NL-08-153, Request for Extension of Completion Dates for Indian Point Units 2 and 3 Corrective Actions Required by Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Wat

Request for Extension of Completion Dates for Indian Point Units 2 and 3 Corrective Actions Required by Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Wate

ML083010239
Person / Time
Site:	Indian Point
Issue date:	10/17/2008
From:	Pollock J E Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL-04-002, NL-08-153, TAC MC4689, TAC MC4690
Download: ML083010239 (11)

Text

Indian Point Energy Center 450 Broadway, GSB P.O. Box 249 Buchanan, N.Y. 10511-0249 E----mw Tel (914) 734-6700 J.E. Pollock Site Vice President Administration October 17, 2008 Indian Point Nuclear Generating Unit Nos. 2 and 3 Docket No. 50-247 and 50-286 NL-08-153 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Request for Extension of Completion Dates for Indian Point Units 2 and 3 Corrective Actions Required by Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors"

REFERENCES:

1) Entergy letter NL-08-025, 02/28/08, "Supplemental Response to NRC Generic Letter 2004-02, Potential Impact Of Debris Blockage On Emergency Recirculation During Design Basis Accidents At Pressurized-Water Reactors" 2) NRC Generic Letter 2004-02, 09/13/04, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" 3) NRC letter to Indian Point Vice President of Operations, 09/17/08, "Indian Point Nuclear Generating Unit Nos. 2 and 3 -Request for Additional Information Regarding Responses to Generic Letter 2004-02 (TAC Nos. MC4689 and MC4690)" 4) Entergy letter NL-08-054, 03/28/08, "Request for Extension of Completion Dates for Indian Point Units 2 and 3 Corrective Actions Required by Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" 5) NRC letter to Indian Point Vice President of Operations, 04/11/08, "Indian Point Nuclear Generating Unit Nos. 2 and 3 -Approval of Revised Extension Request for Corrective Actions Required by Generic Letter 2004-02 (TAC Nos. MC4689 and MC4690)"

NL-08-153 Page 2 of 3

Dear Sir or Madam:

On February 28, 2008, Entergy Nuclear Operations, Inc (Entergy) submitted its supplemental response (Reference

1) to GL 2004-02 (Reference 2). A significant component of that response was Entergy's plan to rely on the test results of the chemical effects testing conducted by Alion Science and Technology at the VUEZ facility.

The NRC witnessed the test setup and conduct of the initial Indian Point test at VUEZ and has raised a number of issues on the 30 day test program for Indian Point and several other plants. Entergy and Alion have endeavored to resolve these issues; however, a number of issues remain open (Reference 3). Consequently, Entergy has determined that an alternate approach will be utilized for GL 2004-02 resolution that will no longer credit VUEZ head loss test results.In response to Reference 3, Entergy held a telecon with the NRC on October 2 nd, 2008 and described the planned alternate approach.

This new approach utilizes a debris and chemical head loss "test for success" methodology and, as such, will determine the plant configuration needed to support strainer qualification, and what, if any, additional plant modifications are required to resolve GL 2004-02. Entergy is in the process of vendor selection and is imposing a schedule that supports completion of testing and all supporting analyses by August 3 1 st, 2009.With this new approach it is likely that an additional Unit 2 modification and license amendment will be required.

This modification will negate the need to assume spurious closure of two motor operated valves within the design basis of the internal recirculation system. It is planned to perform this modification during refueling outage 2R19 (spring 2010).Apart from the new approach, Entergy has determined through testing-and downstream effects analysis that additional modifications are required to support GL 2004-02 compliance.

As described in Reference 4, Entergy has conducted tests on the internal recirculation pump bearing material and has concluded that these bearings need to be replaced.

Entergy is currently working with the pump vendor to identify a suitable replacement bearing material and then plans to expedite bearing procurement and delivery.

In parallel, bearing installation plans are under development for integration into the next refueling outages. Entergy will inform the NRC by December 1, 2008 should these plans not support installation of the replacement bearings during the forthcoming Unit 3 refueling outage 3R15 (spring 2009).As previously reported to the NRC a number of significant modifications have already been made in support of GL 2004-02 compliance.

During the spring 2006 (Unit 2) and spring 2007 (Unit 3)refueling outages, the original internal recirculation and containment sump screens were replaced with strainers.

Other significant modifications were also made including flow channeling.

Subsequent to these outages Entergy has completed additional modifications that include the installation of additional strainer modules in Unit 2, and the replacement of the pH buffer at both units. These modifications represent a significant improvement over the original design by providing greatly increased strainer surface areas, reduced debris transport, reduced downstream effects and a significant reduction in the amount of chemical precipitate.

