IR 05000269/2012011

IR 05000269-12-011, 05000270-12-11, and 05000287-12-011, on February 6 - February 9, 2012, Oconee Nuclear Station Units 1, 2, and 3, Supplemental Inspection - Inspection Procedure (IP) 95002

ML12068A353
Person / Time
Site:	Oconee
Issue date:	03/08/2012
From:	Croteau R Division Reactor Projects II
To:	Gillespie T Duke Energy Carolinas
References
IR-12-011
Download: ML12068A353 (19)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION rch 8, 2012

SUBJECT:

OCONEE NUCLEAR STATION - NRC INSPECTION PROCEDURE 95002 AND OLD DESIGN ISSUE SUPPLEMENTAL INSPECTION REPORT 05000269/2012011, 05000270/2012011, AND 05000287/2012011

Dear Mr. Gillespie:

On February 9, 2012, the U.S. Nuclear Regulatory Commission (NRC) completed a partial supplemental inspection pursuant to Inspection Procedure 95002, Supplemental Inspection for One Degraded Cornerstone or any Three White Inputs in a Strategic Performance Area, at your Oconee Nuclear Station, Units 1, 2, and 3. In addition, the NRC reviewed information to determine if the associated finding warranted treatment as an old design issue. The enclosed inspection report documents the inspection results, which were discussed on February 9, 2012, with you and other members of your staff.

In accordance with the NRC Reactor Oversight Process Action Matrix, this supplemental inspection was performed to follow-up on a Yellow finding with substantial safety significance which was issued in the fourth quarter of 2011. The issue involved standby shutdown facility (SSF) pressurizer heater breakers that were not qualified for the required environmental conditions. This issue was previously documented and assessed in NRC Inspection Report (IR) 05000269/2011017, 05000270/2011017, and 05000287/2011017, as well as in NRC IR 05000269/2011019, 05000270/2011019, and 05000287/2011019. The NRC was informed on January 20, 2012, of your staffs readiness for this inspection.

The objectives of this inspection were to gather information for the NRC to evaluate whether the Yellow finding meets the criteria of Inspection Manual Chapter (IMC) 0305, Operating Reactor Assessment Program, for treatment as an old design issue and to provide assurance that the root causes and the contributing causes for the risk-significant issue were understood.

No findings were identified during this inspection. The inspectors determined that your staff performed an acceptable evaluation of the Yellow finding as it related to providing assurance the root causes and contributing causes were understood. Your staffs evaluation of the Yellow finding identified the most probable cause of the issue to be as follows. At the time of the design change in 1980-1983, the design change process only required addressing the physical changes of the plant and did not address the changes to system design requirements. Although the system design requirements of the SSF pressurizer heaters were changed, no physical changes to the breakers were made. Therefore, they were not evaluated as part of the design change process at the time.

DEC 2 The NRC determined that the Yellow finding meets the criteria specified in IMC 0305 for treatment as an old design issue. The NRC determined that the issue was licensee-identified through walkdowns by an engineer in support of an unrelated modification, a questioning attitude, and an expansion of extent-of-condition review. The issue was corrected within a reasonable time following discussion of significance between you and the NRC by declaring the SSF inoperable on July 8, 2011, and ultimately replacing the breakers with qualified fuses on August 20, 2011. The issue was not likely to be previously identified as it was not observable during normal operations, routine testing, or maintenance. The issue was not reflective of a current performance deficiency associated with existing programs, policy, or procedures because the engineering change process was revised in 2006 with requirements to conduct more extensive reviews during modifications to prevent similar occurrences. The NRC reviewed selected performance deficiencies identified during the previous three years and concluded that none of the issues were significantly similar to the Yellow finding and instead displayed more differences than similarities. Therefore in accordance with IMC 0305, the performance issue will not aggregate in the Action Matrix with other performance indicators and inspection findings.

This partial IP 95002 inspection was conducted primarily to gather information necessary to determine whether the Yellow finding should be treated as an old design issue. Therefore not all inspection objectives required by IP 95002 were completed. The NRC will conduct the remainder of the inspection objectives after you have notified us of your readiness. Although the Yellow finding will not aggregate in the Action Matrix, it will remain open until all IP 95002 inspection objectives have been met and verified by inspection.

