ML20127B800

Discusses Recently Completed Evaluation to Determine Appropriate Course of Action for Licensees to Take Following Inadvertent Containment Spray Event.Licensee Should Perform Immediate Assessment & Develop Action Plan

ML20127B800
Person / Time
Site:	Crystal River
Issue date:	03/13/1991
From:	Murley T Office of Nuclear Reactor Regulation
To:	Martin T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20127B805	List: ML20127B800 ML20127F479
References
NUDOCS 9103250397
Download: ML20127B800 (9)

Text

/'

ATTACHMENT To NRC 1R 50-302/92-25 MAR 131991 HEMORANDUN FOR: Thomas T. Martin, Regional Administrator O' Region !

Stewart D. Ebneter, Regional Administrator Region II A. Bert Davis, Regional Administrator Region !!!

Robert D. Martin, Regional Administrator Region !Y John B. Martin, Regional Administrator Region Y FROM: Thomas E. Murley, Director Office of Nuclear Reactor Regulation

SUBJECT:

INADVERTENT CONTAINMENT SPRAY EVENTS AT COMMERCIAL NUCLEAR POWER PLANTS The Division of Systems Technology (DST) recently completed an evaluation to determine the appropriate course of action for licensees to take following an inadvertent containment spray event. The staff's review was initiated following the most recent of these events which occurred at San Onofra Nuclear

(

Generating Station, Unit No. 2, on November 20,1990. It is interesting to note that 12 of these events have occurred over the past 10 years, six of which occurred during Mode 1 operation.

Based on its review, DST concluded that each containment spray event should be evaluated by the licensee and action should be taken as appropriate based on the results of that evaluation. Unless the specific circumstances of the event dictate otherwise, the licensee should recover from the containment spray event, perform an imediate assessment of existing plant conditions, and develop an action plan to fully address the consequences of the event. Any-deficiencias identified should be evaluated in terms of generic imp 1tcations and appropriate corrective actions shwuld be taken, including reactor plant shut down if warranted.

Although the frequency of inadvertent containment spray events appears to be

! decreasing, it is likely that these events will continue to occur occasionally.

Because an event of this nature can cause significant degradation of plant

, CONTACT: J. Tatum l x20805 l

,- f!

( Le/vam~ y:Ap L m o e y _/ '

n.~. ~ , , , . - . -

~

Regional Administrators 2 SU ' f.

• i.:t equipment, it is important that the Regions follow these events very closely to assure that Itcensee actions are appropriate for the circumstances involved.

I have enclosed a copy of the stsff's SE for your information and future reference. ,

oristnai signed b5 gomas E. geiet <

Thomas E. Murley Office of huclear, Director Reactor Regulation

Enclosure:

Safety Evaluation cc w/ enclosure:

J. Snierek J. Partlow W. Bateman J. Caldwell O DISTRfDUTION Central filei SPlB File TMurley FHiraglia WRussell AThadani GHolahan GFubbard JTatum O

Enclosure SAFETY EVALUATION EY ME viY!$10N OF SYSTEMS TECHNOLOGY REGARDING INADVERTENT CONTAINMEhT SPRAY EVENTS AT COM,'iERCIAL llVOLEAR POWER PLANTS

1.0 INTRODUCTION

On November 20 1990, an inadvertent containment spray actuation occurred at SanOnofraNuclearGeneratingStation,ViitNo.2(50NGS2). The unit was operating at 100 percent power when approximately 5.000 gallons of berated water Southern California wassorsyedintocontainmentduring)surve111sneetesting.

Edison Company ($CE or the licensee opted not to. shutdown 50 following this event based on previous experience with a similar event that occurred in 1984 at 50NGS 2. Following the 1984 avant, SCE conducted a detailed inscoction and testing orogram to evaluate the effects of containment sorsy on equipment and, based on the results of that evaluation, SCE judged that the borated water that was sprayed during the event did not have any imediate adverse effects on safety-related equipment. Therefore, 3CE judged that .'

