IR 05000269/2011018
| ML11277A253 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 10/04/2011 |
| From: | Croteau R Division Reactor Projects II |
| To: | Gillespie T Duke Energy Carolinas |
| References | |
| EA-11-226 IR-11-018 | |
| Download: ML11277A253 (14) | |
Text
UNITED STATES ober 4, 2011
SUBJECT:
OCONEE NUCLEAR STATION - NRC INSPECTION REPORT 050000269/2011018, 05000270/2011018, AND 0500287/2011018; PRELIMINARY GREATER THAN GREEN FINDINGS
Dear Mr. Gillespie:
This letter transmits two findings that have preliminarily been determined to be greater than very low safety significance (greater than Green) resulting in the need for further evaluation to determine significance and therefore the need for additional NRC action. These findings are also apparent violations (AVs) of NRC requirements and are being considered for escalated enforcement action in accordance with the Enforcement Policy, which can be found on the NRCs Web site at http://www.nrc.gov/about-nrc/regulatory/enforcement/enforce-pol.html.
The first preliminary greater than Green finding, as documented in NRC Inspection Report (IR)
05000269, 270, 287/2011017, involved the failure to maintain design control of the Standby Shutdown Facility (SSF) pressurizer heater breakers from 1983 until Duke Energy Carolinas (DEC) identification of the issue in June 2011. This finding was determined to be an AV of 10 CFR 50, Appendix B, Criterion III, Design Control. The NRC has concluded that this apparent violation of 10 CFR 50, Appendix B, Criterion III, also resulted in an apparent violation of Technical Specification (TS) 3.10.1, Standby Shutdown Facility, in that the SSF was inoperable from 1983 until June 2011, a time in excess of the TS allowed outage time.
Enclosures transmitted herewith contains SUNSI. When separated from Enclosures 2 and 3 this transmittal document is decontrolled. DEC 2 The second preliminary greater than Green finding, as documented in the enclosed inspection report, also involves an apparent violation of 10 CFR 50, Appendix B, Criterion III, Design Control and TS 3.10.1, when breakers that were not qualified for expected conditions were installed in containment and declared operable (Unit 1 on June 8, 2011, for Unit 2 on June 6, 2011, and for Unit 3 on June 7, 2011). Based on subsequent NRC review, it was determined that the breakers would not have remained operable if called upon during all SSF design basis events. The licensee corrected the condition on August 20, 2011, by replacing the breakers with environmentally qualified fuses.
Both preliminary greater than Green findings do not represent a current safety concern because the inoperable breakers were replaced with qualified fuses and the SSF was declared operable on August 20, 2011.
These findings were assessed based on the best available information, including influential assumptions, using the applicable Significance Determination Process (SDP). Enclosed is a copy of the SDP Phase 3 analysis. These findings are being classified as preliminary Greater than Green due to the high uncertainty in the Phase 3 analysis. The risk characterization in the Phase 3 was dominated by turbine building bus duct fires, due to their high initiating event frequency relative to the other initiators. The mitigation assumptions in the Phase 3 were bounding values selected to characterize the high and low thresholds for the risk determination.
The values for mitigation were uncertain due to the indeterminate plant state after the loss of the pressurizer heaters caused in part by the use of a thermo hydraulic code which had not been qualified for this condition. In addition, without a defined Event Tree Model, specific values for mitigation actions and components could not be developed.
In accordance with NRC Inspection Manual Chapter (IMC) 0609, we intend to complete our evaluation using the best available information and issue our final safety significance determination within 60 days of the date of this letter. The significance determination process encourages an open dialogue between the NRC staff and the licensee; however, the dialogue should not impact the timeliness of the staffs final significance determination.