In accordance with 10 CFR 2.390 of the NRCs Rules of Practice, a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of NRCs Agencywide Document Access and Management System (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

/RA/

Richard P. Croteau, Director Division of Reactor Projects Docket Nos.: 50-269, 50-270, 50-287 License Nos.: DPR-38, DPR-47, DPR-55

Enclosure:

Inspection Report 05000269/2012011, 05000270/2012011, and 05000287/2012011 w/Attachment: Supplemental Information

REGION II==

Docket No.: 05000269, 05000270, 05000287 License No.: DPR-38, DPR-47, DPR-55 Report No.: 05000269/2012011, 05000270/2012011 and 05000287/2012011 Licensee: Duke Energy Carolinas, LLC Facility: Oconee Nuclear Station, Units 1, 2 and 3 Location: Seneca, SC 29550 Dates: February 6, 2012, through February 9, 2012 Inspectors: E. Stamm, Project Engineer (Lead)

J. Rivera-Ortiz, Senior Reactor Inspector S. Walker, Senior Reactor Inspector Approved by: Richard P. Croteau, Director Division of Reactor Projects Enclosure

SUMMARY OF FINDINGS

IR 05000269/2012011, 05000270/2012011, and 05000287/2012011; February 6 - February 9, 2012; Oconee Nuclear Station Units 1, 2, and 3; Supplemental Inspection - Inspection Procedure (IP) 95002.

This supplemental inspection was conducted by two senior reactor inspectors and a project engineer. No findings were identified. The NRCs program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process.

Cornerstone: Mitigating Systems

The NRC staff performed this supplemental inspection in accordance with IP 95002, Inspection for One Degraded Cornerstone or any Three White Inputs in a Strategic Performance Area, to assess the licensees evaluations associated with installation of standby shutdown facility (SSF)pressurizer heater breakers that were not qualified for the design basis environmental conditions as required by 10 CFR 50 Appendix B, Criterion III, Design Control. The NRC staff previously characterized this condition as having moderate safety significance (Yellow) as documented in NRC Inspection Report (IR) 05000269, 270, 287/2011019. The licensee identified the most probable cause to be that the design change process used to install the SSF at the time (1980-1983) only addressed the physical changes of the plant and did not require addressing the changes to system design requirements. Also, the design change was not implemented in accordance with current licensee standards.

As a result of NRCs determination that this finding meets the criteria of Inspection Manual Chapter (IMC) 0305, Operating Reactor Assessment Program, for treatment as an old design issue, this finding will not aggregate in the Action Matrix with other performance indicators and inspection findings. However, it will remain open until all IP 95002 inspection objectives have been met and verified by inspection. Oconee Units 1, 2, and 3 remain in the Licensee Response column of the NRCs Action Matrix.

REPORT DETAILS

4OA4 Supplemental Inspection

.01 Inspection Scope

The inspectors performed this supplemental inspection in accordance with IP 95002 to assess the licensees evaluation of a Yellow finding, (VIO 05000269, 270, 287/2011017-01) which affected the Mitigating Systems Cornerstone in the Reactor Safety strategic performance area. The inspection objectives were to:

• provide assurance that the root and contributing causes of the risk-significant issue were understood

• gather information to determine whether the Yellow finding meets the criteria for treatment as an old design issue as described in IMC 0305 This finding affected all three units and was associated with the installation of SSF pressurizer heater breakers that were not qualified for the design basis environmental conditions as required by 10 CFR 50, Appendix B, Criterion III, Design Control.

Specifically, the licensee failed to maintain the SSF pressurizer heater breakers and associated electrical components as safety-related Quality Assurance condition 1 (QA-1)and seismically-qualified components in accordance with the licensing and design bases. The licensee implemented the SSF modification and utilized previously installed breakers which had not been tested to verify that they would function at elevated containment temperatures and maintain SSF functionality in accordance with the licensing and design basis. As a result, the SSF was inoperable from 1983 until June 1, 2011, a period in excess of the Technical Specification (TS) 3.10.1.A allowed outage time.

The licensee informed the NRC on January 20, 2012, that they were ready for this supplemental inspection. The licensee performed a root cause evaluation (RCE) for the Yellow finding (RCE Problem Investigation Program (PIP) O-11-06700) to identify the cause of the finding, identify appropriate corrective actions, and to review the extent-of-condition and extent-of-cause.

The inspectors reviewed the licensees RCE and other supporting documents as they related to problem identification and cause evaluation. The inspectors also interviewed licensee personnel to ensure that the root and contributing causes were understood. In addition, the inspectors conducted a review of recent licensee performance to evaluate the Yellow finding against the old design criteria contained in IMC 0305.

