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IR 05000454-11-013; 05000455-11-013, on 01/19/11-06/10/11, Byron Station, Units 1 and 2; Exercise of Enforcement Discretion
	ML11181A031
Person / Time
Site:	Byron
Issue date:	06/29/2011
From:	Reynolds S; Division of Reactor Safety III
To:	Pacilio M; Exelon Generation Co, Exelon Nuclear
	Loretta Sellers
References
	EA-11-051 IR-11-013
	Download: ML11181A031 (11)
	v • d • e

June 29, 2011

SUBJECT:

BYRON STATION, UNITS 1 AND 2 EXERCISE OF ENFORCEMENT DISCRETION 05000454/2011013; 05000455/2011013

Dear Mr. Pacilio:

On June 10, 2011, the U.S. Nuclear Regulatory Commission (NRC) completed an evaluation of an Unresolved Item (URI) in inspection report (IR)05000454/2009007-03; 05000455/2009007-03 to address the licensing bases requirements for a condition related to the analysis of steam generator tube rupture (SGTR) event margin to overfill and the preservation of safety-related equipment functions. The enclosed report documents the results of the evaluation, which were discussed on June 10, 2011, with members of your staff.

The enclosure to this letter closes the Unresolved Item and documents a violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control for the failure to ensure the steam generator power operated relief valves (SG PORVs) power supplies met the design bases. Specifically, you failed to ensure the SG PORVs were capable of performing their safety function assuming a single failure as defined by 10 CFR Part 50 Appendix A General Design Criteria for Nuclear Power Plants in the SGTR analysis.

Although the issue constitutes a Severity Level IV violation of NRC requirements, we have concluded that because a compliance backfit was issued to resolve the technical issue, the violation resulted from matters not reasonably within Exelons ability to foresee and correct; and therefore was not a performance deficiency.

Using the NRCs Enforcement Policy, the violation met the criteria for enforcement discretion.

As such, I have been authorized, after consultation with the Director, NRC Office of Enforcement and the Region III Regional Administrator, to exercise enforcement discretion in accordance with Section 3.5 of the Enforcement Policy and refrain from issuing enforcement action for the violation. If you disagree with the characterization of this violation, you should provide a response within 30 days of the date of this letter, with the basis for your disagreement, to U.S.

Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001, with a copy to the Regional Administrator, U.S. Nuclear Regulatory Commission -

Region III, 2443 Warrenville Road, Suite 210, Lisle, IL 60532-4352; and the Resident Inspector Office at the Byron Station. In accordance with 10 CFR 2.390 of the NRC's "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 System (PARS) component of NRC's document system (ADAMS). ADAMS is accessible from the NRC Website at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

/RA/

Steven A. Reynolds, Director Division of Reactor Safety Docket Nos. 50-454; 50-455 License Nos. NPF-37; NPF-66

Enclosure:

Inspection Report 05000454/2011013; 05000455/2011013 w/Attachment: Supplemental Information

REGION III==

Docket Nos:

50-454; 50-455 License Nos:

NPF-37; NPF-66 Report No:

05000454/2011013; 05000455/2011013 Licensee:

Exelon Generation Company, LLC Facility:

Byron Station, Units 1 and 2 Location:

Byron, IL Dates:

January 19 through June 10, 2011 Inspector:

J. Corujo-Sandín, Reactor Inspector Approved by:

A.M. Stone, Chief Engineering Branch 2 Division of Reactor Safety

Enclosure

SUMMARY OF FINDINGS

IR 05000454/2011013; 05000455/2011013; 01/19/11-06/10/11; Byron Station, Units 1 and 2;

Exercise of Enforcement Discretion.

This report covers several weeks of inspection by a regional inspector. This report contains one NRC-identified violation of NRC regulations which has been dispositioned using enforcement discretion. The NRCs program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process, Revision 4, dated December 2006.

