Text

Station Blackout Rept
	ML20244E258
Person / Time
Site:	Hatch
Issue date:	04/30/1989
From:	; GEORGIA POWER CO.
To:	;
Shared Package
ML20244E254	List: ML20244E253; ML20244E258;
References
	NUDOCS 8904240381
	Download: ML20244E258 (27)
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E. I. HATCH UNITS 1 AND 2 STATION BLACK 0UT REPORT APRIL 1989 8904240381 890412

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PDR ADOCK 05000321 j.

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E. I. HATCH UNITS 1 AND 2 l

STATION BLACK 0UT REPORT TABLE OF CONTENTS EAGE 1.0 Introduction and Background 3

2.0 Objective and Scope 3

3.0 Criteria and' Assumptions 4

4.0 Coping Duration 5

5.0 Evaluation of-Diesel Generator 1B as an AAC Source 5

6.0 AAC Source Reliability Review 13 7.0 Path to Hot Shutdown 13 8.0 Compartment Steady State Temperature Analysis 15 9.0 Equipment Temperature Qualification Review 18 9.1 Equipment not Specifically Addressed by NUMARC 20 9.2 MCR Setpoint Card Reliability 22 10.0 Battery Availability 22 10.1 DC Power Capacity 22 10.2 Loss of Ventilation Effects 23 11.0 Access to Plant Areas 24 11.1 Security Doors / Card Readers 24 11.2 Emergency Lighting 24 12.0 Containment Isolation Requirements 24 13.0 Condensate Inventory 25 14.0 Compressed Air Availability 25 15.0 Procedures and Training 26 16.0 Path to Shutdown for the Non-Blacked Out Unit 26 17.0 Manual Action Overview 26 18.0 Conclusion 27 06191 HL-396 2

1.0 INTRODUCTION AND BACKGROUND

The term " station blackout" (SBO) is defined to mean the loss of offsite AC power to the essential and non-essential electrical buses concurrently with turbine trip and the unavailability of the redundant onsite emergency AC power systems.

To reduce the estimated core damage frequency due to station blackout, the NRC issued the Station Blackout Rule, 10CFR 50.63, which was published on June 21, 1988.

The objective of the rule is to reduce the risk of severe accidents resulting from station blackout by maintaining highly reliable AC electric power systems and, as additional defense-in-depth, assure that nuclear plants can cope with a station blackout for a specific period of time.

The specific station blackout duration is based on the redundancy of the onsite emergency AC power sources; the reliability of the onsite emergency AC power sources; the expected frequency of loss of offsite power; and the probable time needed to restore offsite power.

The reactor core cooling and associated systems provide sufficient capacity and capability to ensure that the core is cooled and appropriate containment integrity is maintained in the event of a station blackout for the determined duration.

2.0 OBJECTIVE AND SCOPE This report documents the criteria, assumptions, analyses, and related information used to demonstrate E. I. Hatch Units 1 and 2 compliance to the SB0 rule.

This report is based on a coping duration and coping analysis.

The

-following tasks define the scope and provide the basis for these items:

a.

Documentation of the coping duration.

b.

Capability to bring the blacked out unit to hot shutdown.

c.

Capability to bring the non-blacked out unit to hot shutdown.

d.

Qualification of Emergency Diesel Generator 1B as an Alternate AC (AAC) source, e.

Loss of ventilation effects.

f.

Station battery availability.

g.

Plant access during SBO.

h.

Manual operator action overview.

These tasks have been reviewed and any necessary changes to the facility or procedures will be in place no later than two years following notification of the acceptance of this report from the Director, Office of Nuclear Reactor Regulation.

0619I HL-396 3

3.0 CRITERIA AND ASSUMPTIONS The " Station Blackout Rule," 10 CFR 50.63, is the governing criteria for this report.

Regulatory Guide 1.155 describes methods acceptable to the NRC staff for compliance to the SB0 rule.

The Nuclear Management and Resource Council (NUMARC) document NUMARC 87-00 provides guidance for conformance to 10 CFR 50.63.

Through use of the NUMARC 87-00 documents, a coping duration of 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months has previously been assessed (refer to Section 4.0 for more information regarding coping duration).

All active systems and components required to bring the SB0 unit to and maintain a safe shutdown (hot shutdown) condition from full power during a postulated SB0 have been identified.

These systems and components have been reviewed to ensure that those portions which are required to mitigate the consequences of an SB0 are available.

Effects of non-availability of support systems such as instrument air, ventilation, and AC power also have been considered.

The initial conditions and assumptions outlined in Regulatory Guide 1.155 and NUMARC 87-00 have been used for general guidance in preparation of this report.

The regulatory assumptions and clarifications listed below are applicable:

a.

SB0 need only be considered to occur at one unit on a two-unit site.

b.

No design basis accidents or other events are assumed to occur immediately prior to or during the SBO.

c.

No independent (single) failures, other than those causing the SB0 event, are assumed to occur in the course of the transient.

However, the non-blacked out unit must assume a single failure of an emergency diesel generator.

d.

Bringing the SB0 unit to hot shutdown and coping for 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months terminates the event.

e.

The AAC source must be available within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months of an SB0 event or the coping duration must consider the longer time.

One hour was assumed for Plant Hatch.

f.

SB0 is not a design basis event or accident.

The following additional assumptions have been used as the basis for this report:

a.

A reactor SCRAM is assumed to follow immediately after LOSP.

1 b.

Both units are considered to be operating at full power prior to the event.

c.

Credit can be taken for operator manual actions.

0619I HL-396 4

d.

Spurious instrument signals due to transmitter or sensing element failure are not postulated.

e.

The equipment identified for use during an SB0 has been evaluated relative to diesel and battery loading capacities.

The above criteria and assumptions are in compliance with Regulatory Guide 1.155 and NUMARC 87-00.

4.0 COPING DURATIQH The NUMAhC 87-00 guideline specifies that either unit must successfully cope with the blackout condition for a predetermined amount of time based on site-specific characteristics.

The Hatch required coping interval is 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months .

The 4-hour coping duration is based on offsite power design.

characteristic group P1, emergency AC power configuration group C, and an allowed emergency diesel generator target reliability of 0.95 and has been calculated based on the analytical techniques presented in NUMARC 87-00 Section 3 which is consistent with the regulatory guidance provided in Reg.

Guide 1.155.

5.0 EVALUATION OF DIESEL GENERATOR 1B AS AN AAC SOURCE Evaluation of the emergency diesel generator (EDG) 1B for use at HNP-1,2 as an AAC p Twer source is in accordance with Regulatory Guide 1.155 and NUMARC 87-00 Appendix B.