.02 Evaluation of the Inspection Requirements

02.01 Problem Identification a. Determine that the licensees evaluation of the issue documented who identified the issue (i.e., licensee-identified, self-revealing, or NRC-identified) and the conditions under which the issue was identified The inspectors verified the licensees RCE documented that the finding was identified by the licensee during preliminary extent of condition research for external flood mitigation.

b. Determine that the licensees evaluation of the issue documented how long the issue existed and prior opportunities for identification The RCE documented that, since original design and installation in 1983, the SSF design credited breakers that would not have performed their function under anticipated design conditions. When the SSF was designed and installed, previously existing pressurizer heater breakers were credited by the design. However, these breakers had thermal overloads which could open due to design basis environmental conditions during SSF events and prevent the pressurizer heaters from performing their function.

The licensee identified multiple previous opportunities to discover the issue. The most probable opportunity to discover the issue was in 1993, when calculation OSC-6013 was issued to provide for environmental qualification of SSF reactor building equipment. This calculation listed pressurizer heaters and cabling, but not the breakers. Had the review of the calculation identified that the pressurizer heater breakers were missing from the list of components, it is likely the issue would have been identified at that time. Other opportunities identified by the licensee included:

(1) a licensee-generated calculation, OSC-0615, from the design phase in 1979, which showed anticipated reactor building temperatures up to 289°F following a loss of offsite power/station blackout;

(2) issuance of NRC Information Notice 89-30 which alerted addressees to potential problems resulting from high temperature environments in areas that contain safety-related equipment or electrical cables;

(3) a self-initiated technical audit of the SSF performed in 2000;

(4) Licensee Event Report (LER) 269/2002, which documented in 2002 that Group B heaters were not sufficient to make up for losses to ambient and added Group C heaters to the SSF but did not evaluate those breakers for the new environmental qualifications; and

(5) an Engineering Change Request in 2007 for protected service water which failed to evaluate the impact of changing the existing design function (re-purposing) of the pressurizer heater breakers for new environmental conditions.

The inspectors found the licensees evaluation of historical events was thorough and included a number of relevant events and missed opportunities to identify the issue associated with the SSF pressurizer heater breakers.

c.

Determine that the licensees evaluation documented the plant specific risk consequences, as applicable, and compliance concerns associated with the issues both individually and collectively The inspectors reviewed the licensees plant-specific risk evaluation documented in calculation OSC-10320, SDP Evaluation for Oconee SSF Pressurizer Heater Breaker Unavailability, and summarized in the RCE for PIP O-11-06700. OSC-10320 documented a probabilistic risk assessment analysis that assumed loss of pressurizer heaters with a subsequent loss of the letdown line due to increased cycling to maintain solid water operations. This calculation concluded a combined supplemental increase in core damage frequency of 1.74 E-06 (for Unit 1), 1.19 E-06 (for Unit 2) and 1.02 E-06 (for Unit 3) per year. The results were dominated by fire initiating events led by 4kV bus duct fires in the Oconee Turbine building that result in a station blackout.

The inspectors determined the licensees evaluation to be adequate.

d. Findings

No findings were identified.

02.02 Root Cause Evaluation a.

Determine that the licensee evaluated the issue using a systematic methodology to identify the root and contributing causes The licensee used various methods to determine the root and contributing causes in accordance with procedure NSD 212, Cause

Analysis.

The RCE individually addressed the cause of the failure to maintain design control of the plant when the SSF modification credited the pressurizer heater breakers for its design function, as well as the causes of the failure to identify that the breakers were not qualified in subsequent opportunities. The RCE included an Event and Causal Factor Chart which depicted the events chronology, inappropriate acts, failed barriers, and the contributing and root causes for each of the associated events.

Additionally, the licensee employed a TapRoot/Root Cause Tree analysis for each causal factor identified in the Event and Causal Factor Charts. The licensee also employed a Barrier Analysis to check that all causal factors were identified. Finally, the evaluation included a Safety Culture Impact Review to identify contributing safety culture components as described in IMC 0310, Components with Cross-Cutting Areas. The RCE identified a most probable cause for the original SSF design deficiency, and a root cause and contributing causes for the failure to identify the original design deficiency in subsequent opportunities involving the design change process.

