05000321/LER-2006-001, Regarding Inadequate Surveillance Procedure Acceptance Criteria Resulted in Exceeding Secondary Containment Drawdown Time
| ML061090108 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 04/18/2006 |
| From: | Sumner H Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-06-0558 LER 06-001-00 | |
| Download: ML061090108 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3212006001R00 - NRC Website | |
text
H. 1. Sumner, Jr.
Vice President Hatch Project April 18,2006 Docket No.:
50-321 Southern Nuclear Operating Company, Inc.
Post Off~ce Box 1295 Birm~ngham, Alabama 35201 Tel 205.992.7279 COMPANY Energy to Serve Your WorldsM U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Unit 1 Licensee Event Report Inadequate Procedure Results in Exceeding; Secondary Containment Drawdown Time Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(i)(B), Southern Nuclear Operating Company is submitting the enclosed Licensee Event Report concerning an inadequate surveillance procedure acceptance criteria which resulted in exceeding the secondary containment drawdown time.
This letter contains no NRC commitments. If you have any questions, please advise.
Sincerely, A
H. L. Sumner, Jr.
Enclosure: LER 1-2006-00 1 cc:
Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. D. R. Madison, General Manager - Plant Hatch RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Dr. W. D. Travers, Regional Administrator Mr. C. Gratton, NRR Project Manager - Hatch Mr. D. S. Simpkins, Senior Resident Inspector - Hatch
LICENSEE EVENT REPORT (LER) 20503. If a means used to On 02/17/2006 at approximately 1200 EST, Unit 1 was in the Refuel mode and aligned to Secondary Containment Type C. At that time, it was determined that within the past three years of operation the plant had operated in Secondary Containment Type A with Technical Specification Surveillance Requirement (TS SR) 3.6.4.1.3 not met. TS SR 3.6.4.1.3 requires that Standby Gas Treatment (SGT) be capable of drawing the secondary containment down to at least 0.2 inches of water vacuum, within 120 seconds. The procedure used to perform this surveillance test allowed 120 seconds to accomplish this drawdown using an energized bus and did not account for the 12 second delay in SGT initiation during an LOSP due to the diesel generator start time. On 12/12/2001 a Secondary Containment Type A test required 1 15.8 seconds to drawdown the Refuel Zone. The plant operated in Type A Secondary Containment for approximately 757 days before this same test was performed on 3/8/2004 when 56.4 seconds were required to drawdown the Refuel Zone.
A review of the latest TS SR 3.6.4.1.3 tests was performed and determined that all of the Secondary Containment configurations for Types A, B 1, and C were within the 120 seconds. This event was caused by NRC FORM 366 (6-2004)
(If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC FOR 366A)
All of the most recent secondary containment tests were reviewed and found to be less than 108 seconds establishing sufficient margin to account for the diesel generator start time.
CAUSE OF EVENT
The surveillance procedure (34SV-T22-001-0 Secondary Containment Test) for ensuring compliance with the plant's Technical Specifications did not account for the 12 second diesel generator start times. This resulted in accepting surveillance tests that exceeded the overall drawdown time of 120 seconds contained in the plant's Technical Specifications.
REPORTABILITY ANALYSIS AND SAFETY ASSESSMENT This event is reportable per 10 CFR 50.73 (a)(2)(i)(B) because an event occurred in which the plant was in a condition which was prohibited by the plant's Technical Specifications. A three year period for the reportability review was used because NUREG 1022 Revision 2 notes that conditions that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material within three years of the date of discovery are reportable. This three year limitation does not apply to events where safety limits or limiting safety system settings are exceeded.
The plant's Technical Specification Surveillance Requirement TS SR 3.6.4.1.3 requires that Standby Gas Treatment (SGT) be capable of drawing the secondary containment down to at least 0.2 inches of water vacuum, within 120 seconds. The procedure used to perform this surveillance test did not account for the 12 seconds delay in SGT initiation in an LOSP due to the diesel generator start time.
The following is an evaluation of the dose impact from a longer drawdown time; specifically 120 seconds plus an assumed 2 seconds signal generation and processing time plus 12 seconds diesel start time for a total of 134 seconds from the initiation of the accident until the secondary containment air is being processed through the SGTS.
Design Input References:
- 1. BH1-M-V999-0040, Version 0, "Post-LOCA Control Room and Offsite Doses."
- 2. GE-NE-A13-00402, March 1998, "Extended Power Uprate Evaluation Report for Edwin I. Hatch Units 1 and 2, Radiological Impact."
- 4. BH2-M-V999-0044, Version 0, "Post-LOCA Control Room and Offsite Doses."
- 2. DOCKET 05000-32 1
- 3. PAGE 4 0 F 6
- 6. LER NUMBER YEAR 2006 --
001
-- 00 SEQUENTIAL NUMBER REVISION NUMBER
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) 2006 -- '
001 -- 00 Conclusion:
A bounding evaluation of extended drawdown modeling using 134 seconds until SGTS effectiveness results in offsite and control room doses meeting all acceptance criteria, and meeting the minimal increase limits of 10 CFR 50.59. Based upon this analysis, it is concluded that this event had no adverse impact on nuclear safety. The analysis is applicable to all power levels.
CORRECTIVE ACTIONS
The most recent secondary containment tests were reviewed and found to be less than 108 seconds establishing sufficient margin to account for the diesel generator start time.
Procedure 34SV-T22-001-0, Secondary Containment Test, was revised to account for the 12 second diesel start time during an LOSP. The new acceptance criteria is listed as 107 seconds to account for signal generation time as well as the diesel start time.
Both Unit 1 and Unit 2 Technical Specification Bases for TS SR 3.6.4.1.3 will be revised to state that this surveillance assumes a concurrent LOSP as part of the drawdown time. This revision will be completed by October 2006.
ADDITIONAL INFORMATION
Other Systems Affected: No systems other than those already mentioned in this report were affected by this event.
There were no Failed Components identified for this event.
Commitment Information: This report does not create any permanent licensing commitments.
Previous Similar Events
There were no previous similar events in the last two years in which an inadequate acceptance criteria in a surveillance procedure resulted in the plant being in a condition prohibited by the plant's Technical Specifications.
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