50NGS-2 could continue to operate following the 1990 avant while a thorough evaluation was completed. It was not unti SCE found a ground indication

- estociatedwithoneofthecontrolelementdrivemechanism(CEDM)motorgenerator sets that SCE decided to shutdown 50H 5 t in order to perform additional and 50NGS 2 was subsequently shutdown troubleshooting on and repair November 23, 1990. The of the CEDHs,ided licensee prov a description of its actions following this event in a letter dated November 27,1990, and Licensee Event Report (1.ER) No. 90-14 was submitted for 50NGS 2 regarding this event on Oscarber 20,1990.

Following the 50NG5 2 event, the Division of Systems Technology (D5T) was requested to evaluate whether the actions taken by SCE were sopropriate and in general to determine the appropriate course of action for licensees to take following a containment soray event. Therefore, the purpost of this safetyevaluation(SE)istoaddresstheseissuesandtoprovide recomendations as accrooriste.

2.0 REY!EW HETH000 LOGY In order to determine whether SCE's actions in response to the conuinment scray event of November 20 1990 were acceptable and in developing a position regardingwhatthesporoorlateIIcenseeresponseshouldbefollowinga containment spray event, the staff reviewed inforeation to determine what effects containment spray could have on plant systems and components. In this regard, DST reviewed information certaining to previous containmant spray evtnts and other industry experiences that m87 have so:ne relevance.

05T also considered Technical Specification requirements and environmental qualification requirements during the review.

3.0 PREVIOUS CONTAINMENT SPRAY EVENTS Following the containment spray event that occurred at 50hG5 2 on Neverber 20, 1990,theOfficeforAnalysisandEysluationofOperationalData(AE00)Derformed

-2 A study of pt 1ous containment spray events that have occurred. The results of that studj w re documented in a remorandum dated December 6, 1990. The AE00 study encNded that "...there was a limited amount of short term damage these aveets.

caused electricab)l shorts a d corrosion.Some electrical The fact equipment that electrical equipment was degraded inside due to containment must be cesigned to operate during postulated accident environments (e.g., hot ans wet) appears to havs limited the damage to safety-related equipment..."

The date compild by AE00 regarding cor'sinment spray events is represented in Table l'. A review of this data indicates that the containment spray events to data have had minimal impact on both ufety related and on nonsafety-related equipment. Of the six events that occurred during power operation, only one event was identified where the licensis decided to shut down the reactor to facilittte subsequent inspection and testing activities (Oyster Creakt December 21,19M). Also, one event wat identified where an inadvertent ECCS actuation initiated emergency boration which causod tb reactor to shut down in addition to initiating containment spray (San Onofo , March 9,1984). The amount of water sprayed during inadvertent containment spray events ranged typically from several hundred gallons to several thousand gallons.

For the most part, the LERs reporting previous containment spray events did O not provide much detail regarding actices taken to identify and resolve equipment deficiencies resulting from these events and specific deficiencies identified during stniquent follow up inspections were not described (the LERs for the Armaunee event (305/85-01) hndtheCalvertCliffsevent(317/87-08) were a little better than the other LERs in this respect). Although the LERs were lacking in details of this nature, licensees typically concluded that safety-related equipment was not damaged as a result of the containment spray events.

4.0 RELEVANT INDUSTRY EXPERIENCE DST performed an abbreviated review of relevant industry experience and HRC generic comunications in order to identify potential effects that containment spray events could have on plant equipnnt. The review focused principally on moisture intrusion and corrosion problems.

Inferration Notice 84-57 " Operating Experience Related to Moisture Intrusion in Safety-Related Electrical Eripment at Cemerciti Power Plants," dated July 27, 1984, and Information Notice 89-63, "possible Submergence of Electrical Circuits Located Above the Flood Level Because of Water intrusion and lack of Drainage," dated Septerter 5, 1989, discuss-potential electrical equipment problems that can occur as a result cf moisture intrusion. In most instances, moisture intrusion will cause electrical components to short-circuit, corrode, and ultimately fail. Additional industry experience indicates that, :iven the 9 proper circumstu nes, snubbers een becce, inoperable as a result of pralonged submergence an! N ric acid solutions can cause significant corrosion and degradation of carbon steel materials. However, QST believes that for the most part, these ef ? acts are eithe* imsdiately obvious or occur over a prolonged period of time such that licensees nay evaluate tae e'fects of moisture intrusion on plant equipment witho. necessarily shuu :ng down the reactor.