The inspectors determined that the problem was evaluated using a systematic methodology to identify the root and contributing causes.

b. Determine that the licensees RCE was conducted to a level of detail commensurate with the significance of the issue The RCE was performed by a multidisciplinary team from Design Engineering, Regulatory Compliance, Training, and Performance Improvement organizations. The team also included a member from outside the Oconee organization. The RCE contained an adequate description of facts associated with the SSF Pressurizer Heater Breaker Yellow finding. The RCE team employed various cause analysis tools to identify the root and contributing causes. Each root cause technique was documented in adequate detail to understand the rationale behind the conclusions.

The inspectors found that the RCE was objective, self-critical, and adequately evaluated all the inappropriate acts leading to the Yellow finding, and therefore, was conducted to a level of detail commensurate with the significance of the problem.

The inspectors identified an observation in that the RCE did not acquire or review the guidance contained in the Design Engineering Quality Assurance Program Manual in effect during the time of the SSF design. This information was important to better understand what guidance was in place at the time the SSF was designed and to evaluate how it had evolved to the current guidance in support of the identified most probable cause. The guidance was produced for the inspectors upon request. A review determined that the guidance did not contradict the conclusions reached in the RCE.

c. Determine that the licensees RCE included a consideration of prior occurrences of the issue and knowledge of Operating Experience (OE)

The RCE included a review of internal and external operating experience to determine if the issue could have been prevented through OE. The licensee evaluated internal PIPs and external OE items to determine if the issue was recurrent or OE-preventable. The licensee did identify some previous opportunities to discover the condition. Particularly, the licensee recognized that the review of NRC Information Notice (IN) 89-30, High Temperature Environments at Nuclear Power Plants, presented a good opportunity to identify the environmental challenges to the pressurizer heater breakers. The licensee determined that it might have been possible to detect the issue had this IN been more broadly interpreted than just the equipment groups and operating temperatures discussed in the IN. This IN was received by Duke and routed to Design Engineering, I&E, Mechanical Maintenance, and Valve Maintenance for awareness. The RCE effort could not identify documentation indicating the specific actions taken in response to this IN. However, the licensee concluded that the OE was not a significant contributor to the failure to identify the environmental qualification issue of the pressurizer heater breakers.

The licensees OE review did not identify any identical examples of a similar condition at Oconee or other utilities that could have alerted the licensee about the specific failure mechanism introduced by the breaker thermal overloads under high environmental temperature.

The inspectors determined that the evaluation included a consideration of prior occurrences of the problem and knowledge of prior operating experience.

The inspectors identified an observation in that a 1981 McGuire LER evaluated by the inspectors, which reported an event where the pressurizer heater breakers tripped open due to design issues with the breakers thermal overloads, was not considered in the licensees RCE. Although this LER was not identified or evaluated in the licensees OE review, it was not likely that the LER would have prompted the licensee to review the environmental qualification of the pressurizer heater breakers.

d. Findings

No findings were identified.

02.06 Evaluation of IMC 0305 Criteria for Treatment of Old Design Issues The licensee requested credit for self-identification of an old design issue during a Regulatory Conference on November 16, 2011. Based on the information provided by the licensee and the independent assessment conducted by the NRC inspectors, it was determined that the Yellow finding meets the four criteria specified in IMC 0305 (below)for treatment as an old design issue.

a.

The finding was licensee-identified as a result of a voluntary initiative, such as a design basis reconstitution The inspectors reviewed the licensees RCE, contained in PIP O-11-06700, and other supporting documentation to gather the facts involving how the issue was identified. The degraded condition was initially identified by the licensee on June 1, 2011, by design engineers during preliminary extent-of-condition research for an unrelated modification.

Breakers in the east penetration room were discovered to have thermal overloads that could open due to expected ambient conditions during a loss of offsite power event.

Upon identification of this thermal overload feature, the licensee conducted an extent-of-condition review which discovered that the original SSF design project relied on similar previously existing panel board breakers inside the reactor building.

Although the method of discovery was not the result of a specific voluntary initiative to discover this type of issue, the discovery of the condition leading to the Yellow finding was the result of the licensees questioning attitude and initiative upon identifying temperature concerns for breakers and broadening their evaluation to look at the SSF pressurizer heater breakers in containment.

The NRC determined that credit for this criterion was appropriate.

b.

