Text

Transmittal of TSTF-531, Revision 0, Revision of Specification 3.8.1, Required Actions B.3.1 and B.3.2
	ML12089A317
Person / Time
Site:	Technical Specifications Task Force
Issue date:	03/29/2012
From:	Browning R, Croft W, Steelman W, Stringfellow N; Technical Specifications Task Force
To:	; Office of Nuclear Reactor Regulation, Document Control Desk
References
	TSTF-12-07, TSTF-531, Rev 0
	Download: ML12089A317 (39)
	v • d • e

11921 Rockville Pike, Suite 100, Rockville, MD 20852 Phone: 301-984-4400, Fax: 301-984-7600 Administration by EXCEL Services Corporation TECHNICAL SPECIFICATIONS TASK FORCE A JOINT OWNERS GROUP ACTIVITY TSTF March 29, 2012 TSTF-12-07 PROJ0753 Attn: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001

SUBJECT:

Transmittal of TSTF-531, Revision 0, "Revision of Specification 3.8.1, Required Actions B.3.1 and B.3.2" Enclosed for NRC review is Revision 0 of TSTF-531, "Revision of Specification 3.8.1, Required Actions B.3.1 and B.3.2." TSTF-531 is applicable to all plant types.

The TSTF requests that the NRC bill the Boiling Water Reactor Owners' Group and the Pressurized Water Reactor Owners Group for the review of this Traveler.

Should you have any questions, please do not hesitate to contact us.

Norman J. Stringfellow (PWROG/W)

Roy A. Browning (BWROG)

William J. Steelman (PWROG/CE)

Wendy E. Croft (PWROG/B&W)

Enclosure cc:

Robert Elliott, Technical Specifications Branch, NRC Michelle Honcharik, Licensing Processes Branch, NRC

TSTF-531, Rev. 0 WOG-205, Rev. 1 NUREGs Affected:

Revision of Specification 3.8.1, Required Actions B.3.1 and B.3.2 Technical Specifications Task Force Improved Standard Technical Specifications Change Traveler 1430 1431 1432 1433 1434 Classification 1) Technical Change Recommended for CLIIP?: Yes Correction or Improvement:

Improvement NRC Fee Status:

Not Exempt Benefit:

Prevents Unnecessary Actions See attached.

Revision History OG Revision 0 Revision Status: Closed Original Issue Revision

Description:

Revision Proposed by:

Wolf Creek Owners Group Review Information Date Originated by OG:

16-Mar-11 Owners Group Comments (No Comments)

Date: 23-Jun-11 Owners Group Resolution:

Approved TSTF Review Information TSTF Received Date:

23-Jun-11 Date Distributed for Review 23-Jun-11 TSTF Comments:

(No Comments)

Date:

TSTF Resolution:

OG Review Completed:

BWOG CEOG WOG BWROG OG Revision 1 Revision Status: Active Complete rewrite based on NRC feedback at TSTF/NRC meeting.

Revision

Description:

Revision Proposed by:

NRC 29-Mar-12 Traveler Rev. 3. Copyright(C) 2012, EXCEL Services Corporation. Use by EXCEL Services associates, utility clients, and the U.S. Nuclear Regulatory Commission is granted. All other use without written permission is prohibited.

TSTF-531, Rev. 0 WOG-205, Rev. 1 Affected Technical Specifications OG Revision 1 Revision Status: Active Owners Group Review Information Date Originated by OG:

03-Jan-12 Owners Group Comments (No Comments)

Date: 20-Feb-12 Owners Group Resolution:

Approved TSTF Review Information TSTF Received Date:

06-Mar-12 Date Distributed for Review 06-Mar-12 TSTF Comments:

(No Comments)

Date: 29-Mar-12 TSTF Resolution:

Approved OG Review Completed:

BWOG CEOG WOG BWROG NRC Review Information NRC Received Date:

29-Mar-12 Action 3.8.1.B A. C. Sources - Operating Action 3.8.1.B Bases A. C. Sources - Operating 29-Mar-12 Traveler Rev. 3. Copyright(C) 2012, EXCEL Services Corporation. Use by EXCEL Services associates, utility clients, and the U.S. Nuclear Regulatory Commission is granted. All other use without written permission is prohibited.

TSTF-531, Rev. 0 Page 1

1.

SUMMARY

DESCRIPTION The proposed change will revise Condition B of Specification 3.8.1, "AC Sources - Operating,"

to clarify the requirements for performance of a common cause failure determination for an inoperable Diesel Generator (DG).

2.

DETAILED DESCRIPTION Specification 3.8.1, "AC Sources - Operating," Condition B for one DG inoperable, Required Actions B.3.1 and B.3.2, require the performance within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of either:

1) A common cause failure determination for the inoperable DG, or

2) Performance of a DG start per Surveillance Requirement (SR) 3.8.1.2 (Slow Start Test) on the Operable DG.

If these Required Actions are not completed within the associated Completion Times, Condition G is met ("Required Action and associated Completion Timenot met"), which then requires a plant shutdown.

Need For Change The existing Required Actions create a problem if the licensees initial determination of the cause of the DG inoperability is later found to be incorrect. The licensee may have believed (based on available information at the time) that the cause of the DG inoperability was known, and may have determined that no common cause failure existed. However, after the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is reached, the licensee may discover that the assumed cause of the inoperability was incorrect. The existing TS do not specify how to address this situation (or other similar situations, described in more detail in the Technical Evaluation section), which has led to confusion. This confusion could lead to unnecessary starts of diesels (which results in unnecessary wear and tear), or unnecessary entries into shutdown action statements and resultant plant transients.

In addition, some activities should be exempted from the requirement to perform a common cause failure determination or to start the redundant DG, because the cause of the inoperability is already known to not affect the other diesel (such as preplanned maintenance or testing), or the appropriate actions are governed by a different Limiting Condition for Operation (LCO) for a TS support system.

Proposed Change The proposed change to the Technical Specifications will:

Revise Required Action B.3.1 Completion Time from "[24] hours" to "24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from discovery of potential common cause failure mechanism", and remove the brackets from the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months value in the Completion Time for Required Action B.3.2.

Add a Note to Required Action B.3 which states, "Required Actions B.3.1 and B.3.2 are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system."

Changes to the Technical Specification Bases are made to directly reflect the changes to the Technical Specifications and clarify the use of those requirements.

TSTF-531, Rev. 0 Page 2 A model application is included as Enclosure 1. The model may be used by licensees desiring to adopt TSTF-531 following NRC approval.

3.

TECHNICAL EVALUATION

3.1 System Description

The improved Standard Technical Specifications (ISTS) assume the onsite standby power sources consist of two DGs. As described in 10 CFR 50, Appendix A, General Design Criteria 17, the design of the AC electrical power system provides independence and redundancy to ensure an available source of power to the Engineered Safety Feature (ESF) systems. The Technical Specifications for dual unit sites with a shared DG treats the shared DG as a redundant DG for each unit. Each DG starts automatically on receipt of a safety signal. After the DG has started, it will automatically tie to its respective bus if offsite power is lost. The DGs can also start and operate in the standby mode without aligning to a safety bus. In the event of a loss of preferred power, the safety electrical loads are automatically connected to the DGs in sufficient time to provide for safe reactor shutdown and to mitigate the consequences of an accident.

