ML100470199

Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter (GL) 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal and Containment Spray Systems

ML100470199
Person / Time
Site:	Cooper
Issue date:	02/02/2010
From:	Minahan S Nebraska Public Power District (NPPD)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL-08-001, NLS2010008
Download: ML100470199 (8)

Text

H 50.54(f)

Nebraska Public Power District "Always there when you need us" NLS2010008 February 2, 2010 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001

Subject:

Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" Cooper Nuclear Station, Docket No. 50-298, DPR-46

Dear Sir or Madam:

The purpose of this letter is to provide Nebraska Public Power District's (NPPD) Nine-Month supplemental (post-outage) response to Nuclear Regulatory Commission (NRC) Generic Letter (GL) 2008-01 for Cooper Nuclear Station (CNS). The attached post-outage response is being submitted within 90 days of startup from the outage in which the deferred actions were completed. The attachment to this letter provides an update on evaluation results and corrective actions taken since NPPD's submittal of the Nine-Month response to GL 2008-01 on October 10, 2008.

In summary, NPPD has concluded that the systems subject to GL 2008-01 at CNS are operable.

CNS is currently in compliance with the licensing basis documentation and applicable regulations, including 10 CFR 50 Appendix B, Criteria III, V, XI, XVI, and XVII, with respect to the concerns outlined in GL 2008-01.

This letter does not contain any new NRC commitments.

I declare under penalty of perjury that the foregoing is true and correct.

Executed On

, /

o*9i 7 (Date)

Sincerely, A

24 tewar B iahan Vice President - Nuclear and Chief Nuclear Officer

/dm COOPER NUCLEAR STATION F.0. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211 www nppd corn

NLS2010008 Page 2 of 2 cc:

Regional Administrator w/ attachment USNRC - Region IV Cooper Project Manager w/ attachment USNRC - NRR Project Directorate IV-l Senior Resident Inspector w/ attachment USNRC - CNS Nebraska Health and Human Services w/ attachment Department of Regulation and Licensure CNS Records w/ attachment NPG Distribution w/ attachment

NLS2010008 Attachment Page 1 of 5 Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter 2008-01 This attachment provides the Nine-Month Supplemental (Post-Outage) Response to Generic Letter (GL) 2008-01 (Reference 1) as requested by the Nuclear Regulatory Commission (NRC) in Reference 4. This post-outage response is being submitted within 90 days from Refueling Outage 25 (RE25) in which the deferred actions were completed.

The following information is provided in this attachment:

A description of the results of evaluations that were performed pursuant to GL 2008-01 on the previously incomplete activities, such as system piping walkdowns, at Cooper Nuclear Station (CNS) (see section A of this attachment).

A description of any additional corrective actions determined necessary to assure system operability and compliance with the quality assurance criteria in Criteria III, V, XI, XVI, and XVII of Appendix B to 10 CFR Part 50, and a commitment status update (see Section B of this attachment).

The original conclusions documented in the Nine-Month response (Reference 3) with respect to the licensing basis evaluation, testing evaluations, and corrective action evaluations have not changed. This post-outage response discusses the results of design evaluation reviews conducted during the recent refueling outage associated with previously uncompleted activities.

There are no new commitments in this post-outage response.

A. EVALUATION RESULTS

1. Design Basis Documents Nebraska Public Power District (NPPD) is using the industry accepted interim methodology regarding suction and discharge void size acceptance criteria in support of operability evaluations. This interim methodology has been adopted via Engineering Evaluation.

A modification has been performed which added vent valves in various locations to facilitate system fill-and-vent and monthly verifications. An Updated Safety Analysis Report (USAR) change has been processed to revise USAR Table V-2-2 to show the applicable configuration changes. The affected system flow diagrams were updated to reflect the new vent valves.

2. Confirmatory Walkdowns Walkdowns of piping subject to GL 2008-01 and located in primary containment have been completed for inaccessible Core Spray (CS) piping. The walkdowns confirmed that as-found piping configuration was in agreement with the piping isometrics drawings and system flow diagrams. No new unvented high points were identified where gas could accumulate and challenge system safety/design functions.

