ML072560272

Amendment Implementation of LCO 3.0.9 on the Unavailability of Barriers Using the Consolidated Line Item Improvement Process

ML072560272
Person / Time
Site:	Calvert Cliffs
Issue date:	09/27/2007
From:	Pickett D NRC/NRR/ADRO/DORL/LPLI-1
To:	Spina J Calvert Cliffs
Shared Package
ml072560259	List: ML072560272
References
TAC MD5437, TAC MD5438
Download: ML072560272 (22)

Text

September 27, 2007 Mr. James A. Spina, Vice President Calvert Cliffs Nuclear Power Plant, Inc.

Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702

SUBJECT:

CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 -

AMENDMENT RE: IMPLEMENTATION OF LCO 3.0.9 ON THE UNAVAILABILITY OF BARRIERS USING THE CONSOLIDATED LINE ITEM IMPROVEMENT PROCESS (TAC NOS. MD5437 AND MD5438)

Dear Mr. Spina:

The Commission has issued the enclosed Amendment No. 282 to Renewed Facility Operating License No. DPR-53 and Amendment No. 259 to Renewed Facility Operating License No. DPR-69 for the Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2. These amendments consist of changes to the Technical Specifications (TSs) in response to your application transmitted by letter dated May 2, 2007.

Consistent with the Nuclear Regulatory Commission approved Technical Specification Task Force (TSTF)-427, Revision 2, the amendments add a new limiting condition for operation (LCO) 3.0.9, to the TS. LCO 3.0.9 will allow the licensee to delay declaring an LCO not met for equipment supported by barriers unable to perform their associated support function for up to 30 days provided that risk is assessed and managed.

A copy of the related Safety Evaluation is enclosed. A Notice of Issuance will be included in the Commissions next regular biweekly Federal Register notice.

Sincerely,

/RA/

Douglas V. Pickett, Senior Project Manager Plant Licensing Branch I-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318

Enclosures:

1. Amendment No. 282 to DPR-53

2. Amendment No. 259 to DPR-69

3. Safety Evaluation cc w/encls: See next page

September 27, 2007 Mr. James A. Spina, Vice President Calvert Cliffs Nuclear Power Plant, Inc.

Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702

SUBJECT:

CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 -

AMENDMENT RE: IMPLEMENTATION OF LCO 3.0.9 ON THE UNAVAILABILITY OF BARRIERS USING THE CONSOLIDATED LINE ITEM IMPROVEMENT PROCESS (TAC NOS. MD5437 AND MD5438)

Dear Mr. Spina:

The Commission has issued the enclosed Amendment No. 282 to Renewed Facility Operating License No. DPR-53 and Amendment No. 259 to Renewed Facility Operating License No. DPR-69 for the Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2. These amendments consist of changes to the Technical Specifications (TSs) in response to your application transmitted by letter dated May 2, 2007.

Consistent with the Nuclear Regulatory Commission approved Technical Specification Task Force (TSTF)-427, Revision 2, the amendments add a new limiting condition for operation (LCO) 3.0.9, to the TS. LCO 3.0.9 will allow the licensee to delay declaring an LCO not met for equipment supported by barriers unable to perform their associated support function for up to 30 days provided that risk is assessed and managed.

A copy of the related Safety Evaluation is enclosed. A Notice of Issuance will be included in the Commissions next regular biweekly Federal Register notice.

Sincerely,

/RA/

Douglas V. Pickett, Senior Project Manager Plant Licensing Branch I-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318

Enclosures:

1. Amendment No. 282 to DPR-53

2. Amendment No. 259 to DPR-69

3. Safety Evaluation cc w/encls: See next page Package No.: ML072560259 Amendment No.: ML072560272 Tech Spec No.: ML OFFICE LPLI-1/PM LPLI-1/LA ITSB/BC LPLI-1/BC NAME DPickett SLittle TKobetz as MKowal signed on DATE 09 /17/ 07 09 / 17 / 07 09 / 11 / 07 09 /27/ 07 OFFICIAL RECORD COPY

DATED: September 27, 2007 AMENDMENT NO. 282 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-53 CALVERT CLIFFS UNIT 1 AMENDMENT NO. 259 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-69 CALVERT CLIFFS UNIT 2 PUBLIC LPLI-1 R/F M. Kowal RidsNrrDorlLpi-1 T. Kobetz RidsNrrDirsItsb S. Little RidsNrrLASLittle D. Pickett RidsNrrPMDPickett G. Hill (2)

OGC RidsOgcMailCenter ACRS RidsAcrsAcnwMailCenter A. Lising G. Dentel, R1 cc: Plant Service list

Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 cc:

Mr. Michael J. Wallace, President Regional Administrator, Region I Constellation Generation Group U.S. Nuclear Regulatory Commission 750 East Pratt Street 475 Allendale Road Baltimore, MD 21202 King of Prussia, PA 19406 Mr. John M. Heffley Ms. Kristen A. Burger, Esquire Senior Vice President and Maryland People's Counsel Chief Nuclear Officer 6 St. Paul Centre Constellation Generation Group Suite 2102 1997 Annapolis Exchange Parkway Baltimore, MD 21202-1631 Suite 310 Annapolis, MD 21401 Ms. Patricia T. Birnie, Esquire Co-Director President Maryland Safe Energy Coalition Calvert County Board of P.O. Box 33111 Commissioners Baltimore, MD 21218 175 Main Street Prince Frederick, MD 20678 Mr. Roy Hickok NRC Technical Training Center Mr. Carey Fleming, Esquire 5700 Brainerd Road Sr. Counsel - Nuclear Generation Chattanooga, TN 37411-4017 Constellation Generation Group, LLC 750 East Pratt Street, 17th floor Baltimore, MD 21202 Mr. Jay S. Gaines Director, Licensing Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702 Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 287 St. Leonard, MD 20685 Mr. R. I. McLean, Manager Nuclear Programs Power Plant Research Program Maryland Department of Natural Resources 580 Taylor Avenue (B wing, 3rd floor)

Tawes State Office Building Annapolis, MD 21401

CALVERT CLIFFS NUCLEAR POWER PLANT, INC.

DOCKET NO. 50-317 CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NO. 1 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 282 Renewed License No. DPR-53

1. The Nuclear Regulatory Commission (the Commission) has found that:

A. The application for amendment by Calvert Cliffs Nuclear Power Plant, Inc. (the licensee) dated May 2, 2007, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act) and the Commission's rules and regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C. There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.

2. Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.2. of Renewed Facility Operating License No. DPR-53 is hereby amended to read as follows:

2. Technical Specifications The Technical Specifications contained in Appendices A and B, as revised through Amendment No. 282, are hereby incorporated into the license. The licensee shall operate the facility in accordance with the Technical Specifications.

3. This license amendment is effective as of the date of its issuance and shall be implemented within 60 days.

FOR THE NUCLEAR REGULATORY COMMISSION

/RA/

Mark G. Kowal, Chief Plant Licensing Branch I-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the License and Technical Specifications Date of Issuance: September 27, 2007

CALVERT CLIFFS NUCLEAR POWER PLANT, INC.

DOCKET NO. 50-318 CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NO. 2 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 259 Renewed License No. DPR-69

1. The Nuclear Regulatory Commission (the Commission) has found that:

A. The application for amendment by Calvert Cliffs Nuclear Power Plant, Inc. (the licensee) dated May 2, 2007, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act) and the Commission's rules and regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C. There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.

2. Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.2. of Renewed Facility Operating License No. DPR-69 is hereby amended to read as follows:

2. Technical Specifications The Technical Specifications contained in Appendices A and B, as revised through Amendment No. 259, are hereby incorporated in the license. The licensee shall operate the facility in accordance with the Technical Specifications.

3. This license amendment is effective as of the date of its issuance and shall be implemented within 60 days.

FOR THE NUCLEAR REGULATORY COMMISSION

/RA/

Mark G. Kowal, Chief Plant Licensing Branch I-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the License and Technical Specifications Date of Issuance: September 27, 2007

ATTACHMENT TO LICENSE AMENDMENTS AMENDMENT NO. 282 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-53 AMENDMENT NO. 259 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-69 DOCKET NOS. 50-317 AND 50-318 Replace the following page of the Facility Operating License with the attached revised page.

The revised page is identified by amendment number and contains marginal lines indicating the areas of change.

Remove Page Insert Page 3 3 Replace the following pages of the Appendix A Technical Specifications with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.

Remove Pages Insert Pages 3.0-3 3.0-3 3.0-4 3.0-4 3.0-5 3.0-5

- 3.0-6

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 282 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-53 AND AMENDMENT NO. 259 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-69 CALVERT CLIFFS NUCLEAR POWER PLANT, INC.

CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-317 AND 50-318

1.0 INTRODUCTION

By letter dated May 2, 2007 (Agencywide Documents Access and Management Systems (ADAMS) Accession No. ML071270371), Calvert Cliffs Nuclear Power Plant, Inc. (the licensee) submitted a license amendment request (LAR) regarding the Calvert Cliffs Nuclear Power Plant, Units Nos. 1 and 2. This operating license improvement was made available by the Nuclear Regulatory Commission (NRC) on October 3, 2006 (71 FR 58444) as part of the consolidated line item improvement process (CLIIP).