Before we make a final decision on this matter, we are providing you with an opportunity (1) to attend a Regulatory Conference where you can present to the NRC your perspective on the facts and assumptions the NRC used to arrive at the finding and assess its significance, or (2)
submit your position on the finding to the NRC in writing. If you request a Regulatory Conference, it should be held within 30 days of the receipt of this letter and we encourage you to submit supporting documentation as discussed below as soon as possible but at least 14 days prior to the conference in an effort to make the conference more efficient and effective. If a Regulatory Conference is held, it will be open for public observation. If you decide to submit only a written response, such submittal should be sent to the NRC within 30 days of your receipt of this letter. If you decline to request a Regulatory Conference or submit a written response, you relinquish your right to appeal the final SDP determination, in that by not doing either, you fail to meet the appeal requirements stated in the Prerequisite and Limitation sections of Attachment 2 of IMC 0609. DEC 3 Should DEC request a Regulatory Conference or choose to submit its position on the findings in writing, the NRC requests specific supporting information to allow for the reduction of the uncertainty associated with these issues. In particular, a well defined Event Tree Model for this failure mode is requested to more properly characterize the risk associated with this issue.
Also, an analysis that has defined mitigation actions and components that can be used after the heater failure to maintain the plant in a safe condition should be submitted to reduce the uncertainty. In addition, analyses that support the use of the thermo hydraulic codes used in your engineering calculations and in your simulator, relative to the performance deficiency, are requested.
Please contact Jonathan Bartley at (404) 997-4607 and in writing within 10 days from the issue date of this letter to notify the NRC of your intentions. If we have not heard from you within 10 days, we will continue with our significance determination and enforcement decision. The final resolution of this matter will be conveyed in separate correspondence.
Because the NRC has not made a final determination in this matter, no Notice of Violation is being issued for these inspection findings at this time. In addition, please be advised that the number and characterization of the apparent violations described in the enclosed inspection report may change as a result of further NRC review.
Additionally, AVs 05000269, 270, 287/2011017-02 and -03 were determined to be of very low safety significance (Green) and are dispositioned in the enclosed report as one non-cited violation of 10 CFR 50, Appendix B, Criterion V, Procedures, with two examples. These inspection results were discussed with Mr. Robert Guy and other members of your staff on September 29, 2011.
In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter and its enclosure will be made available electronically for public inspection in the NRC Public Document Room or from the NRCs document system (ADAMS), accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html
Sincerely,
/RA By William Jones For/
Richard P. Croteau, Director Division of Reactor Projects Docket Nos.: 50-269, 50-270, 50-287 License Nos.: DPR-38, DPR-47, DPR-55
Enclosures:
1. Inspection Report 050000269/2011018, 05000270/2011018, and 0500287/2011018 w/Attachment: Supplementary Information 2. Phase 3 Significance Determination, Apparent Violation 2011017-01 3. Phase 3 Significance Determination, Apparent Violation 2011018-01
REGION II==
Docket Nos.: 50-269, 50-270, 50-287 License Nos.: DPR-38, DPR-47, DPR-55 Report No.: 05000269/2011018, 05000270/2011018, 05000287/2011018 Licensee: Duke Energy Carolinas, LLC Facility: Oconee Nuclear Station, Units 1, 2, and 3 Location: Seneca, SC 29672 Dates: September 7 - 20, 2011 Inspectors: A. Sabisch, Senior Resident Inspector R. Bernhard, Senior Reactor Analyst Approved by: R. Croteau, Director Division of Reactor Projects Enclosure 1 2 IR 05000269/2011-018, 05000270/2011-018, 05000287/2011-018; 09/07/2011 - 09/20/2011; Oconee Nuclear Station Units 1, 2 and 3; Other Activities The report covers a review of the Standby Shutdown Facility (SSF) pressurizer heater breakers by the resident inspectors and a senior reactor analyst. One preliminary greater than Green finding with an Apparent Violation (AV) and one Green non-cited violation were identified. The significance of most findings is indicated by their color (Green, White, Yellow, Red) using Inspection Manual Chapter (IMC) 0609, Significance Determination Process (SDP). Cross-cutting aspects were determined using IMC 0310, Components Within The Cross-Cutting Areas. Findings for which the SDP does not apply may be Green or be assigned a severity level after NRC management review. The NRC's program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process.
