05000250/LER-2005-002
| Docket Number Sequential Revmonth Day Year Year Month Day Yearnumber No. 05000 | |
| Event date: | 2-9-2005 |
|---|---|
| Report date: | 4-11-2005 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2502005002R00 - NRC Website | |
FACILITY NAME Ill DOCKET NUMBER (21 UR NUMBER 161 PAGE 131 Turkey Point Unit 3 05000250 2005 - � 002 00
DESCRIPTION OF THE EVENT
containment isolation valve [EIIS: NH, ISV] CV-3-956D and the fittings were tightened. CV-3-956D is located outside containment. The inlet fitting adjustment altered the leak tightness of the containment boundary. An as-found local leak rate test (LLRT) was not performed prior to fitting adjustment.
Turkey Point Units 3 and 4 were operating in Mode 1 at 100% power at the time of the event.
This condition was determined to be reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a required as-found LLRT surveillance test was missed and could not be subsequently performed.
BACKGROUND
Isolation provisions limit radioactive effluent releases from the containment building in the event of a reactor [EIIS: AC] accident. Isolation valves either close automatically or remain closed to perform this function. Containment isolation valves and penetrations [EIIS: PEN] are tested to ensure leakage is within allowed limits.
CV-3-956D is associated with a 3/8 inch safety injection accumulator [EIIS: BQ, ACC] sample line at piping penetration 55. CV-3-956D is normally closed, and if open for accumulator sampling, closes automatically by a Phase A containment isolation signal in the event safety injection is needed.
The fittings were tightened due to minor leakage when the line was pressurized during sampling. No testing requirements were specified in the work order prepared for the activity.
CAUSE OF THE EVENT
The apparent cause of the missed as-found LLRT is a failure, during work planning, to recognize LLRT requirements when disturbing a containment boundary. While planning the work, it was mistakenly assumed that since the listed inservice test (IST) component (CV-3-956D) was not directly impacted by the work activity, an IST or LLRT did not apply. Subsequent reviews by station personnel did not identify the omission.
ANALYSIS OF THE EVENT
In response to observed leakage at the inlet and outlet Swagelok® fittings joining tubing welded to the body of containment isolation valve CV-3-956D, the fittings were tightened. Adjusting the inlet fitting altered the leak-tightness of the containment boundary at penetration 55. This is an infrequent evolution as leakage between a containment penetration and an outboard isolation valve is rare. The Containment Leakage Rate NIC fOIM 36611140011 MC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION 17-2001) LICENSEE EVENT REPORT [LEM FACILITY NAME ID DOCKET NUMBER 121 LEE NUMBER MI PAGE 131 Turkey Point Unit 3 05000250 2005 -�002 00 Testing Program requires an as-found LLRT to be performed prior to any maintenance, repair, modification, or adjustment activity if the activity could affect the penetration's leak tightness. The failure to perform the as-found LLRT is a missed surveillance test.
Reportability A review of the reporting requirements of 10 CFR 50.72 and 10 CFR 50.73 and NRC guidance provided in "Event Reporting Guidelines," 10 CFR 50.72 and 10 CFR 50.73 (NUREG-1022, Rev. 2) was performed for the subject condition. As a result of this review, the condition is reportable as described below.
1. Part 50.73(a)(2)(i)(B) of Title 10 CFR states that the licensee shall report "Any operation or condition which was prohibited by the plant's Technical Specifications except when:
(1) The Technical Specification is administrative in nature; (2) The event consisted solely of a case of a late surveillance test where the oversight was corrected, the test was performed, and the equipment was found to be capable of performing its specified safety functions; or (3) The Technical Specification was revised prior to discovery of the event such that the operation or condition was no longer prohibited at the time of discovery of the event.
Technical Specification (TS) Surveillance Requirement (SR) 4.6.1.2 requires that "...containment leakage rates shall be demonstrated at the required test schedule and shall be determined in conformance with the criteria specified in the Containment Leakage Rate Testing Program.
TS 6.8.4.h requires the establishment of the Containment Leakage Rate Testing Program "as required by 10 CFR 50.54(o) and 10 CFR 50, Appendix J, Option B, and as modified by approved exemptions. This program shall be in accordance with the guidelines contained in Regulatory Guide 1.163..." as modified by certain deviations or exemptions. None of the deviations or exemptions contained in TS 6.8.4.h provide relief from performing as-found LLRTs.
Procedure 0-ADM-531, Containment Leakage Rate Testing Program, implements SR 4.6.1.2 and TS maintenance, repair, modifications, or adjustment activity if the activity could affect the penetration's leak tightness." An as-left Type B test is also required "...following the maintenance, repair, modification or adjustment activity.
10 CFR 50, Appendix J does not explicitly require the performance of as-found LLRTs; however, Appendix J refers to Regulatory Guide (RG) 1.163, "Performance-Based Containment Leak-Test Program," as providing the specific guidance for implementing an Option B program.
RG 1.163 states that "NEI 94-01, Revision 0, dated July 26, 1995, 'Industry Guideline for Implementing Performance-Based Option of 10 CFR 50 Appendix J,' prepared by the Nuclear Energy Institute, provides methods acceptable to the NRC staff for complying with the provisions of Option B in Appendix J to 10 FACILITY NAME ID DOCKET NUMBER 121 NUMBER 161 PAGE (31 Turkey Point Unit 3 05000250 CFR Part 50, subject..." to certain conditions. One of the conditions pertains to the performance of as-found LLRTs "...prior to any maintenance, repair, modification, or adjustment activity if it could affect a valve's leak-tightness." The NRC staff did not endorse the "alternative test or analysis" in lieu of an as-found LLRT contained in NEI 94-01, Section 10.2.3.3, for Type C tests of valves. NEI 94-01, Section 10.2.1.3 does not contain a similar alternative for Type B tests.