The on-site standby AC power supply system for HNP-1 and HNP-2 consists of five EDGs units 1 A,1C,18, 2A, and 2C.

These units supply power to 4160V emergency buses 1E, 1F, 1G, 2E, 2F, and 2G.

EDGs lA and 1C supply Unit i emergency buses 1E and 1G, respectively.

EDGs 2A and 2C supply Unit 2 emergency buses 2E and 2G, respectively.

Diesel generator 1B is a shared facility and can supply either Unit 1 emergency bus IF or Unit 2 emergency bus 2F.

EDGs lA and 1C are assigned to the redundant essential load group divisions I and II of Unit 1 and EDGs 2A and 2C are assigned to the redundant essential load group divisions I and II of Unit 2.

EDG 1B is a shared power source between HNP-1 and 2 and can be connected to either Unit 1 or Unit 2 on complete loss of offsite power (LOSP).

The F bus on each unit supplies 4 KV ECCS pumps in both divisions I and II.

In the evaluation of the required station blackout coping duration category, EDG 1B was not considered as an Essential AC (EAC) power source. Two EDGs (EACs), i.e. A and C, were assumed to be normally available to the blacked out unit's safe shutdown equipment. Therefore, the EDG 1B is available for safe shutdown purposes of either unit in the event of a station blackout.

L At either Hatch unit, only one EDG is necessary to operate safe shutdown equipment during a station blackout to achieve and maintain a hot shutdown condition.

The required loads during the station blackout for either unit 0619I HL-396 5

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can be provided from the bus normally powered from EDG 1B or from other buses via manual disconnect links Therefore, ED'i 1B is considered as an AAC source for station blackout.

I Reg. Guide 1.155 and NUMARC 87-00 require that station blackout only be assumed for one unit on a two-unit site and specifies that no other accidents or failures be assumed concurrent to the blackout event except for the failure of a redundant EDG on the non-blacked out unit.

In performing tie evaluation to qualify EDG 18 as an AAC source, it is not necessary to consider single failures which would, themselves, disable the AAC source.

The only single failure assumed is the one that causes one of the EDG sources required to shut down the non-blacked out unit to be inoperable.

Since there are two EDGs available to shut down the non-blacked out unit and since only one EDG is required to shut down the non-blacked out unit, no other single failures are assumed.

EVALUATION TO NUMARC-87-00 APPENDIX B CRITERIA AAC Power Source Criteria B.1 The AAC system and its components need not be designed to meet Class lE or safety system requirements.

If a Class lE EDG is used as an Alternate AC power source, this existing Class 1E EDG must continue to meet all applicable safety-related criteria.

Discussion: All diesel generators at HNP-1 and 2 are Class lE and meet the requirements of the relevant safety-related standards.

The Class lE EDG 1B is proposed as an Alternate AC (AAC) power source for HNP units 1 and 2.

Onsite inspection and testing of EDG 1B is conducted per the requirements of the Technical Specifications and the HNP plant procedures.

EDG 1B will continue to meet the safety-related codes and standards per the HNP licensing basis, in addition to being considered as an AAC source for station blackout scenarios.

==

Conclusion:==

EDG 18 is in compliance with the above criterion.

B.2 Unless otherwise provided in this criterion, the AAC system need not be protected against the effects of:

(1) failuro of misoperation of mechanical equipment, including (i)

fire, (ii) pipe whip.

(iii) jet impingement, (iv) water spray, (v) flooding from a pipe break, (vi) radiation, pressurization, elevated temperature or humidity caused by high or medium energy pipe break, and (vii) missiles resulting from the failure of rotating equipment or high energy systems; or (2) seismic events.

Discussion: This criterion imposes no new requirements on the AAC.

==

Conclusion:==

EDG 1B is in compliance with the above criterion.

0619I l

HL-396 6

9 I

B.3 Components and subsystems shall be protected against the effects of likely weather-related events that may initiate the loss of offsite power event Protection may be provided by enclosing AAC components within l

structures that conform with the Uniform Building Code and burying exposed I

electrical cable run between buildings (i.e.,

connection between the AAC L

power source and the shutdown buses).

Discussion: The EDG 1B design is in compliance with the safety-related codes and standards as specified in the HiiP 1 and 2 FSARs and is housed in a

reinforced concrete seismic category 1

structure.

The structure is designed to withstand effects of natural phenomena such as earthquake, tornadoes, missiles, hurricanes, floods, lightning, rain, ice, or snow without loss of capability to perform its designated functions.

EDG 1B is completely enclosed in its own concrete cell and is isolated from other units.

Automatic fire detection and extinguishing systems are provided.

The electrical cables between the diesel generator building and auxiliary buildings are routed in seismic category 1

underground duct banks.

==

Conclusion:==

EDG 1B is in compliance with the above criterion.

B.4 Physical separation of AAC from safety-related components or equipment shall conform with the separation criteria applicable for the unit's licensing basis.

Discusioni The EDG 1B complies with the HNP emergency diesel generator system design basis for separation (IEEE 308).

Physical separation of safety-related equipment and components is maintained on a divisional basis.

Physical separation between safety-related and non-safety-related equipment is maintained based on the licensing requirements specified in the FSAR.

==

Conclusion:==

EDG 18 is in compliance with the above criterion.

Connectability to AC Power System B.5 Failure of AAC components shall not adversely affect Class lE AC power systems.

4 Discussion: As stated in the evaluations against criteria B.3 and B.4 above, EDG 18 is a part of the Class 1E power system.

Due to independence and physical separation of the Diesel 18 system and its components from other Class lE systems and components, the failure of EDG 1B will have no adverse affect on operation of other Class 1E AC power systems.

==

Conclusion:==

EDG 18 is in compliance with the above criterion.

06191 HL-396 7

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t B.6 Electrical isolation of AAC power shall be provided through an appropriate isolation device.

If the AAC source is connected to Class lE buses, isolation shall be provided by two circuit breakers in series (one Class lE breaker at the Class lE bus and one non-Class lE breaker to protect the source).

Discussion:

Double breaker electrical isolation is required of an AAC source only if the AAC source is a non-Class lE source. As indicated in paragraphs B.3 and B.4, FDG 1B is a Class 1E source supplying power to the Class 1E buses.

Therefore, isolation of EDG 1B from tne Class 1E buses by two circuit breakers in series is not required.

==

Conclusion:==

Double breaker electrical isolation is not applicable to EDG 1B since it and the bus it supplies are both Class 1E.