Cornerstone: Mitigating Systems
- TBD. An NRC-identified preliminarily greater than Green Apparent Violation (AV) of 10 CFR 50, Appendix B, Criterion III, Design Control, was identified for the licensees failure to install Standby Shutdown Facility (SSF) pressurizer heater breakers that were qualified for expected environmental conditions inside of containment during design basis events. The licensee installed replacement breakers and the SSF declared operable without testing to support that the replacement breakers would function under elevated containment temperatures.
The failure to maintain design control of the SSF was a performance deficiency (PD). The PD was more than minor because it was associated with the Mitigating Systems Cornerstone attribute of Design Control and adversely affected the cornerstone objective in that failure to maintain equipment qualification did not provide reasonable assurance that the SSF Auxiliary Service Water (ASW) subsystem would perform its safety function. The finding was assessed using IMC 0609, Attachment 4, and determined that a Phase III analysis was required because the finding involved the loss or degradation of equipment designed to mitigate external initiating events. Therefore, the significance of this finding is to be determined (TBD). This finding had a cross-cutting aspect in the area of Human Performance under the Procedural Compliance aspect of the Work Practices component in that the licensee failed to follow the requirements set forth in EDM 601, Engineering Change.
- Green. An NRC-identified NCV of 10 CFR 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified when the licensee failed to perform an adequate operability evaluation and failed to perform a 50.59 evaluation for a compensatory measure for the SSF ASW subsystem in accordance with Nuclear System Directive (NSD) 203, Operability/Functionality.
The failure to perform an adequate operability evaluation for the SSF ASW subsystem in accordance with NSD 203 was a PD. There were two examples of this PD. The first example was more than minor because it was associated with the Design Control attribute of the Mitigating System Cornerstone and adversely affected the cornerstone objective in that Enclosure 1 3 the licensee failed to assure the SSF pressurizer heater breakers would function under expected environmental conditions before declaring the SSF operable. The second example was more than minor because it was associated with the Procedure Quality attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective in that the compensatory measure used to support the SSF as operable but degraded non-conforming (OBDN) required prior NRC review and approval. The finding was determined to be of very low safety significance (Green) because it did not result in an actual loss of safety function of the SSF ASW system. The PD was related to the cross-cutting aspect of using conservative assumptions in decision-making in the Decision-Making component of the Human Performance cross-cutting area in that the licensee declared the SSF OBDN without validated testing to demonstrate the SSF pressurizer heater breakers would function under design basis conditions and relied on an unapproved analysis method to support a compensatory measure. H.1(b) Enclosure 1 REPORT DETAILS 4. OTHER ACTIVITIES 4OA5 Other Activities a. Inspection Scope The inspectors performed additional in-office review of the SSF pressurizer heater breaker issues previously documented in NRC IR 05000269, 270, 287/2011017. The inspectors evaluated the replacement of the original breakers and subsequent operable declaration of the SSF as well as the two examples of where operability assessments had been performed without sufficient rigor and adherence to station guidance to ensure the proper operability determination was made.
b. Findings
.1 SSF Inoperability Due To Unqualified Breakers Introduction: An NRC-identified preliminarily greater than Green Apparent Violation (AV)
of 10 CFR 50, Appendix B, Criterion III, Design Control, was identified for the licensees failure to install SSF pressurizer heater breakers that were qualified for expected environmental conditions inside of containment during design basis events. The licensee installed replacement breakers and the SSF declared operable without testing to support that the replacement breakers would function under elevated containment temperatures.
Description: On June 2, 2011, the licensee identified that the SSF pressurizer heater breakers installed during initial construction in 1983 would not withstand the expected 267°F temperature inside containment due to the loss of containment cooling during SBO and seismic-induced turbine building flooding events. These breakers had a thermal overload feature that would have caused the breakers to open prematurely under the expected elevated containment temperature. This would have prevented the SSF ASW subsystem from performing its safety function and the SSF was declared inoperable for all three units. The licensee implemented a modification to restore operability by replacing the original breakers; however, the replacement breakers had not been tested to verify they would function at elevated containment temperatures.
