ML20197C700

Application for Amends to Licenses NPF-10 & NPF-15,reducing Pressurizer Water Level Required for Operability to Be Consistent W/Certain Updated FSAR Chapter 15 Events Which Were Recently Reanalyzed

ML20197C700
Person / Time
Site:	San Onofre
Issue date:	12/19/1997
From:	Nunn D SOUTHERN CALIFORNIA EDISON CO.
To:	NRC
Shared Package
ML20197C687	List: ML20197C685 ML20197C700 ML20197C728
References
NUDOCS 9712240255
Download: ML20197C700 (10)

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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Application of SOUTHERN-CAllFORNIA

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Docket No. 50-362 EDISON COMPANY, U AL.

for a Class 103

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License to Acquire, Possess, and Use

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a'Otilization Facility as Part of

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Amendment Application Unit No. 3 of the San Onofre Nuclear

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No. 158 Generating Station'

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LSOUTHERN CALIFORNIA EDISON COMPANY, H AL. pursuant to 10'CFR 50.90, hereby submit Amendment Application No. 158.

This amendment-application consists of Proposed Change Number (PCN) NPF-15-470 to facility Operating License No. NPF-15.

PCN NPF-15-170 is a request to-revise the Unit 3 Technical Specification 3.4.9, " Pressurizer," to be consistent with certain Updated Final Safety Analysis Report Chapter 15 events which were rece tly reanalyzed.

The proposed change will reduce the presserizer water level required for operability.

Subscribed on this day of EYlhbf P

, 1997 Respectfully submitted, SOUTHERN CALIFORNIA EDIS0N 40MPANY

-By Dwight E. Nugn Vice President kD DO 0361 P

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t l State of' California County of San Diego-l Ik 01 before me, Il [l RVID h E 1(b,

On personally-appeared ')ildh4 3 fE Alu su J

, personally known to

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= me to be the person whose ndine'is subscribed' to the within' instrument--and acknowledged to'me that he executed the same in his authorized capacity, and that by his signature on the instrument the person, or the entity upon behalf of which the person acted, executed the instrument.

WITNESS my hand and official seal.

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MARANE SANCHEZ f

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COMM # 1c33763 Wary Pdc - Contomia.f

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ORANGE COUNTY

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6 LE Comm. Expes OCT 14,1990 l

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DESCRIPTION AND SAFETY ANALYSIS OF PROPOSED CNANGE NUMBER NPF-10/15-470 Proposed Change Number 470 is a request to_ revise Technical Specification (TS) 3.4.9,-" Pressurizer," for San Onofre Nuclear Generating Station (SONGS)

Units 2 and 3.

EXISTING TECHNICAL SPECIFICATIONS AND BASES Unit 2:-

See Attachment 1 Unit 3:

See Attachment 2 PROPOSED TECHNICAL SPECIFICATIONS AND BASES Unit 2:

See Attachment 3 Unit 3:

See Attachment 4 UPDATED FINAL SAFETY ANALYSIS REPORT (UFSAR) CHAPTER 15 SAFETY ANALYSIS Units 2 and 3 See Attachment 5 DESCRIPTION OF CHANGE This proposed change is a request to revise the allowed water level for pressurizer operability in both the Technical Specification 3.4.9 Limiting Condition for Operation (LCO) and Surveillance Requirement (SR) 3.4.9.1.

The proposed allowed level for pressurizer operability is requested to be reduced to less than or equal to 57%. Technical Specification 3.4.9 currently requires the water volume to be less than or equal-to 900 ft (whichis 3

approximately 60% pressurizer level).

From certain safety analyses that were performed to support this reduction in pressurizer level it was determined that operator action time needed to be reduced from 30 minutes to 15 minutes to mitigate two types of events. These analyses are for Chemical Volume and Control System (CVCS) Malfunction and Inadvertent Emergency Core Cooling System (ECCS) Actuation During Power Operation. The adequacy of 15 minutes operator action time-has been demonstrated by SONGS operators.

