Text

Request for Technical Specification Interpretation Regarding the Offsite Power Supplies to the Onsite Class 1E AC Power Distribution System
	ML13080A257
Person / Time
Site:	Columbia
Issue date:	03/13/2013
From:	Hettel W; Energy Northwest
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	GO2-13-043
	Download: ML13080A257 (43)
	v • d • e

W. Grover Hettel EG Columbia Generating Station P.O. Box 968, PE23 NORTHW EST Richland, WA 99352-0968 I

Ph. 509.377.8311 F. 509.377.4150 wghettel@energy-northwest.com March 13, 2013 G02-13-043 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001

Subject:

COLUMBIA GENERATING STATION, DOCKET NO. 50-397 REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS 1E AC POWER DISTRIBUTION SYSTEM

Dear Sir or Madam:

In accordance with NRC Inspection Manual Part 9900: Technical Guidance, "Licensee Technical Specification Interpretations," Energy Northwest requests the Nuclear Regulatory Commission provide a written interpretation regarding the intent of the Technical Specification (TS) requirement. Specifically, Energy Northwest requests concurrence with the following position regarding alignment of the offsite power supplies in meeting Technical Specification (TS) 3.8.1, "AC Sources - Operating," and TS 3.8.2, "AC Sources - Shutdown."

The two circuits from offsite are from the Ashe substation and the Benton substation (via transformers TR-S and TR-B, respectively.) The TR-S offsite circuit must be capable of providing power to the Division 3 4.16 kV Engineered Safety Feature (ESF) bus and either the Division 1 or Division 2 4.16 kV ESF bus. The TR-B offsite circuit must be capable of providing power to both Divisions 1 and 2 4.16 kV ESF buses.

Energy Northwest considers this position to be consistent with the licensing basis of the plant and with Columbia Generating Station's compliance with General Design Criteria 17, "Electric Power Systems," as documented in the Final Safety Analysis Report. This position is further elaborated in the enclosure to this letter.

This letter contains no regulatory commitments. Should you have any questions or require additional information regarding this matter, please contact Mr. Z. K. Dunham, Licensing Supervisor, at (509) 377-4735.

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REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS IE AC POWER DISTRIBUTION SYSTEM Page 2 of 2 Respectfully,

,,,,W. G. Hettel - Vice President, Operations

Enclosure:

As stated cc: NRC Region IV Administrator NRC NRR Project Manager NRC Senior Resident Inspector/988C AJ Rapacz - BPA/1399 WA Horin - Winston & Strawn

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS 1E AC POWER DISTRIBUTION SYSTEM Enclosure Page 1 of 12 1.0 Background 1.1 Columbia Generating Station (Columbia) has two qualified offsite power supplies to the Class 1E AC distribution system as follows:

" Startup Transformer (TR-S) - One qualified source (also referred to as the

'preferred' source) is from the 230 kV Ashe substation stepped down through the 230 kV/4.16 kV windings of a 230 kV/6.9 kV/4.16 kV transformer, and

Backup Transformer (TR-B) - The other qualified source (also referred to as the 'backup' source) is from the 115 kV Benton substation stepped down through a 115 kV/4.16 kV transformer.

1.2 The Class 1E AC distribution system supplies electrical power to three divisional load groups, Divisions 1, 2, and 3, with each division powered by an independent Class 1E 4.16 kV engineered safety feature (ESF) bus. By design, the Divisions 1 and 2 4.16 kV ESF buses have two separate and independent sources of offsite power whereas the Division 3 4.16 kV ESF bus has one source of offsite power. Each 4.16 kV ESF bus has a dedicated onsite diesel generator (DG).

The Division 1 4.16 kV ESF bus is also referred to as SM-7. The Division 2 4.16 kV ESF bus is also referred to as SM-8. The Division 3 4.16 kV ESF bus is also referred to as SM-4. The offsite power feeds to the Class 1E 4.16 kV ESF buses is depicted in the Columbia Final Safety Analysis Report (FSAR) Figures 8.1-2.1 and 8.1-2.2 (Reference 5).

2.0 Position 2.1 Current Position: The Limiting Condition for Operation (LCO) of Technical Specification (TS) 3.8.1, "AC Sources - Operating," requires, in part, two qualified circuits between the offsite transmission network and the onsite Class 1E AC power distribution system. This requirement is met as follows:

" The TR-S offsite circuit must be capable of providing power to:

o Division 1 OR Division 2 4.16 kV ESF bus, and o Division 3 4.16 kV ESF bus

" The TR-B offsite circuit must be capable of providing power to:

o Division 1 4.16 kV ESF bus, and o Division 2 4.16 kV ESF bus

" The necessary automatic transfer capability must be operable as follows:

> If power is supplied to Divisions 1, 2 and 3 via the auxiliary transformer (TR-N1), the automatic transfer capability from TR-N1 to TR-S must be

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS IE AC POWER DISTRIBUTION SYSTEM Enclosure Page 2 of 12 operable for Division 3 and either Division 1 or Division 2, and the automatic transfer capability from TR-N1 to TR-B must be operable for both Division 1 and Division 2 (the automatic transfer capability from TR-N1 to TR-B is allowed to go through an intermediate step of transferring to the first offsite source, i.e., TR-S), or

> Ifpower is supplied to Division 1 and Division 2 via TR-S, the automatic transfer capability to TR-B must be operable for both of the ESF buses, or

> Ifpower is supplied to Division 1 and Division 2 via TR-B, then one offsite circuit is inoperable (TR-S) since no automatic transfer capability from TR-B to TR-S exists.

2.2 Alternate Position: This request for TS interpretation has been necessitated by recognition of an alternate position to that described in Section 2.1 above. A teleconference between Energy Northwest, the NRC Resident Inspectors, NRC Region IV, and NRC NRR was conducted on October 2, 2012. The alternate position is that the minimum LCO requirements be set at the design configuration such that Division 1 and 2 must have two sources of offsite power (TR-S and TR-B) for the LCO to be met. Contrary to this, the current position considers the LCO to be met when either Division 1 or Division 2 has two sources of offsite power. A tabular depiction of the current position is provided in Table 1 below.

The alternate position is provided in Table 10 below.

3.0 Basis 3.1 The Energy Northwest current position is documented in Columbia's TS Bases for LCO 3.8.1. Attachment 1 contains relevant excerpts of the LCO and TS Bases text. This position was included in the version of the TS Bases that was submitted to and approved by the NRC during Columbia's conversion to Improved Technical Specifications (ITS) in the 1995 timeframe (Reference 1).

Attachment 2 contains a scanned version of the applicable pages from the submittal. Energy Northwest's ITS submittal was based upon NUREG-1434 Revision 1, "Standard Technical Specifications - General Electric Plants (BWR/6)" (Reference 2). This position has not been altered or re-interpreted since that time.

3.2 As discussed above, the Division 1 and Division 2 ESF buses are capable of being supplied by either one of two offsite sources (TR-S or TR-B) whereas the Division 3 ESF bus is only capable of being supplied by one offsite source (TR-S). Thus, in order for TR-S to be considered operable, it must always be capable of supplying power to Division 3. In order to be able to meet single failure criteria (discussed further below), TR-S must also be capable of powering one of the other divisions - that is, Division 1 or 2. In order for TR-B to be considered

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS IE AC POWER DISTRIBUTION SYSTEM Enclosure Page 3 of 12 operable, it must always be capable of supplying power to both Divisions 1 and 2.

3.3 Regulatory Guide (RG) 1.93, "Availability of Electric Power Sources," (Reference

3) was published in December 1974 to describe guidelines that the NRC considered acceptable when the number of available electric power sources are less than the number of sources required by the LCO for a facility. This guidance forms the basis of the Required Actions and Completion Times for LCO 3.8.1 as described in Columbia's TS Bases and also NUREG-1434. Revision 1 to RG 1.93 was issued in March 2012. Both versions of the RG have been reviewed to ensure the stated position is consistent with the licensing basis of Columbia and the updated NRC guidance.

As documented in the original RG 1.93, the LCO, with respect to available electric power sources, is an electric power system that satisfies General Design Criterion (GDC) 17, "Electric Power Systems," of Appendix A, "General Design Criteria for Nuclear Power Plants," of 10 CFR Part 50 (Reference 4) by including the following electric power sources: (1) two physically independent circuits from the offsite transmission network, each of which is either continuously available or can be made available within a few seconds following a loss-of-coolant accident (LOCA), (2) redundant onsite AC power supplies, and (3) redundant onsite DC power supplies. Both version of the RG discuss that plants with more power sources than are required by GDC 17 may be able to withstand multiple failures and still satisfy the LCO.

Columbia has two qualified sources of power from the offsite transmission network, each of which is associated with a specific transformer, TR-S and TR-B.

