ML20072U044

Forwards Addl Info in Response to IE Bulletin 81-03, Flow Blockage of Cooling Water to Safety Components by Corbicula Species (Asiatic Clam) & Mytilus Species (Mussel). During Refueling Outage,Hx Will Be Inspected for Corbicula

ML20072U044
Person / Time
Site:	Harris
Issue date:	03/25/1983
From:	Hurford W CAROLINA POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
REF-SSINS-6820 IEB-81-03, IEB-81-3, IEB-83-1, LAP-83-86, NUDOCS 8304110168
Download: ML20072U044 (5)

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Carolina Power & Light Comp nu . 05 MAR 251987d EdR -

SERIAL: LAP-83-86 Mr. James P. O'Reilly, Regional Administrator United States Nuclear Regulatory Commission Region 11 101 Marietta Street, NW, Suite 3100 Atlanta, GA 30303 SHEARON HARRIS NUCLEAR POWER PLANT-UNIT NOS. 1 AND 2 DOCKET NOS. 50-400 AND 50-401 IE BULLETIN NO. 81-03 1

Dear Mr. O'Reilly:

As requested by IE Bulletin No. 81-03, " Flow Blockage of Cooling i Water to Safety Components by Corbicula sp. (Asiatic Clam) and Mytilus sp.

2 (Mussel)," dated December 10, 1982, and in accordance with the schedule set forth in our February 8,1983 letter, Carolina Power & Light Company hereby l submits, in the attachment to this letter, responses to the requested additional information for the closing of the issue.

If you have any further questions on this subject, please advise.

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, Yours very truly, W. . Hu:-fo Manager Technical Services PS/ mag (6436PSA)

, Attachment

. cc: Mr. N. Prasad Kadambi (NRC) j Mr. G. F. Maxwell (NRC-SHNPP) I Mr. J. P. O'Reilly (NRC-RII) '

l 0304110168 830325 PDR ADOCK 05000400 0 PDR

.411 Fayetteville Street

• P. O. Box 1551 e Raleigh, N. C. 27602

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REQUEST mR ADDITIONAL INFORMATION IE BULLETIN NO. 81-03

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.l.(4A) No discussion'of instrusion potent'ial if and when Corbicula sp.

becomes' established in' reservoir. Please-assess and respond.

If! and when Corbicula sp.-. becomes established in the. Harris main l and/or auxiliary reservoirs, the potential will exist for adults, larvae, and shells to be entrained ~1nto the service water and fire protection systems of the -SHNPP. However, various design and operating conditions are expected to reduce the probability. of flow reduction or blockage to safety' system components.by Corbicula sp.

i No flow reduction or blockage problems are expected to result'-in the l- normal Service Water System (SWS). This system is designed to withdraw service water f rom the closed-loop Circulating Water System l (CWS) at the cooling towers. Because the physical and chemical climate of the cooling towers will be unfavorable to Corbicula sp.

l habitation; and because the service' water is designed to be chlorinated to maintain a 0.5 ppa residual chlorine concentration at the heat exchanger outlet, Corbicula sp. intrusion of the SWS is not probable.

The Emergency Service Water System (ESWS) 'will withdraw water from the auxiliary reservoir or, if that source is unavailable, fron' the ..

main reservoir. From either source, the ' emergency service . water will be pumped to the normal SWS. Because the ESWS pumps will be operated monthly, no accumulation of silt or Corbicula sp. will occur in the ESWS pipelines from the intake structure to the junction with the normal SWS. Corbicula sp. does not attach, so any young adults that-grow from larvae that settle there- will be flushed through the system before growing large enough to reduce or block service water flow.

The greatest potential for flow reduction or' blockage in the'SWS will result from the acccaulation of silt and'Corbicula adults and/or shells in the ESWS pump suction bays behind the travelling screens.

The travelling screens with a mesh size of 3/8" will prevent other.

adults or shells from entering the ESWS intake bays. If significant buildups occur, the adults or shells would be picked:up by the ESWS pumps suction; however,1/16" self cleaning strainers are. located at the discharge of the ESWS pumps to preclude passage 'into the ESWS. .

