ML20009D922

Forwards Response to IE Bulletin 81-03, Flow Blockage of Cooling Water to Safety Sys Components by Corbicula Sp (Asiatic Clam) & Mytilus Sp (Mussel).

ML20009D922
Person / Time
Site:	Catawba
Issue date:	07/08/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
IEB-81-03, IEB-81-3, NUDOCS 8107240503
Download: ML20009D922 (4)

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h OFFIC,IAL COPY DUKE POWER COMPANY PowzR BUILDING 422 Sourn Gnuncu SrazzT, CsuntoTTE, N. C. asa4a ,.

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WILLI AM O. PAR M ER, J R.

Vier PagsiotNT TELEpwoNg; AngA 704 Strau PaoovctioN j g g 373-4083 Dj /9 Mr. James P. O'Reilly, Director g

%Q U. S. Nuclear Regulatory Commission g .) l 'g Region II  ?

101 Marietta Street, Suite 3100 t JULn- 3gggjw n }.5, Atlanta, Georgia 30303 3 ,

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Catawba Nuclear. Station ' 'co , j , \D Docket Nos. 50-413 and 50-414

Dear Mr. O'Reilly:

Please find attached a response to IE Bulletin 81-03 for the Catawba Nuclear Station. ,

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g, , n William O. Parker, Jr.

RWO/php Attachment cc: Director Mr. P. K. VanDoorn Office of Inspection and Enforcement NRC - Resident Inspector

- Washington, D. C. 20555 Catawba Nuclear Station i

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8107240503 810708 PDR ADOCK 05000413 G PDR l-i

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Mr. James P. O'Reilly, Director July 8, 1981 Page 2 ilILLIAM 0. PARKER, JR., being duly sworn, states that he is Vice President of Duke Power Company, that he is authorized on the part of said Company to sign and file with the Nuclear Regulatory Commission this response to IE Bulletin 81-03 and that all :.tatements and matters set forth therein are true and correct to the best of his knowledge.

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' William O. Parker, Jr., Vic Q sident S

Subscribed and sworn to before me this 8th day of July, 1981 Cbs L hJr ru Stie C. Sherrill,' Notary Public Notarial Seal My Commission Expires:

September 20, 1984

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• Duke Power Company Catawba Nuclear Station Response to IE Bulletin 81-03 July 8, 1981 Int roduction Duke Power Company has more than 10 years experience dealing with Jouling caused by Asiatic clams at its generating facilities. The Asiatic clam has been present in the Duke service area since the mid 1960s. It became a nui-sance at one of the fossil fueled plants in 1970 and a program of remedial actions'was initiated to minknize the effects of the clams. As the clams extended their range throughout the Duke system, an ad hoc committee was officially formed in 1978 to daal with clam related problens at all Duke generating facilities. This c'ommittse is reviewing each plant to determine, in general,.how best to protect raw water systems from fouling by clams.

If the clams become a nuisance at a plant, then specific changes involving

-piping modification, maintenance procedures, and/or biocide application are developed on a case by case basis. All of Duke's nuclear plants will be reviewed by the committee and the status of clam infestation will be care-fully monitored at'each plant. At Catawba,Jclams are a potential problem

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in the Nuclear Service Water System (RN), the Fire Protection Systems (RF & RY) and the Conventional Low Pressure Service Water System (RL). Of these three systems only the Nuclear Service Water System (RN) and the Fire Protection Systems ( RF.and RY) have safety related implications or functions.

Asiatic clam control methods Of the methods available to control Asiatic clams, preventing mature clams from being pumped into the system, backflushing to remove clams that grow in

- the piping, and chlorinating closed systems appears to be effective.

The Catawba Nuclear Service Water System (RN) as described in FSAR Section 9.2.1.6 includes provisions to prevent the introduction of clams into the system from the lake via the RN intake structure by filtering the water dis-charged from each RN pump through a strainer with 1/32 inch openings. Pro-visions have also been made to allow backflushing the redundant heat exchanger trains and piping to remove any clams in the safety related RN :omponents and piping. Sufficient flow elements have been provided in the RN System to allow verification of adequate RN flow to safety related heat exchangers during performance monitoring programs.

The Catawba Fire Protection Systems (RF and RY) are described in FSAR Section 9.5.1. Normal makeup to the fire protection systems are through two 25 GPM jockey pumps which pump chlorinated filter water (drinking water quality) to maintain pressure in the system. A larger 200 GPM jockey pump can also supply chlorinated filtered water or as an op' tion, lake water from the Conventional Low Pressure Service Water System (RL) discharge header. The main fire pumps

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O on the RL intake structure are equipped with basket strainers on the pump suctions which prevent mature clams from being pumped into the system. Peri-odic operational testing of the main fire pumps will detect any blockage of the pump suction screens and verify' acceptable pump performance. The exterior fire hydrants, the main fire protection headers, and the transformer deluge systems will also be periodically flow tested. Fire protection strainera on deluge and sprinkler systems will be visually checked for clams during periodic maintenance.

Environiental monitoring programs and visual examinations of affected systems The presence of Asiatic clams in Lake Wylie has been confirmed by previous sampling programs and the Catawba standby nuclear service water pond is scheduled to be sampled in the fall of 1981.

Recently the Nuclear Service Water (RN), the Fire Protection (RF & RY), and the Conventional Low Pressure Service Water (RL) Systems at Catawba were inspected for clams. No clams were found in the RN System, one small h inch clam was found in the RL supply header, and three small k inch clams were found in the RF System. Some small clam shells and shell fragments were previously found in some of the RF deluge nozzles during an inservice test.

The Fire Protection Systems (RF and RY) at Catawba are still on temporary Construction lake water supplies which are not chlorinated.

Conclusion )

As discussed, provisions have been designed into the station to minimize the introduction of clams into the raw water systems and to aid in removing them if they do get into the piping and components. Performance monitoring programs to verify adequate flow, and visual inspection of the intake piping and inlet heat exchanger heads during maintenance will provide early detection of any clam infestation of raw water systems. If these monitoring or inspection programs indicate any potential problems, appropriate corrective action will be taken.

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