ML20100J565
| ML20100J565 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 02/22/1996 |
| From: | Eric Simpson Public Service Enterprise Group |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-95-002, IEB-95-2, LR-N96050, NUDOCS 9602290149 | |
| Download: ML20100J565 (7) | |
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Nbhe sewice Electric and Gas Company E. C. Simpson Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 605 339-1700 Senor Vice PresKlent Nucmar Engineenng FEB 221996 LR-N96050 United States Nuclear Regulatory Commission i
Document Control Desk Washington, D.C.
20555 l
Gentlemen:
NRC BULLETIN 95-02, UNEXPECTED CLOGGING OF A RESIDUAL HEAT REMOVAL (RHR) PUMP STRAINER WHILE OPERATING IN SUPPRESSION POOL COOLING MODE HOPE CREEK GENERATING STATION l
FACILITY OPERATING LICENSE NO. NPF-57 DOCKET NO. 50-354 i
Nuclear Regulatory Commission (NRC)Bulletin 95-02, Unexpected Clogging of a Residual Heat Removal (RHR) Pump Strainer While Operating in Suppression Pool Cooling Mode, identified five (5)
" Requested Actions" to be completed for Hope Creek Generating i
Station.
These Requested Actions are to ensure that unacceptable buildup of debris that could clog suppression pool suction strainers does not occur during normal operation.
In a letter to the NRC dated November 15, 1995 (LR-N95195), Public Service Electric & Gas Company (PSE&G) provided the initial response to the five Requested Actions in Bulletin 95-02.
This letter provides a supplemental response addressing
" Requested Action No.
2" of the subject Bulletin which requested PSE&O to confirm'the initial operability evaluation submitted to the NRC in letter LR-N95195 through appropriate tests (s) and strainer inspection (s) within 120 days of the date of Bulletin 95-02.
NRC Bulletin 95-02 requires submittal of the confirmatory test / inspection results within 10 days of completion.
The additional test and inspections confirming the operability of pumps which take suction from the suppression pool were completed during the current Hope Creek refueling outage (RFO6).
A summary of the results is provided in Attachment 1.
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FEB 221996 Document Control Desk 2
LR-N96050 Please contact us should you have any questions regarding this submittal.
Sincerely, Attachment (1)
Mr.
T.
T. Martin, Administrator - Region I 1
U.
S.
Nuclear Regulatory Commission i
475 Allendale Road King of Prussia, PA 19406 Mr. D. Jaffe, Licensing Project Manager - Hope Creek U.
S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 14E21 Rockville, MD 20852 1
1 Mr. R. Summers (X24)
Senior Resident Inspector Mr.
K. Tosch, Manager, IV Bureau of Nuclear Engineering 33 Arctic Parkway j
CN 415 Trenton, NJ 08625 1
4 REF:
LR-N96050-STATE OF NEW JERSEY
)
)
SS.
COUNTY OF SALEM
)
E. C. Simpson, being duly sworn according to law deposes and t
says:
I am Senior Vice President - Nuclear Engineering of Public Service Electric and Gas Company, and as such, I find the matters set forth in the above referenced letter, concerning Hope Creek Generating Station, are true to the best of my_ knowledge, information and belief.
l Subscribed.and Sworn to before me this e2 1 day o As 96 de Notary Pub 3Td of New Jdr'sey
]
l ANN L. SHIMP l
My Commission expires on NOTARY PUBLIC 0F NEW JERSEY my commission Empires Oct.13,1997
l Q
LR-N96050 ATTACHMENT 1 RESPONSE TO NRC BULLETIN 95 UNEXPECTED CLOGGING OF A RESIDUAL HEAT REMOVAL (RHR) PUMP STRAINER WHILE OPERATING IN SUPPRESSION POOL COOLING MODE NRC REOUESTED ACTION No. 2 ThE operability evaluation in Requested Action 1 should be confirmed through appropriate tests (s) and/or strainer inspection (s) within 120 days of the date of this bulletin.
PSEEG RESPONSE In the initial response to Bulletin 95-02 (letter LR-N95195 dated November 15, 1995), PSE&G committed to complete the following actions during the current Hope Creek refueling outage (RFO6) to support the confirmation of the operability of pumps which take suction from the suppression pool.
The response to each commitment is provided below.
Commitment:
PSE&G committed to complete an inspection of the strainers and accessible areas of the suppression pool during the current Hope Creek outage (RF06).
Response
Inspection of the as-found condition of the suppression pool was completed January 3, 1996.
The inspection identified a thin 3ayer of sediment approximately 1/32" thick, and a minor amount of foreign debris on the bottom of the suppression pool (e.g.
wrench, pencil, nut, etc.).
The as-found condition indicated an acceptable level of cleanliness of the pool.
The as-found l
condition did not warrant additional cleaning or vacuuming.
However, debris found in the initial inspection will be removed prior to restart from RFO6.
Commitment:
PSE&G committed to obtain samples of the bottom sediment in several locations and torus water during RFO6.
Testing of the sediment and water samples would be performed to determine the composition of the sediment and to detect the presence of fibrous material.
Response
Samples were taken of bottom sediment and torus water on Page 1 of 4
1 i
LR-N96050 ATTACHMENT 1 1
RESPONSE TO NRC BULLETIN 95 UNEXPECTED CLOGGING OF A RESIDUAL HEAT REMOVAL (RHR) PUMP STRAINER WHILE OPERATING IN SUPPRESSION POOL COOLING MODE January 3, 1996.
These samples were sent to an offsite laboratory for analysis.
