ML073460410

Request for Extension of Completion Dates for Corrective Actions Required by NRC Generic Letter (GL) 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water

ML073460410
Person / Time
Site:	Catawba
Issue date:	12/07/2007
From:	Morris J Duke Energy Carolinas, Duke Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL-04-002
Download: ML073460410 (22)

Text

Duke JAMES R MORRIS rEnergy.

Vice President Catawba Nuclear Station 4800 Concord Road / CNO0 VP York, SC 29745-9635 803 831 4251 803 831 3221 fax December 7, 2007 U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTENTION: Document Control Desk

Subject:

Duke Power Company LLC d/b/a Duke Energy Carolinas, LLC Catawba Nuclear Station, Units 1 and 2 Docket Nos. 50-413 and 50-414 Request for Extension of Completion Dates for Catawba Units 1 and 2 Corrective Actions Required by NRC Generic Letter (GL) 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" Duke Power Company LLC d/b/a Duke Energy Carolinas, LLC (Duke) requests that the date for completing the corrective actions required by GL 2004-02 at Catawba Units 1 and 2 be extended to April 30, 2008 in order to complete the formal documentation of the Integrated Prototype Testing (chemical effects) testing. The requested period of

,extension is two (2) months after the February 29, 2008 date specified by the November 30, 2008 NRC letter to NEI concerning licensee supplemental responses to GL 2004-

02. This request falls under the Case 2 scenario as outlined in the November 8, 2007 letter, "Plant-Specific Requests for Extension of Time to Complete One or More Corrective Actions for Generic Letter 2004-02."

On February 9, 2006 the Commission issued RAIs to the site to be answered within 60 days. In Duke's April 7, 2006 response to that letter and its June 28, 2006 update on the status of GL 2004-02 corrective actions, Duke stated that the RAIs would be completed by December 31, 2006 and the remaining corrective actions would complete no later than December 31, 2007. The NRC's January 4, 2007 letter stated that the Commission would prefer that licensees have a complete response for closure of all of the GSI-1 91 issues (including the RAIs) no later than December 31, 2007 rather than a partial response by December 31, 2006. On November 21, 2007 a revised copy of the "Content Guide for Generic Letter GL 2004-02 Responses" was sent to NEI for distribution to all licensees. Duke is fully committed to providing a supplemental response to Generic Letter 2004-02 (including the RAIs) by February 29, 2008.

However, the Duke Integrated Prototype Test (IPT) reports and other calculational refinements are still being performed in support of the Catawba Units 1 and 2 ECCS www. duke-energy, com

U. S. Nuclear Regulatory Commission December 7, 2007.

Page 2 Sump Strainer design. As a result, final IPT reports and formal documentation of this information will not be available from the vendor in sufficient time to be incorporated into the refined Catawba sump strainer analyses prior to February 29, 2008. Therefore, Duke is requesting until April 30, 2008 to provide an amended response to GL 2004-02 based on the revised information resulting from the IPT report.

The requested extension of the Catawba Unit 1 and Unit 2 dates for completion of the corrective actions required by GL 2004-02 will have no impact on the health and safety of the public because:

Duke has conducted in-house analyses and testing, and has implemented physical improvements to ensure a high level of sump performance;

• Catawba has put in place permanent mitigative and compensatory measures to minimize the risk of degraded ECCS/CSS functions during the requested period of extension;

" Duke's IPT is designed to provide a representative post-accident sump environment and sump strainer challenge for both Catawba Units; and

" Insights gained from Duke's previous in-house chemical effects testing and the preliminary IPT results provide a high degree of confidence that the modified ECCS strainer assemblies will yield an acceptable NPSH margin.

Additionally, the Unit 2 ECCS sump strainer assembly is completed and installed. The Unit 1 strainer assembly will be installed in May 2008. Given these factors, and the fact that Duke endeavors to provide an accurate and complete response commensurate with the significance of GSI 191, a two month extension is prudent. provides the bases for the proposed extension of the Catawba Unit 1 and 2 GL 2004-02 completion date. Enclosure 2 provides the regulatory commitments made in this letter.