Following installation of the replacement breakers, the SSF was declared operable on June 8 (Unit 1), June 6 (Unit 2), and June 7 (Unit 3). Environmental qualification testing performed on the replacement breakers revealed that they would not remain functional for the required mission time under elevated containment temperatures. The licensee removed these breakers and replaced them with fused protection on all three units which was environmentally qualified. The SSF was declared operable for all three units on August 20, 2011. Enclosure 1 5 The inspectors discussed the SSF operability determination with the licensee and identified that the licensee had not entered this condition into their corrective action program for assessment and development of corrective actions.
Analysis: The failure to maintain design control of the SSF was a PD. The PD was more than minor because it was associated with the Mitigating Systems Cornerstone attribute of Design Control and adversely affected the cornerstone objective in that failure to maintain equipment qualification did not provide reasonable assurance that the SSF ASW subsystem would perform its safety function during certain SSF-credited events. The finding was assessed using IMC 0609, Attachment 4, and determined that a Phase III analysis was required because the finding involved the loss or degradation of equipment designed to mitigate external initiating events. Therefore, the significance of this finding is to be determined (TBD). This finding had a cross-cutting aspect in the area of Human Performance under the Procedural Compliance aspect of the Work Practices component in that the licensee failed to follow the requirements set forth in Engineering Directive Manual (EDM) 601, Engineering Change. H.4(b).
Enforcement: 10 CFR Part 50, Appendix B, Criteria III, Design Control, required, in part, that measures shall be established to assure that deviations from appropriate quality and design standards are controlled and that the review for suitability of application of equipment essential to safety-related functions of SSCs is maintained. Procedure EDM-601, Engineering Change, Section 601.5.2.1, Engineering Change Program - Design Phase, Commercial Controls, required that components acquired commercially be tested to verify they will perform the required safety function prior to actual installation.
Technical Specification 3.10.1.A required that with SSF ASW inoperable the system be restored to an operable status within seven days or the unit placed in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 within 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br />. Contrary to the above, on June 4, 2011, a review for suitability of application of equipment essential to safety-related functions of SSCs was not performed. The licensee developed a modification that installed replacement breakers in the circuit supplying power to the pressurizer heaters from the SSF without test data to demonstrate that they would function at elevated containment temperatures and maintain the SSF functionality in accordance with the licensing and design bases.
As a result, the SSF was inoperable from the time of new breaker installation (Unit 1 on June 8, 2011, for Unit 2 on June 6, 2011 and for Unit 3 on June 7, 2011) until August 20, 2011, a period in excess of TS 3.10.1.A allowed outage time.
The SSF was declared operable following installation of the new breakers for Unit 1 on June 8, 2011, for Unit 2 on June 6, 2011 and for Unit 3 on June 7, 2011. It was subsequently determined that the breakers would not have remained operable if called upon during all SSF design basis events. The licensee corrected the condition on August 20, 2011, by replacing the breakers with environmentally qualified fuses.
Because this finding is potentially greater than Green, this violation is being treated as an AV: AV 05000269, 270, 287/2011018-01, Installation of Non-Qualified SSF.
Pressurizer Heater Breakers Impacting Operability During Certain SSF-Credited Events.
The condition associated with this Criterion III AV resulted in an apparent violation of Technical Specification 3.10.1, Standby Shutdown Facility. Enclosure 1 6
.2 (Closed) AV 05000269, 270, 287/2011017-02, Failure to Perform an Adequate Operability Evaluation for the SSF (Closed) AV 05000269, 270, 287/2011017-03, Failure to Perform a Safety Evaluation for a Compensatory Measure Introduction: A Green NRC-identified NCV of 10 CFR 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified when the licensee failed to perform an adequate operability evaluation and failed to perform a 50.59 evaluation for a compensatory measure for the SSF ASW subsystem in accordance with NSD 203.
