ML19095A493

Response to IE Circular 76-06, Addressing Five Actions Identified in the Letter

ML19095A493
Person / Time
Site:	Surry
Issue date:	01/11/1977
From:	Stallings C Virginia Electric & Power Co (VEPCO)
To:	Moseley N NRC/RGN-II
References
IEC-76-006, Serial No. 345/112476
Download: ML19095A493 (3)

Text

e e VIRGINIA ELECTRIC A.ND POWER COMPANY RICHMOND, VIRGINIA 23261 January 11, 1977 Mr. Norman C. Moseley, Director

()dl~

Serial No. 345/112476 Office of Inspection and Enforcement PO&M/GRMjr:clw U.S. Nuclear Regulatory Conunission Region II - Suite 818 Docket 230 Peachtree Street, Northwest Atlanta, Georgia 30303 License

Dear Mr. Moseley:

In your letter of November 24, 1976 you forwarded IE Circular 76-06, "Stress Corrosion Cracking in Stagnant, Low Pressure Stainless Piping Containing Boric Acid Solution at PWR's, 11 for our review. This circular defines five (5) actions required to be taken by the licensee. The purpose of this letter is to address those action items identified in your letter.

The aforementioned circular cites a recent occurrence at Unit Nos. 1 and 2 of Surry Power Station associated with the piping of the recirculation spray sys-tems. The cracking of the Surry piping has been determined to be intergranular stress corrosion cracking which initiated on the inside of the piping. However, the three (3) conunon factors associated with the corrosion mechanism identified in the circular may not be completely applicable for the Surry event. In our letter of November 22, 1976, Serial No. 308A, we forwarded Licensee Event Report No. USRE-S2-76-15 which provides a complete description of the Surry event, there-fore, it will not be described herein. Each of the action items identified in your letter are listed below.

NRC ACTION ITEM

1. "Description of your program for assuring continued integrity of those safety-related piping systems which are not frequent-ly flushed, or which contain nonflowing liquids. This pro-gram should include consideration of hydrostatic testings in accordance with ASME Code Section XI rules (1974 Edition) for all active systems required for safety injection and contain-ment spray, including their recirculation modes, from source of water supply up to the second isolation valve of the pri-mary system. Similar test should be considered for other safety related systems."

. . ~

VIRGINIA ELECTRIC AND POWEil COMPANY TO Mr. Norman C. Moseley Page 2

RESPONSE

Portions of the safety related system, i.e. the high head safety injection system, the low head safety injection system, and the containment spray systems are presently flushed on a monthly basis to avoid stagnation resulting in a con-centration of p'otential contaminants. The flushing and sampling is defined in Technical Specification 4.1.E. The recirculation spray and containment spray piping are normally dry, except for testing of the pumps of the outside recircu-lation spray system. As mentioned in the aforementioned circular, portions of the recirculation spray piping installed at the Surry Power Station, Unit Nos. 1 and 2, recently experienced stress corrosion cracking as a result of the intrusion of contaminants from foreign sources. In addition, the inside containment sump was identified to contain contaminants. A program is being initiated to assure th~

sump is dry prior to testing of the inside recirculation spray pumps. In our letter of November 22, 1976, Serial No. 308A, we forwarded Licensee Event Report USRE-S2-76-15 update, which describes the event and our corrective action. We believe that the current flushing program in conjunction with the nondestructive examination programs proposed below will provide assurance that degradation of pip-ing will be detected.

NRG ACTION ITEM

2. "Your program should also consider volumetric examination of a representative number of circumferential pipe welds by nondestructive examination techniques. Such examination should be performed generally in accordance with Appendix I of Section XI of the ASME Code, except that the examined area should cover a distance of approximately six (6) times the pipe wall thickness (but not less than 2 inches and need not exceed 8 inches) on each .side of the weld. Supplementary examination techniques such as radiography, should be used where necessary for evaluation or confirmation of ultrasonic indications resulting from such examinations."

RESPONSE

A volumetric examination will be performed on the recirculation and contain-ment spray system. Twenty (20) selected circumferential pipe welds with pre-ference given to welds located in low areas will undergo nondestructive examination.

The nondestructive examination will be performed at each scheduled refueling outage. The examination will be performed generally in accordance with Appendix I of Section XI of the ASME Code, except that the examined area will cover a distance of approximately six (6) times the pipe wall thickness (but not less than two (2) inches and need not exceed eight (8) inches) on each ~ide of the weld.

Supplementary examination techniques such as radiography, will be used where necessary for evaluation or confirmation of ultrasonic indications resulting from such examinations.

,_ VIR~INIA E~CTRIC AND POWER Co~'NY TO Mr. Norman c.

Moseley Page 3 NRC ACTION ITEM

3. "A report describing your program and schedule for those inspections should be submitted within 30 days after receipt of this Circular."

RESPONSE

This letter is intended to satisfy the requirements of Item No. 3.

NRC ACTION ITEM

4. "The NRC Regional Office should be informed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of any adverse findings during nondestructive evaluation of the accessible piping welds identified above."

RESPONSE

The NRC Regional Office will be informed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of any confirmed adverse findings resulting during nondestructive evaluation of the accessible piping welds identified in the test program.

NRC ACTION ITEM

5. "A summary report of the examination and evaluation of results should be submitted within 60 days from the date of completion of proposed testing and examinations.

This summary report should also include a brief description of plant conditions, operating procedures or other activities which provide assurance that the effluent chemistry will maintain low levels of potential corrodants in such stagnant regions within the piping."

RESPONSE

A summary of the examination and evaluation of the results will be submitted within 90 days of completion of the proposed testing and examination. This report will also include a brief description of activities which will provide assurance that the piping will be dry or flushed to maintain the low levels of corrodants.

Very truly yours,

.1-;*, ) /;. ,_;;(<( / ;,)_;

C. M. Stallings Vice President-Power Supply and Production Operations