Your approval of this extension is requested by December 31, 2007.

U. S. Nuclear Regulatory Commission December 7, 2007 Page 3 If any questions arise or additional information is needed, please contact Tony Jackson at (803) 831-3742.

Very truly yours, James R. Morris

U. S. Nuclear Regulatory Commission December 7, 2007 Page 4 James R. Morris affirms that he is the person who subscribed his name to the foregoing statement, and that all the matters and facts set forth herein are true and correct to the best of his knowledge.

Ja es R. Morris Vice President Duke Energy Corporation Subscribed and sworn to me:

/

A-/_/_"7 Date Notary PublicJ My commission expires:

A7/_-/____

Date SEAL

U. S. Nuclear Regulatory Commission December 7, 2007 Page 5 xc: w/attachments W. D. Travers, Region II Administrator U.S. Nuclear Regulatory Commission Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 J. F. Stang, Jr., Senior Project Manager (CNS & MNS)

U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 8 G9A Rockville, MD 20852-2738 A. T. Sabisch Senior Resident Inspector U. S. Nuclear Regulatory Commission Catawba Nuclear Station S. E. Jenkins, Manager Division of Radioactive Waste Management Bureau of Land and Waste Management Department of Health and Environmental Control 2600 Bull Street Columbia, SC 29201

U. S. Nuclear Regulatory Commission December 7, 2007 Page 6 bxc: w/attachments J. R. Morris (CN01VP)

J. W. Pitesa (CN01SM)

T. M. Hamilton (CNS01SA)

R. D. Hart (CN01 RC)

R. L. Gill (EC05P)

A. P. Jackson (CN01 RC)

S. B. Putnam (CN03SE)

M. L. Murdock (CN03SE)

A. D. Tuckman (CN03SE)

K. L. Ashe (MG01 RC)

R. S. Lytton (MG05SE)

M. H. Shipley (EC05P)

G. D. Robison (EC09E)

NCMPA-1 NCEMC PMPA SREC Catawba Document Control File: 801.01 - CN04DM Catawba RGC Date File ELL-EC050 Bases for Request for Extension of Completion Dates for Catawba Units 1 and 2 Corrective Actions Required by Generic Letter 2004-02

Bases for Request for Extension of Completion Dates for Catawba Units 1 and 2 Corrective Actions Required by Generic Letter 2004-02

Background

Generic Letter (GL) 2004-02 required that licensees provide a description of and implementation schedule for all corrective actions, including any plant modifications that were identified in responding to the Generic Letter. The Generic Letter further requested that all licensees complete all required corrective actions by December 31, 2007, or provide justification for continued operation until those actions were completed. On November 30, 2007 permission was granted to extend the deadline for the RAIs and supplemental content guide licensee responses to February 29, 2008.

On November 1, 2006 Duke requested an extension to the Spring of 2008 to install the new Catawba Unit 1 ECCS Sump Strainer. That request for extension was granted by NRC letter dated October 31, 2007 via an amendment to the Unit 1 Facility Operating License (FOL).

On March 1 and September 1, 2005, Duke submitted a listing of those actions it was taking to address GL 2004-02 and updated the status of those actions in its letter of June 28, 2006. The current status of those actions is listed in Table 1.

Catawba has installed a new ECCS Containment Sump Strainer in Unit 2, which increases the size of this Unit's strainer from the original 135 square feet to approximately 2400 square feet. A similar increase in the area of the Unit 1 strainer is planned during the Spring 2008 outage. In addition to providing a significant increase in strainer surface area, the new design in both Units incorporates a reduction in strainer hole size from 1/8" inch nominal (original strainer) to less than 3/32" inch nominal (new strainer).

Originally, Catawba's Unit 1 and 2 modified ECCS Sump Strainers were based on baseline evaluations for debris loading, which would have been accommodated by a 1800 square foot strainer area. Subsequently, the Catawba modified strainer designs were expanded to approximately 2400 square feet, which is the largest practical installation in the existing Unit 1 and Unit 2 lower containment area. This expanded strainer area was intended to provide margin for issues that have not been resolved in the industry.

