ML20004D388

Responds to IE Bulletin 81-03, Flow Blockage of Cooling Water to Safety Sys Components by Corbicula Sp (Asiatic Clam) & Mytilus Sp (Mussel). No Evidence of Plugging or Fouling by Corbicula Found

ML20004D388
Person / Time
Site:	Arkansas Nuclear
Issue date:	05/22/1981
From:	Trimble D ARKANSAS POWER & LIGHT CO.
To:	Madsen G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
0CAN058114, CAN58114, IEB-81-03, IEB-81-3, NUDOCS 8106090335
Download: ML20004D388 (7)

Text

ARKANSAS POWER & LIGHT COMPANY POST CFFICE BOX 551 UTn.E RCCX. ARKANSAS 72203 (501) 371-4XJO May 22,1981 (f Ihz OCAN058114 S

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Mr. G. L. Madsen, Chief "'TI"L^^*" c[/

Reactors Projects Branch U. S. Nuclear Regulatory Comm.

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Region IV .Q

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SUBJECT:

Arkansas Nuclear One - Units 1 & 2 Docket Nosl'50 313'and'50-368 Licente Nos. DPR-51 and NPF-6 IE But ietin 81 Flow Slockage to Safety System Comoonents by Corbicula & Mytilus (File: 1510,1. 2-1510.1)

Gentlemen:

The subject bulletin' requires the submittal of certain infomation relative to the fouling of safety system components by Corbicula (Asiatic Clams). Following is the requested infonnation.

I. OBSERVATIONS AND PLANT MODIFICATIONS As reported in LER's 50-368/80-072 for ANO-2 and 50-313/80-35 for ANO-1, the presence of a.,iatic clams (Corbicula) has been confirmed in the Arkansas Nuclear One intake and Corbicula were found in portions of the service water systems of botn units.

These findings were made during outages of both units during September, 1980. Since the inspecticas made during this period have been previously reported to NRC and the findings are the basis for this bulletin, no description of the September,1980 inspections are included in this response. Instead, this response will serve as an update on recent inspections perfonned at Arkansas Nuclear One.

A. ANO-1 REFUELING OUTAGE gg In January 1981 ANO-1 was shutdown for refueling and i several modifications and inspections were perfonned.

1) Flow orifices and indicators were added to cervice l water headers supplying cooling water for the Reactor )

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m Mr. G. L. Madsen, Chief May 22,1981 1

, Building Cooling units. A Technical Specification change was made to require measurement of the service water flow rate through each cooling group once per two weeks.

2) Isolation valves were added in some of the service water supply lines to allow isolation of portions of the system for later installation of flow rate measuring devices when designs and procursment are complete. Previously, the affected service water loop had to be shutdcwn and drained in order i to accomplish such modifications. This severely  :

limited the ability to mah modifie$tions.

3) Inspections of the following service water supplied components were completed:

E35-A Decay . Heat Coolet .. .

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VUC-1A Aux. Bldg'. DH Room'CooTer VUC-1B Aux. Bldg. DH Room Cooler ,

VUC-1C Aux. Bldg. DH Room Cooler VUC-ID Aux. Bldg. DH Room Cooler E39-B MU Pump Lube Oil Cooler E39-C MU Pump Lube Oil Cooler .

VUC-78 MU Pump Room Cooler E47-A RB Spray Pump Lube Oil Cooler  :

E47-B RB Spary Pump Lube Oil Cooler E50-A DH Pump Bearing Cooler E50-B DH Pump Bearing Cooler  :

In all cases the components inspected did not show evidence of plugging or fouling by Corbicula. As stated in t'e bulletin, these components were not identified to have been plugged or fouled with Corbicula during the September 1980 outage either.

4) The Service Water pump bays and pump discharge strainers were inspected and cleaned of debris and clams.  !

f i B. ANO-2 FLOW PATH VERIFICATION l

I 1) During January 1981, the flow path through the following

' ANO-2 service water supplied components was verified to be open by isolating the returns and verifying flow

! through drain valves downstream of the components:

2VUC-1A Auxiliary Building S.D. HX Room Cooler l 2VUC-1B Auxiliary Building S.D. HX Room Cooler 2VUC-1C Auxiliary Building S.D. HX Room Cooler 2VUC-1.0 Auxiliary Building S.D. HX Room Cooler  :

2VUC-1E Auxiliary Building S.D. HX Room Cooler 2VUC-1F Auxili arf Building S.D. HX Room Cooler 2VUC-6A EFW Pump Room Cooler