Based on the above, this letter requests a Unit 2 extension to restart from refueling outage 2R1 9 (currently scheduled to start March 10, 2010) and a Unit 3 extension to August 31, 2009, to complete analysis, plant modifications and licensing activities determined to be needed to achieve compliance with the regulatory requirements of GL 2004-02. The basis for the proposed extensions is provided in Attachment

1. The currently approved extensions for both Unit 2 and Unit 3 expire on October 3 1 st, 2008 (Reference

5) and therefore Entergy respectfully requests approval of this extension request by October 30, 2008.

NL-08-153 Page 3 of 3 There are no new commitments being made in this submittal.

Should you have any questions or require additional information, please contact Mr. R. Walpole, Manager, Licensing at (914) 734-6710.I declare under the penalty of perjury that the foregoing is true and correct. Executed on October\'__ , 2008.Sincerely, J. E. Pollock Site Vice President Indian Point Energy Center Attachments:

1. Request for Extension of Completion Dates for Indian Point Units 2 and 3 Corrective Actions Required by Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" cc: Mr. John P. Boska, Senior Project Manager, NRC NRR DORL Mr. Samuel J. Collins, Regional Administrator, NRC Region 1 NRC Resident Inspector, IP2 NRC Resident Inspector, IP3 Mr. Robert Callender, Vice President, NYSERDA Mr. Paul Eddy, New York State Dept. of Public Service ATTACHMENT 1 TO NL-08-153 Request for Extension of Completion Dates for Indian Point Units 2 and 3 Corrective Actions Required by Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" ENTERGY NUCLEAR OPERATIONS, INC.INDIAN POINT NUCLEAR GENERATING UNIT NOs. 2 and 3 DOCKET NO. 50-247 and 50-286 NL-08-153 Attachment 1 Page 1 of 7 Request for Extension of Completion Dates for Indian Point Units 2 and 3 Corrective Actions Required by Generic Letter 2004-02 1.0 Background In Generic Letter (GL) 2004-02 (Reference 1), the NRC requested licensees to perform a mechanistic evaluation of the potential for the adverse effects of post-accident debris blockage and operation with debris-laden fluids to impede or prevent the recirculation functions of the Emergency Core Cooling System (ECCS) and Containment Spray System (CSS) following all postulated accidents for which these systems are required.

The GL requested that all licensees complete the GL related actions by December 31, 2007. By letters dated September 1, 2005 (Reference 2)December 15, 2005 (Reference 3), and February 28, 2008 (Reference 4), Entergy provided responses to GL 2004-02 for Indian Point Units 2 and 3.Requests for extensions and NRC granted approvals (References 5 through 10) extended the completion dates to October 3 1 st, 2008 for both units. The intent of these extensions was to allow Entergy additional time to perform the final corrective actions, facility modifications, and licensing activities to achieve compliance with GL 2004-02. For the reasons presented below, this letter requests a Unit 2 extension to restart from refueling outage 2R19 (currently scheduled to start March 10, 2010) and a Unit 3 extension to August 31, 2009, to complete analysis, plant modifications and licensing activities determined to be needed to achieve compliance with the regulatory requirements of GL 2004-02.As previously reported to the NRC a number of significant modifications have already been made in support of GL 2004-02 compliance.

During the spring 2006 (Unit 2) and spring 2007 (Unit 3)refueling outages, the original internal recirculation and containment sump screens were replaced with strainers.

Other significant modifications were also made including flow channeling.

Subsequent to these outages Entergy has completed the modifications described in Reference 7.These modifications include the installation of additional strainer modules in Unit 2 and the replacement of the pH buffer to sodium tetraborate for both units. These modifications represent a significant improvement over the original design by providing greatly increased strainer surface areas, reduced debris transport, reduced downstream effects and a significant reduction in the amount of chemical precipitate.

2.0 Reason

for the Request for Extension On February 28, 2008, Entergy Nuclear Operations, Inc (Entergy) submitted its supplemental response (Reference

4) to GL 2004-02 (Reference 1). A significant component of that response was Entergy's plan to rely on the test results of the chemical effects testing conducted by Alion Science and Technology at the VUEZ facility.

The NRC witnessed the test setup and conduct of the initial Indian Point test at VUEZ and has raised a number of issues on the 30 day test program for Indian Point and several other plants. Entergy and Alion have endeavored to resolve these issues; however, a number of issues remain open (Reference 11). Consequently, Entergy has determined that an alternate approach will be utilized for GL 2004-02 resolution that will no longer credit VUEZ head loss test results.With this new approach it is likely that an additional Unit 2 modification and a license amendment will be required.