On May 3, 2006, the industry owners group Technical Specifications Task Force (TSTF) submitted a proposed change, TSTF-427, Revision 2, to the standard technical specifications (STS) (NUREGs 1430-1434) on behalf of the industry (TSTF-427, Revisions 0 and 1 were prior draft iterations). TSTF-427, Revision 2, is a proposal to add an STS Limiting Condition for Operation (LCO) 3.0.9, allowing a delay time for entering a supported system Technical Specification (TS), when the inoperability is due solely to an unavailable barrier, if risk is assessed and managed. The postulated initiating events which may require a functional barrier are limited to those with low frequencies of occurrence, and the overall TS system safety function would still be available for the majority of anticipated challenges.

This proposal is one of the industrys initiatives being developed under the risk-informed TS program. These initiatives are intended to maintain or improve safety through the incorporation of risk assessment and management techniques in TS, while reducing unnecessary burden and making TS requirements consistent with the Commissions other risk-informed regulatory requirements.

The proposed change adds new LCO 3.0.9 to the TS. LCO 3.0.9 allows licensees to delay declaring an LCO not met for equipment supported by barriers unable to perform their associated support function, when risk is assessed and managed. This new LCO 3.0.9 states:

When one or more required barriers are unable to perform their related support function(s), any supported system LCO(s) are not required to be declared not met solely for this reason for up to 30 days provided that at least one train or subsystem of the supported system is OPERABLE and supported by barriers capable of providing their related support function(s), and risk is assessed and managed. This specification may be concurrently applied to more than one train or subsystem of a multiple train or subsystem supported system provided at least one train or subsystem of the supported system is OPERABLE and the barriers supporting each of these trains or subsystems provide their related support function(s) for different categories of initiating events.

If the required OPERABLE train or subsystem becomes inoperable while this specification is in use, it must be restored to OPERABLE status within 24 hours1 days <br />0.143 weeks <br />0.0329 months <br /> or the provisions of this specification cannot be applied to the trains or subsystems supported by the barriers that cannot perform their related support function(s).

At the end of the specified period, the required barriers must be able to perform their related support function(s), or the supported system LCO(s) shall be declared not met.

2.0 REGULATORY EVALUATION

In Title 10 of the Code of Federal Regulations (10 CFR) 50.36, the Commission established its regulatory requirements related to the content of TS. Pursuant to 10 CFR 50.36, TS are required to include items in the following five specific categories related to station operation:

(1) safety limits, limiting safety system settings, and limiting control settings; (2) LCOs; (3) surveillance requirements (SRs); (4) design features; and (5) administrative controls. The rule does not specify the particular requirements to be included in a plants TS. As stated in 10 CFR 50.36(c)(2)(i), the Limiting conditions for operation are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When a limiting condition for operation of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the technical specifications ... . TS Section 3.0, on LCO and SR Applicability, provides details or ground rules for complying with the LCOs.

Barriers are doors, walls, floor plugs, curbs, hatches, installed structures or components, or other devices, not explicitly described in TS, that support the performance of the functions of systems described in the TS. For purposes of this TS, the term barrier refers to a device which protects one or more trains of a safety system during a given initiating event. A degraded barrier refers to a barrier that has its quality or functional capability reduced, or to a barrier that is purposefully removed or reconfigured to facilitate maintenance activities.

LCO 3.0.9 specifically does not apply to barriers which support ventilation systems or to fire barriers. Nuclear Energy Institute (NEI) 04-08 considers LCO 3.0.9 evaluations as being applicable to snubbers, non-TS systems, or barriers which support TS systems where the unavailability of the barrier does not render the supported system inoperable. This expanded definition of 3.0.9 barriers is considered by the NRC staff to be a recommendation.

Some TS required systems may require one or more barriers in order to perform their intended function(s) for certain initiating events for which the barriers provide a protective support function. For example, there are barriers to protect systems from the effects of internal flooding, such as floor plugs and retaining walls, and which also protect equipment from steam

impingement in case of high energy line breaks. Barriers are also used to protect systems against missiles, either internally generated, or generated by external events.

Barriers are not explicitly described in the TS, but are required to be capable of performing their required support function by the definition of OPERABILITY for the supported system which is described in the TS. Therefore, under the current STS, the supported system must be declared inoperable when the related barrier(s) cannot perform their required support function. However, the magnitude of plant risk associated with the barrier which cannot perform its related support function is much less than the risk associated with direct unavailability of the supported system, since barriers are designed for specific, low frequency initiating events.