Each source must be available from the offsite transmission network up to the respective transformer to meet the LCO. However, the Columbia-specific configuration of the offsite power supply downstream of the two transformers to the three 4.16kV ESF buses exceeds that required by GDC 17 such that the loss of one source to a specific bus can be tolerated, and the GDC 17 requirements are still met. Thus, as described above RG 1.93 states that the LCO is still satisfied. Further analysis is provided below.

4.0 GDC 17 Offsite Source 4.1 GDC 17 requires both an onsite and offsite electric power system. The full text of the GDC is contained in Attachment 3. GDC 17 requires that "electric power from the transmission network to the onsite electric distribution system shall be supplied by two physically independent circuits (not necessarily on separate rights of way) designed and located so as to minimize to the extent practical the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions."

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS IE AC POWER DISTRIBUTION SYSTEM Enclosure Page 4 of 12 The Columbia (FSAR) describes the level and method of compliance with the GDC 17 requirements. FSAR Section 8.2.2.4 documents that both the "preferred source" via the 230-kV startup transformer (TR-S) and the "backup source" via the 115-kV backup transformer (TR-B) satisfy GDC 17 and that the backup transformer is automatically connected directly to the Division 1 and 2 switchgear buses for supply of power to the ESF loads in the event of loss of the preferred power supply.

The primary undervoltage sensing scheme for the 4.16-kV Class 1E distribution system utilizes instantaneous undervoltage relays to start the Divisions 1 and 2 standby DGs immediately on loss of voltage at their associated 4.16-kV Class 1E switchgear buses. These relays also energize timers which allow the system to attempt to establish supply from the startup source [TR-S] (if the plant is operating from the normal source at the time) or verify that voltage loss is maintained (if the plant is operating from the startup source initially). In the event that voltage loss is maintained for 3.5 sec, the Division 1 and/or 2 timers trip the Class 1E bus normal/startup source breakers, institute load shedding, and energize additional 2-sec and 4-sec timers. The 2-sec timer is utilized to attempt closing of the backup source [TR-B] breakers; backup transformer undervoltage relays will inhibit breaker closure in the event of backup source undervoltage.

The 4-sec timers are used to inhibit closure of the DG breakers until the system has had time to attempt reestablishment of supply via the backup source.

4.2 Under the LCO provisions in the TS Bases, the preferred source could be out of service to either Division 1 or 2 4.16 kV ESF bus. For illustration, it is assumed that the preferred source is not available to Division 1. In this instance, should there be a unit trip, the electrical protection system will automatically fast transfer the 4.16kV AC power system from the normal auxiliary transformer, TR-N1, fed by the main generator, to TR-S. This will result in the following 4.16kV AC power system alignments:

" Division 1 - When the feeder breaker does not auto close upon fast transfer since it is tagged out of service, for instance, the Division 1 4.16 kV ESF switchgear bus will see a loss of power (DG-1 will auto start) and the ESF bus source sequence logic will transfer to the backup source (TR-B) to repower the bus after a time delay of 3.5 sec.

" Division 2 - Continues to be fed from TR-S. The ability to power the Division 2 4.16 kV ESF bus from the backup source (TR-B) is still available if needed.

Division 3 - Continues to be fed from TR-S

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS IE AC POWER DISTRIBUTION SYSTEM Enclosure Page 5 of 12 The above alignment is considered acceptable such that the LCO continues to be met. All 4.16 kV ESF buses continue to have a source of offsite power, and two separate sources of offsite power continue to be provided from the transmission network to the onsite electric distribution system. Thus, in the minimum LCO configuration, Columbia would have one 4.16 kV ESF bus capable of being supplied by the preferred source (TR-S), one bus capable of being supplied by the backup source (TR-B) and one bus capable of being supplied by both the preferred (TR-S) and the backup (TR-B) source. The possible combinations are listed in Table 1 below.

Table 1 LCO Configuration 1 LCO Configuration 2 Division 1 TR-B TR-S and TR-B Division 2 TR-S and TR-B TR-B Division 3 TR-S TR-S 5.0 GDC 17 Single Failure 5.1 GDC 17 also contains performance requirements in the event of a single failure in the offsite supply by stating (emphasis added), "Each of these [offsite] circuits shall be designed to be available in sufficient time following a loss of all onsite alternating current power supplies and the other offsite electric power circuit, 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."

In the event of the single failure of loss of one of the two offsite sources, two of the Class 1E 4.16kV ESF buses would still be powered from the other offsite source. One bus would have no source of offsite power. The possible combinations are provided in Table 2 below.

Table 2 LCO Configuration 1 LCO Configuration 2 Single Failure Loss of TR-S Loss of TR-B Loss of TR-S Loss of TR-B Division 1 TR-B None TR-B TR-S Division 2 TR-B TR-S TR-B None Division 3 None TR-S None TR-S FSAR Section 8.2.2.4 specifically discusses how the electric power supply system meets GDC 17 in this regard as follows:

e A separate reactor coolant makeup system, as required by GDC 33 is not

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS 1E AC POWER DISTRIBUTION SYSTEM Enclosure Page 6 of 12 provided as a part of Columbia plant design. Rather, high-pressure core spray (HPCS), automatic depressurization system (ADS), low-pressure core spray (LPCS), and residual heat removal (RHR) systems, acting singly or together (as required), are designed with the capability to make up coolant inventory to the vessel in the event of small breaks in the pressure boundary. The Class 1E 4.16-kV switchgear buses supplying power to these systems are normally connected to the normal power source via the 4.16-kV non-Class 1E switchgear buses. In the event of a loss of normal power and the preferred offsite power is unavailable, the supply feeders from the 4.16-kV non-Class 1E switchgear buses are opened, and the 4.16-kV Class 1E switchgear buses (SM-7 and SM-8) are supplied by the backup transformer, if available, (second offsite source) or directly by their associated diesel generators. The 4.16-kV Class 1E switchgear bus SM-4 is supplied by its diesel generator.

Supply of offsite and onsite power for RHR, emergency core cooling, containment heat removal, containment atmosphere cleanup, and cooling water systems conform to GDC 34, 35, 38, 41, and 44 respectively. All systems are connected to offsite and onsite power sources in a manner similar to that described above for those systems capable of supplying reactor coolant inventory makeup. Each of these systems is supplied on a 100%

redundancy basis (via Division 1 and 2), except Division 3 for HPCS, thereby ensuring completion of each system safety function in the event of a single failure occurring in one of the redundant portions of the system.

The equipment necessary to mitigate anticipated operational occurrences and postulated accidents is designed with the requisite level of redundancy to withstand a single failure as required by GDC 21, 24, 25, 34, 35, 38, 41, and 44.

Generally, two redundant trains of equipment are sufficient to meet this requirement. These trains correspond to the electrical divisions - Division 1 and

2. As long as one of the two divisions is maintained operable assuming a single failure, the function will be assured. The single failure analysis in Table 2 shows that, in all cases, either Division 1 or Division 2 will remain operable thereby ensuring the GDC 17 requirements are met.

5.2 The emergency core cooling system (ECCS) network is made up of HPCS, LPCS, three loops of Low Pressure Coolant Injection (LPCI) - an operating mode of RHR, and the ADS. This network is arranged into three divisions. The Class 1 E AC distribution system provides power to the ECCS loads as illustrated in Table 3.

Table 3 Division 1 LPCI, LPCS, ADS Division 2 2 LPCI, ADS Division 3 HPCS

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS 1E AC POWER DISTRIBUTION SYSTEM Enclosure Page 7 of 12 FSAR Section 6.3.1.1.2.d describes the single failure analysis for the ECCS assuming LOCA in which the pipe break is not part of the ECCS (i.e.,

recirculation line). This analysis is depicted in Table 4 below:

Table 4 Single Failure HPCS LPCS DG LPCI DG Division 1 LPCI, LPCS, ADS None LPCI, LPCS, ADS Division 2 2 LPCI, ADS 2 LPCI, ADS None Division 3 None HPCS HPCS FSAR 6.3.1.1.2.d.1 6.3.1.1.2.d.2 6.3.1.1.2.d.3 The configuration in 6.3.1.1.2.d.1 is the same as that in Table 2 LCO Configuration 1 and 2 with the single failure being TR-S. The configuration in 6.3.1.1.2.d.2 is the same as that in Table 2 LCO Configuration 1 with the single failure being TR-B. The configuration in 6.3.1.1.2.d.3 is the same as that in Table 2 LCO Configuration 2 with the single failure being TR-B. Therefore, the single failure analysis of the ECCS in FSAR 6.3.1.1.2.d (non-ECCS line break) is consistent with the LCO configurations required by TS 3.8.1 assuming a loss of all onsite AC and the other offsite circuit (as required by GDC 17).

5.3 FSAR Section 6.3.1.1.2.e describes the single failure analysis for the ECCS assuming LOCA in which the pipe break is part of the ECCS. This analysis is depicted in Table 5 below:

Table 5 Minimum 2 LPCI, LPCI, LPCS, LPCI, HPCS, LPCS, HPCS, Equipment ADS ADS ADS ADS FSAR 6.3.1.1.2.e.1 6.3.1.1.2.e.2 6.3.1.1.2.e.3 6.3.1.1.2.e.4

Table 6 below shows an ECCS line break coincident with Table 2 for LCO Configuration 1 and a single failure of loss of TR-S.