Two factors which may reduce the likelihood of high Corbicula 'sp.

densities in the intake bays are the water depth and : the monthly operation of.the service water pumps. At normal-water level, the depth at the ESWS intakes on the auxiliary reservoirf and main reservoir will be 60 feet and 30 feet, respectively. Low oxygen levels at these depths during summer months ~should inhibit occurrence l and growth'of Corbicula sp. -~The monthly operation'of the ESWS pumps i should minimize the buildup.of silt in the intake bays thus minimize l favorable substrate for Corbicula larvae to settle and grow into L adults.

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The potential intrusion by Corbicula sp. into' the ' Fire ~ Protection ,

System (FPS) may be possible by makeup ~'of water containing . larvae.

The larvae.could settle in low points of the . system where they may -

grow into. adults. . _ Also, as described forf the ESWS, Corbicula adults.

. and/or shells would be entrained f rom =possible" accumulations behind .

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' travelling screens ats the' intake bays onlthe auxiliary reservoir.

, ~ Any' adults or shells that' enter?or develop in 'the FPS could then ;

reduce or_ block flow through1 small pipes,1 valves, or sprinklers.

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}' Because_the FPS pumps will be-operated _ weekly for testing and'because

portions of .the system will be flushed as of ten as quarterly; Corbicula larvae, and possibly adults ami shells,7 would be entrained. -

I E l. (4 b) No information provided regarding planned control or detectiJn

. methods. Please respond ' and describe inspection -procedures and

}' control technology.under _ consideration.

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! Because . the potential for ' Corbicula sp. intrusion of the SWS,E ESWS, I and' FPS exists, the following -inspection procedures. and _ control

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measures will be planned:

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[ a. During normal refueling outages, selected service water' heat

exchangers will be inspected for_ the presence 'of -Corbicula sp. .

e b. The-SWS will be chlorinated as described'in 1.(4a) above if

[ Corbicula sp. or other biofouling is suspected or found in the i SWS.

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i. c. Once Corbicula sp. are found in the reservoir during regular ,

j environmental monitoring of the benthic macroinvertebrate 1

populations, periodic sampling of the intake bays behind the '  ;

j_ travelling screens will be initiated.

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d. If significant densities of adults or accumulation of shells are found in the intake bays, . periodic treatment of the bays' with oxygen scavenging chemicals [e.g. , soditsm-metabisulfate (Na S 0 )] will be initiated as required to control. the 225

! 1Corbicda sp.

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a. Low point blowdown drains will be used to periodically inspect-the' FPS for evidence of Corbicula sp.

!~ b. Once Corbicula sp. are known to inhabit the auxiliary reservoir, -i '

! chlorination units wili be installed at the intake pumps.L ~

! Chlorine would be injected consistant with pump operation.

I s c. When Corbicula sp. are found in.tta auxil'ary reservoir', the FPS '

1 intake bay behind the travelling screens will be inspected aud-  !

h treated ~as: described for the. ESWS intakes in (c) and (d) .above.~ '

2. (4 b) No information provided regarding _ status of construction. Please respond and, if any_ systems-have.been. filled,; describe-inspection procedures and results.

1 All fire protection-systems have been filled and pressurized as needed to protect equipment already installed..!With_the.. exception ofz fire -protection, no piping associated ~ with those- systems . of: interest

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t j - are presently filled at SHNPP. These systems may be filled for

. hydrostatic testing as early as- May of 1983, and subsequently be i _ flushed, drained, and thoroughly inspected no earlier than January 1984.

3.a Provide last saapling date and results.

Quarterly sampling of the benthic . community developing in the Harris Reservoir was cr>nducted during February, Nay, Auguet, and November 1982. No Corbicula sp. were

found in-any of the j samples collected indicating that the clams are not in the main reservoir.-

!. Sampling planred for 1983. will include two new stations. One will be in the main reservoir near the mouth of the cooling tower makeup intake channel, and the other will be~ in the auxiliary reservoir near

.the mouth of the emergency service water intake' channel.

3.e See 1.(4b) above for planned corrective and preventive actions.

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I-l (6436PSA . mag)

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