3.2 Development of the Existing Requirements The original Standard Technical Specifications (STS), published in the mid-1970's, required that an Operable DG be started when the redundant DG is inoperable (References 1, 2, 3, and 4).

Similar requirements existed prior to the Standard Technical Specifications in plant-specific Technical Specifications.

In July 1984, the NRC issued Generic Letter (GL) 84-15, "Proposed Staff Actions to Improve and Maintain Diesel Generator Reliability." As part of the proposed technical evaluation of Unresolved Safety Issue (USI) A-44, Station Blackout, the staff determined that the risk from station blackout is such that early actions to improve DG reliability would have a significant safety benefit. The GL included example Technical Specification requirements intended to support the maintenance of DG reliability at a specified level. The proposed specification encompassed certain aspects of the existing requirements for surveillance testing of DGs stipulated in Regulatory Guide 1.108, "Periodic Testing of Diesel Generators Used as Onsite Electric Power Systems at Nuclear Power Plants," and the qualitative recommendations of NUREG/CR-0660, "Enhancement of Onsite Emergency Diesel Generator Reliability," February 1979. The proposed Technical Specifications in Appendix A to the GL provided two actions associated with the condition of one inoperable DG, which were: (1) verify correct breaker alignment and power availability of offsite power within one hour and at least once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter, and (2) within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , verify the opposite train DG starts from ambient conditions and achieves rated frequency and voltage. The intent was to demonstrate Operability of the redundant DG to ensure that no common cause failure exists. As evidenced by the NRC-proposed Actions in GL 84-15, 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months was considered to be a reasonable amount of time to confirm that the Operable DG was not affected by the same problem as the inoperable DG.

In May 1992, the NRC endorsed the concept of performing a common cause determination in lieu of starting the redundant diesel(s), and also proposed exceptions to the need for such an evaluation or diesel start in certain instances such as those proposed to be added by the second

TSTF-531, Rev. 0 Page 3 bullet of the Proposed Change discussion above. At that time, the NRC completed a comprehensive examination of Technical Specifications SRs that require testing at power. This evaluation was documented in NUREG-1366, "Improvements to Technical Specification Surveillance Requirements," which was published in December 1992. Section 10.1, "Emergency Diesel Generator Surveillance Requirements (PWR, BWR)," provides a discussion of surveillance testing of DGs. On page 56, it states "The NRC staff recommends that the requirements to test the remaining diesel generator(s) when one diesel generator is inoperable due to any cause other than preplanned maintenance or testing be limited to those situations where the cause for inoperability has not been conclusively demonstrated to preclude the potential for a common mode failure." (emphasis added) In addition, on page 57, one of the recommendations from NUREG-1366 states: "When an EDG itself is inoperable (not including a support system or independently testable component), the other EDG(s) should be tested only once (not every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months ) and within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months unless the absence of any potential common-mode failure can be demonstrated." (emphasis added)

Some (but not all) of these concepts were developed early enough to be incorporated into Revision 0 of the Improved Technical Specifications (ISTS) NUREGs (i.e., NUREG-1430 through -1434), issued in September of that year (1992). These ISTS NUREGs adopted the recommended actions to either demonstrate that a common cause failure does not exist or to start the Operable DG. One difference was that the Completion Time for start time testing or demonstrating that a common cause failure does not exist on the redundant DG was retained at 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , consistent with the earlier GL 84-15 recommendations. Also, the NUREG-1366 exceptions to the required start of the Operable DG or the performance of a common cause failure determination (preplanned maintenance, a support system, or an independently testable component) did not appear in the ISTS.

Following issuance of the ISTS NUREGs, and based on the evaluations documented in NUREG-1366, the NRC issued Generic Letter 93-05, "Line-Item Technical Specifications Improvements to Reduce Surveillance Requirements for Testing During Power Operations,"

dated September 27, 1993. On page 23 of Enclosure 1 to the GL, proposed Technical Specifications wording acceptable to the NRC was provided for licensees to incorporate into their Technical Specifications (note that the proposed wording was based on the format used in the original Standard Technical Specifications (References 1 through 4) and not the ISTS):

"b..If the diesel generator became inoperable due to any cause other than an inoperable support system, an independently testable component, or preplanned preventive maintenance or testing, demonstrate the OPERABILITY of the remaining OPERABLE diesel generator by performing Surveillance Requirements 4.8.1.1.2.a.5 and 4.8.1.1.2.a.6 within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months , unless the absence of any potential common mode failure for the remaining diesel generator is demonstrated." (emphasis in original document)

TSTF-531, Rev. 0 Page 4 3.3 Evaluation The two changes listed in the Proposed Change Section are individually discussed below.

3.3.1 Revise Required Action B.3.1 Completion Time from "[24] hours" to "24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from discovery of potential common cause failure mechanism", and remove the brackets from around the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months value in the Completion Time for Required Action B.3.2.

When a DG is inoperable, Required Action B.3.1 requires a determination that the Operable DG is not inoperable due to a common cause failure within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . This creates potential problems if the licensees determination of the cause of the failure is later found to be incorrect.

The licensee may believe, based upon available information at the time, that the cause of the DG inoperability is known and that no common cause failure exists on the other diesel(s). However, after the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time has been reached, the licensee may discover that the assumed cause of the inoperability was incorrect. The Technical Specifications do not specifically address this situation. If the licensee were to enter Condition G immediately, then a plant shutdown is required, even when the redundant DG is Operable (i.e., there is no common cause failure). However, initiating a plant transient (a shutdown) when one DG is Operable and the inoperable DG is still within its Completion Time for restoration is detrimental to plant safety.

The alternative to performing the common cause failure determination is to start the redundant Operable DG. However, this alternative has the potential to reduce the reliability of the Operable DG due to additional wear and tear and is also detrimental to plant safety. The existing requirements are also not clear about when such a start would be required, if the original Completion Time of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months has been exceeded.

In the second situation, if a separate issue is discovered that would render the diesel inoperable, perhaps during testing of the repairs for the originally identified problem, the existing requirements are similarly unclear. The DG is already inoperable and the Completion Times started when the DG was originally declared inoperable. If the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time has been exceeded, there is no time available to analyze the new issue to determine its common cause potential.

The proposed change revises the Completion Time from "[24] hours" to "Within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of identification of potential common cause failure mechanism." For the majority of circumstances, the revised Completion Time will result in no change to licensee actions. If the cause of the DG inoperability is known or the assumed cause is determined to be correct, the common cause failure determination is still performed within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . However, should a new or different potential common cause failure mechanism be discovered, the licensee is provided 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to perform a revised common cause failure determination. The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is appropriate for performing the determination when a new or different potential common cause failure mechanism is identified. Licensees have continued to improve the quality and depth of their common cause failure determinations and licensee procedural requirements make it difficult to perform, review, and approve an adequate common cause failure determination in less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

TSTF-531, Rev. 0 Page 5 As noted above, the alternative to performing the common cause failure determination is to start the redundant Operable DG(s). Some licensees have already modified their practices to always start the redundant DG because of the difficulties in performing the common cause failure determination discussed above and the associated risk of a plant shutdown. However, this alternative is detrimental to plant safety. As stated in NUREG-1366, "Studies show that [DG]

testing too frequently is counterproductive to safety in terms of equipment availability."

The brackets (indicating plant-specific information) around the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months value in the Completion Time are removed. To our knowledge, this Completion Time has not been shown to be plant-specific.

