserv

May 10, 2013 Mr. Joe W. Shea Vice President, Nuclear Licensing Tennessee Valley Authority P.O. Box 2000 Soddy-Daisy r TN 37384

SUBJECT:

REQUESTS FOR ADDITIONAL INFORMATION FOR THE ENVIRONMENTAL REVIEW OF THE SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION

Dear Mr. Shea:

By letter dated January 7, 2013, Tennessee Valley Authority, submitted an application pursuant to Title 10 of the Code of Federal Regulations (CFR) Part 54, to renew the operating licenses DPR-77 and DPR-79 for Sequoyah Nuclear Plant, Unit 1 and 2, for review by the U.S. Nuclear Regulatory Commission (NRC or the staff). The staff is reviewing the information contained in the license renewal application and has identified areas where additional information is needed to complete the review. The enclosure lists the environmental requests for additional information (RAls), and the Severe Accident Mitigation Alternatives (SAMA) RAls.

These RAls were discussed with Mr. Henry Lee, and a mutually agreeable date for the response is within 60 days from the date of this letter for the environmental RAls and 30 days for the SAMA RAls. If you have any questions, please contact me at 301-415-6223 or bye-mail at david.drucker@nrc.gov.

Sincerely, IRA!

David M. Drucker, Sr. Project Manager Projects Branch 2 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328

Enclosure:

Requests for Additional Information cc w/encl: Listserv DISTRIBUTION: See following pages ADAMS Accession No.: ML13119A083 OFFICE LA:DLR PM:RPB2:DLR BC:RPB2:DLR NAME IKing D Drucker D Wrona DATE 5/9/13 5/9/13 5/10/13

SEQUOYAH NUCLEAR PLANT, UNIT 1 AND 2 LICENSE RENEWAL APPLICATION ENVIRONMENTAL REQUESTS FOR ADDITIONAL INFORMATION

1. Hydrology - Surface Water Resources Provide the following information in order to allow for a thorough review and evaluation of the impacts of license renewal on surface water resources.

a. National Pollutant Discharge Elimination System-Regulated Discharge Compliance

i. Describe the current status of Sequoyah Nuclear Plant's (SQN's) National Pollutant Discharge Elimination System (NPDES) permit renewal (No. TN0026450, expires October 31,2013), including, as applicable, milestones achieved, projected timeframe for issuance, etc. If available, provide a copy of the NPDES permit renewal application for docketing.

ii. The rationale section of SQN's February 2011 NPDES permit indicates that metal cleaning wastes were last discharged to the Metal Cleaning Waste Pond in December 2001, which in turn flows to the Low Volume Waste Treatment Pond.

1. Describe the nature of the metal cleaning waste (i.e., what process generated it and from what plant system(s>>?

2. Have there been more recent discharges and/or does Tennessee Valley Authority (TVA) anticipate the need to direct future discharges to the pond?

3. Has shallow groundwater sampling been conducted in the vicinity of the pond and, if so, provide a summary of the monitoring results.

b. Thermal Discharge and Receiving Water Methodology and Data

i. Provide a description of the in-stream flow and thermal discharge (mixing zone) compliance computational (modeling) method(s) as discussed during the April 9, 2013, site audit hydrology tour.

1. Include the latest calibration report as discussed during the tour.

2. Also, specifically provide the following information for the models of thermal discharge flow rate and mixing zone temperatures:

a. model description including temporal and spatial discretization and initial and boundary conditions;

b. model calibration approach; and

c. data used to calibrate the most recent model version.

ii. During the site audit, it was indicated by TVA staff that the Tennessee Riverl Chickamauga Reservoir has warmed over the past 15 years.

1. Provide any study(s) or data that depict this trend.

2. Has a predictive analysis of this trend been performed, including any contingency analysis performed relative to SQN operations (e.g.,

ENCLOSURE

-2 need to add cooling capacity)? Describe and provide a summary of any such analyses.

3. Will the existing cooling capacity be sufficient to address climate warming scenarios through 2041?

iii. Is there an atmospheric warming trend in the Tennessee River valley that can be correlated with river/reservoir temperatures noted above? Provide long term temperature measurements from SON meteorological stations that depict this trend (include data for average daily high temperatures and nighttime low temperatures).

c. Thermal Discharges and SON Operational Considerations

i. During the site audit hydrology tour. TVA staff stated that SON has come close to exceeding but has not exceeded any thermal (e.g., T-max or delta-T) discharge limits.

1. Confirm this statement and describe.

2. In addition. provide additional information surrounding the near exceedances and the operating/ambient conditions under which the near exceedance(s) occurred.

3. Specifically. provide the following information for each standard exceeded or approached. as appropriate (i.e., for the timeframe going back to and encompassing the 2006-2007 drought):

a. standard/limit of concern;

b. measurement value that violated/approached the standard;

c. date, time. location for each such incident; and

d. hourly discharge, stage, temperature at the time of the violation/near exceedance.

ii. Has there been any observable trend in the number of days SON has had to operate in "helper mode" over the SON operational history?

1. Describe and provide the following information when helper mode (cooling towers) was invoked:

a. date, times when helper mode was operating;

b. number of towers in operation;

c. discharge through cooling towers; and

d. temperature of effluent before river release including measurement location.

