ML20080H792

Safety Evaluation Supporting Amends 71 & 60 to Licenses NPF-76 & NPF-80,respectively

ML20080H792
Person / Time
Site:	South Texas
Issue date:	02/14/1995
From:	Office of Nuclear Reactor Regulation
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NUDOCS 9502230350
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l UNITED STATES NUCLEAR REGULATORY COMMISSION

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WASHINGTON. D.C. 20MH001

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i SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N05. 71 AND 60 TO FACILITY OPERATING LICENSE N05. NPF-76 AND NPF-80 HOUSTON LIGHTING & POWER COMPANY l

CITY PUBLIC SERVICE BOARD OF SAN ANTONIO CENTRAL POWER AND LIGHT COMPANY CITY OF AUSTIN. TEXAS DOCKET NOS. 50-498 AND 50-499 SOUTH TEXAS PROJECT. UNITS 1 AND 2

1.0 INTRODUCTION

1 By application dated November 7, 1994, as supplemented by letters dated December 20, 1994, and January 23, 1995, Houston Lighting & Power Company, et.

al., (the licensee) requested changes to the Technical Specifications (TSs)

(Appendix A to Facility Operating License Nos. NPF-76 and NPF-80) for the South Texas Project, Units 1 and 2 (STP). The proposed amendments would change the number of standby diesel generators (SDGs) (emergency power supply) required to be operable during Mode 6 with greater than or equal to 23 feet of water above the reactor vessel flange, from two to one. The amendments would also allow limited substitution of an alternate onsite emergency power source for one cf the two required SDGs, in Mode 5, and in Mode 6 with less than 23 feet of water.

In addition, changes to certain system specifications that are affected by the changes for the emergency power supply were also proposed.

The December 20, 1994, and January 23, 1995, supplements provided additional information in response to staff questions. The January 23, 1995, supplement also revised the TS changes initially proposed in the November 7,1994, application to that summarized above and discussed below.

2.0 EVALUATION The SDG system for STP consists of three identical 5500 kW SDGs and their associated controls and support systems.

Each SDG unit including its power sources for controls and support systems, is completely separate from and independent of the others.

Each unit provides 4.16 kV power to its respective Class IE switchgear bus. During a loss of offsite power, each SDG automatically starts and energizes its associated 4.16 kV bus. The system has no inherent cross-train capability or dependability. No sharing capability 9502230350 950214 PDR ADOCK 05000498 P

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L exists between Unit I and Unit 2.

A brief description of the changes and the staff's evaluation of them follow.

TS 3/4.8.1.2. Electrical Power Systems. A.C. Sources. Shutdown This TS currently requires that one offsite circuit and two SDGs be operable i

during Modes 5 and 6.

The proposed change splits 3/4.8.1.2 into two TSs, adding a new TS 3/4.8.1.3.

Revised TS 3/4.8.1.2 provides the_AC power i

requirements for iiode 5 (during all conditions) and Mode 6 during reduced i

reactor coolant inventory conditions (when water level in the refueling cavity 1s less than 23 feet above the reactor vessel flange). TS 3/4.8.1.2 will require the following AC electrical power sources to be operable:

(1) one circuit between the offsite transmission network and the onsite Class IE distribution system, and (2) two SDGs with a separate fuel tank 2 containing a minimum volume of 60,500 gallons of fuel.

Revisions to Action Statement 3/4.8.1.2 are also proposed. One required i

action is to be added:

suspend all operations with a potential for draining the reactor vessel or crane operation with loads over the spent fuel pool.

The current action to depressurize and vent the reactor coolant. system would then be deleted.

In the December 20, 1994, supplement, the licensee stated

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that the proposed deleted phrase is redundant to another TS, and that the

-proposed added phrase will eliminate the possibility of an event that has greater potential to cause core damage. The staff finds the licensee's reasons to be acceptable and notes that the revised wording is consistent with NUREG-1431 (Improved Standard Technical Specifications for Westinghouse i

Plants).

Additionally, the revised TS 3/4.8.1.2 includes a footnote which would allow the use of a non-safety alternate AC onsite emergency power source as a substitute for one of the two required Class IE SDGs during reduced reactor coolant inventory conditions. The licensee intends to provide a rented non-safety diesel generator (NDG) capable of powering, at a miniitum, the equipment required for one train of shutdown cooling.