Table 6 Power Line Break LPCS LPCI*

TR-B Division 1 LPCI, ADS LPCS, ADS TR-B Division 2 2 LPCI, ADS 2 LPCI, ADS None Division 3 None None FSAR More capacity More capacity than than 6.3.1.1.2.e.1 6.3.1.1.2.e.2

The loss of LPCI Train A is depicted here. Loss of any one of the three LPCI trains will result in similar remaining equipment.

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS IE AC POWER DISTRIBUTION SYSTEM Enclosure Page 8 of 12

Table 7 below shows an ECCS line break coincident with Table 2 for LCO Configuration 1 and a single failure of loss of TR-B.

Table 7 Power Line Break HPCS LPCI None Division 1 None None TR-S Division 2 2 LPCI, ADS LPCI, ADS TR-S Division 3 None HPCS FSAR 6.3.1.1.2.e.1 6.3.1.1.2e.3

" Table 8 below shows an ECCS line break coincident with Table 2 for LCO Configuration 2 and a single failure of loss of TR-S.

Table 8 Power Line Break LPCS LPCI*

TR-B Division 1 LPCI, ADS LPCS, ADS TR-B Division 2 2 LPCI, ADS 2 LPCI, ADS None Division 3 None None FSAR More capacity More capacity than 6.3.1.1.2.e.1 than 6.3.1.1.2.e.2

The loss of LPCI Train A is depicted here. Loss of any one of the three LPCI trains will result in similar remaining equipment.

" Table 9 below shows an ECCS line break coincident with Table 2 for LCO Configuration 2 and a single failure of loss of TR-B.

Table 9 Power Line Break HPCS LPCS LPCI TR-S Division 1 LPCS, LPCI, ADS LPCI, ADS LPCS, ADS None Division 2 None None None TR-S Division 3 None HPCS HPCS FSAR 6.3.1.1.2.e.2 6.3.1.1.2.e.3 6.3.1.1.2.e.4 Each configuration in Tables 6-9 meets or exceeds the minimum equipment assumed available in the FSAR. Therefore, the single failure analysis of the ECCS in FSAR 6.3.1.1.2.e (ECCS line break) is consistent with the LCO configurations required by TS 3.8.1 assuming a loss of all onsite AC and the other offsite circuit (as required by GDC 17).

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS IE AC POWER DISTRIBUTION SYSTEM Enclosure Page 9 of 12 6.0 RG 1.93 Regulatory Positions 6.1 RG 1.93 states that the intent of the regulatory positions is to ensure that a nuclear power plant is in an acceptably safe operating mode whenever the available electric power sources are less than the LCO. The RG discusses various levels of degradation of the electric power system; the regulatory position given for each degraded level should be incorporated in the Technical Specifications.

6.2 Regulatory Position C.1 states, "Ifthe available offsite AC power sources are one less than the LCO, power operation may continue for a period that should not exceed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months ..."

Discussion B.1 states, "This degradation level means that one of the required offsite AC sources is not available, and therefore, the offsite AC power system has no redundancy. Thus, operation could safely continue if the availability of the remaining power sources is verified; however, because the system is degraded below the LCO, the TS identify a time limit on continued operation."

As shown in Table 1 above, the LCO configuration ensures redundancy of the offsite power supply from the transmission network up to and including the 4.16 kV ESF buses. As shown in Table 2, with the offsite power supply one less than the LCO, the offsite power system has no redundancy. Columbia TS 3.8.1.A reflects this condition and the RG 1.93 recommended Completion Time of 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to restore the offsite circuit to operable status. In addition, this Condition contains a Required Action to declare required feature(s) with no offsite power available inoperable when the redundant required feature(s) are inoperable. This applies if the division cannot be powered from an offsite source and is intended to provide assurance that an event with a coincident single failure of the associated DG does not result in a complete loss of safety function of critical systems.

6.3 Regulatory Position C.3 states, "Ifthe available offsite AC power sources are two less than the LCO, power operation may continue for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months ..."

Discussion B.3 states, "This degradation level means that the offsite power system is not available or does not have the capability to achieve a safe shutdown and to mitigate the effects of an event when coupled with the predicted loss of generation that occurs along with the unit trip or shutdown. However, the onsite AC system has not been degraded. Thus, this degradation level generally corresponds to total loss of the offsite power sources."

In the LCO configuration shown in Table 1, a loss of two offsite supplies will result in a loss of offsite power consistent with the assumptions in the RG.

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS 1E AC POWER DISTRIBUTION SYSTEM Enclosure Page 10 of 12 7.0 Refutation of Alternate Position 7.1 This request for TS interpretation has been necessitated by an alternate position that has been identified. The alternate position is that the TS require Columbia to have one 4.16 kV ESF bus capable of being supplied by the preferred source (TR-S) and two buses capable of being supplied by both the preferred (TR-S) and the backup (TR-B) source. This is shown in Table 10 below.

Table 10 Alternate LCO Configuration Division 1 TR-S and TR-B Division 2 TR-S and TR-B Division 3 TR-S 7.2 The alternate position is that a loss of one TR-S feed to either Division 1 or Division 2 would constitute one offsite circuit being inoperable as presented in Table 11 below.

Table 11 Single Failure Loss of TR-S to Div 1 Loss of TR-S to Div 2 Division 1 TR-B TR-S and TR-B Division 2 TR-S and TR-B TR-B Division 3 TR-S TR-S The Discussion in RG 1.93 for the available AC power sources one less than the LCO states that, in this configuration, the affected source has lost redundancy.

As can be seen Table 10 above, this is not the case. Two offsite circuits are still available from the transmission network to the Class 1 E AC system. In fact, each of the two sources remains available to two divisions; that is, TR-S would be available to Divisions 2 and 3 or Divisions 1 and 3 while TR-B would be available to Divisions 1 and 2. There is no loss of redundancy relative to RG 1.93. Thus, this interpretation is not consistent with the stated bases of the TS Actions or NUREG-1434.

7.3 The Discussion in RG 1.93 for the available offsite AC power sources two less than the LCO states that this condition "generally corresponds to total loss of the immediately accessible offsite power sources". However, assuming the starting configuration in Table 10, a complete loss of TR-B would not result in a total loss of offsite power as shown in Table 12 below.

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS 1E AC POWER DISTRIBUTION SYSTEM Enclosure Page 11 of 12 Table 12 Single Failure Loss of TR-S to Div 1 Loss of TR-S to Div 2 Subsequent Failure Loss of TR-B Loss of TR-B Division 1 None TR-S Division 2 TR-S None Division 3 TR-S TR-S Two divisions remain powered by TR-S. There is no loss of offsite power. Thus, this interpretation is not consistent with the stated bases of the TS Actions or NUREG-1434.

7.4 The alternate position is based upon language in TS Bases 3.8.1 describing what constitutes a "qualified offsite circuit". The LCO requires two "qualified offsite circuits". Since this is not a TS defined term, the Bases clarifies that it "includes the circuit path and disconnect to the respective transformers, the circuit path and breakers to the respective non-Class 1E 4.16 kV switchgear, SM-1, SM-2, and SM-3 (for the TR-S offsite circuit only), and the circuit path and breakers to the respective Class 1 E switchgear (SM-4, SM-7, and SM-8)." This language also has not been changed since conversion to the ITS. This language is considered by Energy Northwest to apply to those portions of the "qualified offsite circuit" that are required by the LCO. Energy Northwest does not consider this language to be establishing the LCO requirements in and of itself and that the language is not intended to imply that a circuit path and breaker to a respective Class 1E switchgear be required in support of operability of a qualified offsite circuit when the LCO is otherwise met.

8.0 Other Applicable Regulations 8.1 Although the TS minimum LCO configuration may permit unrestricted operation with the TR-S supply to Division 1 or 2 out of service provided all other requirements are satisfied, other regulations ensure that risk associated with corrective or preventive maintenance is appropriately managed. Anytime a component is removed from service for maintenance, it is evaluated and managed under the Maintenance Rule plant configuration control requirement, 10 CFR 50.65(a)(4) (Reference 6), and the associated industry guidance, NUMARC 93-01, "Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants" (Reference 7). Regulatory Guide 1.182, "Assessing and Managing Risk Before Maintenance Activities at Nuclear Power Plants," (Reference 8) endorses Section 11 of the NUMARC guidance. Energy Northwest's procedure for assessing risk during maintenance and surveillance activities and documenting risk assessments incorporates the guidance from these documents.