Laboratory analysis results indicate a very low number of small fibers were present in bottom sediment samples, and no fibers were detectable in the water samples.
Four one liter bottom sediment samples were taken from four suppression pool quadrants and microscopically examined to determine the constituency.
The bottom sediment samples were each filtered through a 0.45pm filter.
The majority of the sediment was red particles (most likely corrosion products) with relatively few fibrous particles.
Two types of fibers were identified (cloth and fiberglass).
The smallest fiber was =125pm with the largest =2500pm.
The average fiber length was 2750pm.
In the worst case sample, a total of 123 fibers and one clump defined as three or more fibers wrapped together were identified.
In conclusion, based on the small length and quantity of fibrous material identified in the water and sediment samples, unexpected clogging of the suppression pool suction strainers would not occur.
Commitment:
PSE&G committed to complete Inservice Testing (IST) of pumps which draw suction from the suppression pool (Residual Heat Removal and Core Spray Pumps) to confirm pump operability.
This j
testing would detect unacceptable debris buildup which could clog the suction strainers.
The pump IST's will be completed by
)
February 14, 1996 in accordance with the Bulletin, j
Response
Following submittal of the initial Bulletin 95-02 response to the NRC and telephone conferences with the NRC on December 21, 1995 and January 29, 1996, PSE&G opted to perform an extended IST to confirm operability of the pumps which draw suction from the suppression pool.
The extended IST consisted of running the C RHR, A Core Spray, and C Core Spray pumps simultaneously (approximately 16,400 gpm total) for six (6) hours.
The test was performed on February 12, 1996.
The test did not identify a
]
reduction in suction pressure during the six hour test that would be indicative of clogging of the suction strainers.
The acceptance criteria for the test was < 0.5 psid across the pump suction strainers.
Pump suction pressure was maintained constant during the test.
Multiple pumps were run simultaneously to ensure adequate agitation to suspend any sediment or fibers in Page 2 of 4
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l LR-N96050 ATTACEMENT 1 l
RESPONSE TO NRC BULLETIN 95-02 UNEXPECTED CLOGGING OF A RESIDUAL HEAT REMOVAL (RHR) PUMP BTRAINER WHILE OPERATING IN SUPPRESSION POOL COOLING MODE the pool.
Follow-up actions included video inspection of the inservice suction strainers.
Inspection of the strainers was completed on February 13, 1996.
The video showed no significant accumulation of debris on any of the inservice suction strainers (one 6" piece of wire, three (3) cloth or metal tags 1" x 2",
and a small metallic object
.5" x
.5" were identified on the strainers from the video inspection).
Based on the results of the extended pump IST, it can be concluded that debris clogging of the suction strainers would not have occurred, and the pumps that take suction from the suppression pool are and were capable of performing their safety related function.
PSE&G also committed to revise the IST procedures for the Core Spray and RHR pumps for suction pressure data collection.
Although perfcrmance of the normal pump IST's may not be of a sufficient duration (approx. 30 minutes) or cause sufficient turbulence in the suppression pool to allow debris collection on the suction strainers surfaces, PSE&G has decided to revise the IST procedures to obtain data at the both the beginning and end of the surveillance test.
The changes will be incorporated into the next revisions of the surveillance test procedures.
This data will be used to trend pump performance.
Commitment:
PSE&G committed to complete torus cleaning concurrent with inspections to confirm the operability of pumps which draw suction from the suppression pool during RF06.
Response
Operability of the pumps which draw suction from the suppression pool was confirmed by performance of the extended IST as j
discussed above.
The resalts of the water and sediment sample analysis which identified minimal quantities of fibrous material, successful performance of the extended pump IST and cleanliness of the strainers before and after the extended pump IST have confirmed that an acceptable level of cleanliness currently exists in the suppression pool.
In addition, pSE&G had completed a partial cleaning of the suppression pool in areas where it was determined that appreciable accumulations of sediment existed during RFO5 (See letter LR-N95195).
Operation of the permanently installed Torus Water Cleanup System will provide further assurance that torus cleanliness will be maintained.
Inspection Page 3 of 4
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LR-N96050 ATTACHMENT 1 RESPONSE TO NRC BULLETIN 95 UNEXPECTED CLOGGING OF A RESIDUAL HEAT REMOVAL (RHR) PUMP STRAINER WHILE OPERATING IN SUPPRESSION POOL COOLING MODE results are indicative of adequate Foreign Material Exclusion (FME) controls to maintain suppression pool cleanliness as discussed above.
The minimal debris found during the initial suppression pool inspection will be removed prior to restart from RF06.
Therefore, PSE&G has determined that additional suppression pool cleaning is not required during the current refueling outage.
As previously committed to the NRC in the initial Bulletin response (See letter LR-N95195), a procedure for torus inspection and cleaning will be developed.
The procedure will include criteria for acceptability of sediment / debris levels, requirements to periodically sample the torus water and/or sediment for the presence of fibrous material, and criteria for determining the inspection and torus cleaning frequency.
This procedure will be issued before 12/31/96.
The criteria for cleaning to be included in this procedure will be utilized to determine if suppression pool cleaning is warranted in the future.
SUMMARY
The successful completion of the extended pump IST, running the C RHR, A Core Spray, and C Core Spray pumps simultaneously for six (6) hours, has confirmed that debris clogging of the strainers will not occur, and the pumps that take suction from the suppression pool are and were capable of performing their intended safety function.
An acceptable level of suppression pool cleanliness currently exists based on the inspections of the strainers and suppression pool, and results of the water and bottom sediment analysis.
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