2. Provide data to cover a sufficiently long timeframe to include the periods of warmest river temperatures and lowest river discharges (e.g., drought).

3. For the historical trend, provide the number of days (or hours?) of helper mode for each year of operation.

iii. How do river stage, discharge, and influent temperature affect the thermal discharge temperature?

1. How does helper mode affect thermal discharge temperature?

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2. Have there been any trends in the plant thermal discharges and temperatures over the SON operational history? If so, describe them.

3. Related to the above, provide the following information for the thermal discharge and temperature (before release into the river):

a. measurement location;

b. dates and times; and

c. thermal discharge and temperature (15-minute or hourly data) data covering a sufficiently long timeframe to include periods of warmest river temperatures and lowest river discharges (e.g., drought).

4. For the historical trend: (daily or weekly or monthly), provide average thermal discharge temperatures.

iv. How effective has the river/reservoir been in attenuating elevated temperatures from the thermal discharge through the diffuser pipes?

1. Provide an explanation of how river stage, discharge and upstream (without SON impact) temperature affect the magnitude and distribution of temperatures upstream and downstream of the diffuser pipes, and outside of the main channel? .

2. Related to the above, provide archived data to explain the interactions of SON thermal discharges with the reservoir.

3. Provide the following information on river temperature, discharge, and stage:

a. measurement locations including upstream background, SON stations, Hiwassee River and tributaries;

b. dates and times of measurements; and

c. river discharge, stage, and temperature (15 minute or hourly data) covering a sufficiently long timeframe to include the periods of warmest river temperatures and lowest river discharges (e.g., drought).

4. For the historical trend (daily or weekly or monthly), provide average river discharge, stage, and temperature.

v. Is upstream surface flow on the Tennessee River an important thermal transport mechanism?

1. Is wind shear the principal driver for upstream surface flow? If so, provide a description.

2. Provide the following information:

a. depth-dependent river velocity measurements;

b. surface wind velocity measurements;

c. conditions for winds from downriver predominating (diurnal, seasonal and interannual);

d. surface wind velocity (15 minute or hourly data) covering a sufficiently long timeframe to include periods of strongest upriver winds and longest period of upriver winds.

3. For the historical trend: (daily, weekly or monthly), provide wind velocity frequency distribution from the SON meteorological station.

-4 vi. Have there been any changes to river water quality regulatory limits (especially thermal) or measurement protocols other than those described in the Environmental Report (ER)? If so, provide history of all changes including:

1. previous and revised standard; and

2. date and rationale for change.

vii. Provide the following information from non-routine intensive monitoring campaigns including:

1. sampling locations, dates, and times; and

2. river temperature, discharge, velocity, and stage.

viii. With respect to extreme operational considerations, is there a maximum fraction of river flow that can be safely diverted to the plant? At the lowest predicted river discharge, what fraction of the river flow will pass through SON?

d. Ambient Water Resources Considerations

i. If available, provide a summary of ambient river water quality monitoring data for sites(s) nearest SON outfall 001 (covering the last 5 years).

ii. Provide a description of operational and maintenance activities (or projects) anticipated to be undertaken during the license renewal term (as possible, identify expected timeframe, location(s) affected, acres disturbed, and activity/project duration).

e. References Requested for Docketing

i. Submit the last 5-years of surface water withdrawal/discharge reports (Le.,

Water Withdrawal Registration forms) submitted to the Tennessee Department of Environment and Conservation (TDEC).

ii. SaN's Section 26a permit (as referenced in the ER).

iii. Submit copies of agency correspondence relating to Notices of Violation (NOVs) to TVA SON, including nonconformance notifications, or related infractions received from regulatory agencies associated with NPDES permitted discharges, sewage systems, groundwater or soil contamination, including spills, leaks, and other inadvertent releases of fuel solvents, chemicals, or radionuclides (covering past 5 years).

2. Hydrology - Ground Water Resources Provide the following information in order to allow for a thorough review and evaluation of the impacts of license renewal on ground water resources.

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a. Provide a map showing the extent and concentration of tritium contamination in the groundwater.

b. Provide a map that shows the locations of those wells that have been sampled for tritium.

c. Provide a table that contains the names of wells that have been sampled for tritium and identifies for each well, the geologic material that it monitors i.e., (a) soil/structural fill, (b) bedrock or (c) both.

d. Provide a table of well names, data sampled, and tritium concentrations for all of 2012 and up to the present.

e. Provide the results of tritium age dating that has been completed for groundwater samples. Also provide the name of the well sampled and the date when the sample was obtained.

f. For the proposed period of licensed activities, provide a description of where tritium contamination in the groundwater is predicted to move in the future and the rate of movement.

g. NRC Regulations (10 CFR 51, Subpart A, Table 8-1) require the staff to conduct additional analysis of groundwater use conflicts for those plants who use greater than 100 gpm (24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />s/day, 7 days/week) of groundwater for service water, potable water, and dewatering activities. Provide an estimate of the total rate of groundwater withdrawal by sump pumps (i.e., dewatering activities) located throughout the facility.