REPORT DETAILS

REACTOR SAFETY

Cornerstones: Initiating Events, Mitigating Systems, and Barrier Integrity

4OA5 Other Activities

Main article: IP 71111.01

.1 (Closed) Unresolved Item 05000454/2009007-03; 05000455/2009007-03, Concerns with

Licensees Margin to Overfill Analysis Related to Steam Generator Tube Rupture Event

a. Inspection Scope

The inspectors pursued resolution to a previously identified Unresolved Item (URI) in inspection report (IR)05000454/2009007-03; 05000455/2009007-03 concerning the ability of the power supplies for the steam generator power operated relief valves (SG PORVs) to meet the single failure criteria. This issue was unresolved pending review of the licensees response to the identified noncompliance.

b.

Results

Introduction:

The NRC staff identified a violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control for the failure to ensure the SG PORVs power supplies met the design bases. Specifically, the licensee failed to ensure the SG PORVs were capable of performing their safety function assuming a single failure as defined by 10 CFR Part 50, Appendix A General Design Criteria for Nuclear Power Plants in their SGTR analysis. The Issue of Concern (IOC) constituted a violation of NRC requirements. However, since the IOC resulted in a backfit, the staff concluded that a licensee performance deficiency did not exist, because the violation resulted from matters not reasonably within Exelons ability to foresee and correct. Using the NRCs Enforcement Policy, the violation met the criteria for enforcement discretion.

Description:

During the 2009 Byron Stations Component Design Bases Inspection (CDBI), documented in IR 05000454/2009007; 05000455/2009007, the inspectors identified a concern related to the appropriateness of the component failure assumed in a design-bases Steam Generator Tube Rupture (SGTR) event. Specifically, the licensees SGTR accident analysis was based on the single failure of one SG PORV to open when required. This issue was documented as URI in (IR 05000454/2009007-03; 05000455/2009007-03).

Following the Byron Station CDBI, the inspectors requested assistance from the Office of Nuclear Reactor Regulation (NRR) in providing a position on the single failure criteria in the SGTR accident analysis. The staff from NRR reviewed the issue and provided a response to Task Interface Agreement (TIA) No. 2010-002 by letter dated December 20, 2010, (ML103230177). In the response, NRR determined that the failure of a breaker to perform its safety function, regardless of how that failure occurs, is considered a single failure as defined by 10 CFR Part 50, Appendix A.

Based on the conclusions documented in TIA No. 2010-002, the inspector concluded the use of a single failure (including passive and active failures of electrical systems) should have been assumed in the SGTR event analysis for the Byron Station. Because the current NRC staff position regarding the requirement to evaluate single passive failures of the electrical components is compliant with Appendix A but was different than the staff position previously communicated to the licensee, the provisions of 10 CFR 50.109 were applicable. After consultation with NRR and the Office of General Counsel, the inspectors determined that no backfit analysis was required under 10 CFR 50.109(a)(2)because the provisions of 10 CFR 50.109 (a)(4), were applicable, in that, a modification is necessary to bring a facility into compliance with the rules or orders of the Commission.

On January 19, 2011, the NRC issued IR 05000454/2011010; 05000455/2011010, and notified the licensee of the agencys decision to issue a compliance backfit in order to address the technical issue. The report listed the licensees initial corrective actions and requested the licensee to provide a written response within 30 days of their assessment of the issue and a description of their intended actions to address the non-compliance, including a proposed schedule to complete those actions and an assessment of the extent of condition of this issue.

The licensee responded by letter dated February 18, 2011, and committed to the following:

1. The power supplies to the Steam Generators PORVs will be modified with a

safety-related battery backup. The committed date for performing this action was no later than Unit 1s October 2012 refueling outage and Unit 2s May 2013 refueling outage.

2. The licensee will issue a supplement to their February 18, 2011, response letter, in

order to communicate any revisions to the modification installation schedule based on the online/outage determination (i.e., whether the modification could be installed online or require an outage). The committed date for performing this action is October 14, 2011.

3. An extent of condition review will be conducted of other transients and accidents

outlined in Chapter 15 of the Byron Station Updated Final Safety Analysis Report to identify similar discrepancies with respect to the inappropriate reliance or assumption of single active failure. The identified discrepancies, if any, would be resolved within the Corrective Action Program and communicated to the NRC Region III Regional Administrator. The committed date for performing this action is August 4, 2011.

