ML20058N926
| ML20058N926 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/09/1990 |
| From: | Shelton D TOLEDO EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 1830, TAC-77207, TAC-M77207, NUDOCS 9008150253 | |
| Download: ML20058N926 (4) | |
Text
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"Y TDtEDO EDISDN A certerer Erwrgy Ctrmany DONALD C. SHELTON Docket Number 50-346
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License Number NPF-3 Serial. Number 1830 August 9.-1990.
United States Nuclear Regulatory Commission Document Control Desk Washington, D. C.
20555
Subject:
Request for Relief from ASME Code Section XI Requirements for VT-2 Visual Examination of Class 1 Piping Located in the Decay Heat Valve Pit.(TAC Number 77207)
Centlemen '
- The purpose of this letter is to request relief pursuant to 10CFR50.55a(g)(5)(iv) from certain requirements of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code regarc'ing visual examination of a pore. ion of Class 1 decay heat removal (DHR) system suction piping located in the DHR valvr,2it at the Davis-Besse Nuclear Power Station (DBNPS).. Technical Specifica'. ions.(TS) prohibit removal of the water tight cover on the DHR valve pit, which is necessary for. unrestricted visual access, under the 'ASME Code speciffec. test conditions. Details of the requested relief are providr.a in the attachment.
Subsection IWB, Table IWB-2500-1. Examination Category B-P, Items B15.50 and B15.51, require leakage or hydrostatic tests in accordance with IWB-5200.every refueling, with a hydrostatic test once each 10-year interval for the entire Class.1' reactor coolant system (RCS) boundary, including the section of DHR suction piping located in the DHR pit.
The ASME Code specifies a VT-2 visual' examination for test acceptance. The station must be in Operational Modes 1, 2, or 3 to establish the leakage or hydrostatic test pressure required by IWB-5200, since TS 3/4.4.2, " Safety Valves,' restricts RCS pressure to less than the DHR system relief valve setpoint of 330 psig in Modes 4 and 5.
In Modes-1, 2, and 3 TS 3/4.5.2, ' Emergency Core Cooling Systems, ECCS
' Subsystems - Tavg > 2800F,' requires that the DHR valve pit serve as a water tight enclosure for valves DH11 and DH12 that assures that-the motor operators would not be. flooded for at least seven days following a loss of coolant accident (LOCA).kp9
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Dock 0t Numb;r 346
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Siriol Numb;r 1830' Page 2 Removal of the DHR valve pit cover to perform a VT-2 visual examination of the enclosed piping while in Mode 3, would invoke the TS 3.5.2 action statement.
. Removal of the DHR valve pit cover, performance of the hydrostatic or leakage
. test, VT-2 visual examination, and restoration of the DHR valve pit cover as required by T5 surveillance requirement 4.5.2.f. cannot reasonably be accomplished within the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> action statement. Curing of the sealant alonc requires 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Removal of the cover prior to entry into Mode 3, which potentially could save some time is prohibited by TS 3.0.4.
The DHR valve pit has an inspection port which is located at the opposite end of the pit from the piping for which relief from the VT-2 visual examination-j requirements is requested. Although the inspection port has been used in the past to satisfy the VT-2 visual examination requirements, the inspector performing the recent examination and the current Autberized Nuclear Inservice Inspector-(ANII) consider that the inspection port does u,t provide for an adequate view of the l
u piping or floor of the pit directly below the section of piping for the l
examination to be considered ac fully satisfying ASME Code VT-2 requirements.
j A computer alarm exists for the valve pit level which would provide control room indication of any significant leakage into the pit during operation.
In addition, welds in the affected piping-are subject to periodic volumetric and/or surface examinations in accordance with the inservice inspection (ISI) program.
No l
Indications were detected in two welds in the affected piping which were recently examined as part of the ISI program.
Toledo Edison considers that examination the floor of the DHR valve pit for evidence of leakage through the inspection port has provided and will continue-to i
provide adequate assurance of the structural integrity of the e tion of piping for which relief from the visual examination is requested, and therdore provides
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an. acceptable level of quality and safety.