NLS2010008 Attachment Page 2 of 5 Subsequent to the submittal of References 2 and 3, walkdowns were determined as not necessary for Residual Heat Removal (RHR) inaccessible piping in containment due to the availability of laser scan images. The detailed laser scan images provided adequate information to validate the existing piping configuration is in agreement with the piping isometric drawings and the system flow diagrams. No new unvented high points were identified where gas could accumulate and challenge system safety/design functions.

As stated in Reference 2, walkdowns of High Pressure Coolant Injection (HPCI) piping were completed during the as-building process for installation of high point vents on HPCI piping within the steam tunnel.

Ultrasonic testing (UT) was utilized to identify air voids at the CS train B suction supply line from the condensate storage tank (CST), and under RHR loop B steam condensing mode piping relief valve (RV). The CS B supply valve is normally closed and is located a few feet above the regular horizontal suction supply pipe from the suppression pool. The CS fill-and-vent procedure was revised to add a step to vent air trapped under the valve disc which could be entrained in the CS pump suction flow path. The RHR steam condensing mode RVs were removed and replaced with an elbow and high point vent valve assembly as part of the modification to install new vent valves. Air voids were also found in shut down cooling (SDC) piping of RHR, but were dispositioned as no concern since SDC subsystem is manually operated and is filled and vented by a specific system procedure before being used.

3. Vent Valves Vent valves were added to CS A upstream of the flow element (FE), and to emergency condensate storage tank (ECST) outlet pipe diameter enlargement to HPCI suction and upstream of the HPCI FE. CS B does not have a similar configuration, and a vent valve was not needed.

For RHR trains A and B steam condensing mode piping, the RV was removed and replaced with an elbow and vent valve assembly. A vent valve was added to the RHR Train A Service Water (SW) injection connection.

As an enhancement for HPCI restoration after maintenance, vent valves were added to the lube oil cooler and two other unvented high points in the auxiliary cooling subsystem.

4. Procedures The appropriate fill-and-vent and surveillance procedures were revised to add the use of the new vent valves. As described in NPPD's response to Question 3 of the NRC Request for Additional Information (Reference 6), NPPD also revised the appropriate fill-and-vent and surveillance procedures for UT at specific locations. The procedures were also revised to provide specific instructions for documenting in the Corrective Action Program (CAP) gas voids or gas entrained water identified during venting.

NLS2010008 Attachment Page 3 of 5 B. DESCRIPTION OF NECESSARY ADDITIONAL CORRECTIVE ACTIONS

1. Additional Corrective Actions During RE25, several instances of air accumulation were identified during surveillances performed after fill-and-vent had been completed as part of system restoration. These issues were placed in CAP and NPPD is evaluating the fill-and-vent and surveillance sequences to determine the source of air and assure its removal prior to performing future system surveillances.

2. Corrective Action Updates The previously identified corrective actions (Reference 3) having due dates prior to startup from RE25 have been completed. The individual corrective actions consisted of performing UTs on unvented high points, where practical, and performing Operability Evaluations for those locations where gas or void spaces were found.

Unvented high points were individually evaluated and new high point vent valve assemblies were added, where practical, independent of whether gas was found at the time of the UT.

A summary of results for HPCI, CS, and RHR are provided below. The results were entered in CAP. The table identifies the system designation, location of the potential gas, and the final disposition provided to close the condition, e.g., performing UT to determine if gas was present, adding a vent valve (VV), using engineering judgment (EJ) to accept a small void space determined not to affect system operability, or the revision of procedures to facilitate future venting.