3. Cultural Resources Provide the following information in order to allow for a thorough review and evaluation of the impacts of license renewal on cultural resources.

a. Section 106 requirements of the National Historic Preservation Act - All of the following were discussed during the site audit. This information is being requested formally as it is essential to NRC staff for describing the procedures the applicant has in place regarding cultUral resources as well as to describe the cultural affected environment at SON. This information will assist the staff in fulfilling Section 106 requirements of the National Historic Preservation Act. Docketing should follow guidelines from NRC regarding sensitive cultural resources location information.

When submitting cultural resources information, do not include maps or coordinates of site location information.

i. Provide a description of the process or procedures TVA uses to ensure cultural resources are considered in project planning or ground-disturbing activities during normal operation of SON. Include a description of the process or procedures that TVA implements upon inadvertent discovery of cultural resources during ground-disturbing activities.

-6 ii. Provide a description of cultural resource training for TVA staff. The e-mail to Steve Cole regarding this subject, discussed in the cultural resources during the site audit, would be sufficient.

iii. Provide ongoing updates on the status of proposed stabilization and consultation activities for site 40HA22. Provide an update prior to the issuance of the draft supplemental environmental impact statement (SEIS) and an update prior to the publication of the final SEIS (FSEIS).

4. Protected Species and Habitats Provide the following information in order to allow for a thorough review and evaluation of the impacts of license renewal on protected species and habitats.

a. Because the Commission approved the NRC staff's proposal to publish a final rule revising 10 CFR 51 on December 6,2012 (ML12341A250), the NRC staff is addressing the new and revised issues in its National Environmental Policy Act (NEPA) reviews effective immediately. In its environmental review, the NRC will consider transmission lines as defined in Table B-1 of 10 CFR 51, Subpart A, Appendix B, under the revised final rule, which states that in-scope transmission lines are those lines that "connect the nuclear power plant to the substation where electricity is fed into the regional power distribution system and transmission lines that supply power to the nuclear plant from the grid" (see footnote 4 in the revised Table B-1, which starts on page 123 ofthe Federal Register notice associated with SECY-12-0063 (ML110760045>>.

i. Clarify where the substation is located that connects the transmission lines to the regional grid and which portions of the 12 lines described in Section 3.2.10.1 of the ER are in scope for the license renewal review according to this revised definition.

b. Sections 9.1.1 and 9.1.3.16 of the ER points the reader to TVA's June 2011 FSEIS for documentation of Endangered Species Act Section 7 consultation and TVA's assessment of impacts to Federally-listed species. Pages 3-69 of TVA's FSEIS states that TVA completed a Natural Heritage Database query for a 6-mile radius around SQN in March 2010, which is documented in FSEIS Table 3-15.

i. Because this database query is now 3 years old, confirm that this table remains accurate and that each of the species in the table remains relevant to the review according to the revision definition of in-scope transmission lines in Table B-1 of 10 CFR 51, Subpart A, Appendix B, in the 2012 revised final rule.

ii. Provide any new protected species occurrence data, if applicable, or confirm that new data does not exist.

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c. Provide records from the TVA Natural Heritage Database of all the protected resource records which were identified in the ER (all records within a 6-mile radius of SON and a few selected records which lie just outside that radius within 1/4 mile that have a high potential to occur within 6 miles of SON). During the site audit, TVA staff referred to this as an "EO Dump Report."

d. Section 2.5.1 of the ER states that suitable habitat for the large-flowered skullcap and pink mucket mussels may occur along some portions of the in-scope transmission lines. Do these statements remain true under the revised definition of in-scope transmission lines in Table B-1 of 10 CFR 51, Subpart A, Appendix B, in the 2012 revised final rule?

e. Section 2.5.1 of the ER states that one dromedary pearlymussel individual was identified in the late 1970s approximately 3 miles from SON. However, during the ecology discussion at the environmental site audit, TVA staff indicated that this statement was not accurate. Provide an updated statement regarding the occurrence of the dromedary pearlymussel to resolve this discrepancy.

f. Section 2.5.1 of the ER states that pink mucket mussels were identified in the early 1960s approximately 5.5 miles from SON. Provide more information on this record of occurrence as well as a reference to the study under which the mussels were identified, if available.

5. Terrestrial Ecology Provide the following information in order to allow for a thorough review and evaluation of the impacts of license renewal on terrestrial ecology.

a. Section 2.4 of the ER, and portions of the TVA (2011) SON final EIS and the TVA (2009) steam generator environmental assessment (EA), describe various terrestrial resources on the SEa site, including herbaceous vegetation, invasive species, wetlands, common wildlife, and heron rookeries.

i. If available, provide any additional reports, field notes, or updated surveys for these terrestrial resources, other than the ER, TVA (2011) SON final EIS, or the TVA (2009) steam generator EA.

b. In addition, provide a description of the methodology used to conduct the desktop or field surveys.

c. Section 4.9.5 of the ER states that TVA has not planned to conduct construction activities during the period of extended operations in undisturbed areas.

i. Describe typical construction activities that may occur in previously disturbed areas during the period of extended operations.

ii. If available, provide any environmental evaluations related to such activities.

d. Docket the following documents:

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i. Tennessee Valley Authority Division of FFWD. Forestry Bulletin 143, June 1969. (Note that this document is reference #7 from Section 1.2 in the TVA 1974 Final Environmental Statement).

ii. Henry, T. H. 2011 a. Results of the Tennessee River Valley Shorebird Initiative. Final Report. December 2011.

iii. TVA. 1974a. Final Environmental Statement Sequoyah Nuclear Plant Units 1 and 2. February 13, 1974.

iv. TVA. 1974b. Cooling Tower Contract M02712_0044459421, Invitation, Bid and Acceptance, Guaranteed Data, Performance Under Specified Design Conditions. TVA Reference No. 74C53-83659.