Early operator recognition and actions to mitigate pressurizer overfill events within approximately 5 minutes have been demonstrated by operator. response experience on the SONGS 2 and 3 simulator and also in: actual plant operating conditions. Additionally, the availability of operator alarms and indications in the SONGS control room further support the adequacy of this reduced operator action time. Two other events in the Updated Final Safety Analysis Report (UFSAR) Chapter 15 Safety Analyses take

. t credit for operator action in less than 30 minutes. lThese events are Dropped Control Element Assembly (CEA)-and Boron Dilution; both credit operation action to mitigate the event within~15 minutes.

- For information only, Technical Specification Bases 3.4.9.is to be revised to reflect a less than or equal to 57% Pressurizer level and to correct the l

Background text by revising "2750 psig to "2750 psia."

Also for information, this' proposed change includes results-of the reanalysis of certain UFSAR Chapter 15 safety analysis events that are sensitive to pressurizer level (See attachment 5).

DISCUSSION i

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Background

--The control room indicated pressurizer level indication Total Loop Uncertainty (TLU)wasrecalculatedaspartofaSouthernCaliforniaEdison(SCE) program to evaluate instrument loop uncertainties in instruments used for Technical Specification Surve111ances. This TLU calculation was performed using the current instrument accuracy calculation methodology developed by SCE as part

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of the TLU program.

The recalculation yielded a control room indicated pressurizer level maximum TLU value of 3.9%.

Incorporation of this TLt' value 3

requires restricting Pressurizer Level to 57% (i.e., approximately 860 ft ),

which is less than the current Technical Specification 3.4.9 value of 900 ft'.

UFSAR Chanter 15 events that are sensitive to Pressurizer water volume were reanalyzed to accommodate the 3.9% TLU by assuming a bounding 4.0% TLU.

The events are the Chemical and Volume Control System (CVCS) Malfunction with and without Concurrent Single Failure of an Active Component (UFSAR Sections.

15.5.2.1and15.5.1.1),InadvertentOperationoftheEmergencyCoreCooling System (ECCS)duringPowerOperation(UFSARSection15.5.1.2),andFeedwater Systein Pipe Breaks (UFSAR Section 15.2.3.1).

Additionally, " Inadvertent 4-Operation of the ECCS During Power Operation was analyzed with concurrent single failure of an active component." The results of this analysis, which are bounded by the results of a Chemical and Volume Control System (CVCS)

M*.~ unction, will be added to the UFSAR as Section 15.5.2.2.

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. Analyses

The reanalysis of these events was performed using the approved CESEC-III computer code. The analytical value assumed for pressurizer level was 61%

-(i.e...theproposed57%TechnicalSpecificationvalue.andupto4.0%TLU).

.The results of the reanelyses are summarized as follows:

1.

UFSAR Section 15.5.1.1, Chemical and Volume Control System -

Malfunction Summary of Analysis The CVCS' malfunction is classified as a moderate frequency event.

The initiating malfunction is a failure of the pressurizer level control system which could initiate operation of all 3 charging pumps and' isolate letdown.

Depending on the failure mode the pressurizer level control system may not automatically terminate the event, so that operator action would be required. Various pressurizer level and pressure control indications and alarms are available to alert the

-operator of the event. Operator action within 15 minutes to correct the additional charging f'ow will terminate this event prior to filling the pressurizer.

The operator action tir: for this event was previously 30 minutes.

In order to support a reduction of the operator action time required for this event from 30 minutes to 15 min'utes SCE performed a simulation of this event on the Full Scope Simulator. Operators recognized and terminated this event on the Simulator in approximately 5 minutes.

Operator simulator training and available alarms and indications in the control room support early operator recognition.

It is also important to note that the CVCS malfunction event occurred at SONGS Unit 3 on March 2, 1995.

