ML20004D412
| ML20004D412 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 05/29/1981 |
| From: | Phyllis Clark GENERAL PUBLIC UTILITIES CORP. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-81-03, IEB-81-3, NUDOCS 8106090364 | |
| Download: ML20004D412 (6) | |
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" ' May 29, 1981 Mr. Boyce H. Grier, Director Office of Inspection and Enforcement Region I U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 08731
Dear Mr. Grier:
Subj ect: Oyster Creek Nuclear Generating Station Docket No. 50-219 IE Bulletin No. 81-03 The subject bulletin involves a fouling problem in cooling water systems resulting from the presence of Corbicula sp. (Asiatic Clam) and Mytilus sp. (Mussel).
Listed below are the " Actions to be taken by Licensees" as des-cribed in the bulletin as well as our response to each item. The numbering scheme is consistent with that used in the bulletin.
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
A review of past biological studies has determined that one of the fouling organisms in question, Mytilus edulis (Blue Mussel), is present in the Barnegat Bay area. This organism is fairly common in the spring of the year and uncommon during the remainder of the year. The indivi-duals that have been found have all been juveniles (less than 2 cm in length) as this species apparently cannot survive summer ambient temperatures in the Barnegat Bay System.
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Mr. Boyce H. Grier, Director May 29, 1981 2.
If it 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 protection systems. The sample shall have included a distribution of components with supply and return piping of various diameters which exist in the potentially affected systems. This inspec-tion shall have been conducted since the last clam or mussel spawning season or within the nine month period preceding the date of this bulletin.
If the absence of organisms or shell debris has been confirmed by such an inspection or 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 rapplicable to holders of an operating license.
Response
During the recent shutdown of the Oyster Creek plant, the containment spray heat exchangers were inspected for fouling although not specifically for the concerns identified in the subject Bulletin. The inspection revealed some fouling; however, not to the extent of requiring cleaning.
3.
If clams, mussels or shells vete 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 potentia? Ly 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 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 bockage or degradation to unacceptably low flow rates has not occurred.
If another method is used, the basis of its ac-ceptance for this determination shall be included in the response to this bulletin.
,Mr. Boyce H. Grier, Director May 29, 1981
.. If the above flow rates cannot be measured or indicate significant flow degradation, potentially affected systems shall be inspected according to 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
Since the absence of shells was not confirmed by action in 2 above, flow measurements were taken on the cooling water side of the Containment Spray Heat Exchanger. Tha coolinE water systems con-sists of two independent headers each supplying two parallal heat exchangers. Flow measurements were taken on each header as well as each parallel flow path to assure that each heat exchanger received adequate flow. Ultrasonic me qurements were made on each header and one parallel flow path with the flow in the second parallel path determined by difference. An analysis of those readings have determined that -
t than adequate flow exists through each heat exchanger to assure che proper operation of the containment spray system.
Fire protection water at the Oyster Creek Station is provided from a fresh water pond which overflows to Barnegat Bay over a weir system; therefore it is not possible for fouling of this nature to occur.
4.
Describe methods either in use or planned (including implementa-tion date) for preventing and detecting future flow blockage or degradation due to clams or musnels 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 detec-tion methods used in the past or present or planned for future use.
Response
Presently, as a part of the Inservice Testing program, being implemented at the Oyster Creek Station, ESW flow rates will be measured on a periodic basis. The appropriate testing pro-cedures will be modified to assure flow measurements are taken in parallel patha in order that any flow blockage will be de-tected. Additionally, we are currently performing a feasibility study for establishing a chlorination program for this system.
Mr. Boyce H. Grier, Director May 29, 1981 The major fouling mechanism would be intrusion of the mussel larvae with the ultimate growth of survivors resulting in fouling or the system by either live mussels or shell debris following their death. This type of fouling will be readily indicated by periodic flow measurements as discussed above.
Furthermore, should chlorination prove feasible, this may prevent the growth of the larvae and juveniles thereby pre-cluding the fouling problem.
5.
Describe the actions taken in items 1 through 3 above and include the following information:
a.
Applicable portions of the environmental monitoring program including last sample date and results.
b.
Ccmponents and systems affected.
c.
Extent of fouling if any existed.
d.
How and when fouling was discovered.
e.
Corrective and preventive actions.
Response
The actions taken as a result of items 2 through 3 are explained in our responses above. Attachment one is a graph of the latest biological studies of the Mytilus adulis (Blue Mussel) popula-tion in the area around Oyster Creek Station.
At Oyster Creek the fire protection systems are not subject to this type of fouling as discussed above. The only safety-related system that may be affected is the Emergency Service Water System (ESW) which supplies cooling water for the Contain-ment Spray System.
As discussed above, an inspection of the heat exchangers subsequent flow tests did not indicate any degradation of system capabilities due to fouling problems.
As discussed above, periodic flow tests and possible chlori-nation will serve to prevent a fouling problem. The periodic flow tests have been initiated and will be conducted monthly for the next several months to establish a base line and in accordance with our IST program thereafter until such time that
Mr. Boyce H. Grier, Director May 29, 1981
. an effective means of precluding this fouling problem is implemented. The results of the chlorination study are not yet available; therefore, it is not possible at this time to establish any implementation date should chlorination be deemed feasible.
This concludes our response to the subject bulletin and should you have any further questions plesse contact. Mr. Michael I.aggart at (.609) 693-6932. As requested, actions taken with regard to this bulletin involved approximately 120 man hours.
Yours very truly, f/
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Phillip dlark Executive Vice President Signed and sworn to before me this M9 day of 7// W
, 1981.
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Notary Public 77/t,=
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MICHAEL (ACCAM me NOTARY PUBLIC OF NEW JER*,EY
% cannome hava o,c u, g,gs cc: Director Office of Inspection and Erforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Resident Inspector Oyster Creek Nuclear Generating Station Forked River, New Jersey i
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9 10 11 12 MONTH Density of Mytilus edulis at four stations in Oyster Creek and Forked River, July 1976 - June 1977.
FR 1 = Forked River at the Route 9 Bridge FR 2 = Forked River Midway between Route 9 and Barnegat Bay OC 1 = Oyster Creek at the Route 9 Bridge CC 2 = Oyster Creek Midway between Route 9 and Barnegat Bay 4
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