6. Meteorology, Air Quality, and Noise Provide the following information in order to evaluate the impacts of license renewal on air quality meteorology, air quality, and noise.

a. Meteorology and Air Quality

i. Provide a summary of SON, Units 1 and 2, annual greenhouse gas emissions (GHG). Identify sources and provide GHG amount emitted (C02equivalent) for each source and calculations. Include GHG emissions such as carbon dioxide (C0 2), sulfur hexafluoride (SF 6 ), hydroflurocarbons (HFC),

perflurocarbons (PFC). Include stationary combustion source emissions, mobile combustion source emissions, refrigerant leakage emissions, emissions from switchyard, and other sources.

ii. Provide the associated annual air emissions (air pollutant and amount) for the most recent 5 years of operation for air permitted emissions sources at SON.

Identify sources and provide amount emitted (include particulate matter (PM),

PM 1o , PM 2.5 , carbon monoxide (CO), nitrogen oxides (NO x), sulfur dioxide (S02), lead (Pb), volatile organic compounds (VOCs), hazardous air pollutants (HAPs), and CO2 equivalent (C0 2e ) emissions) and calculations.

iii. Identify any expected upgrade/replacement activities for equipment/operation (e.g., diesel generators, diesel pumps) that could increase air emissions over the license renewal period. Provide fuel consumption, estimated use, expected annual air emissions (air pollutant and amount), and expected date(s) of installation.

iv. Provide the following meteorological information from the data recorded at SaN's meteorological facility. The meteorological data should include the most recent 5 years for which data is available. Provide the following information:

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1. mean monthly and annual temperatures;

2. mean monthly precipitation and annual precipitation; and

3. provide seasonal and annual summary wind statistics in the form of wind direction and speed frequency distribution tables and wind roses.

Discuss predominant wind direction and speed by season and annual average, local terrain features affecting wind direction and speed, and provide a value for annual average wind speed and peak wind gust.

v. References Requested for Docketing:

1. SON. 2007g. Hours of Operation Annual Report, S58 070503 800 Air Correspondence. May 3, 2007.

2. SON. 2008e. Hours of Operation Annual Report, S58 080501 800 Air Correspondence. May 1, 2008.

3. SON. 2009h. Hours of Operation Annual Report, S58 090507 801 Air Correspondence. May 7,2009.

4. SON. 2011 h. Hours of Operation Annual Report. May 12, 2011.

5. SON. 2012e. Hours of Operation Annual Report. May 10, 2012.

b. Noise

i. Identify noise sources at SON, Units 1 and 2, and in the vicinity of SON.

ii. Provide information about any noise complaints for the most recent 5 years resulting from plant operation.

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7. Severe Accidents Mitigation Alternatives

a. Provide the following information regarding the probabilistic risk assessment (PRA) used for the severe accidents mitigation alternatives (SAMA) analysis.

Basis: Applicants for license renewal are required by 10 CFR 51.53(c)(3)(ii)(L) to consider SAMAs if not previously considered in an environmental impact assessment, related supplement, or environmental assessment for the plant. As part of its review of the SON SAMA analysis, NRC staff evaluates the applicant's treatment of internal events and calculation of core damage frequency (CDF) in the Level 1 PRA model. The requested information is needed in order for the NRC staff to reach a conclusion on the sufficiency of the applicant's Level 1 PRA model for supporting the SAMA evaluation.

i. ER Section E.1.1 states that the SON PRA models reflect the SON configuration and design as of November 30, 2009. Identify and discuss any completed or planned changes to the plant design or operation since these dates that might impact the SAMA analysis.

ii. Describe the primary reasons for the differences in major CDF contributors between the two units as shown in Tables E.1-1 and E.1-2 as well as the significant differences in SAMA CDF reductions between the two units as shown in Tables E.2-1 and E.2-2.

iii. It is noted that the loss of offsite power (LOOP) initiator contributes only 1 to 2% to the CDF while station blackout (SBO) contributes 10 to 13%. Also the Level 1 importance analysis does not include any events for failure of the emergency diesel generators. Explain the reason that the LOOP contribution is greater than the SBO contribution to CDF and the reason for not including the failure of the emergency diesel generators in the Level 1 analysis.

iv. Discuss the modeling of consequential LOOP events in the SON PRA and, if not considered, estimate the impact of this omission on the selection of cost beneficial SAMAs.

v. ER Section E.1.4.5 describes the CAFTA, Revision 0, as a complete revision of the model that involved converting the model from the RISKMAN software platform into CAFTA format. Clarify the extent to which models, data, success criteria, etc. from the prior version were utilized in the CAFTA version. Was there a peer review of any RISKMAN PRA versions?

vi. Identify any systems shared between the two SON units and how the availability/unavailability of these systems is incorporated in the SON PRAs during normal operation, shutdown, and dual unit trips.