4

" - - - - - ~ _ . . _ - _ _ _ _ _ _ . _ _ _ _ _ _ . _ __ _ _ _ _ _ _ _ _ _ _ _ _ _

O ->-

TABLE 1 COMPILATION OF C0_NTAINHENT SPRAY EVENTS Event Amount Facility Date Mode 30 rayed Cements 5t. Lucie 1 11/3/78 5 2000 gal No damaged equipment (PWR) (LER335/78041)

NC 2 4/8/80 3 300 gal Effect on equicment not

PWR) specifically addressed (LER368/80-24)

$squcyah 1 2/11/81 5 100,000 gal Effect on equiement not (PWR) specifically addressed (LER327/8121) ,

San Onofre 1 9/25/81 5 400 gal No damaged equiement

( PW'.) (LER206/8123)

Oyster Creek 12/21/82 1 2200 gal Plant was shutdewn fer (BWR) testing)andinscaction (noLER Kewaunea 2/21/83 1 -- ICS ocerated for 15 sec.

(PWR) containment inscected, no-damage _

(LER30$/8306)

AND 2 3/8/83 1 2450 gal Visual inscection, no (PWR) damage

(>JR 368/8315)

San Onofre 2 3/9/84 1 6000 gal ECC$ actuation also (PWR) caused emergaaty beration and plant shutd wn, inscection and testing performed, no damage (LER361/84-16)

Palisades 7/19/84 4 3000 gal Effect on equiement not (PWR) scecifically addressed (LER255/84-11)

Pilgrim 1 9/29/84 6 10,000 gal Damage to lagging

(~~'

s (BWR) (LER293/84-15)

O TABL5 1 CONTINUED Event Amount facility Date_ Hode Sornyed Coccants Kewaunee 1/22/85 1 2500 gal Plant shutdown on 2/8/85 for refueling, misc.

(PWR) sourious indications related to nonsafety-related equipment, battery ground alarms on A and B batteries, subsequent sourious start of RCP on 2/10/85 (LER305/85-01)

Waterford 3 2/20/85 3 500 gal Minor ground on colar crane, isolation of CCW (PWR) caused degradation of RCP seals (LER382/85-06)

Calvert 4000 gal Inspection and testing 4/14/87 5 conducted, no damaged Cliffs 1 equipment (PWR)

(LER317/87-08)

San Onofra 2 11/20/90 1 5000 gal Insoection and testing._

subsequent shutdown due (PWR) to degraded CEDM electrical connectors (SCEletter 11/27/90; LER361/90-14)

O

- - . - .. . = - .

O 5.0 TECHNICALSPECIFICATIONANDEJVIR0hMENTALQUALIFICATIONREQUIREMENTS Technical Specification requirerents specify limiting conditions for operation (LCOs) that must be satisfied during various modes of reactor operation. The Technical Specifications do not soscifically require that reactors be shut down fellcwing containment spray events, but licensees must satisfy LC0 requirements for equipment that becomes degraded as a result of these events. Additionally, decending on the specific circumsten:es involved, certain LCOs may be directly imoneted following containment spray events and these LCOs deserve scacial consideration. For example rea:ter coolant system leakage detection systems may become degraded, the ability to satisfy operational leakage surveillance requirements may be impacted, the inventory of trisodium phoschate (for iodine removal) may be affected, ice condsnser cerformnce capability may be degraded, refueling water storage tank level cay se reduced, etc. Therefore, scacific act15ns required by Technical Specifications following containment spray events will depend on the actual circumstances involved and licensees should croceed accordingly.