It is important to note that the Completion Time of "[24] hours" for Required Action B.3.2 (the diesel start requirement) is only revised by removing the brackets from around the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months value.

Removal of the brackets is done for the same reason as discussed above. The remainder of the phrase that was added into the Completion Time for Required Action B.3.1 is not similarly added into B.3.2. This is because if the redundant diesel(s) have already been started as a means of demonstrating the lack of a common cause failure mechanism, the identification of a new or different problem on the inoperable diesel does not require a second start of the other diesels.

The first successful start of the other diesels within the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is sufficient to show that no important issues are present on those other diesels. The proposed Bases reflect this concept by stating "The Completion Time for Required Action B.3.2 is simply "24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months " because even if a new or different potential common cause failure mechanism should be identified subsequent to the initial one, if redundant diesels are started during a specific entry into ACTION B, those starts suffice to provide assurance of continued OPERABILITY of those DG(s)".

3.3.2 Add a Note to Required Action B.3 which states, "Required Actions B.3.1 and B.3.2 are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system."

When a DG is removed from service for preplanned maintenance or testing, the cause of the inoperability is known and it is an unnecessary diversion of control room operator attention to document the common cause failure determination or to start the redundant DG to demonstrate its Operability. However it should be noted that the proposed revision to the Completion Time would require a common cause failure determination or starting of the Operable DG if the preplanned maintenance or testing revealed a potential common cause failure mechanism. This exception for preplanned maintenance or testing has been accepted by the NRC in the past, as detailed in Section 3.2 "Development of the Existing Requirements."

The other exception being added is when an inoperable support system governed by its own Technical Specification renders a supported DG inoperable. (Note: if the support system was not governed by its own LCO it would be "not functional" instead of "inoperable," as Operability only applies to Technical Specification systems.) Under the ISTS usage rules, inoperability of a Technical Specification supported system would usually be addressed in the actions of the inoperable support system through application of LCO 3.0.6. In those cases, the Required Action to perform a common cause failure determination would not apply. However, in some cases the support system LCOs (such as cooling water) direct that the Conditions and Required

TSTF-531, Rev. 0 Page 6 Actions of LCO 3.8.1 be followed. In these cases the cause of the inoperability is known (the inoperable support system) and the Conditions and Required Actions of the inoperable support system contain the appropriate compensatory measures. This exception for inoperable support systems was accepted by the NRC in the past as detailed in Section 3.2 "Development of the Existing Requirements.

The other concept the NRC discussed in NUREG-1366 and Generic Letter 93-05 was that of independently testable components. Although valid, this concept is not specifically added into the body of the Specifications because performing tests on independently testable components would actually be part of a common cause failure determination, which is already required to be done. Performance of such tests is not a true exception to the requirement to perform a common cause failure determination, so it is addressed by including a sentence within the Bases. The proposed Bases sentence states "If the DG is inoperable due to a DG component that can be tested without starting the OPERABLE DG (e.g., [cooling water, ventilation equipment, starting air pressure, diesel fuel oil or diesel lubricating oil volume or quality]), testing of the component on the OPERABLE DG may be sufficient to determine the redundant DG is not inoperable due to common cause failure, thereby meeting B.3.1."

Such a proposed change to the Technical Specifications Bases simply clarifies that the determination that the Operable DG is not inoperable due to a common cause failure may include testing of DG components. Some DG components can be tested and shown to be functional without starting the DG. For example, if low fuel pressure results in an inoperable DG, the fuel pressure on the redundant DG can be determined to be sufficient to demonstrate redundant DG Operability. Starting the Operable DG in accordance with Required Action B.3.2 and SR 3.8.1.2 will not necessarily reveal a common cause failure of a supporting component. Using the previous example, low fuel pressure may be sufficient for the DG to start under test conditions but not under all accident conditions. In this case, starting the DG in accordance with SR 3.8.1.2 would not demonstrate the DG was Operable but measurement of the fuel pressure could reveal a common cause failure mechanism. The change to the Bases is a clarification to document that testing of DG components is a valid method to support performance of Required Action B.3.1 in lieu of performing Required Action B.3.2.

Safety Significance of the Common Cause Failure Determination The proposed changes will result in a small decrease in the number of times that licensees perform Required Action B.3.1 or B.3.2. This small decrease will not affect plant safety for the reasons discussed above and because of very low likelihood that the Required Actions would identify a common cause failure of two DGs.

A review of Licensee Event Reports (LERs) from 2005 thru August 2010 was performed to identify common cause failures of two or more trains of DGs. This resulted in the identification of 31 LERs that documented the simultaneous inoperability of two or more DGs. Each LER was then reviewed to determine if the simultaneous inoperability of the DGs was due to a common cause failure and, if so, if the common cause failure was identified by performance of Required Action B.3.1 (common cause failure determination) or Required Action B.3.2 (slow start of the

TSTF-531, Rev. 0 Page 7 Operable DG). There are no instances in which the other DG was found to be inoperable due to a common cause failure. There was only one instance in which the redundant DG was found to be inoperable by Required Action B.3.2 (Slow Start Test). In this instance, there was no common cause failure.

A survey of licensees identified that plants enter Condition B an average of 27 times per year per unit. Based on this data, it is estimated that Condition B would have been entered approximately 14,000 times over the five year period examined above without a single instance of a common cause failure. Therefore, the likelihood that Required Action B.3.1 or B.3.2 would identify an inoperable redundant DG is very remote and the marginal reduction in the performance of Required Action B.3.1 and B.3.2 for preplanned maintenance and testing or due to an inoperable support system will have no significant effect on plant safety.

4.

REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria 10 CFR 50.65(a)(1) states the following:

"Each holder of a license to operate a nuclear power plantshall monitor the performance or condition of structures, systems, or componentsin a manner sufficient to provide reasonable assurance that these structures, systems, and componentsare capable of fulfilling their intended functions."

10 CFR 50, Appendix A, Criterion 17Electric power systems. Requires onsite electric power systems to have sufficient capacity and capability to assure that (1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents, and to have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure.

10 CFR 50, Appendix A, Criterion 18Inspection and testing of electric power systems. Electric power systems important to safety shall be designed to permit appropriate periodic inspection and testing of important areas and features, such as wiring, insulation, connections, and switchboards, to assess the continuity of the systems and the condition of their components. The systems shall be designed with a capability to test periodically (1) the operability and functional performance of the components of the systems, such as onsite power sources, relays, switches, and buses, and (2) the operability of the systems as a whole and, under conditions as close to design as practical, the full operation sequence that brings the systems into operation, including operation of applicable portions of the protection system, and the transfer of power among the nuclear power unit, the offsite power system, and the onsite power system.

10 CFR 50, Appendix B, "Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," Criterion XI, "Test Control," states:

TSTF-531, Rev. 0 Page 8 "A test program shall be established to assure that all testing required to demonstrate that structures, systems, and components will perform satisfactorily in service is identified and performed in accordance with written test procedures which incorporate the requirements and acceptance limits contained in applicable design documents."

10 CFR 50, Appendix B, Criterion XVI, "Corrective Action," states the following:

"Measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances are promptly identified and corrected. In the case of significant conditions adverse to quality, the measures shall assure that the cause of the condition is determined and corrective action taken to preclude repetition."

The proposed change does not affect plant compliance with these regulations.