B.7 The AAC power source shall not normally be directly connected to the preferred or on site emergency AC power system for the unit affected by the blackout. In addition, the AAC system shall not be capable of automatic loading of shutdown equipment from the blacked out unit unless licensed with such capability.

Discussion:

The on site emergency AC power system is comprised of 5 EDGs.

The A and C EDGs are dedicated to a specific unit as detailed in the opening discussion of this evaluation.

EDG 1B is shared and is independent of the other emergency AC power systems on either unit; it is designed to supply the safety-related standby loads on either unit as warranted by the conditions discussed below:

All the 1 cads on the IF or 2F buses are normally powered from offsite sources.

In the event of a LOSP, EDG 1B would automatically start as discussed in the Hatch FSARs (section 8.4 for Unit 1 and section 8.3 for Unit 2) and provide essential power to one plant service water pump and equipment essential to the operation of EDG 1B which is consistent with the licensing basis for the plant.

==

Conclusion:==

EDG 1B complies with this criterion.

Minimal Potential for Common Cause Failure B.8 There shall be minimal potential for common cause failure of the AAC power source (s). The following system features provide assurance that the minimal potential for common cause failure has been adequately addressed.

(a) The AAC power system shall be equipped with a DC power source that is electrically independent from the blacked out unit's preferred and Class 1E power system.

0619I HL-396 8

___-________-____a

3 Discussion:

Each of the HNP EDGs have their own dedicated 125Vdc power source.

The battery for EDG 18 supplies power for control of the EDG and for control of all breakers associated with the operation of EDG 18 and its auxiliaries.

The batteries for all EDGs are Class 1E and located in separate rooms in the diesel building. All diesel generator battery systems are physically and electrically independent and designed to Class 1E requirements.

Co_n_C]usion:

EDG 1B complies with the above criterion.

n (b) The AAC power system shall be equipped with an air-start system, as applicable, that is independent of the preferred and the blacked out unit's preferred and Class 1E power supply.

Discussion: An independent air-starting system is furnished for each diesel generator.

Each air-starting system has two air receiver tanks each designed with sufficient capacity to provide five diesel engine start attempts without recharging.

Further, one of the two IB EDG start system air compressors would be powered via 4160V bus lE or 1G if Unit Two were blacked out or via 4160V bus IF if Ur.it One were blacked out.

In either event, the 1B ED(i air start system compressors are independent of the blacked out unit's preferred and Class 1E power supplies.

==

Conclusion:==

EDG 1B complies with the above requirement.

(c) The AAL power system shall be provided with a fuel oil supply, as applicable, that is separate from the fuel oil supply for the onsite emergency AC power system.

A separate day tank supplied from a common storage tank is acceptable provided the fuel oil is sampled and analyzed consistently with applicable standards prior to transfer to the day tank.

Discussion:

EDG IB has a dedicated fuel day tank.

The day tank is supplied from a dedicated main storage fuel tank. The day tank provides enough fuel for approximately 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months of full-load operation of the diesel generator unit.

At least once per 92 days Technical Specifications require a sample of diesel fuel from the main fuel storage tank be analyzed.

The analysis is performed per ASTM procedures for acceptable limits of viscosity, water, and sediment.

==

Conclusion:==

EDG 1B complies with the above criterion.

(d) If the AAC power source is an identical machine to the emergency onsite AC power source, active failures of the emergency AC power source shall be evaluated for applicability and corrective action taken to reduce subsequent failures.

0619I HL-396 9

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L Discussion:

Failures of any EDG are, and have

been, evaluated for applicability to all other EDGs.

The EDG 1B is essentially identical to the other four DGs.

Each diesel generator and its associated control and support system is independent of the others such that failure of any one component / diesel does not affect the operation of any other diesel generator system. In case of a common component failure, a systematic corrective action program is in place to modify all the affected EDGs at the plant.

The EDGs have been in active service for at least 12 years.

Conclusions EDG 1B complies with the above criterion.

(e) No single-point vulnerability shall exist whereby a

likely weather-related event or single active failure-could disable any portion of the onsite emergency AC power source or the preferred power sources and simultaneously fail the AAC power source (s).

Discussion:

The diesel generator units and all necessary control and support systems are designed to Class 1E requirements, are housed in seismic category 1 structures and are protected against the effects of all naturs1 phenomena such as tornadoes, floods, lightning, rain, ice, and w w.

The safe shutdown loads are divided among the emerg.,

tuses for each reactor such that the failure of any compone 5 EDG will nc,t prevent the

. cafe shutdown of the units.

Each EDG and its associated system is independent and separate.

Therefore, failure of any one component cannot affect the operation of more than one diesel generator system ~.

Conclusion:

EDG 1B complier with the above criterion.

(f) The AAC power system shall be capable of operating during and after a station blackout without any support systems powered from the preferred power supply or the blacked out unit's Class IE power sources affected by the event.

Discussion:

The EDG 1B supoort systems are completely independent of other on-site and offsite power sources.

EDG 1B has its own independent DC battery.

The swing diesel (IB) supplies its own auxiliary loads such as service

water, fuel oil

supply, compressed air systems, and room ventilation.

Therefore, EDG 1B is capable of operating during and after a station blackout without any support system powered from other preferred power or from any othEr ondte power sources.

==

Conclusion:==

EDG IP complies with the above criterion.

0619I HL-396 10 L

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(g) The portions of the AAC power system subjected to maintenance activities shall be tested prior to returning the AAC power system to service.

Discussion:

The EDG 18 -is a Class 1E diesel generator with maintenance activities and test and surveillance procedures specified in the Technical Specifications.

EDG 18 will continue to be covered by such maintenance and testing activities as required for safety-related equipment.

==

Conclusion:==

EDG 1B complies with the above criterion.

Availability After Onset of Station Blackout B.9 The AAC power system shall be sized to carry the required shutdown loads for the required coping duration determined in Section 3.2.5 and be capable of maintaining voltage and frequency within limits consistent with established industry standards that will not degrade the performance of any shutdown system or component.

At a multi-unit plant, except for 1/2 shared or 2/3 emergency AC power configurations, an adjacent unit's Class 1E power source may be used as an AAC power source for the blacked-out unit if it is capable of powering the required loads at both units.

Discussion:

The required safe shutdown loads for both the units have been evaluated.

EDG 1B has the required capacity to safely bring either unit to a stable hot shutdown condition for the required coping duration of 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months .

Upon demand, EDG 18 starts automatically and attains rated frequency and voltage within 12 seconds, which is consistent with the requirements of Reg.

Guide 1.9.

HNP will always have one EDG available for the safe shutdown of the non-blacked out unit, and EDG 1B will be available for shutdown of the blacked-out unit.

