ML20138C737

Responds to 850930 Request for Addl Info Re Action Plan 16 Contained in 850910 Course of Action.Bore Size on Inlet Piping Will Not Impair Main Steam Safety Valve Performance. Flow Testing Will Be Performed

ML20138C737
Person / Time
Site:	Davis Besse
Issue date:	10/18/1985
From:	Williams J TOLEDO EDISON CO.
To:	Stolz J Office of Nuclear Reactor Regulation
References
1193, TAC-59425, NUDOCS 8510230025
Download: ML20138C737 (4)

Text

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Docket No. 50-346 TOLEDO License No. NPF-3 E!()ll$()lY' Serial No. 1193 JOE VVILUAMS. JR.

Senar Vce Presdert-Ntamar October 18, 1985 $$$$$$$$

Director of Nuclear Reactor Regulation Attention: Mr. John F. Stolz Operating Reactor Branch No. 4 Division of Licensing United States Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Stolz:

This letter is in response for information requested during a September 30, 1985 telephone conversation between Mr. G. Hammer (NRC MEB) and members of the Toledo Edison Nuclear Staff. The requested information concerns details regarding Action Plan No. 16 contained in Toledo Edison's Course of Action (Section IV.C.I.1) submitted September 10, 1985 (Serial No. 1182).

Request No. 1 Provide information regarding the required size of the inlet piping to the Main Steam Safety Valves (MSSV's) versus the installed inlet piping size.

Response

The Dresser Instruction Manual for Type 3700 Consolidated Safety Valves, May 1978 edition, requires the inlet pipe for the MSSV's to have at least a six inch bore. This requirement does not appear in the original instruction manual nor on the drawings which were supplied with the valves. Piping for the inlet pipe was specified in the original instal-lation to be six inch schedule 160 which has an inside dimension of 5.189 inches. This dimension has been verified by field measurements. The concern is that the "as built" configuration does not conform to the National Board configuration which was used for certification purposes.

-Further evaluation indicates this condition will not impair MSSV perform-ance. The maximum flow restriction occurs in. the upper portion of the nozzle. In this area, the flow diameters for Dresser valves with Q and R orifices are respectively 3.750 and 4.515 inches. Furthermore, there has never been any concern raised regarding the valves capability to relieve an overpressure condition. Per Dresser recommendation, flow testing will be performed to ensure that all applicable ASME Code and National Board

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requirements are met. This concern is being tracked by Nonconformance Report 85-0117.

/ 8510230025 851018 \

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• Docket No. 50-346 l License No. NPF-3 Serial No. 1193 October 18, 1985 )

Page 2 i Request No. 2 Provide information regarding any planned piping modifications resulting from analysis conducted under Action Plan No. 16.

Response

To ensure that the main steamlines properly support the MSSV's, analyses are underway to examine the flexibility of the Main Steam System piping.

Fluid transient loads and structural system response will be included in the analysis. A modification is being considered, as an interim measure, to add a restraint to the steamline for Steam Generator No. 1-2. The purpose of this restraint is to increase the stiffness of the main steam line.

Request No. 3 Provide the testing history for the Main Steam Safety Valves (MSSV's),

Atmospheric Vent Valves (AVV's), and Main Steam Isolation Valves (MSIV's).

Response

There have been several occurrences of MSSV blowdown in excess of rated 3%. Prior to the 1984 refueling outage, reseat pressure experienced during recent plant trips ranged from approximately 980 to 900 psig.

In March 1984, the A4 MSSV stuck open after a reactor trip resulting in boiling dry Steam Generator 1-2. The root cause of this occurrence was failure of a cotter pin permitting the release nut to travel unrestricted down the spindle threads. Maintenance Procedure MP 1401.28, Main Steam Safety Valve Disassembly Inspection / Repair and Reassembly, has been revised to require installation of new stainless steel cotter pins when maintenance is performed on a MSSV.

Previous maintenance experience on MSSV's has shown:

a. Excessive wear of guides and holders

b. Bending of spindles

c. Damage to the disc seats requiring replacement

d. Greater maintenance requirements for the low set pressure MSSV's All MSSV's on the No. 2.("A") header were rebuilt during the 1984 refueling outage. Valve B2 was rebuilt in March 1985. Valves B1 and B7 were rebuilt in 1983, and the other valves on the B header were last rebuilt in 1982.

Four of the eighteen installed MSSV's have a smaller capacity ("Q" orifice).

These valves have required considerably less maintenance than the large

("R") orifice MSSV's.

Dock;t No. 50-346 Liccnaa No. NPF-3 Serial No. 1193 October 18, 1985 Page 3 60th AVV's were rebuilt during the 1984/1985 refueling outage.

Recent maintenance and testing histories of the MSSV's, AVV's and Integrated Control System were reviewed. Nothing of significance was noted.

Additional Inservice Test (IST) histories for the MSSV's, AVV's and MSIV's were previously been made available for NRC Mechanical Engineering Branch review.

Request No. 4 Provide the results of the "as received" testing of the first eight MSSV's which were tested at Wyle Laboratory.

Response

The Wyle Laboratory test results for the first eight MSSV's tested in the "as received" condition is provided as an Attachment to this letter. The first part of this testing was witnessed by NRC personrel from the Vendor Programs Branch.

Very truly yours, b8dNmy JW:LLH:DJS:lah attachments cc: DB-1 NRC Resident Inspector 6

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Davis-Besse Main Steam Safety Valves (as received condition) ], y p' M 03

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• Wyle Test Data g g.

Valve 8 vi 8 :a c-6' Run 1 'Run 2 Run 3 Run 4 Run 6 Leakage "*

P sition Parameter Run 5 Disposition Disc lift '1.16 0.20 1.16 1'.18 .

Al Setpoint 1024 995 993 1009 No Leakage Rebuild i Blowdown 3.8 NM 1.1 2.8 Disc lift 1.06 1.06 1.04 A2 Setpoint 1020 1025 1015 Yes Rebuild Blowdown 4.3 19.0 2.7 Dise lift 1.13 1.14 0.25 1.14 A3 Setpoint- 1025 1020 1031 1025 No Leakage Rebuild Blowdown l'. 3 2.5 NM 1.8 Dise lift 0.62 1.12 1.12 1.12 A4 Setpoint 1014 1015 1006 1005 No Leakage Rebuild Blowdown NM 5.3 5.7 5.2 Dise lift 1.15 1.14 1.16 NM 1.14 B1 Setpoint 1042 1041 1044 1044 1040 Yes Rebuild Blowdown 4.6 4.5 5.2 5.2 19.7 Dise lift 1.12 1.09 1.10 1.09* 1.10 1.10 B2- ,Setpoint 1051 1037 1037 1042 1043 1049 No Leakage Passed Blowdown 4.8 3.2 2.7 2.6 2.8 3.1 Dise lift 1.16 1.20 1.20 1.20 B3 Setpoint 1074 1070 1077 1070 Yes Rebuild Blowdown 1.8 2.8 2.4 3.4 Dise lift 1.20 1.20 1.18 B4 Setpoint 1080 1071 1069 Yes Rebuild Blowdown 3.3 2.5 2.3 All disc lifts in inches All cetpoints in psi All blowdown in percent NM Indicates the parameter war not measured

• Compression screw was. adjusted one flat clockwise prior to this run.

ca b/40

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