In a conference call on December 22, 1994, the staff informed the licensee that the NDG used for one of the Class IE SDGs during reduced reactor coolant inventory conditions should be highly reliable and that there should be some time limit for its use as a substitute for a Class IE SDG.. In the past, the staff has allowed an SDG to be inoperable for up to 14 days during reduced reactor coolant inventory conditions when an alternate AC source is j

substituted for it, provided the alternate source is demonstrated to be functional and is capable of being aligned to the engineered safety feature (ESF) buses associated with the inoperable SDG. The staff informed the licensee that if the NDG is substituted for one Class IE SDG, the proposed TS 3/4.8.1.2 needs to be revised to include the following requirements:

(1) verify that the NDG is functional by verifying, within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, it starts and achieves steady state voltage and frequency within an appropriate time (minutes), (2) verify that it is capable of being aligned to the ESF buses associated with the inoperable Class IE SDG within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter, and (3) restore the required SDG to operable status within 14 days.

- In a letter dated January 23, 1995, the licensee submitted a revised TS 3/4.8.1.2. The licensee stated that the reliability of the NDG will be established by conducting 5 start and load tests at the manufacturer's site.

The testing will also include starting a pump equivalent to the largest load needed during shutdown and verifying that the voltage and frequency requirements are met. The licensee will then subject the NDG to various tests, including a load rejection test, a rated load test, a load acceptance test, and subsystem tests.

In addition, the licensee will review the vendor's available maintenance records to verify the suitability of the NDG for its intended function. The licensee will verify that the NDG is not scheduled for any major recommended maintenance during the expected duration of its use at STP.

The NDG is self-contained, with its own battery start system, engine controls, switchgear, and cooling system. The NDG has a continuous rating of 2000 kW and a short-term rating of 2200 kW. The total required loading on the NDG during shutdown is 1926 kW.

Fuel is provided from a temporary storage tank located near the unit.

The NDG will be manually started. During the outage, the licensee will station an individual near the NDG when the TSs require the NDG to be available. Operators in the main control room and the individual near the NDG will communicate via the plant radio system. The plant radio system has backup power sources independent of offsite power and the Class IE SDG.

After the NDG is installed at the site, its reliability will be verified by two start and load tests. The NDG will be manually started at the local panel. The ESF bus will be energized with the bus unloaded. Once the ESF bus has been energized, loads will be manually connected to the bus. The NDG will be capable of powering simultaneously at least the following equipment:

one train of the residual heat removal (RHR), essential cooling water (ECW),

component cooling water (CCW), control room makeup and cleanup filtration systems and a 150-ton electrical auxiliary building chiller. The NDG will be capable of being started and loaded in sufficient time to prevent the reactor temperature from exceeding design limits.

Additionally, within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of taking credit for the NDG as a Class 1E SDG, the licensee will demonstrate the NDG is functional by verifying that it starts and achieves steady state voltage within 110 percent and frequency within 12 percent in 5 minutes. Within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of taking credit for the NDG as a Class IE SDG and every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter, the licensee will also perform a breaker alignment check to verify that the NDG is capable of being aligned to the required ESF bus. The NDG may be substituted for one of the required Class lE SDGs for up to 14 days. However, for Unit 1 Refueling Outage 5 and Unit 2 Refueling Outage 4, the licensee has requested a one-time substitution of an NDG for a Class IE SDG for up to 21 days instead of 14 days. This extension is necessary because the licensee is doing a 10-year teardown on one of the SDGs in each unit. The staff finds this one time request to be acceptable, considering the work involved for a complete teardown of the SDGs.

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1 1 l The licensee has reviewed their Updated Final Safety Analysis Report (UFSAR)

I for events that would be affected by this proposed TS change. They also

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reviewed the safety functions required during an outage and the systems required to mitigate the consequences of accidents. They determined that required systems can (1) perform their required safety functions during any postulated design basis accident condition during the applicable Modes, and (2) perform their system design functions and meet their operability requirements during the applicable Modes with the power supplies required by the proposed TSs.

Based on the licensee's determinations and with the onsite power redundancy provided by the NDG (and the associated reliability testing and maintenance review of the NDG), the staff finds that the proposed changes are acceptable.