Safety-related equipment located insida containment must be environmentally

• qualified in accordance with 10 CFR 50.49 requirements and, to a large degree, this helos to minimtze the adv vse effects that containment spray will have on this equipment. However, environental qualification (EQ) requirements vary decending on how long the eemoonent must function following an accident.

O' Some comoonents may only be qualifie( to function for a few minutes into an accident while others may et qualiftad to function for the duration of the accident. Depending on the circumstances, containment spray events could jecoardize the qualification status of ;omeonents that are not required to coerete cost-accident. Therefors, the EQ status and ocerability of equiement located inside containment must be evaluated in detail following containment -

spray events and corrective actions cust be taken as accropriate.

6.0 STAFF POSITION The infomation reviewed by DST as discussed in this safety evaluation indicates-that inadvertent containment spray events do not necessarily cost an imediate nuclear safety hazard and reactor shutdown following such events may not be necessary. In fact, an imediate reactor shutdown following a containment scray event could make it difficult to fully assess the effects of the event on plant equipment and could further confuse the situation if any complications occur while shutting down the plant. Additionally. Technical Specification requirements and EQ requirements do not impose restrictions on continued reactor coeration following containment spray events. Therefore, unless the specific circumstances of the event suggest othnwuo, continued reactor operation following containment spray events is N otable. However continued coeration must be succorted by an imediats asser.. ant of plant conditions and an action plan must be developed to fully evaluate the consequences of the event on plant systems and comoenants. Any deficiencies identified should be

.g evaluated in terms of generic imolications and corrective actions should be taken as accropriate, which could include subsequent reactor shutdown.

6-As a minimum, the licensee's incediate assessment of plant conditions should include the following considerations:

(a) Duration of the event and tha accunt of water sprayed.

(b) Spurious equipment actustions, grcund indications, and alarms.

(c) Compliance with Technical Specification requirements.

The licensee's action plan to fully evaluate the consequences of the event on systems and components should include as a minimum the following elements and consideYations. ,

(a) Personnel hazards.

(b) Duration of the event and the amount of water sprayed.

(c) Containment type and configuration of systems and components located inside containment.

(d) Appearance of accessible artes of containment.

(e) Control room indication and annunciation.

(f) Operability of safety-related equipment and compliance with Technical Specification requirements.

(g) Operability of nonsafety-ralated aquipment and electrical interaction considerations.

(h) Containment spray system status and boron precipitation considerations.

(1) Ssatus of snubbers and long ttrm effects.

(j) Status of equipment qualification and long term effects.

( k) Statusofmaterialsandlongtermeffects(i.e.,acceleratedcorrosionof carbon steel, thermal shock, etc.).

(1) Development of short term sH ions term inspection, testing, and surveillance programs.

(m) Previous industry experience.

The actions taken by SCE in response to the 50NGS-2 containment spray event of November 20, 1990, as descriced in their letter dated November 27,19901 satisfies the staff's positien on this issue and are therefore acceptacle in most respects. However, in reviewing the November 27 letter, it is not 9 apparent that $CE completed a detailed review of Technical Specification requirements following the event, and SCE's planned review of industry experience should not be narrowly focused on previous containment spray events but should also include a review of industry experience and M "' , 3 3 * ** m -

e _m.- _ _ _ __ _ . _. _ _ _ _ . _ _ _ _ ______m __

NRC generic comunications that may b4 relevant (i.e., moisture intrusion problems,bericacidcorrosionproblens,etc.). SCE should take action as appropriate to correct these weaknessoa.

As a comparison, D5T would question the decision that was made by Wisconsin Public Service Corporation to continue reactor plant operation following the Kewaunee containment spray event of January 22,1985(seeTable1). The battery ground alarms could have been Indicative of seriously degraded safety-related equipment, and the generic implications relative to EQ would have to be addressed. In this case, continued operation ray not have been appropriate.

Therefqre, it is important to recognize that the Regions must play an important role in following events of this nsture and in as.suring that tie actions taken by Itcensees are appropriate.

