ML20009C202

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

ML20009C202
Person / Time
Site:	Byron, Braidwood, LaSalle
Issue date:	07/09/1981
From:	Swartz E COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-81-03, IEB-81-3, NUDOCS 8107200371
Download: ML20009C202 (6)

Text

.- _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

1

,' '. O C;

s Commonwrith Edison One First National Plaza. Chicago, litinois Q '))/ Chicago Address Reply to: Post Office Box 767 Illinois 60690 July 9, 1981 w bN

'I/Q)

Mr. James G. Keppler, Director

(.'

Directorate of Inspection and f q\Yy cf -

D NQ Enforcement - Region III 1- 12 U.S. Nuclear Regulatory Commission 799 Roosevelt Road C, a # f Glen Ellyn, IL 60137 /b

$d

Subject:

Byron Station Units 1 and 2 Braidwooa Station Units 1 and 2 LaSalle County Station Units 1 and 2 Response to IE Bulletin 81-03 Concerning Flow Blockage Due to Corbicula and Mytilus NRC Docket Nos. 50-454/455, 50-456/457 and 50-373/374 Reference (a): J. G. Keppler letter to Cordell Reed dated Anril 10, 1981.

(b): T. J. Rausch letter to J. G. Keppler cated May 26, 1981.

(c): E. D. Swartz letter to J. G. Keppler dated June 4, 1981.

Dear Mr. Keppler:

References (b) and (c) provided the Commonwealth Edison Company response to the subject Bulletin for our Dresden, Quad Cities and Zion Stations. The enclosure to this letter provides the Reference (a) requested 90 day report for our Byron, Braidwood and LaSalle County Stations.

To the best of my knowledge and belief, the statements contained herein and in the enclosure are true and correct. In some respects, these statements are not based on my personal knowledge but upon information furnished by other Commonwealth Edison employees. Such information has been reviewed in accoraance with Company practice and I believe it to be reliable.

IGS //

/ / I 8107200371 810709 4 PDR ADOCK 05000373 G PDR $ ,$@

ej0L' 1

J. G. Keppler July 9, 1981 Please address any further questions you may have regarding this matter to this office.

Very truly yours, J A .-

~

7 E. Douglas Swartz Nuclear Licensing Administrator Enclosure cc: Director, Office of Inspection and Enforcement, Washington, D.C.

Region III Inspector - Byron Region III Inspector - Braidwood Region III Inspector - LaSalle SUBSCRIBED AND SWORN to before this 9d d o f _ e<_/u, , 1981 b f-. tb >

( Notary Public Im 2273N l

l 1

1 l

l

I ENCLOSURE C

Commonwealth Edison Company Byron Station Units 1 and 2 Braidwood Station Units i and 2 LaSalle County Station Units 1 and 2 Response to I.E.Bulletin 81-03 BVRON and BRAIDWOOD UNITS 1 and 2 RESPONSE:

Itam 1 This item requires the holders of construction permits to complete items 1 and 4 that apply to holders of operating licenses.

1. Our Environmental Affairs Department has confirmed that Asiatic clams have not been found in the Rock River which is the source of water for Byron Station. Therefore, they do not foresee any problems at Byron with clam infestation. However, such problems are anticipated at Braidwood Station. Asiatic clams have been found in the Kankakee River, the water source for Braidwood, and there is a possibility that they will colonize in the cooling lake. With regard to Mussels, our Environmental Affairs Deprrtment has informed us that this species will not be a problem at Byron or Braidwood. Mussels are a salt water species similar to Asiatic clams and cannot live in fresh water which is used in the cooling systems at Byron and Braidwood Stations.

4a. Clams can easily enter the intake structure when they are in the larvae stage. Although microscopic in size, these larvae pass through the traveling screens and infest the cooling water.

Beyond the larvae stage, the clams can be easily carried along by river currents or pipeline flow. As they grow larger inside water systems, they can seriously degrade waterflow in the pipelines.

4b. If clam intrusion becomes a significant problem at Byron and Braidwood Stations, appropriate actions will be taken to detect and prevent flow blockage. At the present time, Byron is not expected to have a clam problem. At Braidwood, the extent of the problem is unknown because the lake presently does not have any heat load and the growth rate that the clams will demonstrate during plant operation cannot be accurately determined. As a result of filling the Braiawood lake during the clams' non-spawning season, there is a possibility that the lake has not yet been infested. Since the filling of the lake was completed, no sizable quantity of river water has been adoitionally pumped into it.

