ML20062M251

Responds to IE Bulletin 82-02, Degradation of Threaded Fasteners in RCPB of PWR Plants. Maint Procedures Written to Include Procedures for Proper Threaded Fastener Practices

ML20062M251
Person / Time
Site:	Davis Besse
Issue date:	08/04/1982
From:	Crouse R TOLEDO EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
REF-SSINS-6820 1-284, IEB-82-02, IEB-82-2, NUDOCS 8208200046
Download: ML20062M251 (5)

Text

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Docket No. 50-346

$ce License No. NPF-3

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• 22' Serial No. 1-284 August 4, 1982 Mr. James G. Keppler, Director United States Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137

Dear Mr. Keppler:

This is in response to IE Bulletin 82-02 dated June 2, 1982 (Log No.

1-643) concerning Degradation of Threaded Fasteners in the Reactor Coolant Pressure Boundary of PWR Plants. The attachment contains Toledo Edison responses for Davis-Besse Nuclear Power Station Unit No. 1.

Very truly yours, f

^ --. =v RPC: GAB: lab attachment cc: DB-1 NRC Resident Inspector 8208200046 820804 PDR ADOCK 05000 g

a THE TOLEDO EDISON COMPANY EO; SON PLAZA 300 MADISON AVENUE TOLEDO OHIO 43G52 -

AUS 13 $82

ATOMIC ENERGY ACT OF 1954 SECTION 182 SUBMITTAL IN RESPONSE FOR THE DAVIS-BESSE NUCLEAR POWER STATION UNIT NO. 1 FACILITY OPERATING LICENSE NPF-3 This response is submitted in conformance with Atomic Energy Act of 1954, Section 182 relating to IE Bulletin 82-02 dated June 2, 1982. This deals with Degradation of Threaded Fastener in the Reactor Coolant Pressure Boundary of PWR Plants.

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Vice President, Nuclear Sworn to and subscribed before me this 4th day of August, 1982.

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Docket No. 50-346 License No. NPF-3 Serial No. 1-284 August 4, 1982 RESPONSE TO IE BULLETIN 82-02 ITEM 1:

Develop and implement maintenance procedures for threaded fastener practices.

Include:

(1) maintenance crew training of proper bolting / stud practices, tools applic-ation, specifications and requirements, (2) detensioning and retensioning practices (torque iteration), specified tolerances, and other controls for disassembly and reassembly of component closure / seal connections, (3) gasket installation and controls, and (4) retensioning methods and other measures to eliminate reactor coolant leakage during operations.

Quality Assurance measures should also be established for proper selection, procurement, and application of fastener lubricants and injection sealant compounds to minimize fastener susceptibility to stress corrosion cracking.

ITEM 1 Davis-Besse Nuclear Power Station maintenance procedures

RESPONSE

have been written to include procedures for proper threaded fastener practices.

The training department will work with maintenance to develop any additional training required for threaded fastener practices.

Quality Assurance measures have been established for proper selection, procurement and application of lubricants and injection sealant compounds.

Engineering is presently working with Babcock and Wilcox to develop an alternative to lubricants that contain molybdenum disulfide (MoS )*

2 ITEM 2:

Threaded fasteners of closure connections, identified in the scope of IE Bulletin 82-02, when opened for component inspection or maintenance shall be removed (fasteners

" seized" or designed with interference fit, may be inspected in place), cleaned, and inspected per IWA-2210 and IWA-2220 of ASME Code Section XI (1974 Edition or later) before being reused.

ITEM 2 Toledo Edison has added inspection,of all threaded

RESPONSE

fasteners identified in the scope of IE Bulletin 82-02 to maintenance procedures. The following threaded fasteners were cleaned and inspected in June, 1982, per IWA-2210 and IWA-2220 of ASME Code Section XI (1974 Edition or later):

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Control rod drive hold down bolts on ten I

control rod drives.

b)

Steam Generator primary manway and hand hole studs on four manways and four hand holes.

Threaded fasteners of' closure connections in Item 2 will l

be inspected each time when opened for component inspection or maintenance.

ITEM 3a:

Identify those bolted closures of the Reactor Coolant

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Pressure Boundary that have experienced leakage, particularly those locations where leakage occurred during the most recent plant operating cycle. Describe

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the inspections made and corrective measures taken to eliminate the problem.

If the leakage was attributed to gasket failure or its design, so indicate.;

e ITEM 3a 1)

Control rod drive mechanism reactor vessel nozzle l

RESPONSE

flanges at ten of 69 locations showed signs of

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leakage. The eighty hold down bolts were removed and q

the gasket sealing surfaces were cleaned and inspected.

Prior to re-installation during the current outage, the bolts under went visual and liquid penetrant

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examinations. A total of fifty bolts were rejected, forty-seven due to visual thread damage and three due i

i to cracks found during liquid penetrant examination.-

The damage to the studs was caused by the extreme torque it took to remove the bolts. The remaining thirty bolts passed both examinations and were re-installed, along with fif ty new replacement bolts.

2)

Steam Generator-1-1 and 1-2' lower primary hand holes -

showed signs of leakage. Studs, nuts, cover and j

backing plate were. removed and all surfaces were cleaned and new gaskets were installed..All studs i

~ and nuts were cleaned and inspected'per IWA-2210 and i

IWA-2220 of.ASME Code Section XI.

Twelve hand hole-studs and nine hand hole nuts were rejected due to

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visual thread damage.

Four manway studs'also were l

rejected due to visual thread damage. _None of the l

studs failed the magnetic particle' examination. All rejected' studs and nuts were replaced with new studs-and nuts.

The leakage identified.in 1 and 2 above is attributed to gasket leakage..

f ITEM 3b:

Identify those closures and connections where fastener lubricants.and injection sealant materials have been or are'being usednd report'on plant experience with their-l-

a application particularly'and' instances of: stress i' '

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corrosion cracking of fasteners.

Include types and composition of materials used.

ITEM 3b 1)

Control rod drive reactor vessel nozzle bolts are

RESPONSE

lubricated with FELPRO N-1000 lubricant.

2)

Steam Generator manway and hold down bolts are lubricated with Molykote "G" rapid spray.

3)

No evidence of stress corrosion cracking was found on any of the above bolts.

4)

One of the RCS cold leg thermowell penetrations has an injection sealant box (Furminite) in place to stop leakage. This penetration will be repaired during Davis-Besse's ten year outage when the reactor is de-fueled. At this time, the penetration cannot be checked for stress corrosion cracking.

In addition, this thermowell is made of Inconnel SB 166 which is generally resistant to stress corrosion cracking.

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