1CAN030905, Post-Outage Supplemental Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems, Arkansas Nuclear One

Post-Outage Supplemental Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems, Arkansas Nuclear One

ML090760502
Person / Time
Site:	Arkansas Nuclear
Issue date:	03/16/2009
From:	Mitchell T Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
1CAN030905, GL-08-001
Download: ML090760502 (3)

Text

Entergy Operations, Inc.

1448 S.R. 333 Russellville, AR 72802 Tel 479-858-3110 Timothy G. Mitchell Vice President, Operations Arkansas Nuclear One 1CAN030905 March 16, 2009 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Post-Outage Supplemental Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems Arkansas Nuclear One, Unit 1 Docket No. 50-313 License No. DPR-51

REFERENCE:

1. Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems, dated January 11, 2008 (0CNA010801)

2. Nine-Month Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems, dated October 14, 2008 (0CAN100801)

Dear Sir or Madam:

The U. S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2008-01 (Reference 1) to request that each licensee evaluate the licensing basis, design, testing, and corrective action programs for the Emergency Core Cooling Systems (ECCS), Decay Heat Removal (DHR) system or Shutdown Cooling (SDC) system, and Containment Spray system, to ensure that gas accumulation is maintained less than the amount that challenges operability of these systems, and that appropriate action is taken when conditions adverse to quality are identified.

Entergy Operations, Inc., (Entergy) provided the GL 2008-01 required nine-month response for Arkansas Nuclear One, Units 1 and 2 (ANO-1 and 2) in Reference 2. As committed to in Reference 2, ANO-1 has completed its assessments of the inaccessible while at power portions of these systems during the Fall 2008 refueling outage. This supplemental information is being provided within 90 days of the startup from the outage. These activities are considered to be confirmatory.

1CAN030905 Page 2 of 3 In consideration of the walkdowns during the outage, data reviews, and additional operational data results, Entergy concludes that the subject ANO-1 systems are being operated and maintained in such a way as to minimize the presence of gas voids. In addition, it is further concluded that these systems are fully operable in regards to the nuclear industry gas voiding concerns. Except for the Sodium Hydroxide (NaOH) outlet gas voids, there were no additional ANO-1 condition reports generated as a result of the walkdowns and assessments during the outage.

The voids in the NaOH system are downstream of the isolation valves and the point where the NaOH piping connects to the suction piping of the Building Spray and Low Pressure Injection (LPI) pumps (~0.1 ft3 and ~0.52 ft3). In the evaluation of the voids, it was assumed that the voids were air bubbles resulting from the vent/fill operations at the end of the last refueling outage. It was determined that the voids were below the operability limits for each line. The acceptance criteria developed for this evaluation is that an acceptable volume fraction of gas is 10% by volume for no more than 5 seconds. Based on this, the maximum volume of air permissible in 5 seconds for the Spray pump is 1.67 ft3. For the LPI pump, a maximum of 3.34 ft3 in 5 seconds is acceptable. The voids that were found in the system were significantly smaller than the allowable volume. These voids do not challenge the structural operability of the affected systems. No mechanisms were identified that is increasing the volume of the voids.

Any procedure revisions related to the filling and venting of the subject systems are considered to be enhancements.

In summary, Entergy has concluded that the subject systems at ANO-1 are operable and that ANO-1 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 regarding managing gas accumulation in these systems/functions.

The next refueling outage for ANO-2 is scheduled for the Fall of 2009. The supplemental information for ANO-2 will be provided to the NRC as previously committed.

This supplemental response does not include any new commitments.

If you have any questions or require additional information, please contact David Bice at 479-858-4710.

I declare under penalty of perjury that the foregoing is true and correct. Executed on March 16, 2009.

Sincerely, TGM/rwc

1CAN030905 Page 3 of 3 cc: Mr. Elmo E. Collins Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 NRC Senior Resident Inspector Arkansas Nuclear One P. O. Box 310 London, AR 72847 U. S. Nuclear Regulatory Commission Attn: Mr. Alan B. Wang MS O-7 D1 Washington, DC 20555-0001 Mr. Bernard R. Bevill Arkansas Department of Health Radiation Control Section 4815 West Markham Street Slot #30 Little Rock, AR 72205