ML18036B142
| ML18036B142 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 01/22/1993 |
| From: | Zeringue O TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-88-14, NUDOCS 9301270168 | |
| Download: ML18036B142 (11) | |
Text
1 ACCELERATED DOCUMENT DISTRIBUTION=SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
DOCKET g 05000259 05000260 05000296 ACCESSION NBR:9301270168 DOC.DATE: 93/01/22 NOTARIZED: NO CIL:$0-259 Browns Ferry Nuclear Power Station, Unit 1, Tennessee
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50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee AUTH.NAME
'UTHOR AFFILIATION ZERINGUE,O.J.
Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
Responds to NRC 921223 ltr re deviations noted in insp repts 50-259/92-41,50-260/92-41 a 50-296/92-41.Corrective actions:
TVA will replace DCA sys refigeration dryer temperature switches w/switches that have smaller deadband.
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TITLE: General (50 Dkt)-Insp Rept/Notice of Violation Response'OTES:
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0 NOTE TO ALL"RIDS" RECIPIENTS:
J PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
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LTTR 26 ENCL 26
Te'nneSSee Valley Authcrrty. POSt OffiCe BOX 2000. Deoatur, Alabama 35609.2000 O. J. "Ike" Zeringue Vice President, Browns Perry Nuclear Plant JAN 32 1993 U.S. Nuclear Regulatory Commiss'ion ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of Tennessee Valley Authority Docket Nos.
50-259 1
50-260 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) NRC INSPECTION REPORT 50-259, 50-260, 50-296/92-41 REPLY TO NOTICE OF DEVIATION This letter provides TVA's reply to the Notice of Deviation transmitted by letter from B. A. Wilson to M. 0. Medford dated December 23, 1992.
In that letter, NRC cited TVA with a deviation for failure to meet commitments made in TVA's response to Generic. Letter 88-14, "Instrument Air Supply System Problems Affecting Safety-Related Equipment."
Enclosure 1 to this letter is TVA's "Reply to the Notice of Deviation."
A listing of commitments made in. this letter is provided in Enclosure 2.
If you have any questions regar'ding this reply, please telephone G.
D. Pierce at (205) 729-7566.
Sincerely, f.
g~~gfiAi'.
J. Zeringue Enclosures cc:
See page 2
9301270168 930i22 PDR ADOCK 0500025'P Q
U.S. Nuclear Regulatory Commission JAN 22, l993 Enclosure cc (Enclosure):-
NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637.
- Athens, Alabama 35611 Mr. Thierry M.. Ross, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland.
20852 Mr. B. A. Wilson, Project',Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
ENCLOSURE 1
Tennessee Valley Authority Browns Ferry Nuclear Plant (BFN)
Reply to Notice of Deviation Inspection Report Number 50-259 260 29 /92-41 RESTATEMENT OF DEVIATION 2-41 "In reply to Generic Letter 88-14, Instrument Air Supply System Problems Affecting Safety-Related Equipment, TVA committed to revise Technical Instruction (TI)-34, Monthly Control Air System Dryer Dewpoint Test And Purge Control, prior to Unit 2 restart to verify that adequate margin between the ambient air temperature and dew point range at air dryer outlets is maintained.
Contrary to the above, TI-34 was not revised to verify adequate margin is maintained between the ambient air temperature and dew point range for all components supplied by the drywell control air system.
In
- addition, the system dew point is not maintained to the requirements recommended by the vendors of all the components supplied.
The vendor requirements for the main steam isolation valves for dew point is -40 degrees Fahrenheit (F).
TI-34 only verifies dew point to 30 degrees Fahrenheit.
The following examples indicate that the system repeatedly fails to reach even this setpoint:
1.
February 21,
- 1992, the 2B drywell control air dryer could only achieve a dewpoint of 37.2 degrees F.
2.
March 12,
- 1992, the 2A drywell control air dryer could only achieve a dewpoint of 40.8 degrees F.