Some potential undesirable consequences of the current TS requirements include:

1. When maintenance activities on the supported TS system require removal and restoration of barriers, the time available to complete maintenance and perform system restoration and testing is reduced by the time spent maneuvering the barriers within the time constraints of the supported system LCO;

2. Restoration of barriers following maintenance may be given a high priority due to time restraints of the existing supported system LCO, when other activities may have a greater risk impact and should therefore be given priority; and

3. Unnecessary plant shutdowns may occur due to discovery of degraded barriers which require more time than provided by the existing supported system LCO to complete repairs and restoration of the barrier.

To improve the treatment of degraded barriers and enhance safety, the TSTF proposed a risk-informed TS change that introduces a delay time before entering the actions for the supported equipment, when one or more barriers are found to be degraded, or are removed or reconfigured to support maintenance activities, if risk is assessed and managed. Such a delay time will provide needed flexibility in the performance of maintenance and at the same time will enhance overall plant safety by:

1. Performing system maintenance and restoration activities, including post-maintenance testing, within the existing TS LCO time, and allowing barrier removal and restoration to be performed outside of the TS LCO, providing more time for the safe conduct of maintenance and testing activities on the supported TS system;

2. Requiring barrier removal and restoration activities to be assessed and prioritized based on actual plant risk impacts; and

3. Avoiding unnecessary unscheduled plant shutdowns and thus minimizing plant transition and realignment risks.

3.0 TECHNICAL EVALUATION

The industry submitted TSTF-427, Revision 2 (Reference 1), Allowance for Non Technical Specification Barrier Degradation on Supported System OPERABILITY in support of the proposed TS change. This submittal documents a risk-informed analysis of the proposed TS change. Probabilistic risk assessment (PRA) methods are used, in combination with deterministic and defense-in-depth arguments, to identify and justify delay times for entering the actions for the supported equipment associated with unavailable barriers at nuclear power plants. The industry also submitted implementation guidance NEI 04-08, March 2006 (Reference 2). This submittal provides detailed guidance on assessing and managing risk associated with unavailable barriers. This is in accordance with guidance provided in Regulatory Guides (RGs) 1.174 (Reference 3) and 1.177 (Reference 4).

The risk impact associated with the proposed delay times for entering the TS actions for the supported equipment can be assessed using the same approach as for allowed completion time (CT) extensions. Therefore, the risk assessment was performed following the three-tiered approach recommended in RG 1.177 for evaluating proposed extensions in currently allowed CTs:

1. The first tier involves the assessment of the change in plant risk due to the proposed TS change. Such risk change is expressed (1) by the change in the average yearly core damage frequency (DCDF) and the average yearly large early release frequency (DLERF) and (2) by the incremental conditional core damage probability (ICCDP) and the incremental conditional large early release probability (ICLERP). The assessed DCDF and DLERF values are compared to acceptance guidelines, consistent with the Commissions Safety Goal Policy Statement as documented in RG 1.174, so that the plants average baseline risk is maintained within a minimal range. The assessed ICCDP and ICLERP values are compared to acceptance guidelines provided in RG 1.177, which aim at ensuring that the plant risk does not increase unacceptably during the period the equipment is taken out of service.

2. The second tier involves the identification of potentially high-risk configurations that could exist if equipment in addition to that associated with the change were to be taken out of service simultaneously, or other risk-significant operational factors such as concurrent equipment testing were also involved. The objective is to ensure that appropriate restrictions are in place to avoid any potential high-risk configurations.

3. The third tier involves the establishment of an overall configuration risk management program (CRMP) to ensure that potentially risk-significant configurations resulting from maintenance and other operational activities are identified. The objective of the CRMP is to manage configuration-specific risk by appropriate scheduling of plant activities and/or appropriate compensatory measures.

A simplified risk assessment was performed to justify the proposed addition of LCO 3.0.9 to the TS. This approach was necessitated by (1) the general nature of the proposed TS change (i.e., it applies to all plants and is associated with an undetermined number of barriers that are not able to perform their function), and (2) the lack of detailed modeling in most plant-specific PRAs which do not include passive structures such as barriers.

The simplified risk assessment considers three different parameters:

1. The length of time the affected barrier is unavailable,

2. The initiating event frequency for which the affected barrier is designed to mitigate, and

3. The importance to CDF (or LERF) of the TS equipment (train, subsystem, or component) for which the affected barrier is designed to protect, measured by the risk achievement worth of the equipment.