The NRC staff considered these actions and timeframe adequate for complying with the agencys requirements.

Analysis:

In accordance with the Reactor Oversight Process (ROP) Inspection Manual Chapter (IMC) 0612, Appendix B, Issue Screening, the staff determined that this issue did not meet the definition for a performance deficiency since it was not reasonably within the licensees ability to foresee and correct. In accordance with Inspection Manual Chapter 0612, the inspectors determined whether this issue of concern involved a more than minor violation. In order to assess the significance of the underlying technical issue associated with the violation, the inspectors used the guidance in IMC 0612, Appendix B, Issue Screening, and IMC 0609 Significance Determination Process. Based on these, the underlying technical issue was a Non-Finding (i.e., no performance deficiency),was considered a more-than-minor violation, and from a risk perspective, screened as having very low safety significance.

The inspectors determined that no example from either Section 6.1 or 6.9 of the Enforcement Policy adequately applied or described the situation. Therefore, Regional NRC management considered the risk significance of the underlying technical issue and, in consultation with the Office of Enforcement, determined the issue was best represented as a Severity Level IV violation.

This violation is not considered a finding; therefore, in accordance with IMC 0305, no cross-cutting aspect is assigned to the violation.

Enforcement:

Title 10 CFR Part 50, Appendix B, Criterion III, Design Control, states in part that measures shall be established to assure that applicable regulatory requirements and the design basis, as defined in § 50.2 and as specified in the license application, for those structures, systems, and components to which this appendix applies are correctly translated into specifications, drawings, procedures, and instructions.

Title 10 CFR Part 50 Appendix A defines single failure as:

A single failure means an occurrence which results in the loss of capability of a component to perform its intended safety functions. Multiple failures resulting from a single occurrence are considered to be a single failure. Fluid and electric systems are considered to be designed against an assumed single failure if neither

(1) a single failure of any active component (assuming passive components function properly); nor

(2) a single failure of a passive component (assuming active components function properly), results in a loss of the capability of the system to perform its safety functions

1. Contrary to the above, from January 19, 2011, the date when the licensee was informed of

the issuance of a compliance backfit, until February 18, 2011, the date the licensee committed to the NRC, via letter, to restore compliance, the licensee failed to ensure the SG PORVs power supplies met the design bases. Specifically, the licensee failed to ensure the SG PORVs were capable of performing their safety function assuming a single failure as defined by 10 CFR Part 50 Appendix A General Design Criteria for Nuclear Power Plants in their SGTR analysis.

The NRC staff determined that this violation resulted from matters not reasonably within the licensees control; that is, the requirements could not be readily identified and therefore addressed. Enforcement Policy Section 3.5, Violations Involving Special Circumstances, states in part, the NRC may reduce or refrain from issuing a civil penalty or an NOV [Notice of Violation] for a Severity Level II, III, or IV violation based on the merits of the case after considering the guidance in this statement of policy and such factors as the age of the violation, the significance of the violation, the clarity of the requirement and associated guidance In this case, the lack of clarity of the requirement influenced the licensees ability to comply. As stated above, an exemption to the backfit rule (a compliance backfit) was documented. Therefore, in accordance with the Enforcement Policy, and after consultation with the Director of the Office of Enforcement and the Region III Regional Administrator, the NRC has decided to exercise enforcement discretion in accordance with Section 3.5 of the NRC Enforcement Policy and to refrain from issuing enforcement action for the violation. In accordance with the

1 Single failures of passive components in electric systems should be assumed in designing against a single failure.

NRCs Reactor Oversight Process, this condition will not be considered in the assessment process or the NRCs Action Matrix.

The technical issue is considered open pending completion of the corrective actions (VIO 05000454/2011013-01; 05000455/2011013-01, Restoring Compliance with Respect to Single Failures).

4OA6 Management Meetings

.1

Exit Meeting Summary

On June 10, 2011, the NRC presented the inspection results to Mr. T. Tulon, and other members of the licensee staff. The licensee acknowledged the issues presented. The inspectors confirmed that none of the potential report input discussed was considered proprietary.

ATTACHMENT: