ML20215H436

Responds to Notice of Violation & Forwards $180,000 in Payment of Civil Penalties.Corrective Actions:Check Valves Replaced W/Sized Valves of Improved Design Where Practical

ML20215H436
Person / Time
Site:	San Onofre
Issue date:	10/16/1986
From:	Fogarty D SOUTHERN CALIFORNIA EDISON CO.
To:	Taylor J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
NUDOCS 8610230202
Download: ML20215H436 (8)

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j "&M Southem California Edison Company P. O. B OX 8 00 2244 WALNUT GROVE AVENUE DAvlO J. FOGARTY ^' ^ T E LEPHON E ERECUTsyt VICE PRESIDENT 818 302-2796 October 16, 1986 Mr. James M. Taylor Director, Office of Inspection'and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Subject:

Docket No. 50-206 Response to Notice of Violation and Proposed Imposition of Civil Penalty - EA-86-97 San Onofre Nuclear Generating Station, Unit 1 By letter to Southern California Edison (SCE) dated September 17, 1986, the NRC forwarded a Notice of Violation and Proposed Imposition of Civil Penalty'related to events at San Onofre Nuclear Generating Station, Unit 1.

In accordance with 10 CFR 2.201 and 2.205, please find enclosed the SCE response to the subject notice and a check payable in the amount'of $180,000.

If you require-any additional information regarding this subject, please contact.me.

Subscribed on the / day of b dtv ,1986.

Sincerely, Subscribed and sworn to before me on this I (, day of

! Nfc_fo m _ ,1986. ,

OFFICIAL SEAL _ _ _ _I i C. SALLY SEBO I I

Notary Public-Cahtomia Enc 1osure j LOS ANGELES COUNTY I

My Comm. Exp. Apr. 20,1990 cc: John B. Martin, Region V (NRC) J i g g' R. Huey, Senior Resident Inspector p 2n88! e68)b /f;/M

a ENCLOSURE Resoonse to Notice of Violation (10 CFR2.201)

In accordance with 10 CFR2.201, this enclosure provides the Southern California Edison Company.(SCE) response to the Notice of Violation (NOV) forwarded by NRC letter dated September 17, 1986. Three specific violations are addressed in the NOV. A response for each violation is provided below.

A. The Notice of Violation + ate' in part:

" Technical Specification 3.4.3.A requires both steam generator auxiliary feedwater pumps and associated flow paths be operable in Modes 1, 2, and 3.

Contrary to the above, on November 21, 1985 while in Mode 1, the auxiliary feedwater flow path was not operable and automatic delivery of auxiliary feedwater would not have been assured. Flow was diverted from the steam generators to the east flash evaporator condenser after a manual reactor scram because five feedwater check valves failed to seat.

This is a Severity Level II violation (Supplement I).

(Civil Penalty - $80,000)."

A.1 Admission or Denial of the Alleaed Violation SCE admits that on November 21, 1985 while in Mode 1, the auxiliary feedwater flow path was not operable and automatic delivery of auxiliary feedwater would not have been assured.

A.2 Reason for the Violation The Auxiliary Feedwater System was inoperable on November 21, 1985 due to i failed check valves in the Feedwater System. Upon demand for auxiliary feedwater subsequent to the reactor trip, water was diverted from the steam generators to the Condensate System. Auxiliary feedwater flow to the steam generators was restored by operator action in accordance with procedure, approximately 5 minutes after the reactor trip, by isolating the Feedwater System through the closure of motor operated block valves in the feedwater lines.

The check valves which failed were damaged by the mechanism described in the Water Hammer Investigation Report provided to the NRC by SCE letter dated April 8, 1986, and the subsequent SCE submittal of May 1, 1986. The failure l mechanism described in these submittals can be summarized as having the following contributing factors:

l l (1) The proximity of upstream flow disturbance sources, such as control l valves and elbows, (2) The non-integral design of the check valve disc and hinge arm,

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(3) Reduced power, reduced flow operation for an extended period of time prior to the event, which resulted in increased check valve disc flutter and (4) The fact that the check valves were oversized for the application in which they were used.

The combination of the conditions described above resulted in the accelerated degradation of the check valves and their failure to seat properly at the time when they were required to perform their design function.

A.3 Corrective Steos Hhich Have Been'Taken and the Results Achieved The corrective steps which have been taken in response to the event of November 21. 1985 are described in the SCE submittal of April 8,1986.

These steps include the replacement and, to the extent practical, relocation of the failed check valves with appropriately sized valves of an improved design which is less susceptible to the mechanism that caused the failure. An

. additional check valve was installed inside containment in each feedwater line -

to each of the three steam generators to provide added redundancy for the feedwater line isolation function. Finally, the main feedwater flow control valve logic was modified to provide for automatic isolation using the main feedwater flow control valves. These improvements in design, and additional redundancy, have significantly enhanced feedwater line isolation capability, thereby assuring the operability of the Auxiliary Feedwater System.

In addition, demonstration testing has been, and will be, performed on the replacement check valves as described in response to Question No. 3 of Enclosure 2 of the submittal provided to the NRC-by letter dated May 1, 1986.

The testing has two phases. The first phase, which was completed in. March 1986, consisted of flow stability testing to demonstrate acceptable performance of the new design. The second phase, which is scheduled for

! completion by the end of 1986, involves accelerated wear tests which will be i used to verify the acceptability of the surveillance intervals used in. the IST program.

In order to evaluate the condition of swing type check valves in other

systems, a comprehensive design review and inspection effort was performed.

l The results of this effort were provided to the NRC by SCE letter dated May 1, 1986 (Enclosure 4).

, A.4 Corrective Steos Hhich Hill be Taken to Avoid Further Violations

The corrective steps which will be taken in response to the event of November l 21, 1985, are described in the SCE submittal of April 8,1986. These steps

include enhanced inspections to assure the operability of the newly installed check valves.

These actions will be completed prior to startup from the next refueling i

outage.

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A.5 Date When Full Comoliance Dill be Achieved Full compliance was achieved ca July 10, 1986, when a verification effort was completed to determine that restart commitments resulting from the event of November 21, 1985, either had been completed or would be completed at the appropriate point in the start-up process. Mode 2 was entered on July 15, 1986.

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B. The Notice of Violation states in Part:

"10 CFR Part 50, Appendix B, Criterion XI, Test Control, as implemented by the Southern California Edison Company Topical Report SCE-1-A, Section 17.2.11, requires that testing required to demonstrate that structures, systems, and components will perform satisfactorily in service is identified and performed in accordance with written test procedures and that the test program shall include, as appropriate, preoperational and operational tests.

Contrary to the above, the test program in effect prior to November 21, 1985 for check valves in the feedwater system did not assure that the valves would perform satisfactorily while in service in that on November 21,1985, five check valves (FHS-345 -346, -398, -438 and -439) did not prevent backflow through the feedwater system.

This is a Severity Level III violation (Supplement I).

(Civil Penalty - $50,000)."

B.1 Maission or Denial of the Alleaed Violation SCE admits that the test program in effect prior to November 21, 1985 for check valves in the Feedwater System did not assure that the valves would perform satisfactorily while in service, in that on November 21,1985, five check valves (FHS -345, -346, -398, -438, and -439).did not prevent backflow through the Feedwater System.

B.2 Reason for the Violation Although testing of the Feedwater System check valves was in compliance with the Inservice Testing (IST) Program at San Onofre Unit 1 prior to November 21, 1985, these check valves failed in a manner that IST does not effectively predict. The ASME Code and the IST Program include criteria that the systems under consideration be designed in such a manner that any degradation in component function can be identified within the defined surveillance intervals. As a result of the failure mechanism discussed in A.2 above, the check valves experienced accelerated degradation during the period of operation following their last successful IST and the event on November 21, 1985. This accelerated degradation was not detected by testing conducted in accordance with the Program.

B.3 Corrective Steos Hhich Have Been Taken and the Results Achieved The corrective steps which have been taken in response to the event of November 21, 1985 are described in the SCE submittal of April 8,1986. These included restoring the feedwater line isolation capabilities, through the design changes discussed in A.3 above, to the assumed operating criteria of the ASME Code and the IST program. In order to verify the acceptability of these changes in restoring the desired capabilities, the enhanced inspections indicated in A.4 will be performed. In addition, demonstration testing has been, and will be, performed on the replacement check valves as described in response to Question No. 3 of Enclosure 2 of the submittal provided to the NRC by SCE letter dated May 1, 1986. The testing has two phases. The first phase, which was completed in March 1986, consisted of flow stability testing to demonstrate acceptable performance of the new design. The second phase, which is scheduled for completion by the end of 1986, will involve accelerated wear tests which will be used to verify the acceptability of the surveillance intervals used in the IST program.