This modification will negate the need to assume spurious closure of two motor operated valves within the design basis of the internal recirculation system. It is planned to perform this modification during refueling outage 2R19 (spring 2010).

NL-08-153 Attachment 1 Page 2 of 7 Apart from the new approach, Entergy has determined through testing and downstream effects analysis that additional modifications are required to support GL 2004-02 compliance.

As described in Reference 7, Entergy has conducted tests on the internal recirculation pump bearing material.

These tests and the associated bearing wear analyses have shown that the existing bearings have limited capability in a debris laden fluid environment and Entergy has concluded that these bearings need to be replaced.

The bearings cannot be replaced in situ and require removal of the pumps and motors from the 46' elevation.

Entergy is currently working with the pump vendor to identify a suitable replacement bearing material and then plans to expedite bearing procurement and delivery.

In parallel, bearing installation plans are under development for integration into the next refueling outages. Entergy will inform the NRC by December 1, 2008 should these plans not support installation of the replacement bearings during the forthcoming Unit 3 refueling outage 3R15 (spring 2009).3.0 Technical Basis for Proposed Extension Entergy considers that the conditions at Indian Point Units 2 and 3 meet the criteria identified in SECY-06-0078 (Reference

12) for extension beyond the completion date of December 31, 2007 specified in GL 2004-02. The SECY criteria are, Proposed extensions-to permit changes at the next outage of opportunity after December 2007 may be acceptable if, based on the licensee's request, the staff determines that:* 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.

• 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 extension period.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 ECCS sump performance.

Indian Point Units 2 and 3 meet these criteria as described below.3.1 Plant Specific Technical/Experimental Plan In response to Reference 11, Entergy held a telecon with the NRC on October 2 nd, 2008 and described the alternate approach.

This new approach will. involve a debris and chemical head loss"test for success" methodology and, as such, will determine the plant configuration needed to support strainer qualification, and what, if any, additional plant modifications are required to resolve GL 2004-02. Entergy is in the process of vendor selection and is requiring a schedule that supports completion of testing and all supporting analyses by August 3 1 st, 2009.The technical/experimental plan is as follows: It is planned to perform debris head loss and chemical effects testing using a section of the strainer array. The test protocol will be developed based on the NRC "March 2008 protocol" (Reference 13)and this test protocol will be submitted to the NRC for review and comment. This approach utilizes NL-08-153 Attachment 1 Page 3 of 7 a debris and chemical head loss "test for success" methodology and, as such, will determine the plant configuration needed to support strainer qualification, and what, if any, additional plant modifications are required to resolve GL 2004-02.When performing chemical effects testing, WCAP-1 6530 predicted chemical loads will be used with potential WCAP-1 6785 inhibition and solubility refinements.

Inhibition reduces the quantity of precipitants based on interactions with known inhibitors such as phosphate and silicate.

Solubility of precipitates as a function of temperature and pH can delay the formation of precipitates until the sump water has cooled to temperatures where NPSH margin is increased.

The planned test schedule is as follows:* Development of test protocol -October/November 2008* NRC review of protocol -November 2008* Perform solubility tests -November 2008* Delivery of hardware to test facility -December 2008* Perform 'test for success" testing -February 2009* Preparation of test report -March 2009* Completion of analyses including strainer certification calculation

-August 2009 Should these tests not support the current plant configuration then the plant will be modified to match the acceptable tested condition.

Modifications may include insulation replacement and strainer structural enhancements and would be implemented during the refueling outage following completion of testing and analysis (2R19 (spring 2010) and 3R16 (spring 2011)).With this new approach it is likely that an additional modification and license amendment to Unit 2 will be required.

This modification will negate the need to assume spurious closure of two motor operated valves (745A and 745B) within the design basis of the internal recirculation system. This would be achieved by de-energizing these valves and by providing independent control, room indication.

It is planned to submit a license amendment request by January 31, 2009; and to perform this modification during refueling outage 2R19 (spring 2010).As discussed above, it is planned to replace the Unit 2 bearings during refueling outage 2R1 9 (spring 2010) and the Unit 3 bearings during refueling outage 3R15 (spring 2009) subject to the aforementioned schedule uncertainties.

3.2 Mitiqative

Measures The mitigative measures described in References 5, 6 and 7 are already in place and minimize the risk of degraded ECCS and CSS functions.