The staff's position is based in part on an abbreviated review of industry experience as discussed in Section 4,0 of this safety evaluation. SCE plans to complete a detailed review of industry experience as part of their continuing evaluatien of the SONGS-2 containrent spray event, and Dst will review the details and results of SCE's study to assure that the staff's position on this matter remains valid.

7.0 CONCt.USION Based cr. the foregoing evalur, tion, OST has concluded that continued reactor operation following inadvertert containment spray events is acceptable provided that the specific circumstances of the event do not warrant imediate reactor shutdown. In addition, the actions taken by SCE in response to the

$0NGS-2 e,,ntainment spray event of November 20, 1990, are acceptable in most respects. However, some improvements should be made in SCE's evaluation as discussed in Section 6.0 of this SE.

Author: J. Tatum Date: January 29,1991 O .

l

)

(} Southem Califomia Edison Company e3 #AAFE84 STRFr?

TRvib r, C AUFORNIA 9 2718

... . m .........

I November 27, 1990 i

Hr. John B. Martin, Administrator U. S. Nuclear Regulatory Commission, Region V 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596-5368

Subject:

Docket No. 50-361 Actions Following Inadvertent Containment Spray Actuation San Onofre Nuclear Genentino Station. Unit 2 PURPOSE On November 20, 1990, San Onofre Unit 2 experienced an inadvertent actuation of the Containment Spray System and ather Engineered Safety Feature (ESF) systems during performance of the 'equired monthly channel functional test.

As a result, approximately 4,800 gallons of barated water were discharged into containment during full power operation.

The purpose of this letter is to describe actions taken by Southern California Edison (SCE) as a result of this discharge of the spray water into containment. It is submitted pursuant to discussions between SCE and NP.C staff concerning the scope and sequence of these actions.

SUMMARY

Based on the evaluation of the results of a similar event at Unit 2 in 1984, i SCE initially maintained the unit in stable power operation while conducting inspections and tests to determine if the spray had adversely affected any systems or equipmert. This was dona in a sequence which assigned the highest priority to safety systems.

Although no safety systems were affected by the spray, degraded electrical conditions were identified for a portion of the pcwer supply to the Control Element Drive Mechanisms (CEDMs). Accordingly, Unit 2 was shut down-on November 23, 1990, in order to correct these conditions.

O c;gxixt2ss-

l

~

BACKGROUND

( On March 9, 1984, Unit 2 experienced a similar inadvertent initiation of E5F systems during power operation which resulted in approximately 6,000 gallons of borated water, mixed with about 65 gallons of 42 weight percent sodium hydroxide, being discharged into containment. (Note: Sodium hydroxide is no longer injected into the containment spray flow.)

As a result of that event, SCE impis m ted a detailed inspection and testing program to evaluai.e the spray effects. The program and results are summarized in Enclosure A hereto. (In addition, containment spray was initiated inadvertently at Unit 1 during pcwer operation in 1981.)

DISCUSSION Based on SCE's prior experience follnwing containment spray actuation at power, it was expected that the borated water would not have any immediate, adverse effect on safety related sy>tems or equipment within containment.

Also, SCE considers that under nny circumstances where the status of systems or equipment needs to be verified for any reason, such verification should be conpleted prior to undertaking a major change in plant status, including shutdown. This is consistent with Generic Letter 87 09 which notes in connection with shutdowns resulting from missed surveillance intervals that,

...it usually would be preferable to restore (the system or component) to service before making the change in plant operating conditions".

O V Inmediate Actions Accordingly, Unit 2 was maintained in stable power operation immediately following the event on November 20th while the following actions were taken:

o Verification of proper ESF actuation, o Physical inspection of accessible areas inside containment. As expected, the containment was essentially dry with only light water spotting of equipment surfaces noted.

o Verification that trisodium phos) hate used for recirculation flow pH control was not affected by tie spray.

o Review of our Redundant Instrument Monitoring System to detect any deleterious effect on operational instrumentation. No degradation was noted in any of the 140 instruments monitored by this system.

o Review of ground alarm r9ceived cc, non 1E uninterruptible power supply. This alarm was cleared by opening the circuit breaker supplying power to the movable incore detectors.