Toledo Edison requests-NRC approval of the requested relief by November 30, 1990.
f Should you have any questions regarding this request, please contact Mr. R':W.
Schrauder Manager-Nuclear Licensing, at-(419) 249-2366.
j Very t ly yours,
.&fE PWS Attachment cci P. M. Byron DB-1 NRC Senior Resident Inspector A. B. Davis, Regional Administrator. NRC Region III M. D. Lynch, DB-1 NRC Senior Project Manager State of Ohio Utility Radiological Safety Board of Ohio
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' Docket Numb 2r, 50-346 0
1;Liccuss Numb;r NPF-3
. Serial Numb;r-1830 t_
. Attachment.
DAVIS-BESSE NUCLEAR POWER STATION, UNIT 1 RELIEF REQUEST FROM ASME SECTION XI VT-2 VISUAL EXAMINATION Component Description i
ASME Class 1 piping enclosed by the Decay' Heat Valve pit which is non-isolable J
from the Reactor Coolant System. -(See attached drawing, M-033B).
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~ASME Code C1. ass l
ASME Section III, Class 1 Piping
'ASME Examination Requirements 7
Subsection IWB, Table IWB-2500-1, Examination Category B-P, Item Numbers B15.50 l
.AND B15.51,-ASME Section XI, 1977 Edition with Addenda through summer 1978, 4
requires a leakage or hydrostatic test per IWB-5200 every refueling with a i
hydrostatic test once every 10-year interval for the entire Class 1 reactor j
coolant system boundary, including the piping identified above. A VT-2 visual examination is required.for test acceptance, j
Basis for' Relief I
I Relief is requested from the VT-2 Visual Examination for the ASME Class 1 piping enclosed by the Decay Heat Valve Pit.
This piping is not isolable from the reactor coolant system (RCS).
j The isolable' portion of the Class 1 piping in the decay heat valve pit is-J subjected to: a ' leakage or hydrostatic test every afuelir'g. Welds-in the affected j
piping are. subject to periodic volumetric and-surf ace xaminations.n accordance.
'l wi th the inservice inspection (ISI) program.
Two piping welds in the affected. ~
i I
area have been subjected to volumetric and/or surface examinations as required by the ISI. program.
No indications were detected.
1 S
Davis-Besse Technical Specification (TS) 3/4.5.2, ' Emergency Core Cooling 1
. Systems," requires that the decay heat valve pit serve as a water tight enclosure for valves DH11 and DH12 + hat assures the motor operators on valves DH11 and DH12 will not be flooded for at 19ast 7' days following a LOCA during Modes 1, 2, and 3.
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The reactor coolant system lea' age and hydrostatic tests must-be performed in at l
least Mode 3. since TS 3/4.4.2, " Safety Valves," in effect restricts'RCS pressure to;1esu than the decay heat removel system relief valve setpoint of 330 psig in 1 Modes.4 and'5.
-]
1 Removal of the valve pit cover in Modes 1, 2, and 3 would invoke the TS 3.5.2 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> action statement. The removal of the valve pit cover, the inspection, and 3
restoration of the valve pit cover and completion of testing required by TS.4.5.2.f. cannot be reasonably accomplished within the 72. hour limit permitted byrthe action statement. The cure time of the RTV sealant used on the cover is a minimum of 24-hours.
In addition, a vacuum leakage rate test is required after the seal is established.
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W Docket Number 50 346 4
.,1,1c nsa Number NPF-3
'E S; rial' Numb 3r 1830 Attachment
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The valve pit also.has an inspection-port.
However, this irispection port is at the opposite end of the valve pit from the affected piping.
The inspection port only allows for a view of the floor _directly below the port, and not the floor below the concerned piping.
The valve pit has a computer alarm for the water level in the pit which would provide control room indication of any major leakage during operation.
The extent t..
of visual examination permitted by the inspection port, coupled with the computer level alarm and other ISI program requirements provide reasonable assarance of the structured integrity of the section of piping for which relief is requested.
Alternative Examination During every leakage and hydrostatic test the examination shall consist of a visual examination of the floor of the decay heat valve pit for evidence of
' leakage by viewing through the decay heat valve pit inspection port.
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