- 11 vii. It is stated that no changes were made to the Level 1 CAFTA Rev. 0 PRA to produce the SQN SAMA Level 1 model. The peer review is stated to have been performed on the January 14, 2011, version of the SQN CAFTA PRA, while the Rev. 0 model is given in Table E.1-17 as having an issue date of June 3, 2011. Apparently, the peer review was performed on an earlier version of the CAFTA PRA. Provide the CDF and large early release frequency (LERF) for the model that was peer reviewed. Confirm that all of the changes described in the resolution of the peer review findings in Section E.1.4. 7 have been implemented in the Revision 0 model and a summary of the more significant changes to the peer reviewed model to make the Revision 0 model.

viii. For the peer review results discussed in ER Section E.1.4.7:

1. For Finding 1-10; what is the significance on the results of the SAMA analysis of the assumption that the operator is successful in providing feedwater to the ruptured steam generator?

2. For Finding 1-14, clarify if the data used for the Revision 0 PRA has been updated to exclude the post maintenance test data. If not, what is the impact on the results?

3. For Finding 4-3, was the impact of spraying from glycol system failures included in the analysis?

4. Finding 1-15 identifies certain deficiencies in the general transient event tree including lack of a separate tree for SBO events and not addressing the operation of systems such as charging and auxiliary feedwater (AFW) following power recovery. Provide more information on this finding and its resolution to address these two issues.

ix. Anticipated transient without scram (ATWS) sequences make up a relatively high and significant contribution to CDF and are dominant contributors to offsite risk. Discuss the reasons for this high frequency and potential additional SAMAs to mitigate this risk.

x. Discuss the modeling of dual unit initiators such as LOOP or failure of shared support systems.

xi. For both units, the internal flooding initiator contributed more than half of the CDF. Discuss any influence of the occurrence of internal flooding at one unit with the PRA modeling at the other unit.

b. Provide the following information relative to the Level 2 analysis. Basis: Applicants for license renewal are required by 10 CFR 51.53(c)(3)(ii)(L) to consider SAMAs if not previously considered in an environmental impact assessment, related supplement, or EA for the plant. As part of its review of the SQN SAMA analysis, NRC staff evaluates the applicant's treatment of accident propagation and radionuclide release in the Level 2 PRA model. The requested information is needed in order for the NRC staff to reach a

- 12 conclusion on the adequacy of the applicant's Level 2 PRA model for supporting the SAMA evaluation.

i. Provide a brief history of the current SQN Level 2 PRA model development.

ii. In several places in the ER, the accuracy of the Level 2 model is discussed.

For example, in Section E.1.2.1 it is stated:

"However, the quantification of the non-LERF end states is not as accurate as would be obtained from a rigorous Level 2 model."

and "The event tree nodes and split fractions were reviewed to ensure that the consequences, in terms of release frequencies, would be larger than would be expected with a fully developed Level 2 modeL" and in Section E.1.2.3.2 "Quantification of the SQN SAMA Model results in release frequencies that are over predicted ..."

Provide a discussion of the bases for these statements and the reasons for the inaccuracies as well as steps taken to insure that any inaccuracies do not adversely impact the SAMA identification or cost-benefit analysis process.

iii. What is the frequency for the intact containment event tree (CET) end state?

iv. While SEQSOR was used to determine the fission product release fractions, a phenomenological based code such as MAAP is necessary for other inputs, such as available operator action time windows and the evaluation of accident progression to determine containment failure probabilities and release timing. Briefly describe the scope of these additional analysis performed for the SON PRA and identify the code or codes used including the version.

v. The discussion of the LERF end state in ER Section E.1.2.1 states "A bypass release does not have an opportunity to undergo scrubbing within the containment. However, the SGTR tube rupture cases may have an opportunity for scrubbing."

The steam generator tube rupture (SGTR) initiating event does not appear in the Levell/importance analysis results. Discuss further the reasons for the apparent lack of importance of SGTR initiators and treatment of SGTRs (both those as an initiating event and those induced) including the release categories which incorporate both scrubbed and unscrubbed SGTRs.

- 13 vi. The subcategory definitions given in ER Tables E.1-13 and E.1-14 appear to exclude some combinations of the listed characteristics such as SBO versions of Release Categories (RCs) I and III and transient contributors similar to RC Va. Provide a discussion of the development of the release categories and of the logic used to insure that all containment failure CET endpoints are incorporated.

vii. Provide a discussion of the representative accident scenarios used for the determination of the release characteristics for each of the release categories including:

1. a description of each scenario;

2. the bases for the selection of the representative scenarios; and

3. steps taken to insure that the benefit of a SAMA is not underestimated for situations in which a SAMA impacts scenarios that could have a lower (non-dominant) frequency but significantly larger consequence than that for the representative scenario.

viii. Provide a listing of the characteristics used to describe each representative scenario for each RC as input to the SEQSOR emulator.

ix. Provide a discussion of the steps taken to ensure the technical adequacy of the SON Level 2 model and analysis.

x. Provide an expanded discussion of the mapping of Level 1 sequences to the Level 2 analysis. Describe how the plant damage state (PDS) bins are utilized in the Level 2 analysis.