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS IE AC POWER DISTRIBUTION SYSTEM Enclosure Page 12 of 12 8.2 The normal configuration of the plant is to maintain the TR-S feed to Divisions 1, 2, and 3 operable. A search over the past 10 years was performed to determine the total time that the TR-S feed to either Division 1 or 2 was not available during Modes 1, 2, and 3 but the LCO was still considered to be met. This time was determined to be 446 hours0.00516 days 0.124 hours 7.374339e-4 weeks 1.69703e-4 months . The total hours the reactor was critical during this same timeframe was 76,695 hours0.00804 days 0.193 hours 0.00115 weeks 2.644475e-4 months . This represents an unavailability of 0.6%.

9.0 Conclusion The Completion Times established in the Columbia TS are based upon RG 1.93 as discussed in the TS Bases and NUREG-1434. The LCO Configuration supported by Energy Northwest's stated historical position corresponds to the Discussion and Regulatory Positions in RG 1.93. This position was originally submitted as part of the conversion to the Improved Technical Specifications and has not been altered since that time. Consequently, Energy Northwest requests a written TS interpretation from the NRC that is consistent with Energy Northwest's current position to assure that offsite power circuit configurations and the impact to TS 3.8.1 LCO are clearly defined and understood.

10.0 References

1. Letter G02-95-265, JV Parrish (Energy Northwest) to NRC, "Request for Amendment to Technical Specifications," dated 12/8/95

2. NUREG-1434 Revision 1, "Standard Technical Specifications - General Electric Plants (BWR/6)"

3. Regulatory Guide 1.93, "Availability of Electric Power Sources"

4. Appendix A to 10 CFR Part 50, "General Design Criteria for Nuclear Power Plants"

5. Columbia Generating Station Final Safety Analysis Report Amendment 61

6. 10 CFR 50.65, "Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants"

7. NUMARC 93-01, "Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants"

8. Regulatory Guide 1.182, "Assessing and Managing Risk Before Maintenance Activities at Nuclear Power Plants" 11.0 Attachments - Excerpt from LCO 3.8.1 and TS Bases for Columbia Generating Station - Excerpt from the ITS Conversion Submittal Attachment 6, "Deviations from NUREG-1434" - GDC 17

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS IE AC POWER DISTRIBUTION SYSTEM Excerpt from LCO 3.8.1 and TS Bases for Columbia Generating Station

AC Sources-Operating 3.8.1 3.8 ELECTRICAL POWER SYSTEMS 3.8.1 AC Sources-Operating LCO 3.8.1 The following AC electrical power sources shall be OPERABLE:

a.

a. Two qualified circuits between the offsite transmission network and the onsite Class 1E AC Electric Power Distribution System; and

b. Three diesel generators (DGs).

APPLICABILITY: MODES 1, 2, and 3.

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

Division 3 AC electrical power sources are not required to be OPERABLE when High Pressure Core Spray System is inoperable.

ACTIONS

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

LCO 3.0.4.b is not applicable to DGs.

I CONDITION REQUIRED ACTION COMPLETION TIME A. One offsite circuit A.1 Perform SR 3.8.1.1 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months inoperable, for OPERABLE offsite circuit. AND Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter AND (continued)

Columbia Generating Station 3.8.1-1 Amendment No. 149,169 187

AC Sources-Operating 3.8.1 ACTIONS CONDITION E REQUIRED ACTION COMPLETION TIME A. (continued) A.2 Declare required 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from feature(s) with no discovery of no offsite power offsite power available inoperable to one division when the redundant concurrent with required feature(s) inoperability are inoperable. of redundant required feature(s)

AND A.3 Restore offsite 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months circuit to OPERABLE status. AND 6 days from discovery of failure to meet LCO when not associated with Required Action B.4.2.2 AND 17 days from discovery of failure to meet LCO B. One required DG B.1 Perform SR 3.8.1.1 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months inoperable. for OPERABLE offsite circuit(s). AND Once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter AND (continued)

_____________________________________ I I Columbia Generating Station 3.8.1-2 Ampndmpnt No. 449.469 197

AC Sources-Operating 3.8.1 ACTIONS CONDITION IREQUIRED ACTION I COMPLETION TIME B. (continued) B.2 Declare required 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months from feature(s), supported discovery of by the inoperable DG, Condition B inoperable when the concurrent with redundant required inoperabi Iity feature(s) are of redundant inoperable. required feature(s)

AND B.3.1 Determine OPERABLE 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months DG(s) are not inoperable due to common cause failure OR B.3.2 Perform SR 3.8.1.2 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months if not for OPERABLE DG(s). performed within the past 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months AND B.4.1 Restore required DG to OPERABLE status.

72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months from discovery of an I

inoperable DG AND 6 days from discovery of failure to meet LCO OR (continued)

I Columbia Generating Station 3.8.1-3 Amendment No. 205 149, 169, 19, 197

AC Sources-Operating 3.8.1 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME B. (continued) B.4.2.1 Establish risk 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months management actions for the alternate AC sources.

AND B.4.2.2 Restore required DG 14 days to OPERABLE status.

AND 17 days from discovery of failure to meet LCO C. Two offsite circuits C.1 Declare required 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months from inoperable, feature(s) inoperable discovery of when the redundant Condition C required feature(s) concurrent with are inoperable. inoperability of redundant required feature(s)

AND C.2 Restore one offsite 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months circuit to OPERABLE status.

(continued)

Columbia Generating Station 3.8.1-4 Amendment No. 149,169 197

AC Sources-Operating 3.8.1 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME D. One offsite circuit ------------ NOTE-----------

inoperable. Enter applicable Conditions and Required Actions of AND LCO 3.8.7, "Distribution Systems-Operating," when One required DG Condition D is entered with inoperable, no AC power source to any division.

D.1 Restore offsite 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months circuit to OPERABLE status.

OR D.2 Restore required DG 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months to OPERABLE status.

E. Two required DGs E.1 Restore one required 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months inoperable. DG to OPERABLE status. OR 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months if Division 3 DG is inoperable F. Required Action and F.1 Be in MODE 3. 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months Associated Completion Time of Condition A, AND B, C, D, or E not met.

F.2 Be in MODE 4. 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months G. Three or more required G.1 Enter LCO 3.0.3. Immediately AC sources inoperable.

Columbia Generating Station 3.8.1-5 Amendment No. 149,169 197

AC Sources - Operating B 3.8.1 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.1 AC Sources - Operating BASES BACKGROUND The unit Class 1 E AC Electrical Power Distribution System AC sources consist of the offsite power sources and the onsite standby power sources (diesel generators (DGs) 1, 2, and 3). As required by 10 CFR 50, Appendix A, GDC 17 (Ref. 1), 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 Class 1 E AC distribution system supplies electrical power to three divisional load groups, Divisions 1, 2, and 3, with each division powered by an independent Class 1E 4.16 kV ESF bus (refer to LCO 3.8.7, "Distribution Systems - Operating"). Divisions 1 and 2 4.16 kV ESF buses have two separate and independent offsite sources of power. Division 3 4.16 kV ESF bus has one offsite source of power. Each 4.16 kV ESF bus has a dedicated onsite DG. The ESF systems of any two of the three divisions provide for the minimum safety functions necessary to shut down the unit and maintain it in a safe shutdown condition.

Offsite power is supplied to the switchyard from the transmission network.

From the switchyard two qualified, electrically and physically separated circuits provide AC power to the Divisions 1 and 2 4.16 kV ESF buses (SM-7 and SM-8), while only one qualified circuit provides AC power to the Division 3 4.16 kV ESF bus (SM-4). One qualified circuit (to all 4.16 kV ESF buses) is from the 230 kV Ashe substation stepped down through the 230 kV/4.16 kV windings of a 230 kV/6.9 kV/4.16 kV transformer (the startup transformer, TR-S). The other qualified circuit (to Divisions 1 and 2 4.16 kV ESF buses only) is from the 115 kV Benton substation stepped down through a 115 kV/4.16 kV transformer (the backup transformer, TR-B). The offsite AC electrical power sources are designed and located so as to minimize to the extent practicable the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions. A detailed description of the offsite power network and circuits to the onsite Class 1E 4.16 kV ESF buses is found in FSAR, Chapter 8 (Ref. 2).

The ASHE 230 kV bus has two transmission network connections, one from the Midway 230 kV substation via the HEW--ASHE Tap 230 kV transmission line and one from the White Bluffs 115 kV substation via ASHE-White Bluffs #1 230 kV transmission line. The 230 kV source from Midway to ASHE via the HEW--ASHE Tap 230 kV transmission line is the analyzed and credited path for Columbia Generating Station service which supports the Design Bases/Licensing Bases requirements for separate offsite power system interconnections.

Columbia Generating Station B 3.8.1 -1 Revision 73

AC Sources - Operating B 3.8.1 BASES BACKGROUND (continued)

The 230 kV transmission line from the White Bluffs substation to the ASHE 230 kV bus is derived from a 115 kV/230 kV transformer at White Bluffs substation. With the Midway 230 kV connection to ASHE substation out of service and the ASHE bus energized entirely from the White Bluffs #1 230 kV line would mean the 230 kV source to Columbia Generating Station is locally derived from the 115 kV network. In this configuration, Columbia Generating Station service would be entirely supported by the 115 kV transmission system, (via the BENTON and White Bluffs Switchyards) which is contrary to Columbia Generating Station Design Bases/Licensing Bases requirements.