3.
April 13,
- 1992, the 2B drywell control air dryer could only achieve a dewpoint of 39 degrees F.
4.
April 16, 1992 the 2B drywell control air dryer could only achieve a dewpoint of 38 degrees F.
This deviation is applicable to Unit 2."
TVA'S RFPLY TO DEVIATIO Reason for the Deviation In TVA's response to Generic Letter (GL) 88-14, TVA stated that the BFN drywell control air (DCA) system was designed to supply compressed air with a dew point of 30 degrees F at line pressure.
TVA also stated that the air supplied to the main steam isolation valves (MSIVs) and the main steam relief valves=(MSRVs) was required to have a dew point of minus 40 degrees F at 0 psig.
In addition to these statements of fact, TVA committed to revise.
Technical Instruction (TI) 34, "Monthly Control Air System Dryer Dew Point Test and Purge Control;" to verify that adequate margin between the ambient air. temperature and dew point at the air dryer outlets is maintained..
Subsequently, TVA revised TI-34 to add requirements to verify that the difference between the ambient temperature and dryer dew point was greater than or equal to 18 degrees F.
This satisfied the above referenced commitment.
TUA also revised TI-34 to add requirements to verify that the DCA system dryer dew point was less than 35 degrees F at line pressure.
TVA has determined that this dew point is acceptable for-DCA system applications.
During the current operating cycle, TVA has experienced difficulty attaining a 35 degree F dew point for the DCA system dryers.
TVA believes that this is due to excessive deadbands in DCA system refrigeration dryer temperature switches.
TVA is currently in the process of replacing these switches.
Notwithstanding these actions, TVA recognizes that discrepancies exist in certain information provided to NRC in the GL response.
- First, TVA cannot determine the basis for stating the DCA system was designed to provide air with a dew point of 30 degrees F.
This
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dew point is not consistent with vendor information or with the capabilities of a refrigeration-type dryer"system such as the DCA system.
- Second, at the time of TUA's response to the GL the vendor documents for the MSIVs and MSRVs specified a minus 40 degree F dew point.
- However, TVA's drywell control -system has never been able to attain this requirement.
Additionally, this requirement for the MSRVs has since been deleted from vendor documents and replaced with qualitative requirements (e.g.,
provide oil free, moisture free air).
TVA is currently working with the vendor to remove or revise this requirement for the MSIVs,
l
2.
Correct:ive Ste s Taken and Results Achieved TVA has verified that a
- 35. degree dew point at line pressure for the DCA system is acceptable, and has initiated appropriate actions to address the failure,to'meet this dew point.
TVA has identified a problem with the DCA system refrigeration dryer temperature switches and has initiated work orders to replace the switches.
TVA has also contacted the vendor to resolve the minus 40 degree dew point. requirement for the MSIVs.
3.
Corrective Ste s That have been or Mill Be Taken to Avoid Further Deviations TVA wil'1 replace DCA system refrigeration dryer temperature switches with switches that have a smaller deadband.
TVA will also resolve the discrepancy with the minus 40 degree dew point requirement for the MSIVs with the vendor'.
Following. these
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Date When Pull Com liance Will Be Achieved I
TVA will achieve full compliance by July 30,
- 1993, when the revised response to GL 88-14 is submitted.
ENCLOSURE 2 Tennessee Valley Authority Browns Ferry Nuclear Plant (BFN)
Reply to Notice of Deviation Inspection Report Number 50-25 260 2
2-41 List of Commitments TVA will replace drywell control air refrigeration dryer t'emperature switches with switches that have a smaller deadband.
TUA expects to complete this by March 1, 1993.
2.
3 ~
TVA will resolve the discrepancy with the minus 40 degree dew point requirement for the main steam isolation valves with the vendor.
TVA expects to complete this April 30, 1993.
N TVA will submit a revised response to Generic Letter 88-14; TVA expects to submit the 'revised response by July 30, 1993.