4.2 No Significant Hazards Consideration Determination The industry has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, Issuance of Amendment:

1.

Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed change revises LCO 3.8.1, "AC Sources - Operating," Required Actions B.3.1 and B.3.2, which require performance of a common cause failure determination or a start of the Operable Diesel Generator(s) (DG) when one DG is inoperable. The time allowed to perform the common cause failure determination is changed from a fixed 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period to within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months after identification of a potential common cause failure mechanism. Required Action B.3 is modified by a Note which states the Required Actions do not need to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. DGs are not an initiator of any accident previously evaluated. As a result, a change to the Required Actions when a DG is inoperable will have no effect on the probability of an accident previously evaluated.

The Required Actions taken when a DG is inoperable are not mitigating actions assumed in any accident previously evaluated. As a result, the change to the Required Actions has no effect on the consequences of any accident previously evaluated.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2.

Does the proposed amendment create the possibility of a new or different kind of accident from any previously evaluated?

Response: No

TSTF-531, Rev. 0 Page 9 The proposed change revises LCO 3.8.1, "AC Sources - Operating," Required Actions B.3.1 and B.3.2, which require performance of a common cause failure determination or a start of the Operable DG(s) when one DG is inoperable. The time allowed to perform the common cause failure determination is changed from a fixed 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period to within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months after identification of a potential common cause failure mechanism. Required Action B.3.1 and B.3.2 are modified by a Note which states the Required Actions do not need to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. The change does not involve a physical alteration of the plant (i.e., no new or different type of equipment will be installed) or a change in the methods governing normal plant operations. The change does not alter assumptions made in the safety analysis for DG performance.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

3.

Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No The proposed change revises LCO 3.8.1, "AC Sources - Operating," Required Actions B.3.1 and B.3.2, which require performance of a common cause failure determination or a start of the Operable DG when one DG is inoperable. The time allowed to perform the common cause failure determination is changed from a fixed 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period to within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months after identification of a potential common cause failure mechanism. Required Action B.3 is modified by a Note which states the Required Actions do not need to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. The proposed change does not alter the manner in which safety limits, limiting safety system settings or limiting conditions for operation are determined. The safety analysis acceptance criteria are not impacted by this change. The evaluation of the proposed change determined that the change to the Required Actions will not have a significant effect on safety as identification of an inoperable DG by the Required Actions is very rare and the change results in a small reduction in the number of common cause failure determinations.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

TSTF-531, Rev. 0 Page 10 4.3 Conclusions In conclusion, based on the considerations discussed above, (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 Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

5.

ENVIRONMENTAL CONSIDERATION A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or a significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.

Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

6.

REFERENCES

1.

NUREG-0452, "Standardized Technical Specifications for Westinghouse PWRs," May, 1976.

2.

NUREG-0123, "Standardized Technical Specifications for General Electric Boiling Water Reactors," October, 1976.

3.

NUREG-0212, "Standardized Technical Specifications for Combustion Engineering Pressurized Water Reactors," March, 1977.

4.

NUREG-0103, "Standardized Technical Specifications for Babcock and Wilcox Pressurized Water Reactors," August, 1976.

TSTF-531, Rev. 0 Model Application

TSTF-531, Rev. 0 Page 1

[DATE]

10 CFR 50.90 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 DOCKET NO.

PLANT NAME 50-[xxx]

SUBJECT:

APPLICATION TO REVISE TECHNICAL SPECIFICATIONS TO ADOPT TSTF-531, "REVISION OF SPECIFICATION 3.8.1, REQUIRED ACTIONS B.3.1 AND B.3.2" Pursuant to 10 CFR 50.90, [LICENSEE] is submitting a request for an amendment to the Technical Specifications (TS) for [PLANT NAME, UNIT NOS.].

The proposed amendment modifies the TS actions taken when a Diesel Generator is inoperable as described in TSTF-531, Revision 0, "Revision of Specification 3.8.1, Required Actions B.3.1 and B.3.2." provides a description and assessment of the proposed changes. Attachment 2 provides the existing TS pages marked up to show the proposed changes. Attachment 3 provides revised (clean) TS pages. Attachment 4 provides existing TS Bases pages marked to show the proposed changes for information only.

Approval of the proposed amendment is requested by [date]. Once approved, the amendment shall be implemented within [ ] days.

In accordance with 10 CFR 50.91, a copy of this application, with attachments, is being provided to the designated [STATE] Official.

[In accordance with 10 CFR 50.30(b), a license amendment request must be executed in a signed original under oath or affirmation. This can be accomplished by attaching a notarized affidavit confirming the signature authority of the signatory, or by including the following statement in the cover letter: "I declare under penalty of perjury that the foregoing is true and correct.

Executed on (date)." The alternative statement is pursuant to 28 USC 1746. It does not require notarization.]

TSTF-531, Rev. 0 Page 2 If you should have any questions regarding this submittal, please contact [NAME, TELEPHONE NUMBER].

Sincerely,

[Name, Title]

Attachments:

1. Description and Assessment

2. Proposed Technical Specification Changes (Mark-Up)

3. Revised Technical Specification Pages

4. Proposed Technical Specification Bases Changes (Mark-Up) cc: NRC Project Manager NRC Regional Office NRC Resident Inspector State Contact

TSTF-531, Rev. 0 Page 3 ATTACHMENT 1 - DESCRIPTION AND ASSESSMENT

1.0 DESCRIPTION

The proposed amendment modifies the Technical Specifications (TS) actions taken when a Diesel Generator (DG) is inoperable as described in Technical Specifications Task Force Traveler, TSTF-531, Revision 0, "Revision of Specification 3.8.1, Required Actions B.3.1 and B.3.2." The proposed change will revise Condition B of Specification 3.8.1, "AC Sources -

Operating," to clarify the requirements for performance of a common cause failure determination for an inoperable Diesel Generator (DG).

2.0 ASSESSMENT

2.1 Applicability of Published Safety Evaluation

[LICENSEE] has reviewed the model safety evaluation dated [DATE] as part of the Federal Register Notice of Availability. This review included a review of the NRC staffs evaluation, as well as the information provided in TSTF-531. [LICENSEE] has concluded that the justifications presented in TSTF-531 and the model safety evaluation prepared by the NRC staff are applicable to [PLANT, UNIT NOS.] and justify this amendment for the incorporation of the changes to the [PLANT] TS.

2.2 Optional Changes and Variations

[LICENSEE is not proposing any variations or deviations from the TS changes described in the TSTF-531, Revision 0, or the applicable parts of the NRC staffs model safety evaluation dated

[DATE].] [LICENSEE is proposing the following variations from the TS changes described in the TSTF-531, Revision 0, or the applicable parts of the NRC staffs model safety evaluation dated [DATE].]

[The [PLANT] TS utilize different [numbering][and][titles] than the Standard Technical Specifications on which TSTF-531 was based. Specifically, [describe differences between the plant-specific TS numbering and/or titles and the TSTF-531 numbering and titles.] These differences are administrative and do not affect the applicability of TSTF-531 to the [PLANT]

TS.]

3.0 REGULATORY ANALYSIS

3.1 No Significant Hazards Consideration Determination

[LICENSEE] requests adoption of TSTF-531, Revision 0, "Revision of Specification 3.8.1, Required Actions B.3.1 and B.3.2," which is an approved change to the Standard Technical Specifications (STS), into the [PLANT NAME, UNIT NOS] Technical Specifications (TS). The proposed change revises Condition B of Specification 3.8.1, "AC Sources - Operating," to clarify the requirements for performance of a common cause failure determination for an inoperable Diesel Generator (DG).