The ICCDP can be calculated based on the following equation:

ICCDP =

TC x

IE i 8766 IE T

[( )

x RAWj x CDFbase CDFbase ]

where:

- Tc is the time the barrier is unavailable (hours)

- Tc/8766 is therefore the fraction of the year during which the barrier is unavailable,

- IEi/IET is the ratio of the initiating event frequency for which the affected barrier designed to mitigate, IEi, and the total initiating event frequency, IET,

- RAW j is the risk achievement worth of the component(s) for which the barrier provides protection, and

- CDFbase is the baseline core damage frequency (per year).

ICLERP also may be similarly determined, using baseline LERF and RAW values with respect to LERF. It is assumed that the magnitude of the LERF risk resulting from the barrier unable to perform its related support function would be generally at least one order of magnitude less than the corresponding CDF risk. Containment bypass scenarios, which are typically the significant contributors to LERF, would not be uniquely affected by application of LCO 3.0.9, and initiating events which would be significant LERF contributors, such as steam generator tube rupture and interfacing systems loss-of-coolant accident (LOCA), are not typically associated with barriers within the scope of LCO 3.0.9. Therefore, the assumption regarding LERF risk is reasonable and acceptable for the generic risk evaluation, provided that LERF risk impacts are considered on a plant-specific basis for unavailable barriers, as described in Section 3.1.3.

The relevant initiating events (i.e., events for which barriers subject to LCO 3.0.9 provide protection) are:

- internal and external floods

- high energy line breaks

- feedwater line breaks

- LOCA (small, medium, and large)

- tornados and high winds

- turbine missiles.

Generic frequencies for most of these initiating events were obtained from NUREG/CR-5750 (Reference 5). For external floods, turbine missiles, and tornados, other industry source documents were referenced. The most limiting (highest frequency) initiating event was obtained for a high energy line break from NUREG/CR-5750, with a frequency of 9.1E-3 per year. The risk assessment is, therefore, based on this limiting frequency, and the proposed methodology to apply LCO 3.0.9 is similarly restricted to barriers protecting against initiating events whose total frequency is no more than 9.1E-3 per year.

3.1 Risk Assessment Results and Insights The results and insights from the implementation of the three-tiered approach of RG 1.177 to support the proposed addition of LCO 3.0.9 to the TS are summarized and evaluated in the following Sections 3.1.1 to 3.1.3.

3.1.1 Risk Impact The bounding risk assessment approach, described in Section 3.0, was developed for a range of plant baseline CDF values and for a range of protected component RAW values. The maximum allowable 30-day outage time was used. The results are summarized in Table 1.

Table 1 Risk Assessment Results for a Postulated 30-Day Barrier Outage.

Baseline CDF = 1E-6 per year RAW ICCDP ICLERP 2 7.5E-10 7.5E-11 10 6.7E-09 6.7E-10 50 3.7E-08 3.7E-09 100 7.4E-08 7.4E-09 Baseline CDF = 1E-5 per year RAW ICCDP ICLERP 2 7.5E-09 7.5E-10 10 6.7E-08 6.7E-09 50 3.7E-07 3.7E-08 100 7.4E-07 7.4E-08

Baseline CDF = 1E-4 per year RAW ICCDP ICLERP 2 7.5E-08 7.5E-09 10 6.7E-07 6.7E-08 50 3.7E-06 3.7E-07 100 7.4E-06 7.4E-07 The above results represent a sensitivity analysis covering the expected range of plant baseline CDF values and component RAW values. The most limiting configurations involving very high risk components (RAW > 10) would not be anticipated to occur for most planned maintenance activities.

The calculations conservatively assume the most limiting (highest frequency) initiating event and the longest allowable outage time (30 days). Occurrence of the initiating event during unavailability of the barrier is conservatively assumed to directly fail the protected equipment; no credit is taken for event-specific circumstances which may result in the equipment remaining functional even with the barrier unavailable. (For example, a barrier required to protect equipment from steam impingement for high energy line breaks may only be required for breaks occurring in specific locations and orientations relative to the protected equipment, and only for large size breaks.) No credit is taken for avoided risk identified in Section 2.

The risk assessment results of Table 1 were compared to guidance provided in the revised Section 11 of NUMARC 93-01, Revision 2 (Reference 6), endorsed by RG 1.182 (Reference 7),

for implementing the requirements of paragraph (a)(4) of the Maintenance Rule, 10 CFR 50.65.