o Walkdown of ESF piping and equipment outside containment. No evidence of damage was fecnd, g

l Subsecuent Actions The immediate actions verified proper operation of safety related and environmentally qualified (EQ) equipment. Subsequent actions focused on longer term conce"ns, (such as possible corrosion of piping and pipe support members within containment) and effects of the spray on non safety related, non-EQ equipment. On November 22, 1990, while performing monitoring of critical equipment wnich is considered to be a trip hazard, a ground indication on the output of the CECM utor generator sets was detected. On Novemoer 23rd the unit was shut dovn tu enable further troubleshooting and repair. These investigations identified unacceptable resistance readings on several CEDM circuits.

The cause of the unacceptable readings on these CEOMs was moisture intrusion into the connector assembly at the containment penetrations. These connectors and other CEDM connectors mounted in a similar manner have been disassembled, cleaned, and verified to be fully curable.

Coincident with the shut down of the unit an extensive inspection and testing plan was undertaken. Enclosure 3 provides a summary of the actions performed.

These actions complete our prompt 'esponse to the event. Additional monitoring for potent.al long tern effects, such as deterioration resulting from residual boric acid, are discussri in the enclosure.

CONCLUSION Based on the inspections and testing performed it is concluded that there were O no deleterious effects of the contatament spray on safety-related equipment.

The degraded electrical conditions on the CEDM circuits would not have affected the ability to safely shut down the unit, although it did have the potential for one or more dropped CEAs.

The actions described in this latter complete our prompi response to the event. Additional monitoring for long term effects will be performed.

If you have any questions or comments concerning this event and our follow up activities, please let me know.

Sincerely, h& .b t

i cc: Mr. J. H. Taylor, USNRC Executive Director for Operations Mr. C. W. Cald , USNPC Senter Resident Inspector, SONGS Project % ager, SONGS 2 and 3 O

G

Enclosure A Inspection and Testing Program to Evaluate' March 9, 1984 Inadvertent Containment Spray The inspection and testing program to evaluate the March 9,1984, containment spray included the following:

inspection of junction boxes and connectors inspection and calibration of selected instrumentation inspection of selected electrical penetrations inspection of major equipment, including HVAC units, reactor coolant pumps, hydrogen recombiners, etc.

stroking of selected valves inspection of safety injection tanks O inspection of all snubbers V -

1/4 to 1/2k) and wipe down, if necessary, on elosation $5'(and above in the spray path determination of the long term effects of spray on components; e.g. chemical effects on cable insulation:

As a result of this program it was concluded that_ no component or system damage resulted from the containment spray.

O c - . _ . _. - . .. . .

Enclosure B UNIT 2 POST-CONTAllmENT_SPPAY STATUS AND ACTIO_N PLAN COMPLETED ACTIONS I. Containn.ent Area Inspection Inspection of all accessible areas inside containment was performed to assess the inpact of the containment spray.

The containment was fourd to be essentially dry with only light water spotting of equipment noted. Structural -

members were determined to not likely be affected by the spray actuation. Where appropriate, isolated puddles inside containment worn cleaned up.

II. Electrical Equipment Inside Containment on November 22, 1990, degraded resistance was detected on the output of the contro.' element drive mechanism (CEDM) motor generator sets. It was concluded that the degraded resistance was located in either the CEDMs, the CEDM control System, or the Reactor Trip Breakers. As a O result, Unit 2 was shutdown on November 23, 1990 in order to enable further troubleshooting and repair.

The investigation found degraded resistance on the five CEDM circuits associated with electrical penetration 94 and two CEDM circuite associated with penetration 97. The degraded resistance was found to be located inside of -

containment in multi-pin connectors which connect the containment penetration conductors to the remainder of the in-containment CEDM circuitry. These non-EQ connectors were all exposed to direct impingement of containment spray since they are mounted at the top of a cabinet with the wiring from the CEDM entering the top of the connector. Inspection of the internals of these connectors identified roisture intrusion and pre-existing corrosion. The corrosion is unrelated to this event. The moisture combined with the corrosion led to the degraded resistance.

