ML19346A314

Responds to IE Bulletin 81-03 on Flow Blockage of Cooling Water to Safety Sys Components Caused by Mussel & Asiatic Clam.No Indication of Fouling or Blockage Caused by Shells, Clams or Mussels in Sys Components Inspected

ML19346A314
Person / Time
Site:	Duane Arnold
Issue date:	05/18/1981
From:	Root L IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-81-03, IEB-81-3, LDR-81-182, NUDOCS 8106190128
Download: ML19346A314 (5)

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AW lowa Electric IJshe and Pbwer ra== pay May 18, 1981 LDR-81-182 g,,

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Mr. James G. Keppler, Director .

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JL7l 13 ;981 m r t Office of Inspection and Enforcemerit -( ., m., f U.S. Nuclear Regulatory Commission a ;wissea q 4egion III T ^y 799 Roosevelt Raad /,

Glen Ellyn, IL 60137 W / ig W o-Re: Duane Arnold Energy Center

Subject:

IE Bulletin 81-03, Flow Blockage of Cooling Water to Safety System Components by Corbicula Sp. and Mytilus Sp.

File: A-101a, NRC-2, Bulletin 81-03

Dear Mr. Keppler:

In response to your letter transmitting the subject NRC IE Bulletin concerning potential flow blockage problems of cooling water system components in power plants caused by Corbicula Sp. (Asiatic Clam) and Mytilus Sp. (Mussel), we have completed the recommer'ded licensee actions. The D. B. Mcdonald Research, Inc., consulting ecologist finn of Iowa City, Iowa performed the research, data collection and analyses, and evaluation work to allow Iowa Electric Light and Power Co. (IELPC) to adequately address the subject NRC IE Bulletin concerns for the Duane Arnold Energy Center (DAEC). The following discussion is provided to briefly describe the actions taken at DAEC to address these NRC IE Bulletin Conce rns.

ITEM 1: Determine whether Corbicula sp. or M"tilus sp. is present in the vicinity of the station (Tocal environment) in either the source or receiving water body. If the results of current field monitoring programs provide reasonable evidence that neither of these species is present in the local environment, no further action is necessary except for Items 4 and 5 in 'this section for holders of operating licenses.

RESPONSE: As discussed below, it .has been determined that the Corbicula and Mytilus are not present in the vicinity cf the DAEC. In order to make '

this determination, D. B. Mcdonald Research, Inc. re"iewed Cedar River monitoring program history for DAEC and others and reauested additional samples be collected from the G.tEC intake structure, the \ -

cooling tower basins, and the discharge canal.

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Mr. James G. Keppler Page 2 The Asiatic Clam, Corbicula, is common in portions of the Iowa reach of the Mississippi River wh*re suitable substrate is available. This organism requires relttivelv stable substrate and is normally abse.t from areas with a shifting nd/ silt substrate such as nomally found in the Cedar River in the vicinity of the DAEC. Corbicula has not been collected from the Cedar River in the vicinity of tne DAEC during the routine Cedar River monitoring program which was implemented in April 1971. A single Corbicula was however collected in January of 1979 in the vicinity of the Lewis Access (approximately 4 miles upstream of the DAEC) by Hazleton Environmental Science Corporation personnel. The river bottom in this area is somewhat more stable than that present in the vicinity of the DAEC which may account for the presence of this form. No other records of this organism in the Cedar River were found.

Bechse Corbicula has been collected on one occasic, from the Cedar River and is commonly found in power plant intakes on tha Mississippi River, D. B. Mcdonald Peearch, Inc. directed personnel to collect samples from the DAEC intake structure, the cooline Ower basins, and the discharge canal in order to determine if the organism had established itself within the system. On May 6, 1981 six Ponar dredge samples were taken behind the bar rack of the intake structure. The substrate in this area was found to consist of shifting sand and silt and contained no Corbicula. Three Ponar samples were collected from each of the cooling tower basins. The basins were dry at the time of sampling but the " sludge like" substrate contained no evidence of Corbicula. A clam rake was used to sample both ends of the discharge canal. No Corbicula were collected in spite of the fact that fairly stable gravel substrate capable of supporting the organism was present in the upper end of the canal.

The Asiatic Clam (Mytilus) is a marine form and obviously would not occur in the Cedar River.