For this_ case operator action was implemented within approximately 5 minutes which terminated the event, demonstrating that an operator response time of 15 minutes can be accommodated.

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UFSAR Section 15.5.2.1 Chemical and Volume Control System Malfunction with a Concurrent Single Failure of an Active Component Summary of Analysis The CVCS malfunction with a single failure-is classif15d as an infrequent event.

The results are similar to those discussed in Item 1 above with'the exception of the. single failure. The worst case single ~

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a failur_e postulated forL this event is the loss of offsite power at the=

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l time.of reactor _ trip._:An_ operator. action time of 15 minutes has been

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1dentifiedtojmitigatetheconsequencesofthisevent.--Basedonthe savailability.of-operator alarms-and-indications and operator Simulator training, 15 minute operator action is sufficient to~ recognize and

mitigate the inadvertent-CVCS with single failure event,

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-UFSAR Section 15.5.1.2 Inadvertent Operation of the ECCS During-l Power Operation i

E Sumary of Analysis An inadvertent operation'of the ECCS is classified as a moderate-frequency event. The. initiating cause is an unplanned increase. in:

reactor coolant: inventory due to operator error that. erroneously _

actuates a safety: injection actuation signal- (SIAS). The inadvertent

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-SIAS' activates all three charging pumps, isolates letdown-flow, starts.

theboricacidmakeup(BAMU)-pumps, shifts.chargingpumpsuctiontothe highly borated BAMU tanks, starts the. safety injection pumps, and isolates instrument air to containment. The boration causes a reduction-

in Reactor Coolant. System (RCS) temperature and associated shrinkage in pressurizer-liquid volume, which partially mitigates the excess charging

' flow. A reactor. trip eventually-occurs on high pressurizer-pressure or on low steam generator pressure during the plant cooldown.

As a result of the boration af the RCS, the consequences of this event are less adverse than the CVCS malfunction event described in UFSAR Section 4

15.5.1.1 and there is at least as much time for operator' action as in the CVCS malfunction event.

Therefore, there is at least 15 minutes for the operator-to correct the malfunction and prevent filling of the Pressurizer..

4.

UFSAR Section 15.5.2.2 Inadvertent _0peration of.the ECCS During Power Operation with a Concurrent Single Failure of an Active Component Sumary of' Analysis The inadvertent Operation ~of the ECCS with a single failure is classified as aniinfrequent event.

The results are similar to those discussed in Item 3 above with the exception of the single failure.- The

. orst-case single failure postulated for this event is the loss of-w F

- offsite' power at the time of reactor trip. ' As a result of the boration t

of the RCS, there is at-least as much time for operator action as-in the CVCS malfunction with conctrrent single failure event described _in UFSAR.

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section 15.5.2.1

Therefore, there is. atsleast 15 minutes for the operator to correct the malfunction and prevent filling of the Pressurizer.

5.

UFSAR Section 15.2.3.1, Feedwater System Pipe Breaks 1m atry of Analysis Thr. feedwater system pipe break is classified as a limiting fault. event.

The initiating event is a break in a pipe in the main feedwater system.

- A rupture of a feed line will.cause rapid reduction of the liquid inventory in the affected steam generator and therefore create a partial loss of the secondary heat sink. This leads to heatup of the RCS and an increase in RCS-pressure. A reactor trip could occur through either a low Steam Generator Water Level Trip, a low Steam Generator Pressure Trip, or a High Pressurizer Pressure Trip.

Loss of non-emergency AC power was assumed at the time of reactor trip.

Operator action to mitigate the event is assumed to occur 30 minutes after initiation of the event.

Peak RCS pressure will remain below the acceptance criteria of 120%.of design pressure, and no water will be released through the pressurizer safety valves for the maximum RCS pressure case.

C.

Plant Operation Accounting for the pressurizer level control room indication TLU of 3.9%

(boundingsafetyanalysisvalueof4.0%)intheTechnicalSpecification effectively lowers the allowed pressurizer level for operability.

