ML20004D121
| ML20004D121 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 06/02/1981 |
| From: | Maier J ROCHESTER GAS & ELECTRIC CORP. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-81-03, IEB-81-3, NUDOCS 8106080415 | |
| Download: ML20004D121 (13) | |
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ROCHESTER GAS A!!D ELECTRIC CORPORATION e 89 EAST AVENUE, ROCHESTER. N.Y.14649
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June 2, 1981 Csg g'.JUjjR[{ lll'fg'Q:'
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7 ISS/ A p-i l-~d u,1, kfg (A i,i Director of Region 1
\\A Attention:
Mr. Boyce H. Grier,
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Director, Region 1 U.S. Nuclear Regulatory Commission
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631 Park Avenue King of Prussia, Pennsylvania 19406
Subject:
IE Bulletin No. 81-03, " Flow Blockage of Cooling Water to Safety System Components by Corbicula sp. (Asiatic Clam) and Mytilus sp. (Mussel)".
R. E. Ginna Nuclear Power P'
.it, Unit No. 1 Docket No. 50-244
Dear Mr,
. Grier:
IE Bulletin No. 81-03 requests submittal of documentation related to the potential for existence of subject problem.
The attached enclosure contains the information requested.
Additionally, to assist in evaluating the value/ impact of subject bulletin on licensees, manpower expended in conduct of the review and preparation of this report was approximately 75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br />.
Very truly yours, k)A.AM J
E. Maier Subscribed and sworn to me on this i miday of June 1981 J'
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Mr. Victor Stello Jr.
Director U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement fitf f 3
Washington, DC 20555 b
8106086415
I.E.-Bulletin 81-03 Response Position 1.
Determine whether Corbicula sp. or Mytilus sp. is present in the vicinity of the station (local 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
The Rochester Gas and Electric has had a biological study program at the Ginna Nuclear Power Plant since 1974.
Both benthic and entrainment methods have been utilized in the program.
The benthic program determines the type and abundance I
of organisms inhabiting the lake bottom in the vicinity of l
the Ginna Site (Lake Ontario is the source of cooling medium for the Ginna Plant) and the entrainment program determines the type and abundance of organisms entering the Ginna Plant through the circulating water intake.
Each of these methods is described in the appendix.
l To date, the biological study program has not revealed the presence of Corbicula sp. or Mytilus sp. in the vicinity of the Ginna Plant nor are they present in the plant systems.
Sphaeriidae sp. (fingernail clams) have been detected on the i
lake bottom in the vicinity of the Ginna Plant.
Because of their size, these clams could infiltrate the cooling water 4
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. pump screens and presumably grow to maturity (one-half inch in diameter) although none have been detected in plant systems to date.
Position 2.
If is unknown whether either of these species is present in the local environment or is confirmed that either is present, determine whether fire protection or safety-related systems that directly circulate water from the station source or receiving water body are fouled by clams or mussels or debris consisting of their shells. An acceptable method of confirming the absence of organisms or shell debris consists of opening and visually examining a representative sample of components in potentially affected safety systems and a sample of locations in potentially affected fire protecticn systems. The sample shall have included a distribution of components with supply and return piping of various diameters which exist in the pctentially affected systems. This inspection shall have been conducted since the last clam or mussel spawning season or within the nine conth period preceding the. date of this bulletin.
If the absence of organisms or shell debris has been confirmed by such an inspection or
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another method which the licensee shall describe in the response (subject to NRC evaluation and acceptance), no further action is necessary except for items 4 and 5 of actions applicable to holders of an operating license.
Response
The Ginna plant is presently shut down for refueling maintenance.
During the course of the current shutdown maintenance program the service water system piping supplying water to the emergency diesel generator oil coolers was cpened and inspected, tne circulating water piping to the condensate
. 1 cooler was opened and inspected and the fire and se-vice water pump screens were inspected.
No evidence of the presence of Corbicula sp., Mytilus sp. or Sphaeriidae sp.
was detected.
In addition, several modifications to the fire system have been completed in the past year necessitating an opening of the system.
In each case, no mussels or clams were evident.
Position 3.