Such guidance is summarized in Table 2. Guidance regarding the acceptability of conditional risk increase in terms of CDF for a planned configuration is provided. This guidance states that a specific configuration that is associated with a CDF higher than 1E-3 per year should not normally be entered voluntarily. The NRC staff notes that the higher risk configurations documented in Table 1 would exceed this guidance, and would, therefore, not be permitted to be entered voluntarily. For example, with a baseline CDF of 1E-4 per year, a component with a RAW greater than 10 would exceed the 1E-3 per year criteria. Therefore, the sensitivity analyses presented in Table 1 are understood to include higher risk configurations which would not be permitted under the guidance of Reference 6.

Table 2 Guidance for Implementing 10 CFR 50.65(a)(4).

DRCDF Guidance Greater than 1E-3/year Configuration should not normally be entered voluntarily ICCDP Guidance ICLERP Greater than 1E-5 Configuration should not normally be Greater than 1E-6 entered voluntarily 1E-6 to 1E-5 Assess non-quantifiable factors 1E-7 to 1E-6 Establish risk management actions Less than 1E-6 Normal work controls Less than1E-7 Guidance regarding the acceptability of ICCDP and ICLERP values for a specific planned configuration and the establishment of risk management actions is also provided in NUMARC 93-01. This guidance, as shown in Table 2, states that a specific plant configuration that is associated with ICCDP and ICLERP values below 1E-6 and 1E-7, respectively, is considered to require normal work controls. Table 1 shows that for the majority of barrier outage configurations the conservatively assessed ICCDP and ICLERP values are within the limits for what is recommended as the threshold for the normal work controls region.

As stated in the implementation guidance for LCO 3.0.9 (Reference 2), plants are required to commit to the guidance of NUMARC 93-01 Section 11, and, therefore, the above limits would be applicable. Plant configurations including out-of-service barriers may, therefore, be entered voluntarily if supported by the results of the risk assessment required by 10 CFR 50.65(a)(4),

and by LCO 3.0.9.

RG 1.177 (Reference 4) provides guidance of 5E-7 ICDP and 5E-8 ILERP as the limit for a TS allowed outage time. As shown in Table 1, the guidance is met for the typically anticipated configurations, unless either the baseline CDF for the plant approaches 1E-4 per year or the RAW of the protected components is well above 10. Such configurations may exceed the criteria described in Reference 6 (Table 2) and would not be voluntarily entered. Such configurations are not expected to be frequently encountered, and may be addressed on a case-by-case plant-specific basis by limiting the allowed outage time and by implementing plant-specific risk management actions, as per the implementing guidance (Reference 2).

RG 1.174 (Reference 3) provides guidance of 1E-5 per year DCDF and 1E-6 per year DLERF.

The ICCDP calculations demonstrated that each individual 30-day barrier outage is anticipated to be low risk. Although there is no explicit limit on the number of times per year that LCO 3.0.9 may be applied, even assuming barrier outages occurred continuously over the entire year, the risk incurred would still be anticipated to be below the limits of the guidance.

The NRC staff finds that the risk assessment results support the proposed addition of LCO 3.0.9 to the TS. The risk increases associated with this TS change will be insignificant

based on guidance provided in RGs 1.174 and 1.177 and within the range of risks associated with normal maintenance activities.

3.1.2 Identification of High-Risk Configurations The second tier of the three-tiered approach recommended in RG 1.177 involves the identification of potentially high-risk configurations that could exist if equipment, in addition to that associated with the TS change, were to be taken out-of-service simultaneously. Insights from the risk assessments, in conjunction with important assumptions made in the analysis and defense-in-depth considerations, were used to identify such configurations. To avoid these potentially high-risk configurations, specific restrictions to the implementation of the proposed TS changes were identified.

When LCO 3.0.9 is applied, at least one train or subsystem is required to be operable with required barriers in place, such that this train or subsystem would be available to provide mitigation of the initiating event. LCO 3.0.9 may be applied to multiple trains of the same system only for barriers which provide protection for different initiating events, such that at least one train or subsystem is available to provide mitigation of the initiating event. The use of LCO 3.0.9 for barriers which protect all trains or subsystems from a particular initiating event is not permitted. Therefore, potentially high-risk configurations involving a loss of function required for mitigation of a particular initiating event are avoided by the restrictions imposed on applicability of LCO 3.0.9.

LCO 3.0.9 also addresses potential emergent conditions where unplanned failures or discovered conditions may result in the unavailability of a required train or subsystem for a particular initiating event. Such conditions may result during application of LCO 3.0.9 from equipment failure on the operable train, such that all trains of a TS system are not protected from the same initiating event. In such cases, a 24-hour allowed time is provided to restore the conditions to permit continued operation with unavailable barriers, after which the applicability of LCO 3.0.9 ends, and the supported system LCO becomes effective. This allowed time is provided so that emergent conditions with low risk consequences may be effectively managed, rather than requiring immediate exit of LCO 3.0.9 and the potential for an unplanned plant shutdown.