A qualified offsite circuit consists of all breakers, transformers, switches, interrupting devices, cabling, and controls required to transmit power from the offsite transmission network to the onsite Class 1 E ESF bus(es).

The startup transformer normally provides power to all 4.16 kV ESF buses when the main generator is not tied to the grid. An automatic transfer feature is provided for Divisions 1 and 2 such that if power is lost to a 4.16 kV ESF bus (SM-7 and SM-8) due to a loss of the startup transformer supply, the backup transformer supply breaker to the bus will automatically close and provide power. Manual live transfer capability of power between the startup and backup transformer sources is also provided. Power is provided to all the 4.16 kV ESF buses, when the main generator is tied to the grid, by a 25 kV/4.16 kV auxiliary transformer (TR-N1) fed from the main generator 25 kV isolated phase bus.

However, this power source is not allowed to be credited with meeting the requirements of LCO 3.8.1. a since it does not come from an offsite circuit (it is generated onsite, yet is not a standby source that can function under all conditions).

Automatic transfer capability is provided so that failure of the auxiliary transformer supply (from TR-N1) causes immediate tripping of the auxiliary transformer supply breakers and simultaneous closing of the startup transformer supply breakers to the ESF buses. Each startup transformer supply breaker is interlocked to close only if the associated auxiliary transformer supply breaker is not locked out, thus preventing closing onto a fault or tieing a credited source to a non-credited source.

Manual live transfer capability of power between the auxiliary transformer source and the startup and backup (Divisions 1 and 2 only) transformer sources is also provided.

Following an accident signal, certain required Division 1 and 2 plant loads are started in a predetermined sequence in order to prevent overloading the startup transformer supplying offsite power to the onsite Class 1 E Distribution System.

Columbia Generating Station B 3.8.1-2 Revision 73

AC Sources - Operating B 3.8.1 BASES BACKGROUND (continued)

The onsite standby power source for each 4.16 kV ESF bus is a dedicated DG. A DG starts automatically on loss of coolant accident (LOCA) signal (i.e., low reactor water level signal; Level 1 for DG-1 and DG-2, Level 2 for DG-3, or high drywell pressure signal) or on an ESF bus degraded voltage or undervoltage signal (refer to LCO 3.3.8.1, "Loss of Power (LOP) Instrumentation"). After the DG has started, it automatically ties to its respective ESF bus after offsite power is tripped as a consequence of emergency bus undervoltage or degraded voltage, independent of or coincident with a LOCA signal. The DGs also start and operate in the standby mode without tying to the ESF bus on a LOCA signal alone.

In the event of a loss of offsite power, the ESF electrical loads are automatically connected to the DGs in sufficient time to provide for safe reactor shutdown and to mitigate the consequences of a Design Basis Accident (DBA) such as a LOCA.

Certain required plant loads are returned to service or started in a predetermined sequence in order to prevent overloading the DG (Ref. 4).

Division 1 and 2 DGs (DG-1 and DG-2) satisfy the following Safety Guide 9 (Ref. 5) ratings:

a. 4400 kW - continuous;

b. 4650 kW - 2000 hours0.0231 days 0.556 hours 0.00331 weeks 7.61e-4 months ;

c. 4900 kW- 168 hours0.00194 days 0.0467 hours 2.777778e-4 weeks 6.3924e-5 months ; and

d. 5150 kW - 30 minutes.

Division 3 DG (DG-3) satisfies the following Safety Guide 9 (Ref. 5) ratings:

a. 2600 kW - continuous;

b. 2850 kW - 2000 hours0.0231 days 0.556 hours 0.00331 weeks 7.61e-4 months ; and

c. 3030 kW - 30 minutes.

Columbia Generating Station B 3.8.1-3 Revision 73

AC Sources - Operating B 3.8.1 BASES APPLICABLE The initial conditions of DBA and transient analyses in the FSAR, SAFETY Chapter 6 (Ref. 6) and Chapter 15 (Ref. 7), assume ESF ANALYSES systems are OPERABLE. The AC electrical power sources are designed to provide sufficient capacity, capability, redundancy, and reliability to ensure the availability of necessary power to ESF systems so that the fuel, Reactor Coolant System (RCS), and containment design limits are not exceeded. These limits are discussed in more detail in the Bases for Section 3.2, Power Distribution Limits; Section 3.5, Emergency Core Cooling Systems (ECCS) and Reactor Core Isolation Cooling (RCIC)

System; and Section 3.6, Containment Systems.

The OPERABILITY of the AC electrical power sources is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the unit. This includes maintaining the onsite or offsite AC sources OPERABLE during accident conditions in the event of:

a. An assumed loss of all offsite power or all onsite AC power; and

b. A worst case single failure.

AC sources satisfy the requirements of Criterion 3 of Reference 8.

LCO Two qualified circuits between the offsite transmission network and the onsite Class 1E Distribution System, and three separate and independent DGs (1, 2, and 3), ensure availability of the required power to shut down the reactor and maintain it in a safe shutdown condition after an anticipated operational occurrence (AOO) or a postulated DBA.

Qualified offsite circuits are those that are described in the FSAR and are part of the licensing basis for the unit.

The two circuits from offsite are from the Ashe substation and the Benton substation (via transformers TR-S and TR-B, respectively). To ensure the requirements of Reference 1 are met, the TR-S offsite circuit must be capable of providing power to the Division 3 4.16 kV ESF bus (SM-4) and either the Division 1 (SM-7) or Division 2 (SM-8) 4.16 kV ESF bus. The TR-B offsite circuit must be capable of providing power to both Divisions 1 and 2 4.16 kV ESF buses. The qualified offsite circuits include the circuit path and disconnect to the respective transformers, the circuit path and breakers to the respective non-Class 1 E 4.16 kV switchgear, SM-1, SM-2, and SM-3 (for the TR-S offsite circuit only), and the circuit path and breakers to the respective Class 1 E switchgear (SM-4, SM-7, and SM-8).

Each offsite circuit must be capable ot maintaining rated trequency and voltage, and accepting required loads during an accident, while connected to the ESF buses.

Revision 73 Generating Station B 3.8.1-4 Columbia Columbia Generating Station B 3.8.1-4 Revision 73

AC Sources - Operating B 3.8.1 BASES LCO (continued)

Each DG must be capable of starting, accelerating to rated speed and voltage, and connecting to its respective ESF bus on detection of bus undervoltage. This sequence must be accomplished within 15 seconds for Division 1 and 2 DGs and 18 seconds for Division 3 DG.

The DG-3 18 second start time includes the Loss of Voltage - Time Delay Function specified in LCO 3.3.8.1. Each DG must also be capable of accepting required loads within the assumed loading sequence intervals, and must continue to operate until offsite power can be restored to the ESF buses. These capabilities are required to be met from a variety of initial conditions such as DG in standby with engine hot and DG in standby with the engine at ambient conditions. Additional DG capabilities must be demonstrated to meet required Surveillances, e.g., capability of the DG to revert to standby status on an ECCS signal while operating in parallel test mode. Proper sequencing of loads, including tripping of nonessential loads, is a required function for DG OPERABILITY.

The AC sources in one division must be separate and independent (to the extent possible) of the AC sources in the other division(s). For the DGs, the separation and independence are complete. For the offsite AC sources, the separation and independence are to the extent practicable.

One offsite circuit is allowed to be tied to all ESF buses, and not violate the separation criteria, provided the necessary automatic transfer capability is OPERABLE. That is, power can be supplied to SM-7 and SM-8 via TR-S provided the automatic transfer capability to TR-B exists for both of the ESF buses. However, if power is supplied to SM-7 and SM-8 via TR-B, then one offsite circuit is inoperable (TR-S) since no automatic transfer capability from TR-B to TR-S exists. Additionally, power to the ESF buses is allowed to be supplied from the auxiliary transformer (TR-N1). In this case, the TR-S offsite circuit is considered OPERABLE provided the automatic transfer capability from TR-N1 to TR-S is OPERABLE for SM-4 and either SM-7 or SM-8. For TR-B to be considered OPERABLE, the automatic transfer capability to TR-B must be OPERABLE for both SM-7 and SM-8. (The automatic transfer capability from TR-N1 to TR-B is allowed to go through an intermediate step of transferring to the first offsite source, i.e., TR-S).

APPLICABILITY The AC sources are required to be OPERABLE in MODES 1, 2, and 3 to ensure that:

a. Acceptable fuel design limits and reactor coolant pressure boundary limits are not exceeded as a result of AOOs or abnormal transients; and Columbia Generating Station B 3.8.1-5 Revision 73

AC Sources - Operating B 3.8.1 BASES APPLICABILITY (continued)

b. Adequate core cooling is provided and containment OPERABILITY and other vital functions are maintained in the event of a postulated DBA.