Over the past several years, the NRC staff has become increasingly concerned about the safety of operations during shutdown of nuclear power reactors. The loss of decay heat removal during shutdown and refueling has been a continuing problem. The staff decided a rule was needed to ensure that public health and safety are adequately protected when plants are in shutdown and low power conditions. A proposed rule, 10 CFR 50.67, " Shutdown and Low-Power l

Operations," was published in the Federal Register and sent out for comment on October 19, 1994 (59 FR 52707).

The staff also finds the proposed revisions to the requirements of the number of SDGs required to be operable during Mode 5 (during all operations) and Mode 6 with water level in the refueling cavity less than 23 feet above the reactor vessel flange, in TS 3/4.8.1.2, to be consistent with the requirements of the proposed rule. The staff finds the use of the NDG as a substitute for a Class IE SDG to be consistent with the proposed rule. The proposed rule permits the use of non-safety as well as safety equipment to provide safety functions i

during reduced reactor coolant inventory conditions.

TS 3/4.8.1.3. Electrical Power Systems. A.C. Sources. Shutdown This new TS provides the requirements for Mode 6 when water level in the refueling cavity is greater than or equal to 23 feet above the reactor vessel

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flange.

It will require the following AC electrical power sources to be operable:

(1) one circuit between the offsite transmission network and the onsite Class lE distribution system, and (2) one SDG with a separate fuel tank containing a minimum volume of 60,500 gallons of fuel. The action statement for this proposed TS is the same as that proposed for TS 3/4.8.1.2, and is acceptable for the same reasons.

j The licensee has reviewed their UFSAR for events that would be affected by this proposed TS change. They also reviewed the safety functions required during an outage and the systems required to mitigate the consequences of i

accidents.

They determined that required systems can (1) perform their l

equired safety functions during any postulated design basis accident condition during the applicable Mode, and (2) perform their system design functions and meet their operability requirements during the applicable Mode with the power supplies required by the proposed TSs. Based on the licensee's

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. i determinations and with the redundancy to remove decay heat provided by the water level in the refueling cavity being greater than or equal to 23 feet l

above the reactor vessel flange, the staff finds that the proposed changes are acceptable, i

i The staff also finds the proposed revision to the requirements of the number of SDGs required to be operable during Mode 6 when water level in the i

refueling cavity is greater than or equal to 23 feet above the reactor vessel flange, to be consistent with the requirements of the proposed rule.

TS 3/4.8.2.2. Electrical Power Systems. D.C. Sources. Shutdown This TS currently requires that both Channel I and the Channel IV batteries along with two battery chargers, be operable during Modes 5 and 6.

The licensee proposes.to use the wording of NUREG-1431 for this TS. The proposed chance will require these DC power sources to support trains of distribution subsystems required to be operable by TS 3/4.8.3.2. This ensures the availability of sufficient DC power sources to operate the unit in a safe manner and to mitigate the consequences of postulated events during shutdown.

The proposed changes to the action statement include (1) revising the wording to refer to DC power subsystem rather than specific components, (2) adding the requirement to suspend operations involving the potential for draining the l

reactor vessel, (3) adding an alternative action to declare the supported i

equipment inoperable, and (4) deleting the action to depressurize and vent the J

reactor coolant system.

i The staff finds that the proposed changes to TS 3/4.8.2.2 ensures the availability of sufficient DC power sources without imposing unnecessary constraints on the licensee, are consistent with NUREG-1431, and are i

acceptable.

TS 3/4.8.3.2. Electrical Power Systems. Onsite Power Distribution. Shutdown This specification currently requires that Train A and Train C of ESF buses, four 120 volt AC vital distribution panels and Channel I and Channel IV 125 volt DC buses be operable during Mode 5 and 6.

The licensee proposes to use the wording of NUREG-1431 for this TS. The proposed change will require the necessary portion of AC, DC, and AC vital bus electrical power distribution i

subsystems to be operable to support the equipment required to be operable to shutdown the reactor and maintain it in a safe condition, for all conditions during Modes 5 and 6.

The proposed changes to the action statement include (1) revised wording to reflect the revised limiting condition for operation, (2) adding the requirement to suspend operations involving the potential for draining the reactor vessel, (3) adding an alternative action to declare the supported equipment inoperable, and (4) deleting the action to depressurize and vent the i

reactor coolant system.