Each HNP unit has two dedicated EDG units (1A and 1C for Unit 1 and 2A and 2C for Unit 2) and the AAC (EDG 18) which aligns to Unit 1 or 2 as required.

EDG 1B has not been considered as a part of a 1/2 shared or 2/3 shared emergency AC power configuration for a station blackout event.

==

Conclusion:==

EDG 1B complies with the above criterion.

Capacity and Reliability B.10 Unless otherwise governed by Technical Specifications, the AAC power source shall be started and brought to operating conditions that are consistent with its function as an AAC source at intervals not longer than 3

months, following manufacturer's recommendations or in accordance with plant-developed procedures.

Once every refueling outage, a timed start (within the time period specified under blackout conditions) and rated load capacity test shall be performed.

0619I HL-396 11

D Discussion:

The EDG 1B is covered by HNP Technica1 Specifications and meets all the testing requirements specified iherein.

The Technical Specification surveillance requirements are more restrictive i

than those specified in NUMARC 87-00.

1

==

Conclusion:==

EDG 1B complies with the above criterion.

B.11 Unless otherwise governed by Technical Specifications, surveillance and maintenance procedures for the AAC system shall be implemented considering manufacturer's recommendations or in accordance with plant-developed procedures.

Discussion:

The EDG 1B is covered by Technical Specifications.

Surveillance and maintenance procedures developed considering manufacturer's recommendations are in place.

==

Conclusion:==

EDG 1B complies with the above criterion.

B.12 Unless otherwise governed by Technical Specifications, the AAC system shall be demonstrated by initial test to be capable of powering required shutdown equipment within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months of a station blackout event.

Discussion:

The EDG 1B is covered by plant Technical Specifications.

Plant procedures will be developed to demonstrate the use of the EDG 1B to power shutdown equipment within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months of the station blackout event.

==

Conclusion:==

Compliance with the above criterion will be demonstrated.

B.13 The Non-Class lE AAC system should attempt to meet the target reliability and availability goals specified below, depending on normal system state.

In this context, reliability and availability goals apply to the overall AAC system, rather than individual machines, where a system may comprise more than one AAC power source.

(a) Systems Not Normally Operated (Standby Systems)

System reliability should be maintained at or above 0.95 per demand, as determined in accordance with NSAC-108 methodology (or equivalent).

(b) Systems Normally Operated (Online Systems)

Availability:

AAC systems normally online should attempt to be available to their associated unit at least 95% of the time the reactor is operating.

Reliability: No reliability targets or standards are established for online systems.

0619I HL-396 12

Discussion:

EDG 1B is a Class 1E system and meets the availability requirements of Section B.13(a) based on system availability data. (See also Section 6.0 of-this report.)

==

Conclusion:==

EDG 1B complies with the above criterion.

SUMMARY

Emergency diesel generator (EDG) IB qualifies for use as an Alternate AC (AAC) power source for HNP-1 and 2.

The following items will be completed within two years of the GPC receipt of the letter described in 10CFR 50.63(c)(3).

t 1.

Development and implementation of plant procedures to perform 1-hour manual action walkthrough verification assessment (paragraphs B.10 and B.12).

2.

Development and implementation of plant procedures to perform various manual actions (paragraphs B.10 and B.12) 6.0 AAC SOURCE RELIABILITY REVIEH Per Regulatory Guide 1.155 Section 3.3.5.5, the reliability of the AAC power system exceeds 95% as determined in accordance with NSAC/108.

The reliability is based on the number of starts and load-run failures in the last 100 valid demands accumulated over no more than 3 years.

Actual surveillance test data was obtained to calculate the reliability of 99%.

Since the reliability of the AAC diesel IB exceeds the target value of 95%

reliability per Rsgulatory Guide 1.155 Section 3.3.5.5, the reliability requirement is satisfied.

Potential problems associated with attempting to " cold start" the emergency diesel generators at Hatch from ambient conditions have been eliminated through implementation of Generic Letter 84-15 guidance in August, 1987.

Hatch emergency diesel generators are equipped with a lube oil keep warm system and procedures require pre-lubricating of the emergency diesel generators prior to a scheduled run.

7.0 PATH TO HOT SHUTDOWN Safe shutdown for SB0 is defined as bringing the plant to and maintaining a hot shutdown condition (per plant Technical Specifications) from full power. This condition must be maintained for the length of time determined by the coping duration analysis.

The coping duration, from Section 4.0 of this report, was determined to be 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months .

Plant operation is controlled by predominantly DC sources until the AAC source is available for loading.

This duration has been assumed to be 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months (the station batteries are capable of supporting plant operation for up to 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months ), at which time the AAC will be appropriately loaded.

[

0619I HL-396 13 l

9 After the 4-hour coping period, it is assumed that the station operators will either restore offsite power or start the additional emergency diesels and bring the plant to a cold shutdown.

Bringing the plant to a cold shutdown, however, is beyond the scope of this report.

The blacked out unit's' protection sequence and path to hot shutdown will follow the sequence of events outlined in the HNP-2 FSAR, Figure 15C-20 and the HNP-1 FSAR, Figure G.6-15.

The station operators could use the High Pressure Coolant Injection System (HPCI) and/or the Reactor Coolant Isolation Cooling System (RCIC) and one SRV to control the RPV pressure and level.

The HPCI and RCIC systems will be available due to the fact that they are steam driven systems supported by battery powered components.

The SRVs are battery powered for actuation and have a safety grade motive gas supply.

1 As outlined in the Appendix R Safe Shutdown Analysis Report, HPCI and/or RCIC can be used up to 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months before the RPV needs to be depressurized to accommodate the low pressure injection systems.

Hithin 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months after the event, suppression pool cooling will be available to preclude a temperature increase above the suppression pool heat capacity temperature limit (HCTL).

Suppression pool cooling is not required until 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months after the initiation of the SB0 event.

Since no other accident is required to be postulated, the station operators need only to keep the suppression pool bulk temperature below 200*

F.

A manual action to institute a

controlled RPV depressurization rate can be taken, within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months , to get to cold shutdown.

From hot

shutdown, recovery from LOSP will continue with the depressurization of the RPV until shutdown cooling can be established (the emergency diesel generators will be functional or offsite power available at this time).

To preclude powering both trains of divisional power from the single AAC diesel, division I components and equipment were selected to simplify the required load shedding manual actions.

Since the RCIC system is the preferred high pressure makeup system to be used throughout the SB0 event, division I power was chosen.

Division I battery chargers and RCIC room cooling will be available when the AAC source is started and loaded to support RCIC operation (per Section 8 of this report, RCIC room cooling is not required during SBO).