These measures include installation of replacement internal recirculation and containment sump strainers, replacement of the internal recirculation pumps, installation of flow channeling, replacement of pH buffers, implementation of mitigative measures in response to NRC Bulletin 2003-01 (References 14 through 17), and procedural enhancements in the areas of containment cleanliness, foreign material exclusion and insulation control.

NL-08-153 Attachment 1 Page 4 of 7 3.3 Generic Letter 2004-02 Basis for Continued Operation In addition to the mitigative measures identified above the basis for continued operation provided by GL 2004-02 include a number of factors that remain applicable to Indian Point Units 2 and 3 during the period of the proposed extension.

The NRC staff provided a justification for continued operation (JCO) (as discussed in Reference 1), that justifies continued operation of pressurized water reactors through December 31, 2007.Elements of the JCO applicable to Units 2 and 3 include: (1) The containment is compartmentalized making transport of debris to the sump difficult.

(2) Switchover to recirculation from the sump during a LBLOCA would not occur until 20 to 30 minutes after accident initiation, allowing time for much of the debris to settle in other places within containment.

(3) The probability of the initiating event (i.e., large and intermediate-break LOCAs) is extremely low.(4) Leak-before-break (LBB) has been approved by the NRC in relation to breaks in the reactor coolant loop primary piping. Qualified piping is of sufficient toughness that it will most likely leak rather than rupture.(5) The NPSH analyses for the pumps used to perform the recirculation function do not credit containment overpressure.

3.4 Risk Analysis With the installation of the new strainers, flow channeling, buffer replacement and other associated modifications there has been a significant reduction in the vulnerability to debris blockage and downstream effects as compared to the original physical configuration.

The period of extension from the original compliance date to the requested compliance date (from December 31, 2007 through August 31, 2009 (Unit 3) and startup of Unit 2 from refueling outage 2R19 (currently scheduled to start March 10, 2010) represents a very small increase in incremental risk for the following reasons: 1) During a LBLOCA the flowrates through the strainers would be at maximum because the internal recirculation pumps would be supplying both cold leg recirculation and recirculation spray flow requirements with minimal system backpressure.

The LBLOCA Zones of Influence (ZOls) are larger than the ZOls for intermediate and small beak LOCAs. The LBLOCAs therefore generate significantly more debris resulting in more debris transport to the sump strainers and higher sump strainer head loss. However, a LBLOCA has a very low probability of occurrence.

2) The more probable intermediate and small break LOCAs have significantly less potential for debris generation and transport due to the lower ZOIs and reduced flowrates.

3) There are two sumps in containment

-the internal recirculation sump and the smaller containment sump. The internal recirculation sump is the primary sump used for accident mitigation and the containment sump provides backup capability for the internal recirculation system.

NL-08-153 Attachment 1 Page 5 of 7 4) There are four low head pumps available for accident mitigation

-two internal recirculation pumps that draw from the internal recirculation sump and two residual heat removal pumps that draw from the containment sump. Should an internal recirculation pump fail, then the second recirculation pump would be available.

Should both internal recirculation pumps fail then either of the two residual heat removal pumps would be available for accident mitigation.

5) The replacement strainers have 3/32" diameter holes versus the 1/8" original design. The downstream effects evaluation has shown that components are not subject to blockage.6) The replacement strainers consist of hollow concentric cylinders fitted with a bypass eliminator mesh. The bypass eliminator significantly reduces the total quantity of fiber that could bypass the strainer and therefore aids in mitigating downstream effects.7) The head loss across the strainers will be reduced due to a significant reduction in the amount of chemical precipitates generated as a result of the buffer replacement modifications.

8) The ECCS valves, heat exchanger tubing, instrument tubing, and orifices have been evaluated for blockage and erosion and found to be acceptable for their required mission time assuming a debris laden fluid.9) The residual heat removal and high head safety injection pump mechanical shaft seals have been evaluated and are expected to perform satisfactorily during their required mission time assuming a debris laden fluid.10) The residual heat removal and high head safety injection pumps have been evaluated and are expected to perform satisfactorily during their required mission time assuming a debris laden fluid.For these reasons there is reasonable assurance that for intermediate and small break LOCAs the ECCS would continue to provide adequate core cooling.Thus the following quantitative risk evaluation addresses potential vulnerability for large break LOCAs only. Even though there are two sumps in containment and four ECCS pumps available for accident mitigation it is assumed here that both sumps and all four pumps fail at the initiation of recirculation.

It is further assumed that no credit is taken for recovery actions that would be available to the operators.