Currently, the Technical Specifications specify a level for operation at less than or i

equal to 900 cubic feet (which corresponds to approximately 60% level).

With

-a TLU value of 4.0%, the Technical Specification control room indicator value needs to be reduced to 57% to be consistent ~f t'i the safety analyses which were done at 61% pressurizer level. The norni full power pressurizer level for plant operation is approximately 53%. Administrative controls have been implemented to ensure that the pressurizer level does not exceed 57% during operation. SCE has determined that steady state pressurizer operation above 57% during power operation has not occurred.

SAFETY ANALYSIS 1.

Will operation of the facility in accordance with this proposed change involve a significant increase in the probability ur consequences of any accident previously evaluated?

Response: No The limiting events impacted by this Technical Specification change have been reanalyzed.

These events are the Chemical and Volume Control System (CVCS) Halfunction and CVCS Malfunction With a Concurrent Single Failure of an Active Component, Inadvertent Operation of the Emergency Core Cooling System (ECCS) During Power Operation (Including Single Failure of an Active Component), and Feedwater System Pipe Breaks. The probability of these events is not changed by the restriction of the pressurizer level to 57%.

An operator action time of 15 minutes has been identified for the CVCS nialfunction and inadvertent ECCS operation events.

Based on the availability of operator alarms and indications and operator Simulator training, 15 minute operator action is sufficient to recognize and mitigate the inadvertent CVCS or ECCS operation.

Therefore, this change will not involve an increase in the probability or consequences of any previously evaluated accident.

2.

Will operation of the facility in accordance with this proposed change create the possibility of new or different kind of.ccident from any previously evaluated?

Response: No This amendment request does not involve any change to plant equipment or operation.

All the events identified in Chapter 15 of the Updated Final SafetyrealysisRepcrt(UFSAR)wereevaluatedtodeterminetheimpactof the cham in pressurizer level.

In addition to the normally analyzed Inadvertent Operation of the ECCS During Power Operation event a concurrent single failure of an active component was considered in this evaluation.

The analysis of this event with single failure of an active component produced consequences that are bounded by the CVCS malfunction with 31ngle failure of an active component.

No new or different kind of accident wl11 be created as a result of this Technical Specification change.

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

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Will operation of;the1 facility intaccordance with this proposed changeL 1

= involve:aisignificant^ reduction in a' margin of~ safety?

j 1 esponse:-- Noi R

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This1 amendment; request does'not change Lthe manner -in which safety 1

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ilimits, zlimitingLsafety settings, or limiting; conditions for operation ~

3 are determined. 'There are no changes"to the acceptance criteria;for.

these events asia result of the proposed-reduction.in the maximum:

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-pressurizer water level. - This change does.not reduce a margin of safetyJ ~

- since it lowers allowed: pressurizer operationalElevel to.57%.

An:

1 operator action 3 time of:15 minutes has been identified;for the CVCS:

malfunction and inadvertent ECCS operation events.

Based on the Lavailability of-operator alarms-and indications, and. demonstrated operator response in: Simulator training,'15 minute operator action has

been demonstrated to be adequate to. recognize and mitigate the 11nadvertent CVCS or ECCS operation.. Therefore, this proposed change

'does'not involve a reduction in a_ margin of safet"

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l SAFETY.AND SIGNIFICANT NAZARD$' DETERMINATION Based on the above Safety Analysis, it is concluded that:

(1) the: proposed 3

change does not constitute significant hazards consideration as defined by 10CFR50.92~and(2)thert 3 reasonable assurance that the health and safety

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of the public_ will not be endangered by the proposed. change. Moreover, because this action does not involve a significant hazards consideration, it will also not result in a condition which significant1y' alters the' impact-of:

. the station on the environment as described in the NRC Final Environmental Statement.-

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ATTACHMENT 1 EXISTING TECHNICAL SPECIFICATIONS AND BASES UNIT 2 2

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