If clams, mussels or shells were found in potentially affected systems or their absence was not confirmed by action in item 2 above, measure the flow rates through individual components in potentially affected systems to confirm adequate flow rates i.e., flow blockage or degradation to an unacceptably low flow rate has not occurred. To be acceptable for this determination, these measurements shall have been made within six months of the date of this bulletin using calibrated flow instruments.
Differential pressure (DP) measurements between supply and return lines for an individual component and DP or flow measurements for parallel connected individual coolers or components are not acceptable if flow blockage or degradation could cause the observed DP or be masked in parallel flow paths.
Other methods may be used which give conclusive evidence that flow l
l blockage oc degradation to unacceptably low flow rates has not occurred.
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If another method is used, the basis of its acceptance for this determination shall be included in the response to this bulletin.
If the above flow rates cannot be measured or indicate significant flow l
j degradation, potentially affected systems shall be inspected according to l
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item 2 above or by an acceptable alternative method and cleaned as necessary.
This action shall be taken within the time period prescribed for submittal of the report to NRC.
Response
Not Applicable.
Position 4.
Describe methods either in use or planncd (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 intrusion 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 detection methods used in che past or present or planned for future use.
Response
A major concept employed in the design of the Ginna intake water system was to minimize the intake of debris.
The source of all cooling water for the Ginna Plant is Lake Ontario.
The cooling water is drawn through a 50 foot diameter,15 foot high octagon shaped structure located on the lake bottom 3100 feet out in the lake.
The water flows into the structure from around the complete 360 degree circumference at a velocity of 0.8 fps.
From the structure the water passes through a 10-foot diameter concrete-lined tunnel bored through bedrock and then to the forebay of the
. Ginna Plant screenhot're.
From the forebay, the water passes through traveling screens of one-half inch mesh to the suction of the service water, firewater and circulating water pumps, all of which have suction screens except the circulating pumps.
Since the top of the intake structure is fifteen feet below the historical low lake level, low water level will not increase debris intake.
The intake water system design is such that at full flow the water velocity is low enough to minimize the possibility of debris intake outside of the immediate vicinity of the structure.
In the eleven-year operating history of the Ginna Plant, no system or component of a system through which Lake Ontario water flows, has experienced a reduction in flow due to a blockage of clams or mussels.
All major components of systems utilizing Lake Ontario water flow are subjected to l
inspection on a scheduled routine maintenance basis.
- Also, these systems have often been opened and inspected in the course of system modification and/or unscheduled maintenance.
1 In all cases, the presence of subject mussels and clams has never been detected.
Further, flow checks are performed monthly of both the fire water and the service water systems.
To further insure detection of the migration of clams and l
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. mussels into the plant, yearly maintenance procedures for the inspection of the diesel generator oil coolers and the condensate cooler are presently being modified to include a specific step for the inspection of these components for clams and mussels.
The flow checks and equipment inspections will provide an effective means of detecting and impact from clams or mussels.
Position 5.
Describe the actions taken in items 1 through 3 above and include the followiag information:
Applicable portions of the environmental monitoring program including a.
last sample date and results.
b.
Components and systems affected.
c.
Extent of fouling if any existed.
d.
How and when fouling was discovered.
l Corrective and preventive actions.
e.
Response
An investigation to determine whether Corbicula sp. or Mvtilus sp. had ever been detected in the vicinity or piping system of the Ginna Plant has recently been concluded.
Numerous interviews with Ginna Station personnel, consultants and Rochester Gas and Electric engineers who have had experience in the operation, maintenance and/or design of the affected
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. systems (the only systems in direct contact with Lake Ontario water are the fire, service and circulating water systems) revealed that no individual had ever seen clams or mussels in these systems.
As mentioned previously, a part of this investigation was to specifically in act components of suspect systems for clams and mussels during our present refueling shutdown.
- Again, there was no evidence of their presence.
A records investigation indicated that flow reduction through a lak'e water component was never attribut ed to a buildup of clams or mussels.
Flow checks of firewater and service water pumps are made monthly as required by the plant Technical Specifications.
Since fouling of systems has never been experienced, no corrective actions have been taken.
The Ginna Plant benthic and entrainment study programs are ongoing programs.
Data analysis, because of the nature of the programs, lags the sampling effort.
The 1981 January and February entrainment samples (latest samples analyzed) indicate a complete absence of Spheriidae ap., corbicula sp.
and Mytilus sp.