Testing Catawba is an ice condenser plant using a sodium tetraborate buffer, and as such has a post-LOCA environment that is most similar to the industry-generated Integrated Chemical Effects Test (ICET) 5. ICET 5 determined that no significant chemical precipitates were observed in a sodium borate environment.

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Integrated Chemical Effects Test ICET-5-1 -B2_042606, conducted as a follow-on to the ICET 5 testing, showed that no significant pressure drop occurred in a sodium borate environment until the aluminum concentration was increased to 100 ppm. As reported in the test results, an aluminum concentration of 50 ppm produced no significant head loss during approximately 11 days of testing with a sodium tetraborate buffer. The highest aluminum concentration predicted for Catawba is less than 7 ppm (assuming Minimum Safeguards temperatures and minimum containment sump volume to conservatively model the environment).

Vertical Test Loop (VTL) tests have been performed by Duke since June 2006 to gain insight into the behavior of various aluminum chemical species and their effect on pressure drop across a fiber insulation bed deposited on a representative strainer. VTL concentrations used during the testing of both silica and aluminum were considerably higher than the actual concentrations predicted.

The recently concluded VTL tests, with introduced dissolved aluminum, indicate that dissolved aluminum results in little or no pressure drop increase across the strainer at the representative fiber load and the expected aluminum concentrations for Catawba.

The insights gained from the VTL were used to develop test parameters for the Integrated Prototype Test (IPT), which will be integrated chemical effects test for Catawba.

Duke's vendor performed a comprehensive Integrated Prototype Test (IPT) utilizing representative ECCS sump pool chemistry and debris loading, along with one prototype of the strainer assembly module (top-hat). Duke has determined that this IPT will sufficiently model the post-accident scenario and anticipates that test results will demonstrate sump strainer margin for NPSH consideration.

Basis for the Proposed Extension SECY-06-0078, "Status of Resolution of GSI-191, "Assessment of [Effect of]

Debris Accumulation on PWR Sump Performance," dated March 31, 2006, specifies two criteria for short duration Generic Letter 2004-02 extensions, limited to several months, and a third criterion for extensions beyond several months.

Catawba's response to each of these three criteria is provided below.

SECY-06-0078 Criterion 1: The licensee has a plant-specific technical/experimental plan with milestones and schedule to address outstanding technical issues with enough margin to account for uncertainties.

There are three (3) outstanding technical issues related to the extension request:

1. Completion of further analytical refinements for debris generation and transport, 2

2. Completion and evaluation of Duke's final Integrated Prototype Test (IPT),and

3. Incorporation of the IPT results and refinements into the head loss certification calculations and documentation of the IPT inputs:

a) Completion of Further Analytical Refinements Catawba is currently implementing further analytical refinements of its debris generation and transport calculations in order to match them to similar refinements undertaken for Duke's McGuire Nuclear Station.

Duke has a very high level of confidence that these refinements will result in design basis strainer debris loading conditions that are bounded by prototypical array testing performed for both plants.

b) Completion and Evaluation of Duke's Final Integrated Prototype Test The scheduled Integrated Prototype Test for Catawba was designed to be conducted using one prototype strainer assembly module (top-hat),

using representative ECCS sump pool chemistry and postulated strainer debris loading and injection of dissolved aluminum.

Originally postulated strainer debris loading is an input to the IPT resulting from the application of the expected refinements described in

1) above. After the IPT results have been evaluated and documented, the resulting analytical margin will be incorporated into the supporting analyses prior to the finalization of the strainer head loss certification calculation.

The IPT was conducted over a 30 day period which began in October 2007. Preliminary results were obtained in November 2007. Full evaluation and documentation of test results will be completed by April 30, 2008.

c) Incorporation of the IPT results into the head loss certification calculations, and documentation of the IPT inputs Calculations will be updated to incorporate the results from the IPT, and the supporting analyses and certifications will be revised as well.