A Note has been added taking exception to the Applicability requirements for Division 3 sources, provided the HPCS System is declared inoperable.

This exception is intended to allow declaring of the Division 3 inoperable either in lieu of declaring the Division 3 source inoperable, or at any time subsequent to entering ACTIONS for an inoperable Division 3 source.

This exception is acceptable since, with the Division 3 inoperable and the associated ACTIONS entered, the Division 3 AC sources provide no additional assurance of meeting the above criteria.

AC power requirements for MODES 4 and 5 and other conditions in which AC sources are required are covered in LCO 3.8.2, "AC Sources -

Shutdown."

ACTIONS A Note prohibits the application of LCO 3.0.4.b to an inoperable DG.

There is an increased risk associated with entering a MODE or other specified condition in the Applicability with an inoperable DG and the provisions of LCO 3.0.4.b, which allow entry into a MODE or other specified condition in the Applicability with the LCO not met after performance of a risk assessment addressing inoperable systems and components, should not be applied in this circumstance.

A.1 To ensure a highly reliable power source remains, it is necessary to verify the availability of the remaining offsite circuits on a more frequent basis.

Since the Required Action only specifies "perform," a failure of SR 3.8.1.1 acceptance criteria does not result in the Required Action not met.

However, if a second circuit fails SR 3.8.1.1, the second offsite circuit is inoperable, and Condition C, for two offsite circuits inoperable, is entered.

A.2 Required Action A.2, which only applies if the division cannot be powered from an offsite source, is intended to provide assurance that an event with a coincident single failure of the associated DG does not result in a complete loss of safety function of critical systems. These features are designed with redundant safety related divisions (i.e., single division systems are not included, although, for this Required Action, Division 3 (HPCS) is considered redundant to Division I and 2 Emergency Core Cooling Systems (ECCS)). Redundant required features failures consist Columbia Generating Station B 3.8.1-6 Revision 73

AC Sources - Operating B 3.8.1 BASES ACTIONS (continued) of inoperable features associated with a division redundant to the division that has no offsite power.

The Completion Time for Required Action A.2 is intended to allow time for the operator 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. The division has no offsite power supplying its loads; and

b. A redundant required feature on another division is inoperable.

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

Discovering no offsite power to one division of the onsite Class 1 E Power Distribution System coincident with one or more inoperable required support or supported features, or both, that are associated with the other division that has offsite power, results in starting the Completion Times for the Required Action. Twenty-four hours is acceptable because it minimizes risk while allowing time for restoration before the unit is subjected to transients associated with shutdown.

The remaining OPERABLE offsite circuit and DGs are adequate to supply electrical power to the onsite Class 1 E Distribution System. Thus, on a component basis, single failure protection may have been lost for the required feature's function; however, function is not lost. The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time takes into account the component OPERABILITY of the redundant counterpart to the inoperable required feature. Additionally, the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-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.

A.3 According to Regulatory Guide 1.93 (Ref. 9), operation may continue in Condition A for a period that should not exceed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . With one offsite circuit inoperable, the reliability of the offsite system is degraded, and the potential for a loss of offsite power is increased, with attendant potential for a challenge to the plant safety systems. In this Condition, however, the remaining OPERABLE offsite circuit and DGs are adequate to supply electrical power to the onsite Class 1 E distribution system.

Columbia Generating Station B 3.8.1-7 Revision 73

AC Sources - Operating B 3.8.1 BASES ACTIONS (continued)

The Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for repairs, and the low probability of a DBA occurring during this period.

The second Completion Time for Required Action A.3 establishes a limit on the maximum time allowed for any combination of required AC power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO when not associated with Required Action B.4.2.2. The reason for this limit and a third Completion Time limit is further explained below.

The third Completion Time for Required Action A.3 establishes a limit on the maximum time allowed for a combination of required AC power sources that are associated with Required Action B.4.2.2 to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition A is entered while, for instance, a DG is inoperable and that DG is subsequently returned OPERABLE, the LCO may already have been not met for up to 14 days. This situation could lead to a total of 17 days, since initial failure to meet the LCO, to restore the offsite circuit. At this time, a DG could again become inoperable, the circuit restored OPERABLE, and an additional 14 days (for a total of 31 days) allowed prior to complete restoration of the LCO. The 17 day Completion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO. This limit is considered reasonable for situations in which Conditions A and B are entered concurrently. The "AND" connector between the Completion Times means that all Completion Times apply simultaneously, and the more restrictive must be met.

Similar to Required Action A.2, the Completion Time of Required Action A.3 allows for an exception to the normal "time zero" for beginning the allowed outage time "clock." This exception results in establishing the "time zero" at the time the LCO was initially not met, instead of at the time that Condition A was entered.

Columbia Generating Station B 3.8.1-8 Revision 73

AC Sources - Operating B 3.8.1 BASES ACTIONS (continued)

B..1 To ensure a highly reliable power source remains, it is necessary to verify the availability of the remaining offsite circuit on a more frequent basis.

Since the Required Action only specifies "perform," a failure of SR 3.8.1.1 acceptance criteria does not result in a Required Action being not met.

However, if a circuit fails to pass SR 3.8.1.1, it is inoperable. Upon offsite circuit inoperability, additional Conditions must then be entered.

B.2 Required Action B.2 is intended to provide assurance that a loss of offsite power, during the period that a DG is inoperable, does not result in a complete loss of safety function of critical systems. These features are designed with redundant safety related divisions (i.e., single division systems are not included, although, for this Required Action, Division 3 (HPCS) is considered redundant to Division 1 and 2 ECCS). Redundant required features failures consist of inoperable features associated with a division redundant to the division that has an inoperable DG.

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 redundant required feature on another division is inoperable.

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

a redundant 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.

Columbia Generating Station B 3.8.1-9 Revision 73

AC Sources - Operating B 3.8.1 BASES ACTIONS (continued)

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(s), 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 or G of LCO 3.8.1 is entered, as applicable. 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 within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , if not performed within the past 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , suffices to provide assurance of continued OPERABILITY of those DG(s).

In the event the inoperable DG is restored to OPERABLE status prior to completing either B.3.1 or B.3.2, the Problem Evaluation Request process 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. According to Generic Letter 84-15 (Ref. 10),

24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months is a reasonable time to confirm that the OPERABLE DG(s) are not affected by the same problem as the inoperable DG.

B.4 In Condition B, the remaining OPERABLE DGs and offsite circuits are adequate to supply electrical power to the onsite Class 1 E distribution system. The 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Completion Time for Required Action B.4.1 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.

The second Completion Time for Required Action B.4.1 established a limit on the maximum time allowed for any combination of required AC Columbia Generating Station B 3.8.1 -10 Revision 73

AC Sources - Operating B 3.8.1 BASES ACTIONS (continued) power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition B is entered while, for instance, an offsite circuit is inoperable and that circuit is subsequently restored OPERABLE, the LCO may already have been not met for up to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

This situation could lead to a total of 144 hours0.00167 days 0.04 hours 2.380952e-4 weeks 5.4792e-5 months , since initial failure to meet the LCO, to restore the DG. At this time, an offsite circuit could again become inoperable, the DG restored OPERABLE, and an additional 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months (for a total of 9 days) allowed prior to complete restoration of the LCO. The 6 day Completion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO when the required risk management action of B.4.2.1 is not in place. This limit is considered reasonable for situations in which Conditions A and B are entered concurrently. The "AND" connector between the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months and 6 day Completion Times means that both Completion Times apply simultaneously, and the more restrictive Completion Time must be met.

A second optional set of Actions is provided, that if the risk management actions for establishing the alternate AC sources to division 1 or division 2 (AACS) occurs within the 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Completion Time limit, an extended Completion Time up to 14 days from the DG's initial inoperability is allowed.

To establish the AACS, the DG-3 cross-connection to power selected safe shutdown loads is available and an additional AC source, a 480-volt diesel generator (DG-4), is staged and available. The AACS is considered available when DG-3 cross-connection can be implemented in accordance with the emergency procedures for a loss of offsite power or a station blackout event within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and DG-4 can be aligned and supplying the battery chargers within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months . Additional risk management actions in accordance with the configuration risk management program required by 10 CFR 50.65a(4) are to be put in place to assure that significant risk configurations are avoided during the extended DG inoperability.

Similar to Action A.3 Completion Time, when the 14-day extended Completion Time is applicable, the 17 day Completion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO.

Similar to Required Action B.2, the Completion Time of Required Actions B.4.1 and B.4.2.2 allows for an exception to the normal "time zero" for beginning the allowed outage time "clock." This exception results in establishing the "time zero" at the time the LCO was initially not met, instead of the time Condition B was entered.