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.- I The staff finds that the proposed changes to TS 3/4.8.3.2 ensures that the necessary portion of AC, DC, and AC vital bus electrical power distribution subsystems are operable without imposing unnecessary constraints on the licensee, are consistent with NUREG-1431, and are acceptable, i

TS 3/4.9.12. Refuelina Operations. Fuel Hand 11na Buildina Exhaust Air System The proposed changes to TS 3/4.9.12 and its Bases clarifies the emergency power requirements 6 the fuel handling building (FH8) exhaust air system during refueling operations (whenever irradiated fuel is in the spent fuel pool). The current TS requires both (two) filter trains, three booster fans, three main exhaust fans, and associated dampers to be operable. The proposed revision would require two filter trains, two of three exhaust booster fans, two of three main exhaust fans, and associated dampers to be operable.

Additionally, the licensee added a note to the limiting condition for operation to specify that at least one FHB exhaust air filter train, one FHB exhaust booster fan, and one main exhaust fan must be capable of being powered i

from an operable emergency power source. The corresponding Bases section was also modified to describe examples of onsite power sources that satisfy requirements of this TS.

t The basis for the proposed change is that any single train of filters and any single train of main exhaust and booster fans are capable of per?orming the required accident mitigation functions when the plant is not in Nodes 1 i

through 4.

Since the proposed change is to the refueling operations TSs, this is an acceptable basis for the revised TS 3/4.9.12. When only 3DG A or B is l

available, emergency onsite power is available to a single train of all the i

required components to meet all the postulated accident scenarios in Modes 5 and 6.

The heaters for the two filter trains are powered by either electrical train A or B.

Electrical train C, which is backed by SDG C, does not power i

either train of heaters, which is the only electrical component associated with a filter train. Therefore, when only SDG C is available, other actions are necessary to assure that a complete single train of required components l

remain available in the event of a loss of offsite power. The revised Bases section describes the onsite emergency power sources that satisfy this

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requirement.

In Modes 5 and 6, these sources include supplying all the required components via cross tied trains (necessary if only the C train SDG 1s available), allowing one safety-related emergency diesel generator to supply all the loads, or a non-safety-related diesel generator capable of 1

supplying the required filter train loads (heaters) in conjunction with a safety-related SDG (if only SDG C is available).

Based on its evaluation, the staff finds that any single train of filters, main exhaust and booster fans is adequate to mitigate the effects of any postulated event in Modes 5 and 6, and, therefore, the TSs during refueling should be equivalent to any plant with two 100-percent fuel building ventilation system trains (the current TSs requiring three trains of certain equipment is excessive). The proposed change to only require two air filter trains, two booster fans, two main exhaust fans, and associated dampers to be operable during refueling operations is, therefore, acceptable. The other changes related to operable emergency power sources are also acceptable h

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because they are necessary to support single train operation for the plant-specific design (three power trains, two filter trains). The staff, therefore, finds that the proposed changes are acceptable.

Evaluation S - ry Based on the above evaluation, the staff finds that the proposed changes to the TSs for the AC sources, DC sources and onsite power distribution, and the fuel handling building exhaust air system, are acceptable.

Implicit in the staff's acceptance of this license amendment is that the licensee will address the objectives of Attachments 4, 6 and 7 (Engineering Test Guidelines for Vendor Site Testing, Engineering Test Guidelines for Onsite Testing, and Engineered Safety Features Bus Cross-Connect Description) of their January 23, 1995, supplement in plant procedures, with the attendant procedural controls thereof.

3.0 EXIGENT CIRCUMSTANCES

The Commission's regulations,10 CFR 50.91, contain provisions for issuance of amendments when the usual 30-day public notice period cannot be met. One type of special exception is an exigency. An exigency is a case where the staff and licensee need to act promptly and the staff has determined that the amendment involves no significant hazards considerations.

Under such circumstances, the Commission notifies the public in one of two ways:

by issuing a Federal Reaister notice providing an opportunity for hearing and allowing at least two weeks for prior public comments, or by i

issuing a press release discussing the proposed changes, using the local media.

In this case, the Commission used the first approach.