xi. It is noted that ER Section E.1.2.3.2 indicates that RC V includes small containment isolation failures and that Tables E.1-13 and E.1-14 indicate the frequency of this RC makes up approximately 10% of the total frequency of all RCs and is larger than the frequency of RC I. Because it is expected that a small isolation failure would not prevent large early containment failure due to early failure causes such as hydrogen detonation or direct containment heating, describe the Level 2 modeling of small isolation failures to show that the potential for large early releases is properly considered for small isolation failure sequences.

c. Provide the following information with regard to the treatment and inclusion of external events in the SAMA analysis. Basis: Applicants for license renewal are required by 10 CFR 51. 53( c)(3)(ii)(L) to consider SAMAs, if not previously considered, in an environmental impact assessment, related supplement, or EA for the plant. As part of its review of the SON SAMA analysis, NRC staff evaluates the applicant's treatment of external events in the Level 1 PRA model. The requested information is needed in order for the NRC staff to reach a conclusion on the sufficiency of the applicant's Level 1 PRA model for supporting the SAM A evaluation.

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i. The technical evaluation report (TER) of the SQN individual plant examination of external events (IPEEE) concludes that there are several weaknesses in the fire analysis that could lead to optimistic results. These are the inappropriate combining of severity factors and non-suppression probabilities and the assumption of independence of several human actions in the main control room fire analysis. Also, it was observed that the cable spreading room was screened out due to lack of fire sources. While the latter appears to not be strictly true, the cable spreading room fire analyzed in the SQN IPEEE assumes no safe shutdown equipment failure. Discuss these observations and the impact of them on the SQN fire CDF.

ii. Provide a summary of the conservatisms and non-conservatisms in the SQN IPEEE fire analysis in light of the above TER review and the recent research and guidance reported in NUREG/CR-68S0, specifically in the areas of hot short probabilities, fire ignition frequencies, and non-suppression probabifities, that indicates the fire analysis methodologies utilized for the IPEEEs may underestimate fire risk. Discuss the impact on the evaluation of potential SAMAs for fire risk contributors in addition to the use of the external events multiplier.

iii. Provide a discussion of the impact of the recent external flooding developments on the conclusions that external flooding is not a significant contributor to external risk at SQN and need not be considered further in the SAMA assessment.

d. Provide the following information relative to the Level 3 PRA analysis. Basis:

Applicants for license renewal are required by 10 CFR S1.S3(c)(3)(ii)(L) to consider SAMAs, if not previously considered, in an environmental impact assessment, related supplement, or EA for the plant. As part of its review of the SQN SAMA analysis, NRC staff evaluates the applicant's analysis of consequences in the Level 3 PRA model. The requested information is needed in order for the NRC staff to reach a conclusion on the acceptability of the applicant's Level 3 PRA model for supporting the SAMA evaluation.

i. ER Table E.1-18 provides the estimated population distribution within a SO-mile radius for 2041. Describe the current population distribution surrounding SQN.

ii. ER Section E.1.S.2.6 states meteorological data from 200S resulted in the highest release quantities. Confirm that the highest release quantities correspond to the highest public dose risk and highest averted cost risk.

Describe the modeling of precipitation events, including boundary preCipitation modeling, and precipitation influence on calculated doses.

Quantify the amount of missing meteorological data in 2003, 2004, and 200S, which were estimated using data interpolation or replacement.

iii. As described in ER Section E.1.S.2. 7, the maximum preparation time of 10S minutes was applied for the 1O-mile emergency planning zone. This

- 15 value was described to include 75 minutes for notification and 30 minutes for preparation. Provide information to support the total delay time to leave of 105 minutes. Clarify if the evacuation analysis considered generic information for the average evacuation speed or site specific information based on the current (or projected) number of people required to evacuate via existing roads.

iv. Evacuation sensitivity is presented in ER Table E.1-23. Small effects on dose were shown for evacuation fractions of 90,95 and 99.5% (or 10, 5, and 0.5% of individuals who do not evacuate). Considering roughly half of the calculated population dose risk is attributed to late releases, explain the causes of the reported small effects on dose from evacuation. Briefly describe where members of the public would be evacuated in terms of the distance from the plant. Clarify if radiological exposure to evacuees at those destinations was accounted for in the analysis

e. Provide the following information with regard to the selection and screening of Phase I SAMA candidates. Basis: Applicants for license renewal are required by 10 CFR 51.53(c)(3)(ii)(L) to consider SAMAs, if not previously considered, in an environmental impact assessment, related supplement, or EA for the plant. As part of its review of the SQN SAMA analysis, NRC staff evaluates the applicant's basis for the selection and screening Phase I SAMA candidates. The requested information is needed in order for the NRC staff to reach a conclusion on the adequacy of the applicant's Phase I SAMA selection and screening process for the SAMA evaluation.

i. ER Section E.1.1 indicates that the results of the importance analysis were reviewed down to a risk reduction worth (RRW) of 1.005 for the identification of potential cost beneficial SAMAs. This corresponds to a potential maximum benefit including uncertainty of $97K for SQN Unit 1 and $88K for Unit 2.