The high injection volume of the HPCI system is not necessary during this event, since accident (LOCA) conditions are not postulated.

For station operation simplicity, HPCI may be secured immediately following an SBO.

06191 HL-396 14

4 8.0 COMPARTMENT STEADY STATE TEMPERATURE ANALYSIS 1

Station blackout is not a design basis accident and, therefore, is not subject to the requirements of 10 CFR 50.49 and the rigorous certification process for equipment operability.

However, since SB0 coping equipment needs to operate in order to achieve and maintain a safe shutdown, reasonable assurance must be provided to demonstrate that no thermally induced failures will result due to loss of forced ventilation.

The compartments or areas which are considered " dominant areas of concern" per NUMARC are the HPCI/RCIC pump rooms and the main steam pipe chase.

Special attention is also given to the main control room (MCR).

The main steam pipe chase is referenced in NUMARC 87-00 as being a dominant area of concern due to a postulated high temperature cutout for decay heat removal equipment. Upon review of the system logic diagrams for HPCI, RCIC, and RHR, no temperature trip mechanisms exist whereby high temperature in the main steam pipe chase will cause any of these RPV heat removal systems to isolate.

Therefore, for SB0, the main steam pipe chase is not considered a dominant area for HNP-1,2.

At HNP-1,2, a large number of components important for SB0 are located outside the MCR and outside NUMARC dominant areas of concern.

Using a defense-in-depth approach, this report considered nil plant areas where elevated resultant temperatures, due to loss of ventilation, could impact equipment required to be operable during the SB0 copiny duration.

For both units, the areas considered are as follows:

a.

Control Building b.

RCIC Corner Room c.

Reactor Building (other than the RCIC corner room) d.

MCR e.

Diesel Generator Building f.

Intake Structure The effects of loss of ventilation are less severe due to the associated loss of main lighting and certain AC powered equipment heat loads.

The potential for mechanistic failures of systems and components due to loss of ventilation is dependent on the time required for temperatures to rise in closed rooms.

Temperature buildup in a compartment is a slow process due to the normally large thermal lag associated with natural convection and the loss of AC supplied heat sources.

To quantify the resultant compartment environmental conditions upon SB0, a steady state temperature analysis was performed for each of the above areas of concern, where appropriate.

The method and results are presented below:

)

a.

Control Building Control building ventilation will not be available during the 4 l

hour coping period for SBO.

0619I HL-396 15

L The empirical approach of NUMARC, Section 7.2.4 was.used to determine the average steady state temperature for the subject areas in the control building.

The resultant worst-case qualification temperature for equipment located in control building compartments was determined to be approximately 50*C (122*F). for all areas other than the 1CD and 2CD transformer rooms at elevation 130' which will see a resultant SB0 temperature of approximately 54*C (129'F).

The 122*F temperature was used to qualify equipment for operability in the control building for SB0 with the exception of equipment in the transformer rooms.

Transformer operability is addressed separately in Section 9.1 of this report.

Per NUMARC 87-00 Section 2.7.2, opening of doors in compartments is an acceptable method of reducing the rate of temperature increase upon loss of forced ventilation.

Most of the areas of concern in the control building have normally open doors (for example, the 600V switchgear rooms and the CD transformer rooms -

both on elevation 130').

Analysis has shown that the only compartment for which credit needs to be taken for the opening of the room door is the HNP-2 switchgear hallway enclosure (Room 2C135A) on elevation 130'.

The HNP-2 switchgear hallway enclosure door needs to be opened to preclude a room heatup exceeding 50*C (122*F).

b.

RCIC Corner Rooms RCIC corner room cooling will be available 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months after SB0.

A mathematical model which is essentially the analytical version of the NUMARC 87-00 empirical approach, was developed to estimate the temperature rise in the RCIC corner rooms due to loss of forced ventilation during a 4-hour period.

In this analysis, a lumped parameter model was used to calculate the average air temperature as a function of time after loss of ventilation.

The RCIC system was assumed to be in full operation and no credit was taken for the opening of doors.

The resultant temperature profile showed that the compartment temperature would remain below 120*F over a period of 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months without forced ventilation.

All of the equipment located in the RCIC corner rooms required for safe shutdown during SB0 has been qualified to operate in 120*F ambient temperature.

l 0619I HL-396 16 4

7 l

c.

Reactor Building (other than the RCIC corner room) l Reactor building ventilation will not be available during SB0.

J The long-term temperature response of the various HNP-1,2 reactor building compartments can be taken from the temperature profiles generated for the E.

I.

Hatch Environmental Qualification Program.

Since the HELB blowdown data does not take credit for forced-ventilation, the long-term compartment temperature response is indicative of the resultant compartment temperature due to SB0.

The long-term HELB temperature response includes mostly the effect on room temperature due to the absence of ventilation, since the effect on room temperature of. steam blowdown is no longer prominent due to early isolation.

l Inspection of the HELB temperature response profiles shows that all of the areas of concern within the Unit 1 and 2 Reactor buildings have resultant temperatures less than 50*C (122*F).

All of the equipment located in these areas required for safe shutdown during SB0 is qualified to operate in 50*C (122'F) ambient temperature.

d.

Main Control Room HNP-1,2 share a common MCR.

The control room cooling equipment is powered from the Unit i emergency busses.

In the worst case, 501. of the MCR room cooling capacity will be available in 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months since it has been assumed that one diesel on the blacked out unit is lost.

Therefore, equipment operability within the MCR is reasonably assured.

However, a bounding MCR temperature profile using the guidelines of NUMARC 87-00 Section 2.7.1 was generated to evaluate equipment.

Per the NUMARC document, loss of cooling in the MCR for a 4-hour period does not prevent the station operators from performing tasks necessary to cope with SB0.

NUMARC 87-00 considers the MCR to be a Condition 1 room, which is defined as a room of relatively low concern with respect to elevated temperature effects and will likely require no special actions to assure operability for a 4-hour SBO.

This condition is defined within NUMARC 87-00 by a steady state temperature at 120*F.

Although the MCR temperature is not expected to increase significantly due'to the presence of partial cooling, the HNP-1, 2 equipment required to cope with an SB0 was conservatively evaluated at 120*F.

l 0619I HL-396 17

U e.

Diesel Generator Building

- Diese1 ' generator building rooms 1B, 1F,.and - 2F enclose the AAC source',- HNP-1 switchgear, and. HNP-2 switchgear, respectively.

Ventilation -in these ' rooms is only required when the AAC source-

-(diesel 1B) is operating.

Thel ventilation fans will operate when the-high temperature set point is reached.