TSTF-531, Rev. 0 Page 4

[LICENSEE] has evaluated whether or not a significant hazards consideration is involved with the proposed amendment(s) by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:

1.

Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed change revises LCO 3.8.1, "AC Sources - Operating," Required Actions B.3.1 and B.3.2, which require performance of a common cause failure determination or a start of the Operable Diesel Generator(s) (DG) when one DG is inoperable. The time allowed to perform the common cause failure determination is changed from a fixed 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period to within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months after identification of a potential common cause failure mechanism. Required Action B.3 is modified by a Note which states the Required Actions do not need to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. DGs are not an initiator of any accident previously evaluated. As a result, a change to the Required Actions when a DG is inoperable will have no effect on the probability of an accident previously evaluated.

The Required Actions taken when a DG is inoperable are not mitigating actions assumed in any accident previously evaluated. As a result, the change to the Required Actions has no effect on the consequences of any accident previously evaluated.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2.

Does the proposed amendment create the possibility of a new or different kind of accident from any previously evaluated?

Response: No The proposed change revises LCO 3.8.1, "AC Sources - Operating," Required Actions B.3.1 and B.3.2, which require performance of a common cause failure determination or a start of the Operable DG(s) when one DG is inoperable. The time allowed to perform the common cause failure determination is changed from a fixed 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period to within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months after identification of a potential common cause failure mechanism. Required Action B.3.1 and B.3.2 are modified by a Note which states the Required Actions do not need to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. The change does not involve a physical alteration of the plant (i.e., no new or different type of equipment will be installed) or a change in the methods governing normal plant operations. The change does not alter assumptions made in the safety analysis for DG performance.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

3.

Does the proposed amendment involve a significant reduction in a margin of safety?

TSTF-531, Rev. 0 Page 5 Response: No The proposed change revises LCO 3.8.1, "AC Sources - Operating," Required Actions B.3.1 and B.3.2, which require performance of a common cause failure determination or a start of the Operable DG when one DG is inoperable. The time allowed to perform the common cause failure determination is changed from a fixed 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period to within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months after identification of a potential common cause failure mechanism. Required Action B.3 is modified by a Note which states the Required Actions do not need to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. The proposed change does not alter the manner in which safety limits, limiting safety system settings or limiting conditions for operation are determined. The safety analysis acceptance criteria are not impacted by this change. The evaluation of the proposed change determined that the change to the Required Actions will not have a significant effect on safety as identification of an inoperable DG by the Required Actions is very rare and the change results in a small reduction in the number of common cause failure determinations.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above, [LICENSEE] concludes that the proposed change presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of "no significant hazards consideration" is justified.

4.0 ENVIRONMENTAL EVALUATION The proposed change would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed change does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed change meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed change.

AC Sources - Operating 3.8.1 Babcock & Wilcox STS 3.8.1-2 Rev. 4.0 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME A.3 Restore [required] offsite circuit to OPERABLE status.

72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months B. One [required] DG inoperable.

B.1 Perform SR 3.8.1.1 for OPERABLE [required]

offsite circuit(s).

AND B.2 Declare required feature(s) supported by the inoperable DG inoperable when its redundant required feature(s) is inoperable.

AND

NOTE-----------------

Required Actions B.3.1 and B.3.2 are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system.

B.3.1 Determine OPERABLE DG(s) is not inoperable due to common cause failure.

OR B.3.2 Perform SR 3.8.1.2 for OPERABLE DG(s).

AND 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months AND Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months from discovery of Condition B concurrent with inoperability of redundant required feature(s)

[24] hours from discovery of potential common cause failure mechanism

[24] hours TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 Babcock & Wilcox STS B 3.8.1-7 Rev. 4.0 BASES ACTIONS (continued) emergency feedwater pumps. Single train systems, such as turbine driven emergency feedwater pumps, are not included. Redundant required feature failures consist of inoperable features associated with a train, redundant to the train that has an inoperable DG.

The Completion Time for Required Action B.2 is intended to allow the operator time to evaluate and repair any discovered inoperabilities. This Completion Time also allows for an exception to the normal "time zero" for beginning the allowed outage time "clock." In this Required Action, the Completion Time only begins on discovery that both:

a.

An inoperable DG exists and

b.

A required feature on the other train is inoperable.

If at any time during the existence of this Condition (one DG inoperable) a required feature subsequently becomes inoperable, this Completion Time begins to be tracked.

Discovering one required DG inoperable coincident with one or more inoperable required support or supported features, or both, that are associated with the OPERABLE DG, results in starting the Completion Time for the Required Action. Four hours from the discovery of these events existing concurrently is acceptable because it minimizes risk while allowing time for restoration before subjecting the unit to transients associated with shutdown.

In this Condition, the remaining OPERABLE DG and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System. Thus, on a component basis, single-failure protection for the required feature's function may have been lost; however, function has not been lost. The 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the OPERABILITY of the redundant counterpart to the inoperable required feature. Additionally, the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the capacity and capability of the remaining AC sources, a reasonable time for repairs, and the low probability of a DBA occurring during this period.

B.3.1 and B.3.2 Required Action B.3.1 provides an allowance to avoid unnecessary testing of OPERABLE DG(s). If it can be determined that the cause of the inoperable DG does not exist on the OPERABLE DG, a diesel start per Required Action B.3.2 (SR 3.8.1.2) does not have to be performed. If the cause of inoperability exists on TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 Babcock & Wilcox STS B 3.8.1-8 Rev. 4.0 BASES ACTIONS (continued) other DG(s), the other DG(s) would be declared inoperable upon discovery and Condition E of LCO 3.8.1 would be entered. If the DG is inoperable due to a DG component that can be tested without starting the OPERABLE DG (e.g., [cooling water, ventilation equipment, starting air pressure, diesel fuel oil or diesel lubricating oil volume or quality]), testing of the component on the OPERABLE DG may be sufficient to determine the redundant DG is not inoperable due to common cause failure, thereby meeting B.3.1.

If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG(s), performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of those DG(s).

Once the failure is repaired, the common cause failure no longer exists and Required Action B.3.1 is satisfied. If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG(s),

performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of that DG.

In the event the inoperable DG is restored to OPERABLE status prior to completing either B.3.1 or B.3.2, the [plant corrective action program] will continue to evaluate the common cause possibility. This continued evaluation, however, is no longer under the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months constraint imposed while in Condition B.

Required Actions B.3.1 and B.3.2 are modified by a Note which states that the Required Actions are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. If the DG is made inoperable in order to perform preplanned maintenance or testing, it is not necessary to verify the OPERABILITY of the redundant DG because the cause of the inoperability is known to not affect the redundant DG. If the DG is inoperable due to an inoperable support system with its own LCO, the OPERABILITY of the redundant support system is governed by the support system LCO Conditions and Required Actions.

According to Generic Letter 84-15 (Ref. 7), [24] hours is a reasonable time to confirm that the OPERABLE DG(s) is not affected by the same problem as the inoperable DG, either by starting the OPERABLE DG(s) or by performing a common cause failure determination within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from discovery of a potential common cause failure mechanism. Should a new or different potential common cause failure mechanism be identified, the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is restarted for that determination.