The formal sump strainer head loss certification will consist of several elements (i.e., top-hat assembly head losses, water box/plenum head loss, and projected margin for debris loaded conditions, including chemical effects), which will be incorporated after the IPT results are documented.

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SECY-06-0078 Criterion 2: The licensee identifies mitigative measures to be put in place prior to December 31, 2007, and adequately describes how these mitigative measures will minimize the risk of degraded ECCS [Emergency Core Cooling System] and CSS [Containment Spray System] functions during the extended period.

The following mitigative measures and compensatory actions have been implemented to minimize the risk of degraded ECCS and CSS functions during the requested extension period:

Mitigative Measures A. ECCS Design Catawba has installed a replacement ECCS Containment Sump Strainer in Unit 2 that increases that Unit's strainer area from the original 135 square feet to approximately 2400 square feet. Additionally, the design basis fiber loading for this Unit is significantly lower than the design basis for Unit 1. The Unit 1 ECCS strainer will be installed in the Spring of 2008 and has a similar increase in surface area. In addition to providing a significant increase in strainer surface area, the new design in both units incorporates a reduction in strainer hole size from 1/8 inch nominal (original strainer) to less than 3/32 inch nominal (new strainer).

In addition, the design and placement of the ECCS Containment Sump Strainer in the pipe chase provides for the filtration of large debris entrained in the sump pool prior to reaching the strainer via passage of water through openings in the crane wall (credited) for those portions of the strainer located outside the crane wall. A complete description of the modified ECCS Containment Sump Strainer Assembly may be found in Duke's letters of March 29 and September 7, 2007.

B. CSS Design:

In response to NRC Bulletin 2003-01, "Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized Water Reactors," Catawba implemented the option of manually starting one air return fan at a containment pressure of 1 psig during certain small break LOCA (SBLOCA) transient events (NRC Safety Evaluation Report dated September 25, 2006). This is an additional manual operator action to prevent or delay reaching the initiation pressure setpoint for containment spray, reducing the likelihood of operating in the ECCS Sump recirculation mode with the associated sump screen debris buildup.

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Compensatory Measures A. Modifications:

a) Microtherm Insulation Replacement As committed in Duke's September 1, 2005 follow-up response to Generic Letter 2004-02, Microtherm insulation installed on the Unit 1 and Unit 2 reactor vessel heads has been removed and replaced with reflective metal insulation (RMI).

b) Steam Generator (S/G) Insulation Modification This modification replaced the fiberglass blankets (Nukon) insulation on the bottom bowls of the Unit 1 Steam Generators with reflective metal insulation (RMI). This replacement removed approximately 400 cubic feet of fibrous insulation of which approximately 280 cubic feet are below the maximum flood level in containment. Unit 2 does not require a similar modification since RMI insulation is already installed on the bottom SG bowls.

c) Downstream Effects Modifications (Orifice Plate Replacements)

This modification replaced existing orifice plates with smaller diameter orifice plates to allow the ECCS throttle valves to be opened greater than currently allowed for flow balancing. Work on Unit 2 is complete.

Unit 1 requires further modification during the Spring 2008 outage since the initial orifice plate sizing modification was not successful in allowing the throttle valves to be opened the proper amount.

B. Programmatic Controls to Reduce Debris in Containment Catawba has several programmatic controls in place to ensure that potential sources of debris that may be introduced into containment will be assessed for adverse effects on the ECCS and Containment Spray System recirculation functions. These programmatic controls include requirements related to coatings, containment housekeeping, materiel condition, and modifications. Typical programmatic controls are described below:

1. Coatings Program As described in Duke's November 11, 1998 response to Generic Letter 98-04, "Potential for Degradation of the Emergency Core Cooling System 5

and the Containment Spray System after a Loss-of-Coolant Accident Because of Construction and Protective Coating Deficiencies and Foreign Material in Containment," Duke has established controls for the procurement, application, and maintenance of Service Level 1 protective coatings used inside the containment. The requirements of 10 CFR 50, Appendix B are implemented through the specification of appropriate technical and quality requirements for the Service Level 1 coatings program. For Service Level 1 coatings, Duke is committed to comply with Regulatory Guide 1.54 at Catawba. Per the GL 98-04 response, vendor supplied mechanical equipment (valves. pumps, hoists, tanks, etc.) that was procured prior to the issuance of Regulatory Guide 1.54 (or that are impractical to purchase with qualified coatings) all have coatings that cannot be certified to comply with the standards, and are thus defined as unqualified.

2. Containment Housekeeping/Materiel Condition Duke's August 7, 2003 response to Bulletin 2003-01, "Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized Water Reactors," described planned actions regarding containment cleanliness. These actions have been implemented and provide for containment cleaning and visual inspections.

" Containment cleaning is conducted prior to Mode 4.

Extensive containment cleaning is conducted using water spray. In general, washdowns are limited to the space in lower containment that would be submerged under large break LOCA conditions.

Accessible floor and wall surfaces and mechanical equipment are washed down.

Localized washdowns are performed as directed by Radiation Protection.

" Visual inspections are performed on remaining areas of containment. Identified potential debris is cleaned or removed, as necessary.

" Containment cleanliness is verified prior to entry into Mode 4 by an inspection controlled by procedure. This cleanliness inspection ensures that the ECCS sump area is free of debris. Containment FME controls and inspection activities are implemented during Modes 1 through 4. CNS foreign material exclusion (FME) control practices and Inspection activities assuring containment cleanliness during Modes 1 through 4 are described as follows:

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• Containment entries during normal power operations are controlled by an administrative procedure.

& Increased material accountability control at CNS is achieved by requiring material accountability logs be kept for items carried into and out of containment during normal power operations (Modes 1 through 4). These procedural changes have been in place since the Fall of 2003.

3. Modification Process Duke's modification process currently includes an administrative procedure that directs the design and implementation of engineering changes in the plant. This procedure directs that engineering changes be evaluated for system interactions. As part of this evaluation, there is direction to include consideration of any potential adverse effect with regard to debris sources and/or debris transport paths associated with the containment sump.

C. Operator Actions and Training Duke's May 27, 2004 response to NRC Bulletin 2003-01, "Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized-Water Reactors," committed to the following actions recommended by WCAP-1 6204 in order to reduce the risk associated with potential containment emergency sump blockage during ECCS and Containment Spray recirculation functions:

" Initiation of refueling water storage tank makeup following the successful transfer of ECCS and containment spray suction to the containment emergency sump, Describe the symptoms of sump clogging problems, and

• Originate a response procedure to provide guidance for the potential of both trains of ECCS and containment spray being affected by containment sump blockage.

In addition to the above, Duke implemented a procedure change which relocated the step to shut down a containment spray pump when it is-no longer required to mitigate the event. This step now occurs earlier in the procedure.

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These actions have been completed and appropriate operator training conducted. The actions taken to address each of the above listed items are documented in the Duke corrective action program.

SECY-06-0078 Criterion 3: For proposed extensions beyond several months, a licensee's request will more likely be accepted if the proposed mitigative measures include temporary physical improvements to the ECCS sump or materials inside containment to better ensure a high level of ECS sump performance.

Physical mitigative measures put in place in Catawba Units 1 and 2 are described in detail in Section SECY-06-0078 Criterion 2 of this extension request. These measures are not temporary; all physical corrective actions to date are significant permanent changes to the plant taken to address the issues identified in GSI 191. All physical mitigative measures such as the modification to the Unit 1 ECCS Sump Strainer will be completed during the Catawba Unit 1 Spring 2008 refueling outage (1 EOC17).

