ML20064M752
| ML20064M752 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/07/1983 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Jordan E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| REF-SSINS-6820 5211-83-042, 5211-83-42, IEB-81-03, IEB-81-3, NUDOCS 8302150634 | |
| Download: ML20064M752 (4) | |
Text
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GPU Nuclear Corporation c U Nuclear
":==e oss48o Middletown Pennsylvania 17057 717 944-7621 TELEX 84-2386 Writer"s Direct Dial Number:
February 7, 1983 5211-83-042 Mr. Edward L. Jordan, Director Division of Engineering and Quality Assurance Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Sir:
Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 IE Bulletin 81-03 This letter is in response to your letter of December 10, 1982 requesting additional information subsequent to IE Bulletin 81-03 concerning flow blockage of cooling water to safety system components by Corbicula sp. and Mytilus sp. provides requested answers and discussion of IE Bulletin 81-03 Items 4.a.,
4.b.,
5.a.,
and 5.e.
Intrusion potential of the Asiatic Clam as well as prevention and detection methods are outlined. This information supports our initial response in that no immediate preventative action is required for the TMI station.
Sincerely, l
l H. D. Hukill i
Director, TMI-l llDH: RAS:vj f l
Attachment l
cc:
J. Van Vliet fall 0302150634 g h 9 PDR ADOCK PDR O
GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
ATTACHMENT 1 This is in response to your letter dated December 10, 1982 requesting additional information on Items 4 and 5 of I.E. Bulletin No. 81-03, i
" Flow Blockage of Cooling Water to Safety Components by Corbicula sp.
(Asiatic Clam) and Mytilus sp. (mussel).
This information is provided below.
Item 4A 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 cage conditions.
Responsel As previously communicated, the Asiatic Clam continues to be undetected and thus, presumably, has not become established in the Susquehanna River in the vicinity of the Three Mile Island Nuclear Station (TMINS). The Asiatic Clam is present in the Susquehanna River south of the Conowingo Dam, approximately 48 river miles downstream from TMINS.
No additional upstream movement of this clam has been identified to date.
Should Corbicula sp. become established in the immediate area (i.e. York Haven Pond) the short term intrusion potential of this species to TMINS is believed to be reasonably Icu.
Even during the worst case condition of a river flow of 1700 cfs, the i
intake velocities at TMINS remain less than the river velocity and l
are only 0.2 fps. During this condition, TMINS would utilize I
approximately !% of the river.
However, over an extended time, once Corbicula sp. is established in York Haven Pond, the intrusion potential to TMINS is logically significant.
l Item 4B Evaluation of effectiveness of prevention and detection methods used in the past or present or planned for future use.
Response
Detection In that the Asiatic Clam is not yet present in the immediate environs of TMINS, GPU Nuclear's first line of detection is far-field.
Semiannually, CPU contacts three downstream utilities located between TMINS and the Conowingo Dam, the present limit of upstream l
intrusion for Corbicula sp.
The ecological studies performed by these utilities will provide information on the upstream movement, if any, of the Asiatic Clam.
Should such movement be identified, GPU will increase the frequency of this surveillance to quarterly.
l
On a more local basis, GPU also performs ecological monitoring, including the sampling of benthic macroinverteb, rates, that would detect Asiatic Clams in the York Haven Reservoir.
Additionally, accumulated silt in the intake structures is removed by suction dredging every two years. The spoil from this operation is examined for Corbicula sp.
Should the presence of Corbicula_sp.
be confirmed in the immediate area of TMINS, GPU will initiate a monitoring program to sample the intake bays with a Ponar dredge.
This sampling will be performed annually, in the spring, summer, and fall.
c Prevention The present schedule of biannual dredging of the intake bays should provide an effective method of control should the Asiatic Clam become established at TMINS.
Dredging a limits the accumulation of shell debris from dead clams; e prevents the development of older age classes thus limiting size and mortality; e and aids to limit the population of clams in the intakes.
Additionally, all pumps are operated at least quarterly.
Thus no pump remains inactive for an extended period of time consequently limiting the opportunity for undisturbed clam colonization-and growth.
If Corbicula sp. becomes established at TMINS, preventive measures may be increased to include annual dredging, biocide, heat treatment or other measures as dictated by the severity of the infestation.
Item 5 Identify applicable portions of the environmental monitoring a.
program including last sample date and results.
Response
Program Date Result 1.
Benthic Macroinvertebrate Sampling January 1983 No Corbicula sp.
in York Haven Pond detected.
2.
Asiatic Clam Surveillance Fall 1982 No movement of the Asiatic Clam upstream of the Conowingo Dam was detected by downstream utilities.
Program Date Result 3.
Intake Dredging August 1982 No Corbicula sp. detected b.
Components and systems affected.
Response
None s
c.
Extent of fouling if any existed.
Response
None e.
Corrective and preventive actions.
Response
Corrective actions not necessary.
Preventive actions as described above for Item 4b.
We believe the methods of detection and prevention already implemented by GPU Nuclear are fully adequate in response to the existing status of Corbicula sp. in the Susquehanna River.
I l
I l
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