The Completion Time for Required Action B.3.2 is simply 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months because even if a new or different potential common cause failure mechanism should be identified subsequent to the initial one, if redundant TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 Babcock & Wilcox STS B 3.8.1-9 Rev. 4.0 diesels are started during a specific entry into ACTION B, those starts suffice to provide assurance of continued OPERABILITY of those DG(s).

B.4 According to Regulatory Guide 1.93 (Ref. 6), operation may continue in Condition B for a period that should not exceed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

In Condition B, the remaining OPERABLE DG and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System. The 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Completion Time takes into account the capacity and capability of the remaining AC sources, a reasonable time for repairs, and the low probability of a DBA occurring during this period.

C.1 and C.2 Required Action C.1, which applies when two offsite circuits are inoperable, is intended to provide assurance that an event with a coincident single failure will not result in a complete loss of redundant required safety functions. The Completion Time for this failure of redundant required features is reduced to 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months from that allowed for one train without offsite power (Required Action A.2). The rationale for the reduction to 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months is that Regulatory Guide 1.93 (Ref. 6) allows a Completion Time of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months for two required offsite circuits inoperable, based upon the assumption that two complete safety trains are OPERABLE. When a concurrent redundant required feature failure exists, this assumption is not the case, and a shorter Completion Time of TSTF-531, Rev. 0

AC Sources - Operating 3.8.1 Westinghouse STS 3.8.1-2 Rev. 4.0 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME A.3 Restore [required] offsite circuit to OPERABLE status.

72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months B. One [required] DG inoperable.

B.1 Perform SR 3.8.1.1 for the

[required] offsite circuit(s).

AND B.2 Declare required feature(s) supported by the inoperable DG inoperable when its required redundant feature(s) is inoperable.

AND

NOTE-----------------

Required Actions B.3.1 and B.3.2 are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system.

B.3.1 Determine OPERABLE DG(s) is not inoperable due to common cause failure.

OR B.3.2 Perform SR 3.8.1.2 for OPERABLE DG(s).

AND 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months AND Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months from discovery of Condition B concurrent with inoperability of redundant required feature(s)

[24] hours from discovery of potential common cause failure mechanism

[24] hours TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 Westinghouse STS B 3.8.1-7 Rev. 4.0 BASES ACTIONS (continued)

The Completion Time for Required Action B.2 is intended to allow the operator time to evaluate and repair any discovered inoperabilities. This Completion Time also allows for an exception to the normal "time zero" for beginning the allowed outage time "clock." In this Required Action, the Completion Time only begins on discovery that both:

a.

An inoperable DG exists and

b.

A required feature on the other train (Train A or Train B) is inoperable.

If at any time during the existence of this Condition (one DG inoperable) a required feature subsequently becomes inoperable, this Completion Time would begin to be tracked.

Discovering one required DG inoperable coincident with one or more inoperable required support or supported features, or both, that are associated with the OPERABLE DG, results in starting the Completion Time for the Required Action. Four hours from the discovery of these events existing concurrently is Acceptable because it minimizes risk while allowing time for restoration before subjecting the unit to transients associated with shutdown.

In this Condition, the remaining OPERABLE DG and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System. Thus, on a component basis, single failure protection for the required feature's function may have been lost; however, function has not been lost. The 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the OPERABILITY of the redundant counterpart to the inoperable required feature. Additionally, the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the capacity and capability of the remaining AC sources, a reasonable time for repairs, and the low probability of a DBA occurring during this period.

B.3.1 and B.3.2 Required Action B.3.1 provides an allowance to avoid unnecessary testing of OPERABLE DG(s). If it can be determined that the cause of the inoperable DG does not exist on the OPERABLE DG, a diesel start per Required Action B.3.2 (SR 3.8.1.2) does not have to be performed. If the cause of inoperability exists on other DG(s), the other DG(s) would be declared inoperable upon discovery and Condition E of LCO 3.8.1 would be entered. If the DG is inoperable due to a DG component that can be tested without starting the OPERABLE DG (e.g., [cooling water, ventilation equipment, starting air pressure, diesel fuel oil or diesel lubricating oil volume or quality]), testing of the component on the TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 Westinghouse STS B 3.8.1-8 Rev. 4.0 OPERABLE DG may be sufficient to determine the redundant DG is not inoperable due to common cause failure, thereby meeting B.3.1.

If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG(s), performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of those DG(s).

Once the failure is repaired, the common cause failure no longer exists, and Required Action B.3.1 is satisfied. If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG(s),

performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of that DG.

TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 Westinghouse STS B 3.8.1-9 Rev. 4.0 BASES ACTIONS (continued)

In the event the inoperable DG is restored to OPERABLE status prior to completing either B.3.1 or B.3.2, the [plant corrective action program] will continue to evaluate the common cause possibility. This continued evaluation, however, is no longer under the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months constraint imposed while in Condition B.

Required Actions B.3.1 and B.3.2 are modified by a Note which states that the Required Actions are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. If the DG is made inoperable in order to perform preplanned maintenance or testing, it is not necessary to verify the OPERABILITY of the redundant DG because the cause of the inoperability is known to not affect the redundant DG. If the DG is inoperable due to an inoperable support system with its own LCO, the OPERABILITY of the redundant support system is governed by the support system LCO Conditions and Required Actions.

According to Generic Letter 84-15 (Ref. 7), [24] hours is a reasonable time to confirm that the OPERABLE DG(s) is not affected by the same problem as the inoperable DG, either by starting the OPERABLE DG(s) or by performing a common cause failure determination within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from discovery of a potential common cause failure mechanism. Should a new or different potential common cause failure mechanism be identified, the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is restarted for that determination.

The Completion Time for Required Action B.3.2 is simply 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months because even if a new or different potential common cause failure mechanism should be identified subsequent to the initial one, if redundant diesels are started during a specific entry into ACTION B, those starts suffice to provide assurance of continued OPERABILITY of those DG(s).

B.4 According to Regulatory Guide 1.93 (Ref. 6), operation may continue in Condition B for a period that should not exceed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

In Condition B, the remaining OPERABLE DG and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System. The 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Completion Time takes into account the capacity and capability of the remaining AC sources, a reasonable time for repairs, and the low probability of a DBA occurring during this period.

C.1 and C.2 Required Action C.1, which applies when two offsite circuits are inoperable, is intended to provide assurance that an event with a TSTF-531, Rev. 0

AC Sources - Operating 3.8.1 Combustion Engineering STS 3.8.1-2 Rev. 4.0 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME A.3 Restore [required] offsite circuit to OPERABLE status.

72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months B. One [required] DG inoperable.

B.1 Perform SR 3.8.1.1 for the OPERABLE [required]

offsite circuit(s).

AND B.2 Declare required feature(s) supported by the inoperable DG inoperable when its redundant required feature(s) is inoperable.

AND

NOTE-----------------

Required Actions B.3.1 and B.3.2 are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system.

B.3.1 Determine OPERABLE DG(s) is not inoperable due to common cause failure.

OR B.3.2 Perform SR 3.8.1.2 for OPERABLE DG(s).