A limit of 30 days is applied to the LCO 3.0.9 allowed outage time for each barrier, after which the barrier must be restored to an available status, or the supported system TS must be applied. This 30-day backstop applies regardless of the risk level calculated, and provides assurance that installed plant barriers will be maintained available over long periods of time, and that the application of LCO 3.0.9 will not result in long-term degradation of plant barriers.

The NRC staff finds that the restrictions on the applicability of LCO 3.0.9 assuring that one safety train remains available to mitigate the initiating event, along with the 30-day limit applicable to each barrier, assure that potentially high-risk configurations are avoided in accordance with the guidance provided in RGs 1.174 and 1.177.

3.1.3 Configuration Risk Management The third tier of the three-tiered approach recommended in RG 1.177 involves the establishment of an overall configuration risk management program (CRMP) to ensure that potentially risk-significant configurations resulting from maintenance and other operational activities are identified. The objective of the CRMP is to manage configuration-specific risk by appropriate scheduling of plant activities and/or appropriate compensatory measures. This objective is met by licensee programs to comply with the requirements of paragraph (a)(4) of the Maintenance Rule (10 CFR 50.65) to assess and manage risk resulting from maintenance activities, and by LCO 3.0.9 requiring risk assessments and management using (a)(4) processes if no maintenance is in progress. These programs can support licensee-decision making regarding the appropriate actions to manage risk whenever a risk-informed TS is entered.

The implementation guidance for LCO 3.0.9 (Reference 2) requires that the allowed outage time determination for an unavailable barrier be performed using the plant-specific configuration. Further, the risk determinations are to be updated whenever emergent conditions occur. These requirements assure that the configuration-specific risk associated with unavailable barriers is assessed and managed prior to entry into LCO 3.0.9 and during its applicability as conditions change.

These evaluations for the unavailable barrier are performed as part of the assessment of plant risk required by 10 CFR 50.65(a)(4). The numerical guidance identified in Table 2 is applicable to implementation of LCO 3.0.9, using the results of the configuration-specific risk assessment which addresses the risk impact of the unavailable barrier along with all other out-of-service components and plant alignments.

Risk management actions are required to be considered when the calculated risk exceeds specific thresholds per NUMARC 93-01 Section 11, as identified in Table 2. Additional guidance on risk management actions are provided in the implementation guidance for LCO 3.0.9.

The allowed outage time for a barrier is calculated based on an ICCDP limit of 1E-6. This is the NUMARC 93-01 Section 11 guidance for applicability of normal work controls, and is conservatively lower than the guidance of 1E-5 for voluntary maintenance activities. The use of 1E-6 will result in conservatively short allowed outage times for barriers compared to allowed times for other maintenance activities.

If the scope of the PRA model used to support the plant-specific CRMP does not include the initiating event for which a barrier provides protection, then LCO 3.0.9 applicability is limited to one barrier on a single train. Multiple barriers for such initiating events may not be unavailable under LCO 3.0.9, and in such situations the LCO(s) associated with the protected components would be applicable. Applicability of LCO 3.0.9 to the single barrier for an initiating event that is not modeled in the plant PRA is acceptable based on the generic risk analysis provided by TSTF-427, as described in Section 3.1.

Assessment of the LERF risk impact on an unavailable barrier is required to be performed in accordance with NUMARC 93-01 Section 11. If an unavailable barrier provides protection to equipment which is relevant to the containment function, or which protects equipment from the

effects of an initiating event which is a contributor to LERF, then applicability of LCO 3.0.9 must be limited to that one barrier unless a quantified assessment of LERF is performed.

The NRC staff finds that the risk evaluations required to support the applicability of LCO 3.0.9 appropriately consider the risk from unavailable barriers in an integrated manner based on the overall plant configuration. Therefore, potentially high-risk configurations can be identified and managed in accordance with the guidance provided in RGs 1.174 and 1.177.

3.2 Summary and Conclusions The unavailability of barriers which protect TS required components from the effects of specific initiating events is typically a low risk configuration which should not require that the protected components be immediately declared inoperable. The current TS require that when such barriers are unavailable, the protected component LCO is immediately entered. Some potential undesirable consequences of the current TS requirements include:

1. When maintenance activities on the supported TS system requires removal and restoration of barriers, the time available to complete maintenance and perform system restoration and testing is reduced by the time spent maneuvering the barriers within the time constraints of the supported system LCO;

2. Restoration of barriers following maintenance must be given a high priority due to time restraints of the existing supported system LCO, when other more risk important activities may have a greater risk impact and should therefore be given priority; and

3. Unnecessary plant shutdowns may occur due to discovery of degraded barriers which may require more than the existing supported system LCO time to complete repairs and restoration.