NEI 94-01, Section 10.2.1.3, requires an as-found Type B test to "...be performed prior to any maintenance, repair, modification, or adjustment activity if the activity could affect the penetration's leak tightness." An as-left test is also required. Since the purpose of the activity was to reduce or eliminate leakage at the fittings, it could affect the penetration's leak tightness.
The failure to perform an as-found LLRT is not in conformance with 0-ADM-531, which implements SR 4.6.1.2 and TS 6.8.4.h consistent with required regulatory guidance. The as-found LLRT SR was missed and could not be subsequently performed once the fitting adjustment was made. As a result, the exception of 10 CFR 50.73(a)(2)(i)(B)(2) could not be met. The missed as-found LLRT is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a "...condition which was prohibited by the plant's Technical Specifications....
Extent of Condition A review to determine if similar events have occurred was conducted.
On April 28, 2003, during troubleshooting activities for letdown flow control valve CV-3-200B, loose actuator mounting fasteners were tightened. This had the potential to affect valve leak tightness. An as found LLRT was not performed. The operability assessment concluded that there was reasonable assurance that TS leakage limits were not exceeded. That event was incorrectly determined not reportable.
The cause of the 4/28/03 event was inadequate communication regarding the expectation for verification of bolt tightness as specified in the work order. The corrective actions were focused on minimizing the potential for miscommunication. While these events are similar in that as-found LLRTs were missed, their causes differ and the corrective actions for the 4/28/03 event could not be expected to have prevented the 2/9/05 event.
The 4/28/03 event will be reported separately in Licensee Event Report 50-250/2005-003-00.
ANALYSIS OF SAFETY SIGNIFICANCE
Based on the analysis described below, it is concluded that the health and safety of the public were not affected by this event.
Prior to the fitting adjustment on February 9, 2005, an as-left LLRT for CV-3-956D was performed on October 26, 2004. The leakage rate for the valve and associated piping, including the inlet fitting, was 18 NBC 11111366111-20011 17-20011 DOCKET NUMBERFACILITY NAME(11 LER NUMBER I61 PACE L31 TELT lit mote One Is rewired usesddNUonalcopieso/MRCfonn36W (ill standard cubic centimeters (scc)/minute following valve overhaul. The administrative leakage limit for penetration 55, established under the Appendix J, Option B program, is 4400 scc/minute. The administrative limit provides margin to the TS allowable leakage rate and is used to establish a performance basis for extending the periodic LLRT. No maintenance was performed on penetration 55 between the 10/26/04 LLRT and the tightening of the inlet fitting that would have invalidated the prior test.
Since CV-3-956D is used infrequently, degradation associated with wear is considered unlikely since the 10/26/04 LLRT. Review of past LLRT results revealed no significant degradation trends. Review of past stroke time testing also revealed no significant degradation trends. Based on these reviews, leakage through penetration 55 was considered to be within the allowed TS and administrative limits prior to the fitting adjustment.
The coolant leakage recently noted at the fittings can be attributed to the higher differential pressure (approximately 600 psig) experienced by penetration components during accumulator sample operations.
The pressure experienced by these components during a design basis event is expected to be much closer to containment ambient conditions. The expected conditions are accounted for in the LLRT procedure by testing penetrations at an air pressure of 51-53 psig.
Following fitting adjustment, an as-left LLRT was performed and leakage for penetration 55 was 80 scc/min. The results of this as-left test and the as-left test performed on 10/26/04 after valve overhaul were well within the administrative limit of 4400 scc/minute. Based on the 10/26/04 as-left LLRT, the recent post-adjustment LLRT, no maintenance activity on the penetration since 10/26/04 and the remote possibility of excessive wear due to valve operation, there is reasonable assurance that penetration leakage was within allowable limits prior to the fitting adjustment. Even if the leakage through penetration 55 was at the administrative limit of 4400 scc/minute, there was substantial margin to the allowed TS limit of 1.0 La.
Therefore, there was no increase in risk to members of the general public in the event of an accident, since radiological consequences would have remained within the values assumed in the safety analysis.
CORRECTIVE ACTIONS
1. The condition report addressing the missed as-found LLRT was provided to and discussed with work planners emphasizing the apparent cause and contributing factors.
2. Planning supervisors and leads were coached on the importance of performing a quality review of work orders.
3. To enhance error prevention barrier protection Desktop Instruction DTI-701 and Procedure 0-ADM-701, Control of Plant Work Activities, will be revised to include specific action steps when encountering work involving the adjustment or repair of a containment penetration.
FACILITY NAME 111 DOCKET NUMBER 121 LIR NUMBER 161 PAGE 131 Turkey Point Unit 3 05000250 2005 -�002 00 4. The period LLRT interval for CV-3-956D has been reset to the nominal refueling cycle length of approximately 18 months until the performance history provides a basis to extend the interval in accordance with Procedure 0-ADM-531, Containment Leakage Rate Testing Program.
5. The Senior Reactor Operator who reviewed and approved the deficient work order was coached and counseled on the test requirements for containment boundaries when their leak-tightness could be impacted. No process or programmatic weaknesses were identified.
ADDITIONAL INFORMATION
second component function identifier (if appropriate)].
FAILED COMPONENTS IDENTIFIED:�NONE SIMILAR EVENTS: see ANALYSIS OF THE EVENT HC Mil 366111-20011