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Mrs G. L. Madsen, Chief May 22,1981 2VUC-6B EFW Pump Room Cooler 2VUC-11A Auxiliary Building HPSI Pump Room Cooler 2VUC-11B Auxiliary Building HPSI Pump Room Cooler 2VUC-19A Auxiliary Building Electrical Equipment Room Cooler 2VUC-19B Auxiliary Building Electrical Equipment Room Cooler 2VUC-20A Auxiliary Build'ng Electrical Equipment Room Cooler 2VUC-208 Auxiliary Building Electrical Equipment Room Cooler 2VUC-7A Auxiliary Building Charging Pump Room Cooler 2VUC-7B Auxiliary Building" Charging Pump Room Cooler 2VUC-7C Auxiliary Building Charging Pump Room Cooler 2E47A Containment Spray Pump Seal Cooler 2E47B Containment Spray Pump Seal Cooler 2E52A LPSI Pump Seal Cooler 2E52B LPSI Pump Seal Cooler These checks all indicated that the flow paths through these components were not significantly plugged or fouled.

2)Tbefl rate through the ANO-2 Containment Cooling Units (2VCC2A, 2B, 2C and 20) is measured once per two weeks during operation. This data is trended by plotting against expected and previous results. No detectable degradation in flow rate has been observed since cleaning the containment cooling units in September 1980. .

3) The ficw path for the HPSI pump coolers (2E53A, 2E53B and 2E53C) has been verified to be unblocked by the method described in B.1 above during the monthly sur-veillances performed on the HPSI pumps. No blockage of flow has been indicated.

C. ANO-2 REFUELING OUTAGE ANO-2 was shutdown for refueling in late March 1981. As of this report the outage is approximately 2/3 complete and several modifications and inspections related to service water system fouling are in progress.

1) The following equipment will have a portion or all of its associated service water supply and/or return carbon steel piping replaced with 316 L stainless steel piping (1/2" and 3/4" piping will be changed to 1"):

l 2E-47A&B Containment Spray Pump Coolers 2E-52A&B LPSI Pump Seal Coolers '

2E-53A,B&C HPSI Pump Seal Coolers 2VUC-11A&B HPSI Pump Room Coolers 2VUC-7A,B&C Charging Pump Room Coolers 2VUC-6A&B EFW Pump Room Coolers 2VUC-19A&B Electrical Equipment Room Coolers 2VUC-20A&B Electrical Equipment Room Coolers Emergency Switchgear Room Coolers 2VUC-2A-2D

Mr. G. L. Madsen, Chief May 22, 1981 2C-12SA&B Post Accident Hydrogen Analysis Panels 2RE-1525 Fuel Pool Ht. Exchanger Rad. Detector 2RE-1513 Containment Cooler Rad. Detectors

. 2RE-1519 Containment Cooler Rad. Detectors ,

2RE-14S3 Shutdown Cooling Ht. Exchanger Rad.

2RE-1456 Detectors 2VUC-1A-1F - Aux. Bldg. S.D. HX Room Coolers This change is being made to eliminate small piping which has a high potential for plugging with corrosion products.

2) Provisions for flow rate measurement through the following service water supplied components is being added:

2VUC-1A,1B,1C,10,1E,1F Aux. Bldg. S.D. Hx Room Coolers ,

2VUC-11A,11B Aux. Bldg. HPSI Pump Room Coolers 2VUC-2A,2B,2C,2D Ertrgency Switchgear Room Coolers

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2VUC-7A,73,70. Charging' Pump Room C~o olers 2VUC-6A, 6B E.F.W. Pump Room Coolers 2VUC-19A,198 jux. Eldg. Electrical Equip. Room Coolers 2VUC-20A,20B Aux. Bldg. Electrical Equip Room Coolers 2E-52A,52B LPSI Pump Seal Cooler 2E-53A,538,53C HPSI Pump Seal Cooler -

2E-47A,47B Containment Spray Pump Cooler '

3) The service water pump bays and pump discharge strainers are being cleaned. ,

4) Portions of the service water system piping are being inspected concurrent with pipe replacement per C.1 above.