ITEMS 2 AND 3:

RE5PUNSE: These items do not apply to the DAEC since it has been detemined that Corbicula and My,tilus are not present in the vicinity (as discussed in Item 1 above).

ITEM 4: Describe methods eitner in use or planned (including implementation date) for preventing and detecting future flow blockage or degradation due to clams or mussels or shell debris. Include the following information in this description:

a. Evaluation of the potential for instrusion of the organisms into these systems due to low water level and high velocities in the intake structure expected during worst case conditions.

b. Evaluation of effectiveness of prevention and dettction methocs used in the past or present or planned for future use. -

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RESPONSE: . The potential for intrusion of these organisms to DAEC is considered j low, based upon the above o# scribed history and local environment. I l

No specific prevention or detection methods were used in the past since no Corbicula have been found in the immediate vicinity of the DAEC. In order to detect the possible intrusion of these organisms into the system in the future, the sampling cf the intake structure, cooling tower basin and discharge canal will be repeated on a twice yearly basis. These determinations will be in addition to the routine benthic studies which will also be continued. This additional sampling was recommended by D. B. Mcdonald, Inc. and should be adequate to identify any intrusion of Corbicula into the DAEC < ,tems in the future.

As has been previously stated in tne subject NRC IE Bulletin the control of Corbicula in power plant cooling and safety systems has been proven to be difficult due to the resistance of the organism to chlorine and dessication. Illinois Power Company has reported some success in controlling Corbicula by the use of a mixture of sodium metabisulfite to produce anov.ic conditions, and hydrogen sulfide. If these organisms .re found in the DAEC systems at some point in the future the app; apriate method of control will be determiotd at that time consistent with the scope and severity of the problem.

ITEM 5: Describe the actions taken in Items 1 through 3 above and include the following information:

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a. Applicable portions of the environmental monitoring program including last sample date and results.

b. Components and systems affected.

c. Extent of fouling if any existed.

d. How and when fouling was discovered.

e. Corrective and preventive actions.

RESPONSE: The benthic macroinvertebrate community of the Cedar River has been routinely sampled three times yearly (spring, summer and fall) at four locations upstream and downstream of the DAEC by means of a Ponar l dredge since 1971. In addition artificial substrate samples are also l taken with Hester Dendy samplers above and below the station. As

! previously mentioned, no Corbicula have been collected during the course of the study. The last benthic samples were collected on l

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Mr. , James G. Kepplcr Page 4 -

November 18, 1980. The current benthic monitoring program is sufficient to detect the establishment of the organism in the vicinity of the station but, as discussed in Item 1 above, will be expanded to include twice yearly sampling of the cooling water system.

Because of the absence of Corbicula in the river adjacent to the station and the failure to find the organism in the intake structure, the cooling tower basins or the discharge canal, it is not necessary to open and visually examine the DAEC safety system , components.

However, as part of the routine visual inspection program many of the plant system components which would most likely be affected by the intrusion of Corbicula have been inspected recently during the 1931 Refueling Outage. There were no indications of fouling or flow blockage caused by clams, mussels, or shells in any of DAEC system components inspected.

If you have any questions or desire further information regarding this IE Bulletin, please contact this office.

Approximately 20 man-hours were required to collect the additional samples, gather the necessary information, and prepare the response to this IE Bulletin.

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Mr. ' James G. Keppler

' Page 5 This response is.true and accurate .to the best of my knowledge and belief.

IOWA ELECTRIC LIGHT AND POWER COMPAN <

t y: M M Okh.M4 (A.arry D. Root v ~~/

/* AssistantVicePresi'dedt,

• Nuclear Generatien Subscribed and Sworn to before me thisgday of May,1981, by R. W.

McGaughy, for Larry D. Root.

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Notgry PuDlic In and for the State of Iowa LDR/DWT/pl cc: U. S. Nuclear Regulatory Connission Office of Inspection and Enforcement Division of Reactor Operations Inspection Washington, D. C. 20555 U. S. Nuclear Regulatory Comission c/o Document Management Branch Washington, D. C. 20555 D. Tooker D. Mineck D. Arnold D. Wilson -

L. Liu J. Van Sickel S. Tuthill K. Young K. Meyer B. Dye R. McGaughy Dr. D. B. Mcdonald D. B. Mcdonald Research, Inc.

Consulting Ecologists Box 129, Route 1 l Iowa City, Iowa 52240 l

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