Risk Assessment Catawba Unit 2 will complete the planned ECCS strainer modifications prior to Mode 4 ascent from refueling outage 2EOC15 in the Fall of 2007, and Unit 1 will install the modified sump strainer during the Spring 2008 refueling outage. A total of approximately 2400 square feet of surface area per Unit will be available to strain containment sump debris. The final ECCS Sump Strainer design has been sized to accommodate the maximum transportable debris (fibrous insulation, dirt, paint chips and other particulates, and latent debris) from the limiting break location. A very conservative initial approach has been used regarding selection of the fiber insulation ZOI to obtain the debris generation volume. The strainers have been sized and initially tested to accommodate this debris load and demonstrate adequate margin.

Although the Integrated Prototype Test Report (including chemical effects) has not been completed, extensive in-house testing representative of Catawba has been previously performed. Insights from actual chemical effects tests done to date:

Integrated Chemical Effects Test ICET 5 concluded that no significant chemical precipitates were observed in a sodium borate environment. In addition, Integrated Chemical Effects Test ICET-5-1-B2_042606 showed that no significant pressure drop resulted in a sodium borate environment until the aluminum concentration was increased to 100 ppm. As reported in the test results, an aluminum concentration of 50 ppm produced no significant head loss during approximately 11 days of testing with a sodium tetraborate buffer. The highest aluminum concentration predicted 8

for Catawba is less than 7 ppm (assuming Minimum Safeguards temperatures and minimum containment sump volume). The assumption of Minimum Safeguards conditions (i.e., one train CSS operation) and minimum containment sump pool volume results in higher and thus more conservative aluminum precipitate concentrations.

Tests conducted on Duke's vertical test loop indicate that aluminum will stay in solution and no significant precipitates occur at the concentrations expected in the Catawba post-accident ECCS sump. Significant increases in head loss due to precipitates are not anticipated based on these tests.

Therefore, the chemical effects, as determined by the in-progress Integrated Prototype Test, are not expected to have an impact on ECCS Sump Strainer failure probability.

In conclusion, the ECCS Sump Strainers have been designed for more than the expected debris loading, and chemical effects are not expected to have a significant impact on ECCS Sump Strainer performance. There is no change to the Core Damage Frequency beyond that identified in the Duke Request for Extension dated November 1, 2006 of less that 1 E-6.

Conclusion An extension of the Catawba Unit 1 and Unit 2 dates for the completion of all corrective actions required by Generic Letter 2004-02 is acceptable due to the fact that:

Duke has taken action, including extensive in-house analysis and testing, and has implemented physical improvements (including fiber reduction and the installation of larger ECCS Sump Strainer on Unit 2) to ensure a high level of ECCS sump performance,

• Catawba has put in place permanent mitigative procedural and programmatic measures to minimize the risk of degraded ECCS/CSS functions during the requested period of extension, Duke's comprehensive Integrated Prototype Test (chemical effects) is designed to provide a representative post-accident sump environment and sump strainer challenge for the Catawba Units, and Insights gained from Duke's previous in-house chemical effects testing and the preliminary IPT results provide a high degree of confidence that the modified ECCS strainer assemblies will yield an acceptable NPSH margin.

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The requested two month period of this extension is required to allow the Integrated Prototype Test results, which will be available in preliminary form by the end of 2007, to be fully evaluated, properly documented and reviewed, and finally incorporated into the formal head loss certification calculation for Catawba Units 1 and 2. The formal sump strainer head loss certification consists of several parts (i.e., top-hat assembly head loss, water box/plenum head loss, and chemical effects contribution), which will be incorporated after the IPT results are documented. Internal procedures to appropriately process this information, and to assure the quality of that information and the associated regulatory submittals, are also necessarily rigorous.

Additionally, the Catawba Unit 1 ECCS Sump Strainer modifications will be completed during the Unit 1 refueling outage scheduled to begin on or before May 19, 2008 as committed in Catawba's November 1, 2006 extension request.

Given these factors, and the fact that Duke endeavors to provide an accurate and complete response commensurate with the significance of (GSI) 191, a two month extension is prudent.