The ventilation-

-_ equipment is automatically-_ loaded onto the emergency bus when the

' AAC source starts.

Normal operating temperatures are expected; therefore, special equipment high temperature qualification. is not necessary in'the diesel generator building during an SB0.

f..

' Intake Structure-The intake structure ventilation system will be available within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months through the. blacked out or non-blacked out' unit's emergency bus.

Normal operating temperatures are expected.

Therefore, special equipment high temperature qualification is not necessary in the intake structure during an SBO.

9.0 EOUIPMENT TEMPERATURE OUAllFICATION REVIEH Per NUMARC 87-00 Appendix F,Section F.1.4, the following assumptions are consistent with establishing reasonable assurance of operability for

. equipment in SB0 environments:

I a.

Documentation standards for equipment operability are not to be as. rigorous as are typically required to meet the design basis requirements of 10 CFR 50.49.

For example, there is no need to address the'~ effects of aging or synergisms.

In addition, engineering judgement may be exercised to permit the acceptance of installed configurations that diverge from test conditions.

This is consistent with the scope and intent of the SB0 rule.

These assumptions are reasonable due to the low temperatures (and correspondingly slower reaction rates) and thort durations (and

. correspondingly 'short reaction times) expected during a station blackout.

b.

In accordance with NUMARC 87-00 Section 2.7.1, only station blackout response equipment located in dominant areas of concern that have not been previously evaluated as a harsh environment need be assessed for operability.

c.

Determination of similarity does not need to consider the effects of aging or synergisms.

d.

Due to the short expected duration and relatively small temperature rises expected during a station blackout, aging effects on operability do not need to be considered.

l 1

l 0619I HL-396 18

Q (S

All equipment required to mitigate the consequences of a SB0 event has been evaluated to verify that it can operate during a

SB0 environmental condition.

Additionally, all equipment used to respond to a SB0 is well maintained under the Georgia Power Maintenance program assuring its operability.

The following list of generic categories were used to establish reasonable assurance of equipment operability:

a.

Equipment qualified to operate in a harsh environment (per the design basis of 10 CFR 50.49) is automatically qualified to operate during a 4-hour SB0.

b.

Passive components required for pressure boundary integrity have been verified to be in their desired position at the onset of an SB0 through a review of various licensing basis documents such as P& ids and the

FSAR, as well as system normal operating procedures.

Passive components are not required to operate or change state at any time during an SB0.

Their normal plant operating position will remain intact through an SB0 event even if motive force (i.e., AC/DC power or motive gas) is removed or disturbed.

Since these components are all located in SB0 areas of concern where the maximum expected temperature is less than 122*F, it is reasonable to assume that these passive components will not inadvertently operate or change state due to higher-than-normal temperatures.

Therefore, these components are qualified for SB0.

c.

Normal ventilation in the diesel generator building or the intake structure is expected, since AC power to the ventilators is available through the non-blacked out unit or the AAC source in 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months .

Since normal temperatures are expected throughout the SB0 event, the equipment located in these areas will be operable for SBO.

Temperature data is not required for these components.

d.

Vendor temperature limit data, for certain components, is on file and readily available through the HNP-1,2 vendor document control system.

For these components, the location, maximum expected SB0 temperature, vendor qualification temperature, and vendor qualification temperature source was evaluated.

In each of these

cases, the as-purchased vendor qualification temperature completely envelops the maximum expected temperature throughout the S80.

Therefore, these components are qualified to operate throughout the SB0 event.

e.

For the remaining equipment required for a SB0, a maximum expected SB0 temperature was assumed based on the particular component's location.

In each case, the calculated maximum expected SB0 temperature was equal to or less than 50*C (122*F).

This temperature is well below the maximum postulated temperature for equipment operability per the NUMARC 87-00 guidelines Appendix F, Topical Report Table 1-1.

A summary of the NUMARC evaluations showing the maximum SB0 operability temperatures for the specified equipment category is provided below:

0619I HL-396 19 l

J

Equipment SB0 Operability Duration Temperature (*F)

(Hours)

Pumps 180 4

Turbines, Mechanical Governars 180 4

DC Motors, Fans, and Blowers 180 4

Valves 200 4

Motor-0perated Valve Actuators 200 4

(Limitorque) i Cables 185 4

Switches and Relays 185 4

Sensors and Electronic Transmitters 180 4

Electronic Turbine Governors 160 4

All of the components required are qualified for operability during an SB0 where applicable, per the NUMARC guidelines.

The few components that were not specifically addressed by NUMARC are discussed in the next subsection.

9.1 EQUIPMENT NOT SPECIFICALLY ADDRESSED BY NUMARC Haior Electrical Eauioment:

All the major electrical equipment (4.16KV SHGR, 600V SHGR, 600V MCC, 250Vdc SHGR, 250V MCC, 125/250Vdc batteries, 125Vdc batteries, 125V battery chargers),

are qualified for operation in the elevated temperatures at the location where they are installed.

MCCs at HNP-1,2 have been tested and are qualified to operate in a harsh environment.

Due to the relatively low expected SB0 compartment temperatures and the fact that the electrical cabinets are qualified to operate in this elevated ambient temperature per vendor data, it is reasonable to assume equipment operability without the opening of any cabinet doors.

Pane 1 boards:

Per NEMA standard AB-1, molded case circuit breakers typically have an open-air rating at temperatures of

-5'C to 40*C.

However, since breakers are installed in cabinets, only breakers that are listed and marked for 100% application may be fully loaded to their rating. All other breakers are applied at 80% or less of their ampere rating for continuous loads.

At higher temperatures than 40*C, the loading 1

factor must be reduced below 80% of the rating to prevent an inadvertent trip.

At SB0 ambient temperatures approaching 50*C, the trip derating is approximately 14%. Therefore, the breakers should not be continuously loaded above 66% of their ampere rating. Additionally, since breakers from different manufactures have similar operating characteristics, the 66% loading requirement will was assumed to apply to all low voltage thermal magnetic breakers used at Hatch.

06191 HL-396 20

o L

i.

A review of the Hatch Units 1 and 2 panel loading conditions has-demonstrated that they meet these criteria.

. Based upon information readily available and engineering judgement, all breakers for 120Vac and 125Vdc equipment loads required during a station blackout are loaded below 66% of their rating.

Hence, their availability during a

station blackout' when elevated ambient temperatures approach 50'C can reasonably be assured.

' Station Service Transformers:

Per ANSI C57.12.00-1980, " General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers", ratings are based on a usual service temperature of 40*C maximum and 30*C average for any 24-hour period.