The finding was or will be corrected, including immediate corrective actions and long-term comprehensive corrective actions to prevent recurrence, within a reasonable time following identification The inspectors determined that the licensee took prompt corrective actions to address the issue and the TS Action Statement was promptly entered. The issue was identified on June 1, 2011, the TS Action statement was entered on June 2, 2011, and initial replacement breakers (later determined not to be qualified) were installed on June 8, 2011. Testing on the replacement breakers, which revealed that the breakers may not have been qualified for the environmental conditions, led to the licensee declaring the SSF operable but degraded, non-conforming, and an NRC Special Inspection was initiated on July 5, 2011. The installation of these replacement breakers was later dispositioned as a Green non-cited violation for failure to maintain design control of the SSF. Once the potential significance of the performance deficiency was discussed during the Special Inspection in July 2011, prompt and comprehensive corrective actions were taken by the licensee to declare the SSF inoperable on July 8, 2011, and replace the breakers on August 20, 2011, with fuses which were capable of performing their function during design basis environmental conditions inside containment. Fuses were installed within a reasonable time following identification and have been demonstrated to perform their function.

Despite initial problems with the licensees corrective actions, the issue was corrected within a reasonable period of time following initial identification, considering the modifications and testing required, and also within the allowed TS required completion time.

The NRC determined credit for this criterion was appropriate.

c. The finding was not likely to be previously identified by recent ongoing licensee efforts, such as normal surveillance, quality assurance activities, or evaluation of industry information The inspectors determined that the degraded condition of the Yellow finding was not self-revealing, could not be observed during normal operations, routine testing or maintenance, and would only be exposed to the design basis environmental conditions inside containment during extended station blackout event conditions. The inspectors did not identify any recent OE items that addressed similar problems with breaker thermal overloads that would have prompted the licensee to look into the environmental qualification of the breakers. An OE review conducted by the licensee as part of the RCE arrived at the same conclusion. In addition, the inspectors did not identify anything during a review of LERs that could have been seen as a prompt to identify the degraded condition. The inspectors concluded that the issue was not likely to be previously identified by recent ongoing licensee efforts The NRC determined that credit for this criterion was appropriate.

d. The finding does not reflect a current performance deficiency associated with existing licensee programs, policy, or procedure The inspectors evaluated the Yellow finding against 16 current performance issues in the area of design control. The inspectors searched the licensees corrective action program and sampled PIP documents for instances of similar performance deficiencies associated with existing licensee programs, policy and procedures. The inspectors also reviewed a sample of modifications implemented in the past three years to identify any similar performance deficiencies. In addition, the inspectors reviewed self-assessments and quality assurance audits in the area of design control to identify problems with potential similarities to the Yellow finding.

The inspectors review of inspection activities listed above revealed three issues which were considered to have some similarities to the Yellow finding. These issues had some similarities to the Yellow finding such as involving: a design change to a component without re-validating the design function; a misunderstanding of proper design inputs and associated failure modes; a failure to evaluate environmental conditions which impacted design function; and bypassing the engineering change process. Despite some similarities with the Yellow finding, these performance deficiencies also displayed significant differences such as: being associated with a failure to follow current guidance rather than inadequate guidance; involving implementation and post-modification testing errors rather than design errors; and involving different root causes. Of the remaining performance deficiencies reviewed, the issues were either not related to current programs, policy, and procedures, or they were not similar to the cause of the Yellow finding.

Although there were some similarities between the Yellow finding and current performance deficiencies, the inspectors did not identify any issue that was significantly similar to the Yellow finding and instead, issues displayed more differences than similarities.

The NRC determined that credit for this criterion was appropriate.

e. Findings

No findings were identified.

4OA6 Meetings, Including Exit

On February 9, 2012, the inspection team leader presented the inspection results to Mr.

T. Preston Gillespie, Jr., Site Vice President, and members of his staff. No proprietary information is included in this inspection report.

ATTACHMENT:

SUPPLEMENTAL INFORMATION

KEY POINTS OF CONTACT

Licensee Personnel

K. Alter, Regulatory Compliance Manager

S. Batson, Station Manager

D. Coyle, Operations Manager

T. Gillespie, Site Vice President

R. Guy, Organizational Effectiveness Manager

J. Kammer, Design Engineering Manager

C. Nolan, Fleet Safety Assurance Manager

T. Patterson, Safety Assurance Manager

T. Ray, Engineering Manager

NRC Personnel

J. Bartley, Chief, Reactor Projects Branch 1, Division of Reactor Projects, Region II

A. Sabisch, Senior Resident Inspector, Oconee

K. Ellis, Resident Inspector, Oconee

LIST OF REPORT ITEMS

Opened

None

Closed

None

Discussed

05000269, 270, 287/2011017-01 VIO Pressurizer Heater Breaker Installation That Would Not Have Functioned During Certain SSF-

Credited Events