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TABLE 1 STATUS OF 2004-02 CORRECTIVE ACTIONS Item Description Status A baseline evaluation has been Complete performed for Catawba by Enercon Services, Inc. This evaluation was performed using the guidance of NEI 04-07.

A refined evaluation using the guidance Complete of NEI 04-07 will be completed for Catawba by Enercon Services, Inc.

This evaluation will provide plant specific refinements to the baseline evaluation that can be justified for Catawba. This evaluation is expected to provide additional head loss margin for the containment sump.

A downstream effects evaluation will be The downstream effects evaluation for completed for Catawba by Enercon erosion and blockage of components Services, Inc. This evaluation will be (pumps, valves, and orifices) is performed using the methodology complete. Plant modifications (orifice provided by WCAP-16406-P, plate modifications) were installed Rev.0"Evaluation of Downstream Sump during the 2EOC15 Fall 2007 Unit 2 Debris Effects in Support of GSI 191,"

and 1 EOC16 Fall 2006 Unit 1 outages.

An additional modification is required to complete the Unit 1 work since the flow balance showed the valves would not open to the proper width: This modification will be completed 1EOC17.

Vendor calculations for fibrous debris bypass are complete, but not accepted as final by Duke at this time.

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Chemical effects will be evaluated to confirm that sufficient margin exists in the final sump design to account for any associated head loss. Any additional plant modifications or procedure changes associated with this evaluation will be completed by Dec 31,2007.

Conclusive Integrated Prototype Test results may not be available from the vendor in sufficient time to allow for incorporation into the refined Catawba sump strainer analyses.

Catawba will provide all available information in its February 29, 2008 supplemental response. The final response shall be provided by April 30, 2008.

Downstream chemical effects are Duke is investigating downstream under investigation by the industry with chemical effects with the intent of the intent of addressing this issue by addressing this issue as industry Dec 31, 2007.

guidance is developed..

A confirmatory walkdown of Complete containment using the guidance of NEI 02-01, "Condition Assessment Guidelines: Debris Sources Inside PWR Containments" (NEI 02-07) was completed for Catawba Units 1 and 2.

A confirmation of the conservatism of Complete the 200 pound latent debris assumption used in the baseline analysis will be performed by latent debris survey sampling.

The plant labeling process will be Complete enhanced to require that any additional labels or signs placed inside containment are evaluated to ensure that the design basis for transportable debris is not invalidated.

Testing will be performed to confirm Head loss testing has been completed that the replacement strainer head loss by Enercon Services, Inc. Test reports is acceptable under design basis debris have been issued by Enercon and after load conditions.

review of these debris testing reports, they have been found acceptable by Catawba.

A modified containment sump strainer The November 1, 2006 letter from and supporting structure will be Duke requested an extension of the installed in the Fall of 2006 for Unit 1 strainer until Spring of 2008.

Catawba unit 1 and in the Fall of 2007 The Unit 2 installation was completed for Catawba Unit 2.

during 2EOC15 (Fall 2007).

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Replacement of Microtherm insulation(Currently installed on portions of the reactor vessel heads) will be completed in the Fall of 2006 for Catawba Unit 1 and in the Fall of 2007 for Catawba unit 2. The replacement of this insulation will reduce the postulated post-accident debris loading on the sump strainer.

Unit 1 and Unit 2 installation is complete.

Duke will evaluate the modification Complete.

process to determine if additional controls are needed in order to maintain the validity of inputs to analyses performed in resolving GSI-191 concerns.

13 List of Regulatory Commitments

REGULATORY COMMITMENTS:

The following table identifies those actions committed to by Catawba in this document. Any other statements made in this licensing submittal are provided for informational purposes only and are not considered to be regulatory commitments. Please direct any questions you may have in this matter to Tony Jackson at (803) 831-3742.

REGULATORY COMMITMENTS Due Date Duke will provide available information February 29, 2008 (including the RAIs) in its supplemental response to GL 2004-02 Any revised or supplemental information to April 30, 2008 Catawba's previous response to the RAIs will be provided as an amended response to GL 2004-02 1