B/B Response Chemical treatment of cooling water systems aad Amertap condenser cleaning systems are currently planned to be used at both sites.

If future sampling indicates that clam intrusion has occurred, additional surveillance, cleaning and chemical treatment programs will be initiated. These programs may include the following:

a. periodic inspection and cleaning of condenser waterboxes and heat exchangers cooled by service water.

b. monitoring of flow degradation in heat exchangers through the use differential pressure guages.

c. monitoring of containment temperature (which reflects the effectiveness of the Reactor Containment Fan Coolers).

d. addition of hypochlorite to cooling water systems and heat exchangers.

The exact measures taken to prevent flow degradation will be determined by the severity of the problem. These methods have been proven effective at our Dresden, Zion and Quad Cities Stations. Continuous chlorination for two to three weeks during the beginning and the end of the spawning season has helped reduce the clam problems experienced at TVA stations.

Any newly developea methods of clam control that are proven effective will also be considered for use at Byron and Braidwooa Stations.

Items 2 and Item 3 The only systems at Braidwood that have been filled with lake water are the Fire Protection System and the Make-up Demineralizers.

Flow blockage is not likely to occur in the Fire Protection System since it contains larger pipes and no heat exchangers. Procedures will include periodic inspections and operation of this system. The Make-up Demineralizers have only recently been placed in service and not enough time has passed for any blockage to occur. Also, the water that is used in the demineralizers is sent through a chlorination system that kills an< emoves organisms from it.

Since clams are not present at Byron, it is not necessary to determine if infestation has occurred.

0329b

a .'

LASALLE COUNTY STATION RESPONSE Item 1 This item requires the holders of construction permits to complete items 1 and 4 that apply to holders of operating licenses.

1. Our Environmental Affairs Department has confirmed that Asiatic clams have been found in the Illinois River which is the source of water for LaSalle Station. There is a possibility that they will colonize in the cooling lake. With regard to Mussels, our Environmental Affairs Department has informed us that this species will not be a problem at LaSalle. Mussels are a salt water species similar to Asiatic clams and cannot live in fresh water which is used in the cooling systems at LaSalle Station.

4a. Clams can easily enter the intake structure when they are in the larvae stage. Although microscopic in size, these larvae pass through the traveling screens and infest the cooling water.

Beyond the larvae stage, the clams can be easily carriea along by river currents or pipeline flow. As they grow larger inside water systems, they can seriously degrade waterflow in the pipelines.

l 4b. If clam intrusion becomes a significant problem at LaSalle Station, appropriate actions will be taken to detect and l prevent flow blockage, such as indicated in FSAR 9.2.9.4 wherein the primary containment chilled water system has the chiller refrigerant suction and condensing pressures, compressor lubricant pressure, and water pressure differential across the condensers and evaporators of each chiller periodically monitored to ensure that all normally operating equipment is functioning properly.

If future sampling indicates that clam intrusion has occurred, aaditional surveillance, cleaning and chemical treatment programs will be initiated. These programs may include the following:

d. periooiC inspection and Cleaning of Condenser waterboxes and heat exchangers cooled by service water.

b. monitoring of flow degradation in heat exchangers through the use aifferential pressure guages.

c. monitoring of containment temperature.

d. adaition of hypochlorite to cooling water systems ana heat exchangers.

1...

LSCS Response G The exact measures taken to prevent flow degradation will be determined by the severity of the problem. These methods have been proven effective at our Dresden, Zion and Quad Cities Stations. Continuous chlorination for two to three weeks during the beginning and the end of the spawning season has

, helped reduce the clam problems experienced at TVA stations.

Any newly developed methods of clam control that are proven effective will also be considered for use at LaSalle Station.

Items 2 and 3 The Fire Protection System is flushed periodically and to date, the strainers have not shown any evidence of clams or shell oebris.

Other systems have not been in use long enough for any clams to grow and produce blockage.

0365L ll J

i f

f a

1 e

i 4

- , . _ . . _ _ , _ _ , - _ . _ . _ . _ _ _ _ . ~ _ - - _ _ _ . . _ . _ . . . _ _ . . . . . . _ _ . . _ . . . _ _ . . - _ . ._ , . _ _ . . - . - - _ _