There are a total of twelve electrical penetrations associated with the CEDM system. Of these penetrations, nine have the connectors mounted at the bottom of the connector cabinet and three have the connectors mounted at the top of the cabinet (psnetrations 94 and 97 (discussed r

( l 1

1

I d

above), and 95). All of the top mounted connectors for the CEDM system havo been disassembled, cleaned and O verified to be fully operable during this outage.

A containment walkdorn was performed to identify any other penetration enclosurun with top panel entry of cables.

Although no other configurations sinilar to the CEDMs (i.e., with top mounted connectors) were found, 24 of the remaining 60 electrical penetration enclosures have cables passing through the top panel. To determine the acceptability of those configurations, a sample of 10 of these enclosures was examined for moisture intrusion. The termination conditions were found to be satisfactory in all cases.

In addition, a sample of non-EQ junction boxes inside containment were also opened and found to be dry with no evidence of being wetted by containment spray.

III. ESF piping Inspections A walkdown of ESF piping and mechanical equipment outside of containment was performed to ensure there was no damage due to water hammer or other causes. No evidence of damage was found.

IV. Mechanical Equipment Innide Containment Inspection of the mechanical equipment inside of containment indicated that those components which were exposed to the containment spray were found to be dry and in satisfactory condition with only light water spotting noted. Components inepected included valves, reactor coolant pumps, the reactor vessel head area, safety 1 injection tanks, sections of uninsulated piping, the CEDM coolers, the normal and emergency containment coolers and snubbers.

A thorough visual inspection of fourteen snubbers was performed (the snubbers were selected based an accessibility, exposure to the spray, and orientation, and are considered representative of the containment snubber population). Similar to observations of other equipment exposed to the spray, light water spotting was noted but there was no evidence of moisture accumulation or other indication of spray induced damage. Additional inspections and testing are planned for future outages as noted below in long term actions.

2 1,

l -

V. Instrumentation Monthly surveillanen tosting of a sample of safety related instrumentation (Remoto shutdown and Post Accident Instruments) was accelerated. No anomalous conditions were noted. Accordingly, subsequent surveillances will be continued on the previously scheduled interval.

In addition to performing those accelerated surveillances, a review of the Redundant Instrumentation Monitoring System (RIMS) data war. conducted following the containment spray actuation. RIMS provides a database which permits the trending of the output of selected instruments, many of which are located inside containment. The system records and stores the output of critical plant parameters (e.g., pressurizer pressure and level, RCS temperatures, containment pressure and temperature, etc.) and is equipped with the capabi'.ity to construct graphs and charts which can indicato calibration drift or other anomalous conditions. There has been no indication from this review of an instrument malfunction as a result of the containment spray. The periodic engineering review of this data, which is currently performed monthly, is sufficient to identify gradual instrument degradation which may occur as a result of the brief exposure to the containment spray fluid.

VI. Equipment Which Has Been Operated A substantial sample of components (estimated to be 75%)

located inside containment, have been operated satisfactorily since the containment spray actuation (e.g., valves have been stroked, pumps and motors have been energized, etc.). The specific components which have been operated are:

Reactor Coolant _Syston Reector coolant Pumps Pressurizer Spray Valves Reactor Coolant Drsin Tank (RCDT) Outlet Sample System Valve Quench Tank outlet sample Valve Quench Tank to waste Gas Header valve Quench Tank Drain valve to RCDT 3