To remove the overly restrictive requirements in the treatment of barriers, licensees are proposing a risk-informed TS change which introduces a delay time before entering the actions for the supported equipment when one or more barriers are found degraded or removed to facilitate planned maintenance activities. Such a delay time will provide needed flexibility in the performance of maintenance during power operation and at the same time will enhance overall plant safety by (1) performing system maintenance and restoration activities, including post-maintenance testing, within the existing TS LCO time, and allowing barrier removal and restoration to be performed outside of the TS LCO, providing more time for the safe conduct of maintenance and testing activities on the supported system; (2) requiring barrier removal and restoration activities to be assessed and prioritized based on actual plant risk impacts; and (3) avoiding unnecessary unscheduled plant shutdowns, thus minimizing plant transition and realignment risks.

The risk impact of the proposed TS changes was assessed following the three-tiered approach recommended in RG 1.177. A simplified bounding risk assessment was performed to justify the proposed TS changes. This bounding assessment was selected due to the lack of detailed plant-specific risk models for most plants which do not include failure modes of passive

structures such as barriers. The impact from the addition of the proposed LCO 3.0.9 to the TS on defense-in-depth was also evaluated in conjunction with the risk assessment results.

Based on this integrated evaluation, the NRC staff concludes that the proposed addition of LCO 3.0.9 to the TS would lead to insignificant risk increases as stipulated by RG 1.177 and depicted on Table 1 above. This conclusion is true without taking any credit for the removal of potential undesirable consequences associated with the current conservative treatment of barriers. Therefore, the proposed change provides adequate protection of public health and safety and is acceptable provided the conditions set forth below are satisfied.

Consistent with the NRC staffs approval and inherent in the implementation of TSTF-427, licensees interested in implementing LCO 3.0.9 must, as applicable, operate in accordance with the following stipulations:

1. The licensee must commit to the guidance of NUMARC 93-01, Section 11 (Reference 6) which provides guidance and details on the assessment and management of risk during maintenance.

2. Licensee procedures must be revised to ensure that the guidance on the risk assessment and management process described in NEI 04-08 is used whenever a barrier is considered unavailable and the requirements of LCO 3.0.9 are to be applied.

This must be done in accordance with an overall CRMP to ensure that potentially risk-significant configurations resulting from maintenance and other operational activities are identified and avoided.

In accordance with the notice of availability published in the Federal Register on October 3, 2006, the licensees application dated May 2, 2007, included the following plant-specific regulatory commitments:

1. Calvert Cliffs commits to the guidance of NUMARC 93-01, Section 11, which provides guidance and details on the assessment and management of risk during maintenance.

2. Calvert Cliffs will revise procedures as appropriate to ensure that the risk assessment and management process described in NEI 04-08 is used whenever a barrier is considered unavailable and requirements of LCO 3.0.9 are to be applied, in accordance with an overall Configuration Risk Management Program to ensure that potentially risk significant configurations resulting from maintenance and other operational activities are identified and avoided.

Therefore, based upon the risk-informed evaluation and the licensees regulatory commitments described above, the NRC staff finds the licensees proposed TS changes acceptable.

4.0 STATE CONSULTATION

In accordance with the Commissions regulations, the Maryland State official was notified of the proposed issuance of the amendment. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the amounts and no significant change in the types of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no-significant-hazards considerations, and there has been no public comment on the finding (72 FR 33781). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b),

no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

6.0 CONCLUSION

The Commission has concluded, on the basis of the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.

7.0 REFERENCES

1. TSTF-427, Revision 2, Allowance for Non Technical Specification Barrier Degradation on Supported System OPERABILITY, May 3, 2006.

2. NEI 04-08, Allowance for Non Technical Specification Barrier Degradation on Supported System OPERABILITY (TSTF-427) Industry Implementation Guidance, March 2006.

3. Regulatory Guide 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis, USNRC, August 1998.

4. Regulatory Guide 1.177, An Approach for Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications, USNRC, August 1998.

5. Rates of Initiating Events at U.S. Nuclear Power Plants, NUREG/CR-5750, Idaho National Engineering and Environmental Laboratory, February 1999.

6. Nuclear Energy Institute, Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants, NUMARC 93-01, Revision 2, Section 11.

7. Assessing and Managing Risk Before Maintenance Activities at Nuclear Power Plants, Regulatory Guide 1.182, May 2000.

Principle Contributor: A.J. Lising Date: September 27, 2007