Description: This finding was previously described in NRC IR 05000269, 270, 287/2011017003, section 4OA5.5 as AVs 05000269, 270, 287/2011017-02 and 05000269, 270, 287/2011017-03.
Analysis: The failure to perform an adequate operability evaluation for the SSF ASW subsystem in accordance with NSD 203 was a PD. There were two examples of this PD. The first example was more than minor because it was associated with the Design Control attribute of the Mitigating System Cornerstone and adversely affected the cornerstone objective in that the licensee failed to assure the SSF pressurizer heater breakers would function under expected environmental conditions before declaring the SSF operable. The second example was more than minor because it was associated with the Procedure Quality attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective in that the compensatory measure to support the SSF as operable but degraded/non-confirming (OBDN) required prior NRC review and approval. The finding was assessed using IMC 0609, Attachment 4, Phase 1 - Initial Screening and Characterization of Findings, and determined that the finding was of very low safety significance (Green) because it did not result in an actual loss of safety function of the SSF ASW system. The PD was related to the cross-cutting aspect of using conservative assumptions in decision-making in the Decision-Making component of the Human Performance cross-cutting area in that the licensee declared the SSF OBDN without validated testing to demonstrate the SSF pressurizer heater breakers would function under design basis conditions and relied on an unapproved analysis method to support a compensatory measure. H.1(b)
Enforcement: 10 CFR Part 50, Appendix B, Criteria V, Instructions, Procedures, and Drawings, required, in part, that activities affecting quality shall be accomplished in accordance with instructions and procedures. NSD 203, Section 203.7, stated if a degraded/non-conforming SSC is declared operable or OBDN, the evaluation should clearly state the reasonable expectation of operability commensurate with the safety function of the SSC. NSD 203, Section 203.9.1, Compensatory Actions, stated that proposed compensatory actions that constitute changes to the facility or procedures as described in the UFSAR require application of 10CFR50.59 prior to implementation.
Contrary to the above, the licensee failed to accomplish an activity affecting quality in accordance with instructions and procedures on two occasions. Enclosure 1 7
- On June 6 -8, 2011, the licensee did not perform an adequate operability evaluation for the SSF ASW subsystem in accordance with NSD 203 in that the licensee relied on insufficient data to support the determination that the SSF was OBDN.
- On June 24, 2011, the licensee did not perform a 50.59 evaluation in accordance with NSD 203 of a compensatory measure which the licensee used to determine that the SSF ASW subsystem was OBDN. It was subsequently determined that the compensatory measure could not be used because NRC review and approval was required prior to implementation.
Because this finding is very low safety significance and has been entered into the licensees CAP as PIP O-11-6700, this violation is being treated as an NCV and is designated as NCV 05000269, 270, 287/2011018-02, Failure to Perform an Adequate Operability Evaluation for the SSF. AVs 05000269, 270, 287/2011017-02 and -03 are considered closed based on the issuance of this NCV.
4OA6 Management Meetings (Including Exit Meeting)
Exit Meeting Summary The inspection results were presented to Mr. Robert Guy, and other members of licensee management, on September 29, 2011. The licensee acknowledged the findings presented.
Attachment: Supplementary Information Enclosure 1 SUPPLEMENTARY INFORMATION LIST OF ITEMS OPENED AND CLOSED OPENED 05000269, 270, 287/2011018-01 AV Installation of Non-Qualified SSF Pressurizer Heater Breakers Impacting Operability During Certain SSF-Credited Events (Section 4OA5.1)
OPENED AND CLOSED 05000269, 270, 287/2011018-02 NCV Failure to Perform an Adequate Operability Evaluation for the SSF (Section 4OA5.2)
CLOSED 05000269, 270, 287/2011017-02 AV Failure to Perform an Adequate Operability Evaluation for the SSF (Section 4OA5.2)
05000269, 270, 287/2011017-03 AV Failure to Perform a Safety Evaluation for a Compensatory Measure (Section 4OA5.2) Attachment