Under these conditions, the transformer's normal life is defined.

Temperatures higher than these represent a reduced life at rated loading.

Per ANSI C57.92-1981, " Guide for Loading Mineral-0il-Immersed Power Transformers", these transformers (OA/FA) may be derated by 1.0% per each degree higher than 30*C up to 50*C.

Hence, for operation at 50*C, the transformer should not be loaded more than 80% if transformer life is not to be-sacrificed.

Station service transformers 2C or 2D will be loaded to approximately 70% capacity; therefore, no loss of transformer life will occur up for operation in ambient temperatures up to 50'C.

These results can be extended to HNP-1 station service transformers 1C, 1D, and ICD and to HNP-2 station service transformer 2CD.

The standard does not address temperature above 50*C.

In a station blackout situation, ambient temperatures in the vicinity of the station service transformers are expected to be 54*C.

By engineering judgment, it is expected that the transformer life could be slightly affected.

However, with the expected loading being only approximately 70% and the expected temperatures being only 4*C higher, the loss of life will be minimal and operation during an SB0 can be reasonably assured.

Based upon available information and engineering judgment, the operation of the station service transformers at 54*C in a station b bckout is acceptable.

Drv-Tvoe Transformers:

Per ANSI C57.12.01-1979,

" General Requirements for Dry-Type Distribution and Power Transformers", ratings are based on a usual service temperature of 40'C maximum and 30*C average for any 24-hour period.

Under these conditions, the transformer's normal life is defined.

Temperatures higher than these represent a reduced life at rated loading.

0619I HL-396 21

Per ANSI C57.96-1959, " Guide for Loading Dry-Type Distribution and Power Transformers", these transformers may be derated by 0.6% per each degree higher than 30*C up to 50*C.

Hence, for operation of 50

C, the transformer should not be loaded more than 88% if transformer life is not to be sacrificed.

i All of the Safety Division II 600-120/208V transformers are loaded significantly less than 88%.

Based on similarity of

service, 600-120/208V transformers on both safety divisions of both HNP units would also be loaded to less than 88%.

Therefore, no loss of transformer life will occur for operation in ambient temperatures up to 50*C.

Based upon available information and engineering judgement, the operation of the dry-type 600/208/120V transformers at 50*C in a station blackout is acceptable.

9.2 MCR Set Point Card Reliability To assure that no spurious signals were generated due to temperature sensitive set point cards in the MCR (i.e., a spurious ADS signal due to temperature-related set point drift), a review was made of the set point calculations for the ATTS instruments.

The methodology used for the set point calculation of the ATTS instruments is the same as that used by General Electric per the Analog Trip Performance Specification.

For trip unit accuracy and drift, abnormal temperature (130*F) was used.

Therefore, set point stability for instrument cards (Master Trip Units and Slave Trip Units) in the MCR will not be affected by maximum temperature of 120*F in the MCR.

10.0 BATTERY AVAILABILITY 10.1 DC Power Capacity The station service batteries and diesel generator batteries are adequate to supply DC power to the equipment and associated control circuits.

The batteries have the capability to power the loads for a minimum of 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , even assuming a LOSP coincident with a LOCA, i.e., a design basis accident.

The loading of the batteries during an SB0 event is encompassed by the LOCA scenario.

1 l

Two hours of battery capacity is acceptable for Station Batteries lA and 2A (Essential Divi /on I), since the associated battery chargers will be available once the AAC source is connected and power is made available (in less than 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months ) to 600Vac load center buses 1R23-S003 or 2R23-S003.

0619I HL-396 22

7 l

4 i

L Two hours of battery capacity is acceptable for Emergency Diesel Battery 1B, since the associated battery charger will be available once EDG 1B is on-line.

1' The battery chargers for Emergency Diesel Batteries 1A and 2A (essential division I) are expected to be available for an SB0 event.

Motor control centers 1R24-S025 and 2R24-S025, which power the battery

chargers, will be powered by the AAC source when connected.

Therefore, 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months of battery capacity is acceptable for these batteries.

The battery chargers for Station Batteries 18 and 2B (essential division II) are not expected to be available for an SB0 event; therefore, only 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months of battery operation can currently be assured without additional calculations.

This 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months limitation must be noted in conjunction with the HPCI system.

However, no credit is taken for the operation of the HPCI system for SBO.

The battery chargers for Emergency Diesel Batteries 1C and 2C are not expected to be available for an SB0 event.

However, 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months of battery operation can currently be assured.

10.2 LOSS OF VENTILATION EFFECTS Per NUMARC 87-00, battery capacity is reduced if the electrolyte temperature drops significantly below design temperatures.

Class lE batteries are housed in seismic Category 1 structures and are not typically subjected to the direct effects of the external environment.

Therefore, the temperature decrease in the battery room is not significant over a 4-hour period.

Also, the mass of battery electrolyte is sufficient to resist significant temperature drops over a 4-hour period due to lower battery room temperatures, since battery cell materials are not efficient thermal conductors.

Therefore, a decrease in battery capacity due to temperature decreases in electrolyte under station blackout conditions does not warrant further considerat h.

Hydrogen generation rates are only an issue when the batteries are recharging.

Since current battery sizing calculations support discharges over a 2-hour period, the battery chargers will be required to be reconnected during the SB0 event.

Without ventilation and under worst-case hydrogen generation conditions, hydrogen concentration will not reach unsafe limits (27. by room volume) for at least 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months .

Since the battery room emergency exhaust fans will be available at the same time as the battery chargers, unsafe hydrogen levels will not be present during SB0.

Normal battery charging procedures should be followed.

0619I HL-396 23

a.

.11.0 ACCESS TO PLANT AREAS 5

11.1 SECURITY DOORS / CARD READERS i

Plant procedures address the access to those areas where operator actions are required.

The loss of normal AC power does not impact the performance of the HNP-1,2 security system due to the availability of a dedicated security diesel generator.

L 11.2 EMERGENCY LIGHTING Emergency lighting is available for eight hours to enable station operators to perform the necessary manual actions and MCR activity to cope with the SB0.

Emergency lighting is provided via emergency lighting cabinets connected to either the AAC source bus, the DC l

batteries, or the self-contained battery powered Appendix R lighting system.

12.0 CONTAINMENT ISOLATION REQUIREMENTS The 10 CFR 50 General Design Criteria (GDC) 55 through 57 specify requirements for isolating piping systems penetrating containment, including reactor coolant pressure boundaries.

These requirements call for combinations of redundant locked closed and automatic isolation valves for reactor coolant pressure boundaries and any I

containment penetration line directly connected to the containment atmosphere.