AND 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months AND Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months from discovery of Condition B concurrent with inoperability of redundant required feature(s)

[24] hours from discovery of potential common cause failure mechanism

[24] hours TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 Combustion Engineering STS B 3.8.1-8 Rev. 4.0 4.0, BASES ACTIONS (continued)

Discovering one required DG inoperable coincident with one or more inoperable required support or supported features, or both, that are associated with the OPERABLE DG, results in starting the Completion Time for the Required Action. Four hours from the discovery of these events existing concurrently, is acceptable because it minimizes risk while allowing time for restoration before subjecting the unit to transients associated with shutdown.

In this Condition, the remaining OPERABLE DG and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System. Thus, on a component basis, single failure protection for the required feature's function may have been lost; however, function has not been lost. The 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the OPERABILITY of the redundant counterpart to the inoperable required feature. Additionally, the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the capacity and capability of the remaining AC sources, a reasonable time for repairs, and the low probability of a DBA occurring during this period.

B.3.1 and B.3.2 Required Action B.3.1 provides an allowance to avoid unnecessary testing of OPERABLE DGs. If it can be determined that the cause of the inoperable DG does not exist on the OPERABLE DG, a diesel start per Required Action B.3.2 (SR 3.8.1.2) does not have to be performed. If the cause of inoperability exists on other DG(s), the other DG(s) would be declared inoperable upon discovery and Condition E of LCO 3.8.1 would be entered. If the DG is inoperable due to a DG component that can be tested without starting the OPERABLE DG (e.g., [cooling water, ventilation equipment, starting air pressure, diesel fuel oil or diesel lubricating oil volume or quality]), testing of the component on the OPERABLE DG may be sufficient to determine the redundant DG is not inoperable due to common cause failure, thereby meeting B.3.1.

If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG(s), performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of those DG(s).

Once the failure is repaired, the common cause failure no longer exists and Required Action B.3.1 is satisfied. If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG(s),

performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of that DG.

In the event the inoperable DG is restored to OPERABLE status prior to completing either B.3.1 or B.3.2, the [plant corrective action program] will TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 Combustion Engineering STS B 3.8.1-9 Rev. 4.0 4.0, continue to evaluate the common cause possibility. This continued evaluation, however, is no longer under the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months constraint imposed while in Condition B.

Required Actions B.3.1 and B.3.2 are modified by a Note which states that the Required Actions are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. If the DG is made inoperable in order to perform preplanned maintenance or testing, it is not necessary to verify the OPERABILITY of the redundant DG because the cause of the inoperability is known to not affect the redundant DG. If the DG is inoperable due to an inoperable support system with its own LCO, the OPERABILITY of the redundant support system is governed by the support system LCO Conditions and Required Actions.

According to Generic Letter 84-15 (Ref. 7), [24] hours is a reasonable time to confirm that the OPERABLE DG(s) is not affected by the same problem as the inoperable DG, either by starting the OPERABLE DG(s) or by performing a common cause failure determination within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from discovery of a potential common cause failure mechanism. Should a new or different potential common cause failure mechanism be identified, the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is restarted for that determination.

The Completion Time for Required Action B.3.2 is simply 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months because even if a new or different potential common cause failure mechanism should be identified subsequent to the initial one, if redundant diesels are started during a specific entry into ACTION B, those starts suffice to provide assurance of continued OPERABILITY of those DG(s).

TSTF-531, Rev. 0

AC Sources - Operating 3.8.1 General Electric BWR/4 STS 3.8.1-2 Rev. 4.0 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME A.3 Restore [required] offsite circuit to OPERABLE status.

72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months B. One [required] DG inoperable.

B.1 Perform SR 3.8.1.1 for OPERABLE [required]

offsite circuit(s).

AND B.2 Declare required feature(s),

supported by the inoperable DG, inoperable when the redundant required feature(s) are inoperable.

AND

NOTE-----------------

Required Actions B.3.1 and B.3.2 are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system.

B.3.1 Determine OPERABLE DG(s) are not inoperable due to common cause failure.

OR B.3.2 Perform SR 3.8.1.2 for OPERABLE DG(s).

1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months AND Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months from discovery of Condition B concurrent with inoperability of redundant required feature(s)

[24] hours from discovery of potential common cause failure mechanism

[24] hours TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 General Electric BWR/4 STS B 3.8.1-7 Rev. 4.0 BASES ACTIONS (continued)

The Completion Time is intended to allow the operator time to evaluate and repair any discovered inoperabilities. This Completion Time also allows for an exception to the normal "time zero" for beginning the allowed outage time "clock." In this Required Action the Completion Time only begins on discovery that both:

a.

An inoperable DG exists and

b.

A required feature on the other division (Division 1 or 2) is inoperable.

If, at any time during the existence of this Condition (one DG inoperable),

a required feature subsequently becomes inoperable, this Completion Time begins to be tracked.

Discovering one required DG inoperable coincident with one or more inoperable required support or supported features, or both, that are associated with the OPERABLE DG[s] results in starting the Completion Time for the Required Action. Four hours from the discovery of these events existing concurrently is acceptable because it minimizes risk while allowing time for restoration before subjecting the unit to transients associated with shutdown.

The remaining OPERABLE DGs and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System. Thus, on a component basis, single failure protection for the required feature's function may have been lost; however, function has not been lost. The 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the component OPERABILITY of the redundant counterpart to the inoperable required feature. Additionally, the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for repairs, and low probability of a DBA occurring during this period.

B.3.1 and B.3.2 Required Action B.3.1 provides an allowance to avoid unnecessary testing of OPERABLE DGs. If it can be determined that the cause of the inoperable DG does not exist on the OPERABLE DG, a diesel start per Required Action B.3.2 (SR 3.8.1.2) does not have to be performed. If the cause of inoperability exists on other DG(s), they are declared inoperable upon discovery, and Condition E of LCO 3.8.1 is entered. If the DG is inoperable due to a DG component that can be tested without starting the OPERABLE DG (e.g., [cooling water, ventilation equipment, starting air pressure, diesel fuel oil or diesel lubricating oil volume or quality]), testing of the component on the OPERABLE DG may be sufficient to determine TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 General Electric BWR/4 STS B 3.8.1-8 Rev. 4.0 the redundant DG is not inoperable due to common cause failure, thereby meeting B.3.1.

If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG(s), performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of those DG(s).

Once the failure is repaired, and the common cause failure no longer exists, Required Action B.3.1 is satisfied. If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG(s),

performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of those DGs.

TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 General Electric BWR/4 STS B 3.8.1-9 Rev. 4.0 BASES ACTIONS (continued)

In the event the inoperable DG is restored to OPERABLE status prior to completing either B.3.1 or B.3.2, the [plant corrective action program] will continue to evaluate the common cause possibility. This continued evaluation, however, is no longer under the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months constraint imposed while in Condition B.

Required Actions B.3.1 and B.3.2 are modified by a Note which states that the Required Actions are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. If the DG is made inoperable in order to perform preplanned maintenance or testing, it is not necessary to verify the OPERABILITY of the redundant DG because the cause of the inoperability is known to not affect the redundant DG. If the DG is inoperable due to an inoperable support system with its own LCO, the OPERABILITY of the redundant support system is governed by the support system LCO Conditions and Required Actions.

According to Generic Letter 84-15 (Ref. 7), [24] hours is a reasonable time to confirm that the OPERABLE DGs are not affected by the same problem as the inoperable DG, either by starting the OPERABLE DG(s) or by performing a common cause failure determination within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from discovery of a potential common cause failure mechanism. Should a new or different potential common cause failure mechanism be identified, the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is restarted for that determination.