This precludes potential simple procedure changes that according to Section E.2.3 might cost $50K. Discuss the potential for added candidate SAMAs down to a RRW corresponding to a simple procedure change.

ii. As stated in Section E.1.1.1 and the SQN IPEEE safety evaluation report (SER), the limiting plant component (HCLPF) is 0.23g which is less than the review level earthquake (RLE) of 0.3g. The TER (Table 4.1) supporting the SER indicates there are 12 components with HCLPFs below the RLE. While the NRC concluded that the SQN IPEEE meets the intent of Generic Letter GL 88-20, Supplement 4, the result above indicates that there are some components which should be examined for the identification of potential cost beneficial SAMAs.

The TVA responses to the Fukushima Near-Term Task Force Report Recommendation 2.3: Seismic Response Report states that "The statuses of alilPEEE outliers which were not corrected through physical modification were resolved through re-calculation of the

- 16 appropriate HCLPF capacities. All IPEEE outliers are now resolved and have minimum HCLPF Capacities above 0.3g."Discuss the actions taken on these 12 items, the final HCLPF values, if available and the potential for cost-beneficial SAMAs for these SON components. Also, provide a discussion of the current status of the seismic reevaluation and walkdown activities being undertaken in response to the Fukushima Dai-ichi event.

iii. Review of the fire CDF values in ER Table E.1-16 indicates that the CDF for the top 14 fire areas is greater than that, which if mitigated, would have a benefit of the minimum hardware cost of $100,000. While four of these fire areas are addressed by SAMA 287, provide a discussion of the potential for cost beneficial SAMAs for the other fire areas.

iv. One of the screening criteria given in ER Section E.2.2 is:

"Excessive Implementation Cost: If the estimated cost of implementation is greater than the modified Maximum Averted Cost-Risk, the SAMA cannot be cost beneficial and is screened from further analysis."

If the uncertainty multiplier of 2.5 was not considered in performing this screening discuss the impact on the screening results.

v. The dispositions given in the correlation of risk significant terms to SAMAs in ER Tables E.1-3 and E.1-4 do not include Phase II SAMAs for some of the events. While it is stated that Phase I SAMAs have been implemented (to the extent that the implementations are reflected in the current PRA), the following events appear significant enough to warrant further review for additional SAMAs that mitigate the specific failures represented by these events.

1. For events PTSFD1PMP _0030142 and PTSFR1PMP_0030142, representing the random failure of the turbine driven AFW pump to start or run, 4 Phase I SAMAs to improve pump reliability are stated to have been implemented. These failures contribute about 8% and 1%

of the CDF, respectively. Discuss the implemented SAMAs and the potential for other candidate SAMAs to mitigate these failures.

2. For event AFWOP3, representing the failure of operators to depressurize and cool down the vessel in order for low pressure injection to be used following a small or medium loss of coolant accident with failure of high pressure recirculation, three Phase I SAMAs to improve the capacity to cool down and depressurization are stated to have been implemented. Discuss the implemented SAMAs and the potential for other candidate SAMAs to mitigate this operator error.

3. For event TM_1 PMP_003001AS, representing the maintenance unavailability of the turbine driven AFW pump, two Phase I SAMAs to

- 17

4. improve the reliability of the AFW turbine driven pump have been implemented. Discuss the implemented SAMAs and the potential for other candidate SAMAs to mitigate this unavailability.

5. For event TM_1 PMP0030118A, representing the maintenance unavailability of motor driven AFW Pump 1A-A, one Phase I SAMA to improve the reliability of the AFW pumps and valves has been implemented. Discuss the implemented SAMA and the potential for other candidate SAMAs to mitigate this unavailability.

6. For event PMAFD1 PMP_00300118, representing the random failure of motor driven AFW Pump 1A-A failing to start, two Phase I SAMAs are stated to have been implemented. Discuss the implemented SAMAs and the potential for other candidate SAMAs to mitigate this failure.

vi. For basic events %1 RTIE and %1TTIE representing a general reactor trip and a turbine trip, respectively, it is stated in ER Tables E.1-3 and E.1-4 that Phase II SAMA 218, to increase the reliability of power supplies, has been evaluated. Discuss the potential for other SAMAs to reduce the general reactor trip and turbine trip frequency.

vii. One source of Phase I SAMAs is indicated to be the October 2010 Watts Bar, Unit 2, severe accident management deSign alternatives SAMDA submittal.

Consider any additional cost-beneficial SAMAs (SAMDAs) identified during the review of this submittal as documented in TVA responses to RAls and the draft NRC staff review of the SAMDA analysis (if available).

f. Provide the following information with regard to the Phase II cost-benefit evaluations.

Basis: Applicants for license renewal are required by 10 CFR 51.53(c)(3)(ii)(L) to consider SAMAs, if not previously considered in an environmental impact assessment, related supplement, or EA for the plant. As part of its review of the SON SAMA analysis, NRC staff evaluates the applicant's cost benefit analysis of Phase II SAMAs. The requested information is needed in order for the NRC staff to reach a conclusion on the acceptability of the applicant's cost estimations for individual SAMAs and cost benefit evaluation.

i. Identify what is included and what is not included in the SON specific cost estimates including such things as contingency, replacement power, lifetime maintenance, etc.

ii. Discuss the impact of sharing engineering and design cost between units for the SON specific costs as well as the costs based on other plant's SAMA analyses.

iii. Provide the release category frequencies for each Phase II SAMA.