Columbia Generating Station B 3.8.1-11 Revision 73

AC Sources - Operating B 3.8.1 BASES ACTIONS (continued)

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 reduces the vulnerability to a loss of function. The Completion Time for taking these actions is reduced to 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months from that allowed with only one division 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. 9) 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 divisions are OPERABLE. When a concurrent redundant required feature failure exists, this assumption is not the case, and a shorter Completion Time of 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months is appropriate. These features are designed with redundant safety related divisions (i.e., single division systems are not included in the list, although, for this Required Action, Division 3 (HPCS) is considered redundant to Divisions 1 and 2 ECCS). Redundant required features failures consist of any of these features that are inoperable, because any inoperability is on a division redundant to a division with inoperable offsite circuits.

The Completion Time for Required Action C.1 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. Two offsite circuits are inoperable; and

b. A redundant required feature is inoperable.

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

According to Regulatory Guide 1.93 (Ref. 9), operation may continue in Condition C for a period that should not exceed 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . This level of degradation means that the offsite electrical power system does not have the capability to effect a safe shutdown and to mitigate the effects of an accident; however, the onsite AC sources have not been degraded. This level of degradation generally corresponds to a total loss of the immediately accessible offsite power sources.

Because of the normally high availability of the offsite sources, this level of degradation may appear to be more severe than other combinations of two AC sources inoperable that involve one or more DGs inoperable.

Columbia Generating Station B 3.8.1-12 Revision 73

AC Sources - Operating B 3.8.1 BASES ACTIONS (continued)

However, two factors tend to decrease the severity of this degradation level:

a. The configuration of the redundant AC electrical power system that remains available is not susceptible to a single bus or switching failure; and

b. The time required to detect and restore an unavailable offsite power source is generally much less than that required to detect and restore an unavailable onsite AC source.

With both of the offsite circuits inoperable, sufficient onsite AC sources are available to maintain the unit in a safe shutdown condition in the event of a DBA or transient. In fact, a simultaneous loss of offsite AC sources, a LOCA, and a worst case single failure were postulated as a part of the design basis in the safety analysis. Thus, the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time provides a period of time to effect restoration of one of the offsite circuits commensurate with the importance of maintaining an AC electrical power system capable of meeting its design criteria.

According to Regulatory Guide 1.93 (Ref. 9), with the available offsite AC sources two less than required by the LCO, operation may continue for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . If two offsite sources are restored within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , unrestricted operation may continue. If only one offsite source is restored within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , power operation continues in accordance with Condition A.

D.1 and D.2 Pursuant to LCO 3.0.6, the Distribution System ACTIONS would not be entered even if all AC sources to it were inoperable, resulting in de-energization. Therefore, the Required Actions of Condition D are modified by a Note to indicate both the offsite electrical power system and the onsite AC that when Condition D is entered with no AC source to any division, Actions for LCO 3.8.7, "Distribution Systems - Operating," must be immediately entered. This allows Condition D to provide requirements for the loss of the offsite circuit and one DG without regard to whether a division is de-energized. LCO 3.8.7 provides the appropriate restrictions for a de-energized division.

Columbia Generating Station B 3.8.1-13 Revision 73

AC Sources - Operating B 3.8.1 BASES ACTIONS (continued)

According to Regulatory Guide 1.93 (Ref. 9), operation may continue in Condition D for a period that should not exceed 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months . In Condition D, individual redundancy is lost in electrical power system. Since power system redundancy is provided by two diverse sources of power, however, the reliability of the power systems in this Condition may appear higher than that in Condition C (loss of both offsite circuits). This difference in reliability is offset by the susceptibility of this power system configuration to a single bus or switching failure. The 12 hour1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-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.

E..1 With two DGs inoperable, there is one remaining standby AC source.

Thus, with an assumed loss of offsite electrical power, insufficient standby AC sources are available to power the minimum required ESF functions.

Since the offsite electrical power system is the only source of AC power for the majority of ESF equipment at this level of degradation, the risk associated with continued operation for a very short time could be less than that associated with an immediate controlled shutdown (the immediate shutdown could cause grid instability, which could result in a total loss of AC power). Since any inadvertent generator trip could also result in a total loss of offsite AC power, however, the time allowed for continued operation is severely restricted. The intent here is to avoid the risk associated with an immediate controlled shutdown and to minimize the risk associated with this level of degradation.

According to Regulatory Guide 1.93 (Ref. 9), with both DGs inoperable, operation may continue for a period that should not exceed 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months . This Completion Time assumes complete loss of onsite (DG) AC capability to power the minimum loads needed to respond to analyzed events. In the event Division 3 DG in conjunction with Division 1 or 2 DG is inoperable, with the other Division 1 or 2 DG remaining, a significant spectrum of breaks would be capable of being responded to with onsite power. Even the worst case event would be mitigated to some extent -an extent greater than a typical two division design in which this condition represents complete loss of onsite power function. Given the remaining function, a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is appropriate. At the end of this 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period, Division 3 systems (HPCS) could be declared inoperable (see Applicability Note) and this Condition could be exited with only one required DG remaining inoperable. However, with a Division 1 or 2 DG remaining inoperable and the HPCS declared inoperable, a redundant required feature failure exists, according to Required Action B.2.

Columbia Generating Station B 3.8.1-14 Revision 73

AC Sources - Operating B 3.8.1 BASES ACTIONS (continued)

F.1 and F.2 If the inoperable AC electrical power sources cannot be restored to OPERABLE status within the associated Completion Time, the unit must be brought to a MODE in which the LCO does not apply. To achieve this status, the unit must be brought to MODE 3 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and to MODE 4 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months . The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

G.1 Condition G corresponds to a level of degradation in which all redundancy in the AC electrical power supplies has been lost. At this severely degraded level, any further losses in the AC electrical power system will cause a loss of function. Therefore, no additional time is justified for continued operation. The unit is required by LCO 3.0.3 to commence a controlled shutdown.

SURVEILLANCE The AC sources are designed to permit inspection and testing of all REQUIREMENTS important areas and features, especially those that have a standby function, in accordance with 10 CFR 50, GDC 18 (Ref. 11). Periodic component tests are supplemented by extensive functional tests during refueling outages under simulated accident conditions. The SRs for demonstrating the OPERABILITY of the DGs are consistent with the recommendations of Regulatory Guide 1.9 (Ref. 12), Regulatory Guide 1.108 (Ref. 13), and Regulatory Guide 1.137 (Ref. 14). Where the SRs discussed herein specify voltage tolerances for EDG steady state performance, the following summary is applicable. For Division 1 and 2 DGs, the minimum steady state output voltage depends upon whether or not the DG is tied to its respective 4.16 kV ESF bus. If the SR does not require the DG to be tied to its bus, then the minimum steady state output voltage is 3910 V, which is the minimum voltage necessary to meet the DG breaker closure interlock.

If the SR requires the DG to be tied to its respective 4.16 kV ESF bus, then the minimum steady state output voltage is selected as 3910 Volts, a value that is also conservative to the maximum reset of the degraded voltage relays monitoring voltage on the Class 1E 4.16 kV ESF bus (Ref. 15). For the Division 3 DG, the minimum steady state output voltage is also 3910 V.

Columbia Generating Station B 3.8.1-15 Revision 73

AC Sources - Operating B 3.8.1 BASES REFERENCES 1. 10 CFR 50, Appendix A, GDC 17.

2. FSAR, Chapter 8.

3. Deleted.

4. FSAR, Tables 8.3-1, 8.3-2, and 8.3-3.

5. Safety Guide 9, Revision 0, March 1971.

6. FSAR, Chapter 6.

7. FSAR, Chapter 15.

8. 10 CFR 50.36(c)(2)(ii).

9. Regulatory Guide 1.93, Revision 0, December 1974.

10. Generic Letter 84-15, July 2, 1984.

11. 10 CFR 50, Appendix A, GDC 18.

12. Regulatory Guide 1.9, July 1993.

13. Regulatory Guide 1.108, Revision 1, August 1977.

14. Regulatory Guide 1.137, Revision 1, October 1979.

15. Calculations Nos. E/1-02-87-07 and 2-12-58.

16. ASME Code for Operation and Maintenance of Nuclear Power Plants.

17. IEEE Standard 308-1974.

18. ANSI C84.1, 1982.

Columbia Generating Station B 3.8.1-35 Revision 73

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS IE AC POWER DISTRIBUTION SYSTEM Excerpt from the ITS Conversion Submittal Attachment 6, "Deviations from NUREG-1434"

AC Sources -Operating B 3.8.1 APPLICABLE Section 30, aetr_ 31; ye and Section 3.6, SAFETY ANALYSES Containment ystems.

(continued)

The OPERABILITY of the AC electrical power sources is consistent with the initial assumptions of the accident analyses and is based upon meeting the design basis of the unit. This includes maintaining the onsite or offsite AC sources OPERABLE during accident conditions in the event of:

a. An assumed loss of all offslte power or all onsite AC power; and

b. A worst case single failure.