In cases where automatic isolation valves are used, the GDC specifies that the valves fail upon loss of power in a position which provides greater safety.

All other containment penetration valves must meet the requirements of the GDC by being automatic, or locked closed, or capable of remote manual operation.

As directed by NUMARC 87-00 and Regulatory Guide 1.155, appropriate containment integrity must be provided during the 4-hour coping period of the SBO.

Appropriate containment integrity is defined such that the capability for valve position indication and closure of certain containment isolation valves is provided independent of thE preferred or Class lE power supplies.

Per Regulatory Guide 1.155 Section 3.2.7 and NUMARC 87-00 Section 7.2.5, the following containment isolation valves are excluded from the above criteria:

a.

Valves normally locked closed during operation; b.

Valves that fail closed on loss of power or air; c.

Check valves; d.

Valves in non-radioactive closed-loop systems not expected to be breached in a station blackout (with the exception of lines that communicate directly with the containment atmosphere); and, e.

All valves less than 3-inch nominal diameter.

0619I HL-396 24

.o s'

Inspection of the containment isolation valves shows that most valves fall under the exclusion criteria of Regulatory Guide 1.155.

For each containment penetration, at least one of the redundant isolation valves meets the Regulatory Guide 1.155 exclusion criteria or may be closed manually or remotely.

The SB0 event does not require any valves to be manually closed for containment isolation.

Most of the containment isolation valves that do not meet the Regulatory Guide 1.155 exclusion criteria are either normally closed or parts of systems that are expected to be operational during various plant accidents.

Valves that are normally open during plant shutdown can be closed manually.

Valves that are normally. closed during plant shutdown may be verified closed.

Valve position indication will be available in the MCR for most DC valves and locally for all other valves.

13.0 CONDENSATE INVENTORY Regulatory Guide 1.155 and NUMARC 87-00 require HNP-1,2 to ensure that there is adequate condensate inventory for decay heat removal during an SB0.

An extensive review of the availability of sufficient condensate makeup to the RPV was performed and documented for the HNP-1,2 Appendix R program.

It was determined that sufficient condensate for shutdown is available in the condensate storage tank (CST).

The inventory is as specified in the HNP-1,2 Technical Specifications.

Since the SB0 path to shutdown closely follows the prescribed path to shutdown from the Safe Shutdown Analysis Report, then HNP-1,2 has adequate condensate inventory for decay heat removal during an SB0 of 4-hour duration.

i 14.0 COMPRESSED AIR AVAILABILITY In referencing the requirements of NUMARC 87-00 Section 7.2.3 and Regulatory Guide 1.155 Section 3.3.3, no credit is taken for the HNP-1,2 instrument (compressed) air system during the SB0 event.

All l

air operated, safety-related equipment will fail to the desired position upon loss of motive gas.

No station operator actions are required, upon loss of the plant compressed air system, to cope with an SBO.

The only components the station operators must operate which do require motive gas are the RPV safoty relief valves (SRVs).

The station operators may wish to cycle an SRV to control RPV pressure.

Motive gas to the SRVs is supplied by a safety-related nitrogen supply system.

Without any AC or DC power or operator actions, the nitrogen supply system will be available to supply motive gas to the SRVs upon

)

an SB0.

Additionally, there are accumulators on each SRV.

Power is available to the SRV pilot solenoid valves throughout the SB0 event.

l The major nitrogen supply system components are included on the SB0 Equipment List.

0619I HL-396 25

a.

9 s

,a 15.0 PROCEDURES AND TRAINING The following procedures have been implemented and are currently in use at Hatch:

a.

Restoration of Offsite AC Power for the Shutdown of Plant Hatch I

b.

Preparation for Severe Heather Conditions at Plant Hatch

\\

The procedures will be reviewed for SB0 considerations.

If necessary, changes to the procedures will be made to support the regulatory guidance relating to SB0.

The following procedures will be developed / revised and implemented (including the required operator training) at Plant Hatch to comply with the SB0 ruler a.

Station Blackout Coping Procedure b.

EDG 1B One Hour Manual Action Load Walkthrough Verification Assessment Test The Hatch SB0 related procedure review and update will be implemented no later than two years following notification of approval by the NRC of this Station Blackout Report.

16.0 PATH TO SHUTDOWN FOR THE NON-BLACKED OUT UNIT Special attention must be given to the non-SB0 unit per Regulatory Guide 1.155 and NUMARC 87-00.

Specifically, a failure of a redundant EDG on the non-SB0 unit must be considered.

The consequence of considering this failure is that the station operators must exhibit special attention to the remaining EDG's load to avoid an overload situation while attempting shutdown using only one EDG.

The non-blacked out unit can be brought to and maintained in a safe shutdown (hot shutdown) condition with one diesel.

17.0 MANUAL ACTION OVERVIEW Procedures and training will include all operator actions necessary to cope with a station blackout for at least 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months and to restore normal, long-term core cooling and decay heat removal once AC power is restored.

A manual action summary list has been developed which provides a list of specific operator actions and important considerations to assure that:

a.

Proper equipment protection is assured; 0619I HL-396 26

,/

1 b.

Compartment natural ventilation is established where necessary; c.

The SB0 unit's AAC source is not electrically overloaded; d.

The non-blacked out unit's EDG is not electrically overloaded; e.

Drywell cooling is maintained on the non-blacked out unit to avoid a LOCA signal generation.

f.

Reenergize the 600v busses as soon as possible.

18.0 CONCLUSION

The evaluation presented in this report demonstrates compliance to the Station Blackout Rule and Regulatory Guide 1.155 contingent upon operator training and procedure implementation.

A coping duration of 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months was determined using the referenced guidelines.. Emergency diesel generator 1B qualifies as an alternate AC power source and is available within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months to the blacked out unit. All required written procedures to demonstrate this 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months availability are planned and will be implemented by Georgia Power Company.

A combination of battery power and emergency AC power from the AAC source can be used to bring the blacked out unit to and maintain a hot shutdown condition from full power.. Adequate core cooling and equipment necessary to cope with a station blackout will be available without interruption to both the blacked out unit and the non-blacked out unit.

A reasonable set of operator manual actions will be proceduralized and implemented at HNP-1,2.

This final action will demonstrate complete compliance to the Station Blackout Rule.

1 1

06191 HL-396 27

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ML20244E258

Contents

Text

1.0 INTRODUCTION AND BACKGROUND

Conclusion:

SUMMARY

18.0 CONCLUSION

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ML20244E258

Text

1.0 INTRODUCTION AND BACKGROUND

Conclusion:

SUMMARY

18.0 CONCLUSION

Navigation menu

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