Therefore, all LBLOCAs (equivalent to pipe diameter of 6" and greater)are assumed to impact sump performance and lead to core damage.The frequency of the LBLOCA event is very low at 5x10 6/yr. Therefore, based on the above conservative assumption regarding LBLOCA mitigation, the annual increase in Core Damage Frequency (CDF) for each unit is taken to be 5x10 6/yr. This change is considered small and falls into Region II of the Acceptance Guidelines for CDF in Regulatory Guide (RG) 1.174. From the current Probabilistic Risk Assessment models, the baseline CDFs for internal events are 1.79x10 5/yr for Unit 2 and 1.15 x 10 5/yr for Unit 3. Since the contribution of external events to total baseline CDF is 6.33 x 10 5/yr (Unit 2) and 5.20x10 5/yr (Unit 3), even considering the change in risk due to the assumed inability to mitigate a LBLOCA, total CDF for each unit would still remain below 10-4 per yr. The Regulatory Guide (RG) 1.174 guidelines state that when the increase in CDF is between 10-6 per year and 105 per year, an application will be considered only if it can be reasonably shown that the total CDF is less than 10-4 per year. Since the risk associated with this application meets those guidelines, the CDF results remain very low and this risk assessment is considered acceptable for this application.

There is no significant contribution to Large Early Release Frequency (LERF) for loss of recirculation following large LOCAs. External event contributions can also be neglected since they do not result in large LOCAs.

NL-08-153 Attachment 1 Page 6 of 7 4.0 References

1. NRC Generic Letter 2004-02, 09/13/04 "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" 2. Entergy letter NL-05-094, 09/01/05 "Response to NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" 3. Entergy letter NL-05-133, 12/15/05 "Supplemental Response to NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" 4. Entergy letter NL-08-025, 02/28/08, "Supplemental Response to NRC Generic Letter 2004-02, Potential Impact Of Debris Blockage On Emergency Recirculation During Design Basis Accidents At Pressurized-Water Reactors" 5. Entergy letter NL-07-074, 09/17/07, "Request for Extension of Completion Date for Indian Point Unit 2 Corrective Actions and Modifications Required by Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" 6. Entergy letter NL-07-129, 11/30/07, "Revised Request for Extension of Completion Date for Indian Point Unit 2 Corrective Actions and Modifications Required by Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" 7. Entergy letter NL-08-054, 03/28/08, "Request for Extension of Completion Dates for Indian Point Units 2 and 3 Corrective Actions Required by Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" 8. NRC letter to M.A. Balduzzi, 11/20/07, "Indian Point Nuclear Generating Unit No. 2 -Approval of Extension Request for Corrective Actions Required by Generic Letter 2004-02 (TAC No.MC4689)" 9. NRC letter to M.A. Balduzzi, 12/20/07, "Indian Point Nuclear Generating Unit No. 3 -Approval of Revised Extension Request for Corrective Actions Required by Generic Letter 2004-02 (TAC No. MC4690)" 10. NRC letter to Indian Point Vice President of Operations, 04/11/08, "Indian Point Nuclear Generating Unit Nos. 2 and 3 -Approval of Revised Extension Request for Corrective Actions Required by Generic Letter 2004-02 (TAC Nos. MC4689 and MC4690)" 11. NRC letter to Indian Point Vice President of Operations, 09/17/08, "Indian Point Nuclear Generating Unit Nos. 2 and 3 -Request for Additional Information Regarding Responses to Generic Letter 2004-02 (TAC Nos. MC4689 and MC4690)" 12. SECY-06-0078, from L. A. Reyes, NRC Executive Director for Operations, to NRC Commissioners, 03/31/06 "Status of Resolution of GSI-1 91, Assessment of [Effect of] Debris Accumulation on PWR [Pressurized Water Reactor] Sump Performance" NL-08-153 Attachment 1 Page 7 of 7 13. NRC letter to NEI, 03/28/08, "Revised Guidance for Review of Final Licensee Responses to Generic Letter 2004-02, Potential Impact Of Debris Blockage On Emergency Recirculation During Design Basis Accidents At Pressurized-Water Reactors" 14. NRC Bulletin 2003-01, 06/09/03 "Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized-Water Reactors" 15. Entergy letter NL-03-128, 08/07/03 "60 Day Response to NRC Bulletin 2003-01 Regarding Potential Impact of Debris Blockage of Emergency Sumps" 16. Entergy letter NL-04-151, 12/08/04 "Reply to RAI Regarding Bulletin 2003-01, Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized-Water Reactors" 17. NRC letter, 08/22/05 "Indian Point Nuclear Generating Unit Nos. 2 and 3 -Response to NRC Bulletin 2003-01, Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized-Water Reactors (TAC Nos. MB9582 and MB9583)"