The licensee's initial application was noticed in the Federal Reaister on December 7, 1994 (59 FR 63122), at which time the staff proposed a no significant hazards consideration determination.

In the initial application, dated November 7,1994, the licensee stated that approval of these changes was required by February 2,1995, to support the scheduled refueling outage beginning on March 5, 1995. They also stated that they would need this lead time to cover planning and implementation periods. The licensee has been very l

prompt and attentive to addressing all of the staff's questions and concerns, and has provided two supplements, and revised proposed technical specifications (by letter dated January 23,1995), to address them. The staff questions and concerns were not of a nature that could have been reasonably anticipated by the licensee. Approval of this change will allow the licensee to complete the refueling outage (and commence startup) significantly earlier than without the change.

The staff renoticed the supplemented application on January 30, 1995, (60 FR 5739) to include all of the supplements, because the supplemental letters regresented a significant change from what was previously noticed. The staff again proposed to determine that the supplemented application involves no significant hazards considerations. The net effect of the supplements is a I

more restrictive and comprehensive set of TSs than that originally proposed.

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• i Accordingly, pursuant to 10 CFR 50.91(a)(6), the Comission has determined that an exigent situation exists and that failure to act in a timely way will result in an unnecessary delay in the startup from the refueling outage.

Further, the Commissir;n has determined that the exigent situation is not due to the failure of the licensee to act in a timely manner-There was no puMic comments in response to the notice published in the Federal Reaister.

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4.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION

DETERMIN&I1QN j

The Commission's regulations in 10 CFR 50.92 state that the Commission may make a final determination that a license amendment involves no significant i

hazards considerations if operation of the facility in accordance with the amendment would not (1) involve a significant increase in the probability or i

consequences of an tecident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.

Operation of the facility in accordance with the proposed amendment will not involve a significant increase in the probability or consequences of an accident previously evaluated. The equipment affected by the proposed changes are not accident initiators, therefore, the probability of accidents previously evaluated are not increased. The staff's review of the ability to mitigate the consequences of an accident finds that (1) for the TS changes to AC sources, the required systems can perform their required safety functions during any postulated design basis accident condition, (2) for the TS changes to DC sources and onsite power distribution, there is sufficient availability of DC power sources and the necessary portion of AC, DC, and AC vital bus electrical power distribution subsystems, to mitigate the consequences of postulated events, and (3) for the TS changes to the fuel handling building exhaust air system, the required filter trains, main exhaust fans and booster fans are capable of performing the postulated accident mitigation functions.

Operation of the facility in accordance with the proposed amendment wi not create the possibility of a new or different kind of accident from anj accident previously evaluated. The design and purpose of the equipment discussed in (1), (2) rnd (3) above, is not affected by the proposed changes.

Any postulated failure of the equipment discussed above is already addressed in existing accident analysis.

Operation of the facility in accordance with the proposed amendment will not involve a significant reduction in a margin of safety for the same reasons discussed in (1), (2) and (3) :tave.

In addition, regarding the TS changes to AC sources, the staff finds tl% the NDG or the required water level provide an acceptable amount of redundancy to remove decay heat. Regarding the fuel handling building exhaust air subsystem, there is also an accepable level of redundancy since any single train of filters, main exhaust ano i, coster fans are capable of performing the required accident mitigation functions.

Regarding the DC power sources and AC, DC, and AC vital bus distribution

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' subsystems, adopting the standard wording of NUREG-1431 simplifies the TSs, while still requiring that power to and availability of equipment needed for accident mitigation, is provided.

Based on the above considerations, the staff concludes that the amendments meet the three criteria of 10 CFR 50.92. Therefore, the staff has made a final determination that the proposed amendments do not involve a significant hazards consideration.

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5.0 STATE CONSULTATION

i In accordance with the Commission's regulations, the Texas State official was notified of the proposed issuance of the amendments. The State official had no comments.

6.0 ENVIRONMENTAL CONSIDERATION

Tha amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements. The NRC staff has detemined j

that the amendments involve no significant increase in the amounts, and no sigaificant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulatin.

occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (60 FR 5739). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

6.0 CONCWSION The Commission has concluded, based on the considerations discussed above, that:

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

Principal Contributors:

0. Chopra W. Lefave S. Brewer T. Alexion Date:

February 14, 1995

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