5? The following components are being opened and inspections perfonned:

2VUC-1A A S/D heat excnanger room cooler 2VUC-7A A charging pump room cooler 2VUC-11B C HPSI pumo room cooler 2VUC-19B Auxiliary Building electrical equipment room cooler 2E35-A A S/D cooling heat exchanger 2E35-8 B S/D cooling heat exchanger 2VCC-2B Containment Cooling Unit

6) Upon comoletion of piping changes and addition of flow rate measurement devices, the flow rates through the following components will be measured and acceptable flow rates verified:

2VUC-1A,1B,1C,10,1E&lF Aux. Bldg. S.D. Hx Room Cooler 2VUC-11A, 11B Aux. Bldg. HPSI Pump Room Cooler 2VUC-2A,2B,2C,20 Emergency Switchgear Room Cooler .

2VUC-7A,78,7C Charging Pump Room Cooler  !

2VUC-6A,6B EFW Pump Room Coolers  !

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Mr. G. L. Madsen, Chief -S- May 22,1981 2VUC-19A,19B Electrical Equipment Room Coolers  !

2VUC-20A,20B Electrical Equipment Room Coolers .

2E-52A,528 LPSI Pump Seal Coolers  !

2E-53A,538,53C HPSI Pump Seal Coolers  ;

2E-47A,47B Containment Spray Pump Coolers t D. ANO-1 AND ANO-2 FIRE PROTECTION SYSTEM Periodic flushes of the ANO fire protection system piping are ,

performed with ANI personnel witnessing. These are done to insure adequacy of flow and to verify that no flow blockages exist. Since the observation of asiatic clams in the ANO service water systems, particular attention has been given to i any evidence of clam fouling of the fire protection system. i No such fouling has been observed. It is speculated that this is due to the fact that the suction of the fire protection

,; .. , , .s pumps,.is._several- feet, aboye the suction of..the- service.. water. .,~ i pumps in the intake structure,' thus not m'aking' th'em suscept'ible '

to fouling by clam debris. [

II. DETECTION AND PREVENTION

'The major me,thods of preventing clam fouling consists of periodic cleaning ,

of the service water intake bays and service water pump discharge strair.ers '

as well as periodic chlorination during surveillance tests. The service  ;

water bays are cleaned at least once per refueling period. Our experience '

indicates that this is sufficiently frequent to keep the service water .

pump suctions from being contacted with clam buildup. Additionally this l cleaning removes the most significant sour ce of clam larvae. The service i' water pump strainers are fitted with differential- pressure (aP) indicators which are monitored once per shift during pump operation. If AP increases beyond expected values, the strainers are inspected and cleaned.  ;

Due to lack of evidence that the fouling is occuring in the ANO-1 service water system (other than VCC 2C ~& 2D) only periodic inspection of selected  ;

coolers has been performed. The addition of flow indication on the service water supplies for the ANO-1 Reactor Building Cooling Units has allowed i frequent checking of the flow rate. The ficw rates for these coolers is trended to detect evidence of fouling or plugging. It is our intention to add flow rate indications on the following components in the ANO-1 l

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Service Water System during the current refueling cycle:

E-39A,8&C MU Pump Lube Oil Cooler .

VUC-1A,1B,1CalD Aux. Bldg. DH Room Cooler i VUC-7As7B&7C MU Pump Room Cooler  :

E-50A&B OH Pump Bearing Cooler E-47A&B DH Pump Bearing Cooler .

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Mr. G. L. Madsen, Chief May 22, 1981 This will allow periodic flow rate measurement through these coolers at a frequency established based on experience.

The addition of flow rate indications for the ANO-2 service water supplied components described in item I.C.2 will allow periodic flow rate measurement.

The baseline wil' be collected following installation of the indicators and will be repeated at a frequency based on experience gained from The initial measurement frequency will trending of several data points.

be at least quarterly.

Very truly yours, hA t. '74 David C. Trimble i Manager, Licendi r.g DCT:DRH:1p

cc: Mr. Victor Stello, Jr., Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission ,

Washington, D.C. 20555 ,

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STATE OF ARKANSAS ) .

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COUNTY OF PULASKI )

I, DAVID C. TRIMBLE, being duly sworn, subscribe to and say that I am the Manager of the Licensing Section, for Arkansas Power & Light Company; that I have full authority to execute this oath; that I have read the foregoing letter #0CAN058114 and know the contents thereof; and that to the best of my knowl' edge, information and belief the f

.. Statements.made..in it.areitrue,.

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OAVID C. TRIMBLE ,

SUBSCRIBED AND SWORN T0 before me, a Notary Public in and for the County

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and Stato above named, this day of / ~

, 1981.

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. l NOTARY PUBLIC f

MY COMMISSION EXPIRES:

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