AC sources satisfy the requirements of Criterion 3 of the O NRC Policy Statemen LCO Two qualified circuits between the offslte transmission network and the onsite Class 1E Distribution System, and ,--

three separate and independent DGs (4I, P, and $3), ensure availability of the required power to shut down the reactor and maintain it in a safe shutdown condition after an anticipated operational occurrence (AOO) or a postulated DBA.

Qualified offsite circuits are those that are described in the FSAR and are part of the licensing basis for the unit.

In addit on, [one required auto atic load sequencer pe ESF bus] sh 11 be OPERABLE. In ge eral, Division 3 does t have a load sequencer since i has only one large loa (i.e. the high pressure cor spray (MPCS) pump). I such case the LCO should refer the Division 1 and 2 seq ncers only.

Each offsite circuit must be capable of maintaining rated 64'r"38 "frequency and voltage, and accepting required loads durinn Lip' ý_- P an accident, while connected to the ESF buses.

U11-rulL. I-u lt*S ay i,,1u.,i.,11 01UPK*,dI respectiv* service transf (service *ransformers, the dsnect ac o*$1 e t the ers/F. and 21, the 11 an* 21 SF*ansformers 11 and 2 , and the res ective circuit path i luding feeder break s to th 4(.t16 ke ESF buses./

I (continued)

BWR/6 STS 8 3.8-3 Rev 1, 04/07/95

01 INSERT B 3.8-1 LCO-A The two circuits from offsite are from the Ashe substation and the Benton substation (via transformers TR-S and TR-B, respectively). To ensure the requirements of Reference I are met, the TR-S offsite circuit must be capable of providing power to the Division 3 4.16 kV ESF bus (SM-4) and either the Division I (SM-7) or Division 2 (SM-8) 4.16 kV ESF bus. The TR-B offsite circuit must be capable of providing power to both Divisions 1 and 2 4.16 kV ESF buses. The qualified offsite circuits include the circuit path and disconnect to the respective transformers, the circuit path and breakers to the respective non-Class 1E 4.16 kV switchgear, SM-I, SM-2, and SM-3 (for the TR-S offsite circuit only), and the circuit path and breakers to the respective Class IE switchgear (SM-4, SM-7, and SM-8).

Insert Page B 3.8-3

AC Sources -Operating B 3.8.1 BASES LCO Each DG must be capable of starting, accelerating to rated (continued) speed and voltage, and connecting to its respective ESF bus o*n detection of bus undervoltage. This sequence must be accom .li ýdwithin second4. Each DG must also be capa le of accep ing require loads within the assumed loading sequence intervals, and must continue to operate until offsite power can be restored to the ESF buses. These capabilities are required to be met from a variety of 3* initial conditions such as DG in standby with engine hot and S,*,- &OAJ 3 D4. DG in standby with engine at ambient conditions. Additional lie D6-3 18 o DG J capabilities must be demonstrated to meet required ri-4-*f.. *f * ) Surveillances, e.g., capability of the DG to revert to standby status on an ECCS signal while operating in parallel Ls tio Of YId14ce- test mode.

-5PeCfP*eA ;w Ua */ *roper sequencing of loads, including tripping of nonessential loads, is a required function forDG

_ *,,i IOPERABILITY.

The AC sources in one division must be separate and independent (to the extent possible) of the AC sources in the other division(s). For the DGs, the separation and independence are complete. For the offsite AC sources, the k separation and independence are to the extent practical. 1/#is&-r

8. B APPLICABILITY The AC sources and sequencers are required to be OPERABLE in MODES 1, 2, and 3 to ensure that:

a. Acceptable fuel design limits and reactor coolant pressure boundary limits are not exceeded as a result of AOOs or abnormal transients; and

b. Adequate core cooling is provided and containment OPERABILITY and other vital functions are maintained in the event of a postulated DBA.

A Note has been added taking exception to the Applicability requirements for Division 3 sources, provided the HPCS System is declared inoperable. This exception is intended to allow declaring of the Division 3 inoperable either in.

lieu of declaring the Division 3 source inoperable, or at any time subsequent to entering ACTIONS for an inoperable Division 3 source. This exception is acceptable since, with the Division 3 inoperable and the associated ACTIONS (continued)

BWR/6 STS 8 3.8-4 Rev 1, 04/07/95

OINSERT B 3.8.1 LCO-B One offsite circuit is allowed to be tied to all ESF buses, and not violate the separation criteria, provided the necessary automatic transfer capability is OPERABLE. That is, power can be supplied to SM-7 and SM-8 via TR-S provided the automatic transfer capability to TR-B exists for both of the ESF buses. However, if power is supplied to SM-7 and SM-8 via TR-B, then one offsite circuit is inoperable (TR-S) since no automatic transfer capability from TR-B to TR-S exists. Additionally, power to the ESF buses is allowed to be supplied from the auxiliary transformer (TR-NI). In this case, the TR-S offsite circuit is considered OPERABLE provided the automatic transfer capability from TR-N1 to TR-S is OPERABLE for SM-4 and either SM-7 or SM-8.

For TR-B to be considered OPERABLE, the automatic transfer capability to TR-B must be OPERABLE for both SM-7 and SM-8. (The automatic transfer capability from TR-NI to TR-B is allowed to go through an intermediate step of transferring to the first offsite source, i.e., TR-S.)

Insert Page B 3.8-4

JUSTIFICATION FOR DEVIATIONS FROM NUREG-1434, REVISION 1 BASES SECTION 3.8 - ELECTRICAL POWER SYSTEMS

1. Changes have been made (additions, deletions, and/or changes to the NUREG) to reflect the plant specific nomenclature, number, reference, system description, or analysis description.

2. The proper LCO number has been used.

3. Editorial change made for enhanced clarity or to be consistent with similar statements in other places in the Bases.

4. The brackets have been removed and the proper plant specific information/value has been provided.

5. This change has been made since Section 3.5, "ECCS and RCIC System" provides the appropriate limits that are affected by the systems in this LCO.

6. This bracketed requirement/information has been deleted because it is not applicable to WNP-2. The following requirements have been renumbered, where applicable, to reflect this deletion.

7. This change has been made to be consistent with the Applicability of LCO 3.8.2, LCO 3.8.5, or LCO 3.8.7, as applicable.

8. Changes have been made to reflect those changes made to the Specification. The following requirements have been renumbered, where applicable, to reflect the changes.

9. Typographical/grammatical error corrected.

10. Condition G may also apply, since the WNP-2 design includes three DGs.

11. This Reviewer's Note has been deleted. This information is for the NRC reviewer to be keyed in to what is needed to meet the requirement. This is not meant to be retained in the final version of the plant specific submittal.

12. These words have been deleted since, as stated in the actual LCO, the offsite circuit must be supplying onsite Class 1E power distribution subsystems, not just be capable of supplying them.

13. This paragraph has been deleted since it is duplicative of the next to last paragraph in the Applicable Safety Analyses section.

14. All references to D1552 and D2622 have been deleted. These two standards were specifically called out in current Technical Specifications because ASTM D975-81 did not specify a test for sulphur.

ASTM D975-94 provides methods for sulphur analysis, which include D1552 and D2622. Therefore, there is no need to specifically call out these two methods.

WNP-2 I Revision A

REQUEST FOR TECHNICAL SPECIFICATION INTERPRETATION REGARDING THE OFFSITE POWER SUPPLIES TO THE ONSITE CLASS 1E AC POWER DISTRIBUTION SYSTEM 10 CFR 50 Appendix A Criterion 17-Electric power systems: An onsite electric power system and an offsite electric power system shall be provided to permit functioning of structures, systems, and components important to safety. The safety function for each system (assuming the other system is not functioning) shall be to provide 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.

The onsite electric power supplies, including the batteries, and the onsite electric distribution system, shall have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure.

Electric power from the transmission network to the onsite electric distribution system shall be supplied by two physically independent circuits (not necessarily on separate rights of way) designed and located so as to minimize to the extent practical the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions. A switchyard common to both circuits is acceptable. Each of these circuits shall be designed to be available in sufficient time following a loss of all onsite alternating current power supplies and the other offsite electric power circuit, to assure that specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded. One of these circuits shall be designed to be available within a few seconds following a loss-of-coolant accident to assure that core cooling, containment integrity, and other vital safety functions are maintained.

Provisions shall be included to minimize the probability of losing electric power from any of the remaining supplies as a result of, or coincident with, the loss of power generated by the nuclear power unit, the loss of power from the transmission network, or the loss of power from the onsite electric power supplies.

GO2-13-043, Request for Technical Specification Interpretation Regarding the Offsite Power Supplies to the Onsite Class 1E AC Power Distribution System

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GO2-13-043, Request for Technical Specification Interpretation Regarding the Offsite Power Supplies to the Onsite Class 1E AC Power Distribution System

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Dear Sir or Madam:

Enclosure:

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