4

Enorgency Core Cooling _Eystem _-

Emergency Sump Outlet Valves h RCS Cold Leg Drain Valves Safety Injection Tank (SIT) Drain Valves RCS Hot Leg Drain Velves to RCDT SIT / Cold Leg Drains to RCDT Containrent Normal Sumn Normal Sump Pumps Nuclear Service Water Valves Normal Sump Discharge Isolation Valve Chemical Volume and Control System controlled Bleed-off to Quench Tank Isolation Valve Letdown Isolation Valves Reactor Coolant Drain Tank RCDT Pumps RCDT Pump outlet Isolation valves RCDT Vent Isolation Valve Samole System PZR Surge Line Sample Valve 9 P2R Vapor Space Sample Valve Hot Leg Sample Valves Containment Nornal MVAC Containment Recirculation Unit and Heater Containment Normal Coolers and Heaters Containment Normal Cooler Valves Containment Lower Area Fans Containment Normal Chilled Water Supply / Return Valves Containment Airborne Rad Monitor Isolation Valves Containment Mini-purge Supply and Return Valves Reactor Vessel Cavity Cooling Fans Reactor Vessel Cavity Fans Discharge Dampers Control Element Drive Mechanism (CEDM) Cooling Tans CEDM System Cooling Water Supply / Return Valves CEDM System Cooler Suction Dampers Emeraency HVAC Hydrogen Recombiners Hydrogen Monitor Isolation Valves Dome Air Circulating Fans Containment Emergency Coolers e a

VII. Effects of Spray on Lagging UFSAR Section 6.2.2.1.2.6 and associated Table 6.2-32 describe the insulation used, its requirements, and the installation locations within containment. Metal reflective insulation is used exclusively on stainless steel primary components. Secondary side components use metal encapsulated non-metallic insulation. All insulation assemblies are designed to be self supporting (except for the reactor vessel) and are designed to remain intact during and after a LOCA. As only reflective insulation is used on the stainless steel primary '

components, chloride attack is not a concern.  :

VIII. Accounting of RWST Water Sprayed Into Containment It has been determined that approximately 4800 gallons of water were introduced into containment. Factors which were used in this deterr!. nation included containment sump level indication, volume flow rate and run time of the containment sump pumps, and losses due to evaporation and cleanup.

IX. Evaluation of Spray-Effects on Trisodiumphosphate (TSP)

During the inspection of containment described above, all

() five TSP racks were inspected for evidence of borated water intrusion from the inadvertent containment spray actuation. A small amount of standing water was noted on top of one of the five racks (CR053). The remaining racks did not show-evidence of being wetted. CR053 and another rack were opened and the TSP W6d visually inspected.

Small drip holes were noted in the TSP in rack CR053; there was no evidence that the TSP in the other rack had been wetted. The small drip holes in the TSP in rack CR053 indicates that a negligible amount of water had entered the rack and recoved an insignificant amount of TSP.

The average TSP level in the two TSP racks was observed to be approximately 0.25 to 0.50 inch above the minimum level mark-in the racks. The TSP level in the remaining three racks were above the minimum level during the last surveillance; there is no reason to believe that their TSP level has changed. Based on these observations, a conservative calculation of the total TSP volume indicates a volume of approximately 18,275 pounds or 1264 pounds above the Technical Specification minimum 7f 17,461 pounds.

O 5 L

,e

• L .

J r~ Based on the above observations and calculation, the

( )j amount of TSP removed from rack CR053 is considered insignificant and the present condition and quantity of TSP is considered acceptable.

LONG TERM ACTIONS I. During the next refueling outage, scheduled for summer 1991, the following actions will be taken:

o Snubbers Consistant with the normal refueling interval surveillance of mechanical snubbers, a 100% visual inspection and a functional inspection of a sample of snubbers which is determined in accordance with the Technical Specifications will be performed. In addition, all mechanical snubbers which may have been sprayed or show evidence of moisture, and which are oriented such that they could collect moisture in their inertia mass housings, will be manually stroked.

o Carbon Steel Piping A sample of carbon steel piping will be inspected for

(~)

% indications of dotarioration resulting from residual boric acid.

II. A review will be performed of industry experience with containment spray actuations. SCE will follow-up with plants having experienced containment spray to determine if there were any long term effects. A review will be conducted of industry information and NSSS suppliers to determine any other long term corrosion problems which may need to be addressed. The long term actions will be modified, if appropriate, based on this prior experience.

6

_ _ _ _ _ _ _ . . . . . . .... . .