System Suction General Location of Potential Void UT VV EJ Revised or Space Procedure Discharge Line CS-A Suction CST fill line, below CS valve (V) 66 X

X CS-A Discharge Upstream FE-39A X

X X

Under CS-V-26, check valve (CV)

CS-A Discharge 10 bypass X

X X

Vertical line to Pressure Transmitter CS-A Discharge (PT) 38A and relief valve (RV) 11 X

X CS-B Suction CST fill line, below CS-V-67 X

X CS-B Discharge Vertical line to PT38B and RV13 X

X Low Pressure Coolant Injection RHR-A Discharge (LPCI) Line RHR27A X

X X

Heat exchanger (Hx) Steam RHR-A Discharge Condenser mode X

X X

RHR motor operator (MO) 38A RHR-A Discharge suppression pool (SP) spray X

X RHR-A Suction SDC under RHR-V-98 X

dX

NLS2010008 Attachment Page 4 of 5 System Suction General Location of Potential Void UT VV EJ Revised or Space Procedure Discharge Line RHR-A Suction Suction from SP X

X RHR-A Suction RV1O / RV12 X

X Downstream RHRCV20 SW RHR-A Discharge injection X

X X

RHR-B Discharge LPCI Line RHR27B X

X X

RHR-B Discharge Hx B Steam Condenser mode X

X X

RHR-B Discharge RHRMO38B SP spray X

X RHR-BI Suction SDC under RHR-MO-I5BiD X

X RHR-B Suction RV-1 1 / RV-13 X

X RHR-B Discharge RHR-V-82 X

X RHR-B Suction Suction from SP X

X X

HPCI Suction ECST suction supply X

X X

HPCI Suction Condensate return to HPCI suction X

X X

HPCI Suction Gland seal condenser X

X X

HPCI Suction RV-10, RV-11, RV-12 X

X HPCI Discharge Upstream FE80 X

X X

HPCI Suction Downstream restricting orifice 134 X

X X

3. Commitment Status The list of commitments provided in Reference 3, as updated by References 2 and 5, have been completed with the exception of commitment NLS2008081-01. This commitment states the following: "NPPD will evaluate the TSTF Traveler for making changes to individual licensee's TS related to the potential for unacceptable gas accumulation, its applicability to CNS, and evaluate adopting the Traveler to either supplement or replace the current TS requirements."

This commitment is dependent on industry resolution. The committed date is unchanged from the date provided in Reference 3.

Conclusion NPPD has completed the evaluation of the previously inaccessible portions of the applicable systems/functions at CNS that perform the functions described in the GL and has concluded that these systems are Operable, as defined in the CNS TS, and are in conformance with the CNS licensing basis and compliance with all applicable regulations, including 10 CFR 50 Appendix B, Criteria III, V, XI, XVI, and XVII.

References

1) NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" dated January 11, 2008

NLS2010008 Attachment Page 5 of 5

2) Letter from Stewart B. Minahan (NPPD) to USNRC Document Control Desk, dated September 11, 2008, "Request for Extension to Generic Letter 2008-01"

3) Letter from Stewart B. Minahan (NPPD) to USNRC Document Control Desk, dated October 10, 2008, "Nine-Month Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems"

4) Letter from Carl F. Lyon (USNRC) to Stewart B. Minahan (NPPD), dated October 3, 2008, "RE: Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," Proposed Alternative Course of Action (TAC No. MD7815)"

5) Letter from Brian J. O'Grady (NPPD) to USNRC Document Control Desk, dated May 7, 2009, "Revision to Commitment Made in Nine-Month Response to NRC Generic Letter 2008-01"

6) Letter from Brian J. O'Grady (NPPD) to USNRC Document Control Desk, dated December 17, 2009, "Response to Request for Additional Information Regarding Nebraska Public Power District's Nine-Month Response to NRC Generic Letter 2008-01"

ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© 4 ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS04 Correspondence Number: NLS2010008 The following table identifies those actions committed to by Nebraska Public Power District (NPPD) in this document. Any other actions discussed in the submittal represent intended or planned actions by NPPD. They are described for information only and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding-this-document or any associated regulatory commitments.

COMMITMENT COMMITTED DATE COMMITMENT NUMBER OR OUTAGE None N/A N/A 4

4 4

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