ML19283B803

Responds to IE Bulletin 78-14,Deterioration of Buna-N Components in Asco Solenoids. Review of Buna-N Matl in Control Rod Scram Sys Completed.Replacement of Matl Will Be 50% Completed in 1979 & 50% in 1980

ML19283B803
Person / Time
Site:	Cooper
Issue date:	01/25/1979
From:	Pilant J NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
NUDOCS 7903260345
Download: ML19283B803 (3)

Text

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GENERAL OFFICE Nebraska Public Power Distu*ct P. O. BOX 499, COLUMBUS, N E B R ASKA 68601 m E m oNE nou s. .s i January 25, 1979 Mr. Karl V. Seyfrit, Director U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza - Suite #1000 Arlington, Texas 76011

Subject:

IE Bulletin No. 78-14 Deterioration of Buna-N Components in ASCO Solenoids

Dear Mr. Seyfrit:

This letter is written in response to IE Bulletin No. 78-14, Deteri-oration of Buna-N Components in ASCO Solenoids.

The following actions have been taken and the following response sub-mitted in compliance with the " Action to be Taken by Licensees:" of IE Bulletin No. 78-14.

1. A review of the Buna-N material in the control rod scram systems has been completed.

2. Attached in Table I is a listing of the dates of installation and dates of packaging for Buna-N material in the control rod scram systems.

3. A schedule for replacement of Buna-N material in the control rod scram systems is based on General Electric SIL No. 128, Revision 1, Supplement 1, issued in August, 1978 recommending that all BWR operators take the following action:

" Establish a preventive maintenance program to replace all core assemblies, diaphragms and associated parts in all CRD scram pilot valves, backup scram valves, scram discharge volume vent and drain pilot valves, and scram discharge volume test valves at periodic intervals. The Buna-N parts used in these valves have at least a seven-year shelf and in-service life from the packaging date on the rebuild kit. Thus, the valves should be rebuilt periodically to assure that the Buna-N parts are not used in excess of seven years. It is recommended that the work be scheduled in any one outage such that the associated CRD's are selected from a distributed checkerboard pattern. The remaining valves can be rebuilt during subsequent outages."

7 90326 0 ~39/;5i

Mr. Karl V. Seyfrit January 25, 1979 Page 2 The schedule of replacement of Buna-N material in the control rod scram pilot valves will be completed 50% in 1979 and 50% in 1980.

All of the Buna-N material in the scram discharge volume vent and drain pilot, test and backup scram valves will be replaced in 1979. A subsequent periodic replacement program at six-year intervals has been established.

The six-year interval is justified by the statement from General Electric SIL No.128, Revision 1, Supplement 1, given above in the response to Item 3 and by the following statement in General Electric SIL No. 128, Revision 1, dated January 30, 1976:

" General Electric recommends that a maintenance program be established so that all scram pilot valve diaphragms are replaced after three to four years of initial service, (i.e., from date of installation in BWR plant). Replacement diaphragms have an estimated total life from cure date of nine years, (i.e., if the diaphragms are on the shelf for two years from cure date, the operating service life is established to be seven years, etc.).

The shorter initial operating service life is due to the longer storage time of the rubber parts prior to initial plant operation."

If you have any questions regarding this response, please contact the CNS Station Superintendent.

Sincerely, M

J. M. Pilant Director of Licensing and Quality Assurance JMP:PLB:mg Attachment cc: United States Nuclear Regulatory Commission Office of Inspection and Enforcement .

Division of Reactor Operations Inspection Washington, DC 20555

TABLE I Components in the Control Rod Drive Scram Systems with Buna-N Material Component Installation Date Packaging Date

1. Scram Pilot Valves

a. Exhaust Diaphragm 5/76 11/75

b. Pressure Diaphragm 5/76 1/76

c. Body Passage Gaskets 5/76 10/75

d. Core Assemblies *6/69

• Unknown (including associated gaskets)

2. Scram Discharge Volume Vent and Drain Pilot Valves

a. All Buna-N Material *6/69

• Unknown

3. Backup Scram Valves

a. All Buna-N Material *6/69

• Unknown

4. Scram Discharge Volume Vent and Drain Test Valve

a. All Buna-N Material *6/69

• Unknown

• NOTE: The Hydraulic Control Unit (HCU) with scram pilot valves, the Scram Discharge Volume Vent and Drain Pilot Valves, the Backup Scram Valves, and the Scram Discharge Volume Vent and Drain Test Valve were received at Cooper Nuclear Station during construction in June, 1969. Packaging dates for Buna-N material in these valves are not known.

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