The latest Benthic analysis of June 23, 1980 did indicate some presence of Spheriidae on the lake bottom near Ginna.
Therefore, on a preventative basis, specific steps have been incorporated in yearly scheduled maintenance l
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procedures to inspect major components of the service water and circulating water systems for clams and mussels.
In conclusion, the Corbicula sp. and Mytilus sp. are not a problem at the Ginna Plant.
The Spheriidae could be a problem but there is no evidence to that end yet.
Although i
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Spheriidae sp. are present in the lake, it has.not been j
demonstrated that they can migrate or sustain themselves within the Ginna piping systems.
Corrective measures are not necessary at this time, but increased surveillance is and has been initiated.
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APPENDIX Rochester Gas and Electric practices two methods of identifying macro-organisms.
During the five year period,1974 through 1978, benthic programs were conducted at the Ginna site each summer season for purposes of identifying and enumerating bonthic macroinvertebrates present in the area of Lake Ontario adjacent to the GINNA site.
During this period samples were collected by placing a wire mesh case (20 cm x 20 cm x 25 cm), filled with #2 graded rock, on the lake bottom at selected stations in the lake.
Such cages were left in place for 4-6 weeks in order for benthic organisms to colonize these cages.
The cages were then retrieved and any organisms found within the cage were removed cud identified to the lowest practical taxon.
This level of identificats.on I
was at least to family, and in most cases to genus or species.
While the exact locations and number of samples collected may have varied to some degree from year to year, at least one set of samples per month was collected May through September (i.e. the most biologicall productive months) j each year except in 1977 when sampling concluded in August.
The exact number of sampling stations also varied during this five year period, however between 15 and 30 stations,
_10-extending from approximately 900 m to the west of the discharge location to 900 m east of the discharge location, were sampled each year.
Included in these stations, each year a selected number of samples were collected along a transect located directly within the discharge area.
From 1979 through the present sampling season (1981) benthic programs continued at the Ginna site for the same purposes as in previous years.
During this period, however, the sampling technique consisted of utilizing a benthic pumping system which basically " vacuums" organisms from selected areas of the lake bottom.
In this system a diver descends to the 2
desired location and suctions up a 0.146 m area of the lake bottom from each substrate type available at that station.
The suctioned material passes through a hose up to a boat where all material is filtered through a fine mesh net.
The fi.itered material is then analyzed to remove, identify and enumerate all collected organisms.
Again identification is made to the lowest practical taxon (i.e. at least family and normally genus or species).
During these years monthly sampling was conducted from April or May through November, i
except for 1981 which is scheduled to conclude in September.
l The area sampled extended from about 600 m west of the discharge location to the discharge area itself.
Between eight and eighteen stations were sampled during each of these years.
. For a period of over five years (1976 through 1981), entrainment sampling has been conducted in the Ginna screenhouse for purposes of identifying and enumerating organisms which are contained within the circulating cooling water withdrawn from Lake Ontario and utilized in Ginua, primarily as cooling water.
This sampling is accomplished by means of placing a net in the flow of water in the forebay, just prior to its passage through the traveling screens.
This net thus filters a portion of the water entering the plant and subsequently removes any organisms that are entrained within this water.
The sampling intensity and frequency has varied somewhat over the years, however, the degree of sampling has always been sufficient to be representative of the entrainment situation.within the cooling waters.
During all years at least two 0.5 meter plankton nets, with 505 or 569 micron mesh netting, have been simultaneously lowered into the forebay waters.
In 1976 these samples were i
taken for a one-hour period during the day and for another i
one-hour period during the night.
In 1977 and 1978 this was changed to one consecutive four-hour period during the day and a similar period at night.
For 1979 and continuing through 1981, one-hour periods were sampled every four hours over a 24-hour period.
From 1976 through October 1978 l
sampling was scheduled on a weekly basis.
From Fall 1978 l
through the present biweekly sampling has been conducted l
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12-during the lower productive seasons of November through March, and weekly sampling has been conducted during the higher productive spring and summer seasons.
Samples collected in this program are analyzed for macroinvertebrates and ichthyoplankton,'with each organism being identified to the lowest practical taxon, i.e. at least family and often times genus or species.
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