- 18 iv. The benefit for SAMA 8 (increase training on response to loss of two 120V AC buses) was determined by eliminating the inadvertent actuation of safety injection. Identify any other impacts of the loss of the two buses that would benefit from the training. Also, the RRW for loss of a single bus is given, but there is no value for the common cause failure of both buses. Discuss this omission.

v. The impact of adding the gas-turbine in SAMA 14 is only a 0.35% and 0.1%

reduction in CDF. Explain why this so small considering that SSO is about 10% of the CDF.

vi. The title for SAMA 68 on ER page E-122 indicates that an auxiliary feed pump is being added while the text and the title of the SAMA in Table E.2-1 indicates that it is a normal motor driven feed pump. Clarify the intent of this SAMA and revise the discussion of this SAMA to distinguish between main feedwater pumps and AFW pumps.

vii. For SAMA 70 (install accumulators for turbine-driven AFW pump flow control valves), it is indicated that a bounding analysis was performed by eliminating the failure of the existing flow control valves. Confirm that this analysis included the failure due to lack of air.

viii. For SAMA 83 (add a switchgear room high temperature alarm), it is stated that a bounding analysis was performed by eliminating the failure of the ventilation fans in the 480V transformer room, thereby maintaining a proper temperature in the room. Confirm that this room is the only one impacted by loss of switchgear heating, ventilation, and air conditioning (HVAC).

ix. For SAMA 103 (institute simulator training for severe accident scenarios), it is stated that a bounding analysis was performed by reducing the failure probability of important human actions and that the human error probability (HEP) dependency factors for important human actions were also improved.

Identify the HEPs reduced and the amount of the reduction.

x. For SAMA 161 (provide backup ventilation for the emergency diesel generator rooms, should their normal HVAC supply fail), the cost is given as

$1 M with the source being the minimum hardware cost. The minimum hardware cost is $100K. Explain this discrepancy.

xi. For SAMA 188 (implement modifications to the compressed air system to increase the capacity of the system), describe the modification in more detail to support the cost estimate of $2.8M. Note that the cost for SAMA 87 involving replacing the service and instrument air compressors is $900K.

Explain this difference.

xii. If the results of SAMA 268 (perform an evaluation of the CCS/AFW area cooling requirements) indicate that area cooling is required, will alternative SAMAs, other than SAMA 289 (install backup COOling system for CCS/AFW

- 19 xiii. space coolers), be added to mitigate these area cooling failures?ln ER Tables E.2-1 and E.2-2, the source for the cost of SAMA 284 (improve reliability of pressurizer safety relief valves) is given as "Minimum Hardware Cost" while the value is given as $1.6M versus the stated minimum hardware cost of $1 OOK. Correct the source for this cost and describe what makes up this cost.

xiv. Explain how the reduction in population dose and off-site economic cost was determined for SAMA 287 involving mitigating internal fire events.

g. For certain SAMAs considered in the SON ER, there may be lower-cost or more effective alternatives that could achieve much of the risk reduction. In this regard, provide an evaluation of the following SAMAs. Basis: Applicants for license renewal are required by 10 CFR 51.53(c)(3)(ii)(L) to consider SAMAs, if not previously considered, in an environmental impact assessment, related supplement, or EA for the plant. As part of its review of the SON SAMA analysis, NRC staff considers additional SAMAs that may be more effective or have lower implementation costs than the other SAMAs evaluated by the applicant. The requested information is needed in order for the NRC staff to reach a conclusion on the adequacy of the applicant's determination of cost benefical SAMAs.

i. For basic event HASE2 (and others) involving reactor coolant pump (RCP) seal cooling failures, consider automatically tripping of RCPs on loss of CCW.

ii. For SAMA 289 involving installing backup cooling for the component cooling water system (CCWS)/AFW space coolers, consider opening doors and/or stage portable fans, etc. unless this is addressed by SAMA 160.

iii. For Events %690.0-A01-1_067_S and %669.0-A01_067_S representing the initiator for emergency raw cooling water (ERCW) spray events in room 690.0-A 1 and room 669.0-A01 in the auxiliary building which results in the loss of AFW pumps, consider installing spray shields for these events.

iv. For SAMA 71 (install a new condensate storage tank), discuss the alternative of using a portable pump to provide water for the AFW system.

v. For SAMA 161 (provide backup ventilation for the emergency diesel generator rooms, should their normal HVAC supply fail), consider using temporary ventilation, opening doors, etc.

vi. Provide an evaluation of a SAMA to purchase or manufacture a "gagging device" that could be used to close a stuck-open steam generator safety valve for a SGTR event prior to core damage.

SUBJECT:

REQUESTS FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION DISTRIBUTION:

HARD COPY:

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PUBLIC RidsNrrDlr Resource RidsNrrDlrRpb1 Resource RidsNrrDlrRpb2 Resource RidsNrrDlrRerb Resource RidsNrrDlrRarb Resource RidsNrrDlrRasb Resource beth.mizuno@nrc.gov brian. harris@nrc.gov john .pelchat@nrc.gov gena. woodruff@nrc.gov siva.lingam@nrc.gov wesley.deschaine@nrc.gov galen.smith@nrc.gov scott.shaeffer@nrc.gov jeffrey.hamman@nrc.gov craig.kontz@nrc.gov caudle.julian@nrc.gov joel. rivera-ortiz@nrc.gov steven. vias@nrc.gov