The Completion Time for Required Action B.3.2 is simply 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months because even if a new or different potential common cause failure mechanism should be identified subsequent to the initial one, if redundant diesels are started during a specific entry into ACTION B, those starts suffice to provide assurance of continued OPERABILITY of those DG(s).

B.4 According to Regulatory Guide 1.93 (Ref. 6), operation may continue in Condition B for a period that should not exceed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . In Condition B, the remaining OPERABLE DGs and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System. The 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for repairs, and low probability of a DBA occurring during this period.

C.1 and C.2 Required Action C.1 addresses actions to be taken in the event of inoperability of redundant required features concurrent with inoperability TSTF-531, Rev. 0

AC Sources - Operating 3.8.1 General Electric BWR/6 STS 3.8.1-2 Rev. 4.0 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME A.2 Declare required feature(s) with no offsite power available inoperable when the redundant required feature(s) are inoperable.

AND A.3 Restore [required] offsite circuit to OPERABLE status.

24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from discovery of no offsite power to one division concurrent with inoperability of redundant required feature(s) 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AND 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from discovery of two divisions with no offsite power B. One [required] DG inoperable.

B.1 Perform SR 3.8.1.1 for OPERABLE [required]

offsite circuit(s).

AND B.2 Declare required feature(s),

supported by the inoperable DG, inoperable when the redundant required feature(s) are inoperable.

AND 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months AND Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months from discovery of Condition B concurrent with inoperability of redundant required feature(s)

TSTF-531, Rev. 0

AC Sources - Operating 3.8.1 General Electric BWR/6 STS 3.8.1-3 Rev. 4.0 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME

NOTE-----------------

Required Actions B.3.1 and B.3.2 are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system.

B.3.1 Determine OPERABLE DG(s) are not inoperable due to common cause failure.

OR B.3.2 Perform SR 3.8.1.2 for OPERABLE DG(s).

AND B.4 Restore required DG to OPERABLE status.

[24] hours from discovery of potential common cause failure mechanism

[24] hours 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months C. Two [required] offsite circuits inoperable.

C.1 Declare required feature(s) inoperable when the redundant required feature(s) are inoperable.

AND C.2 Restore one [required]

offsite circuit to OPERABLE status.

12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months from discovery of Condition C concurrent with inoperability of redundant required feature(s) 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 General Electric BWR/6 STS B 3.8.1-7 Rev. 4.0 BASES ACTIONS (continued)

The Completion Time is intended to allow the operator time to evaluate and repair any discovered inoperabilities. This Completion Time also allows for an exception to the normal "time zero" for beginning the allowed outage time "clock." In this Required Action, the Completion Time only begins on discovery that both:

a.

An inoperable DG exists and

b.

A required feature on another division is inoperable.

If, at any time during the existence of this Condition (one DG inoperable),

a required feature subsequently becomes inoperable, this Completion Time begins to be tracked.

Discovering one required DG inoperable coincident with one or more required support or supported features, or both, that are associated with the OPERABLE DG(s), results in starting the Completion Time for the Required Action. Four hours from the discovery of these events existing concurrently is acceptable because it minimizes risk while allowing time for restoration before subjecting the unit to transients associated with shutdown.

The remaining OPERABLE DGs and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System. Thus, on a component basis, single failure protection for the required feature's function may have been lost; however, function has not been lost. The 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the component OPERABILITY of the redundant counterpart to the inoperable required feature. Additionally, the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for repairs, and low probability of a DBA occurring during this period.

B.3.1 and B.3.2 Required Action B.3.1 provides an allowance to avoid unnecessary testing of OPERABLE DGs. If it can be determined that the cause of the inoperable DG does not exist on the OPERABLE DG, a diesel start per Required Action B.3.2 (SR 3.8.1.2) does not have to be performed. If the cause of inoperability exists on other DGs, the other DGs are declared inoperable upon discovery, and Condition E of LCO 3.8.1 is entered. If the DG is inoperable due to a DG component that can be tested without starting the OPERABLE DG (e.g., [cooling water, ventilation equipment, starting air pressure, diesel fuel oil or diesel lubricating oil volume or quality]), testing of the component on the OPERABLE DG may be TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 General Electric BWR/6 STS B 3.8.1-8 Rev. 4.0 sufficient to determine the redundant DG is not inoperable due to common cause failure, thereby meeting B.3.1.

If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG(s), performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of those DG(s).

Once the failure is repaired, and the common cause failure no longer exists, Required Action B.3.1 is satisfied. If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG(s),

performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of those DG(s).

TSTF-531, Rev. 0

AC Sources - Operating B 3.8.1 General Electric BWR/6 STS B 3.8.1-9 Rev. 4.0 BASES ACTIONS (continued)

In the event the inoperable DG is restored to OPERABLE status prior to completing either B.3.1 or B.3.2, the [plant corrective action program] will continue to evaluate the common cause possibility. This continued evaluation, however, is no longer under the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months constraint imposed while in Condition B.

Required Actions B.3.1 and B.3.2 are modified by a Note which states that the Required Actions are not required to be performed if the DG is inoperable due to preplanned maintenance or testing, or an inoperable support system. If the DG is made inoperable in order to perform preplanned maintenance or testing, it is not necessary to verify the OPERABILITY of the redundant DG because the cause of the inoperability is known to not affect the redundant DG. If the DG is inoperable due to an inoperable support system with its own LCO, the OPERABILITY of the redundant support system is governed by the support system LCO Conditions and Required Actions.

According to Generic Letter 84-15 (Ref. 7), [24] hours is a reasonable time to confirm that the OPERABLE DG(s) are not affected by the same problem as the inoperable DG, either by starting the OPERABLE DG(s) or by performing a common cause failure determination within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from discovery of a potential common cause failure mechanism. Should a new or different potential common cause failure mechanism be identified, the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is restarted for that determination.

The Completion Time for Required Action B.3.2 is simply 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months because even if a new or different potential common cause failure mechanism should be identified subsequent to the initial one, if redundant diesels are started during a specific entry into ACTION B, those starts suffice to provide assurance of continued OPERABILITY of those DG(s).

B.4 According to Regulatory Guide 1.93 (Ref. 6), operation may continue in Condition B for a period that should not exceed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . In Condition B, the remaining OPERABLE DGs and offsite circuits are adequate to supply electrical power to the onsite Class 1E distribution system. The 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for repairs, and low probability of a DBA occurring during this period.

C.1 and C.2 Required Action C.1 addresses actions to be taken in the event of concurrent failure of redundant required features. Required Action C.1 TSTF-531, Rev. 0

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TAC:ME8309, Revision of Specification 3.8.1, Required Actions B.3.1 and B.3.2 (Open)
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MONTHYEAR2012-03-29 [Table View]

TSTF-12-07, Transmittal of TSTF-531, Revision 0, Revision of Specification 3.8.1, Required Actions B.3.1 and B.3.2

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3.1 System Description

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3.0 REGULATORY ANALYSIS

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TSTF-12-07, Transmittal of TSTF-531, Revision 0, Revision of Specification 3.8.1, Required Actions B.3.1 and B.3.2

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SUBJECT:

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SUMMARY

3.1 System Description

SUBJECT:

1.0 DESCRIPTION

2.0 ASSESSMENT

3.0 REGULATORY ANALYSIS

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