Finally, the valve IST Program has been revised to test check valves based on quantitative leak-rate measurements. The guidelines for this new procedure were also provided in the question response referenced above.

B.4 Corrective Steos Which Hill Be Taken to Avoid Further Violations The corrective steps which will be taken in response to the event of November 21, 1985, are described in the SCE submittal of April 8, 1986. Upon completion of the accelerated wear testing described in B.3 above, and the check valve inspections to be conducted at the next refueling outage, the IST program will be modified as necessary to institute any improvements identified to be necessary. These additional changes, in conjunction with the action i

. described in B.3 above, are considered sufficient to prevent the recurrence of the accelerated degradation which led to the check valve failures.

B.5 Date When Full Comoliance Hill be Achieved Full compliance with the actions required to be implemented prior to return to service was achieved on July 10, 1986 when a verification effort was completed which established that restart commitments resulting from the event of November 21, 1985, either had been completed or would be completed at the appropriate point in the startup process. Mode 2 was entered on July 15, 1986.

C. The Notice of Violation states in part:

"10 CFR Part 50, Appendix B, Criterion XVI, Corrective ~ Actions, as implemented by SCE-1-A, Section 17.2.16, requires that measures be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment and nonconformances are promptly identified and corrected. In the case of significant conditions adverse to quality, the measures shall assure that the cause of the condition is determined and corrective action taken to preclude repetition.

Contrary to the above, the licensee's program failed to assure that adequate corrective actions were taken when a noise was identified on June 24, 1985 in the "B" feedwater line near check valve FHS-346. The investigations and subsequent reviews by the Onsite Review Committee on July 18, 1985 and the Nuclear Safety Group on September 3,1985 failed to identify the potential for, or the safety consequences of, check valve failures which could cause the draining of the feedwater lines or diversion of auxiliary feedwater flow from the steam generators. Also, corrective actions to investigate the valve conditions, planned for outages in August and September 1985, were not conducted.

This is a Severity Level III violation (Supplement I).

(Civil Penalty - $50,000)."

C.1 Admission or Denial of the Alleaed Violation SCE admits that the. safety review program failed to assure that adequate corrective actions were taken when a noise was identified on June 24,1985, in the "B" feedwater line near check valve FHS-346. The investigations conducted by the onsite and offsite safety review organizations failed to identify the potential for, or the safety consequences of, check valve failures which could cause draining of the feedwater lines or diversion of auxiliary feedwater flow from the steam generators. SCE also admits that actic. to investigate the valve conditions, planned for the next available outage which occurred in August and September, was deferred to the planned refueling outage scheduled to begin in November.

C.2 Reason for the Violation l A detailed description of the actions taken by SCE in response to the feedline noise identified on June 24, 1985 is contained in the Water Hammer Investigation Report of April 8, 1986. The evaluation of the "B" Steam l Generator feedwater line noise-included consideration of the possibility that

! a check or block valve had failed, however, postulation of multiple failures was not considered.

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The determination reached during the safety review process that it was safe to continue operating was subsequently extended to allow continued operation until the then upcoming refueling outage. The correctness of this determination was supported by the fact that the noise intensity did not change.

C.3 Corrective Steos Which Have Been Taken and the Results Achieved The corrective steps which have been taken in response to the event of November 21, 1985, are described in the SCE submittal of April 8,1986.

Actions have been taken to strengthen the safety review process by providing an independent consultant, with operating experience and a broad background, to the Onsite Review Committee in order to bring an added and diverse perspective to OSRC deliberations.

The safety review process is being strengthened by including more in-depth review of plant history as a factor in investigations of abnormal conditions.

Improvements in maintenance tracking and trending which had been implemented prior to the event of November 21, 1985, as described in the Water Hammer Investigation Report of April 8, 1986, will facilitate the above described improvement in the safety review process.

Finally, the need for insightful questioning as part of the safety review process has been demonstrated to be a necessity when studying the implications of abnormal situations which arise during the operation of a nuclear plant.

This need has been emphasized to the staff assigned to perform safety reviews.

C.4 Carrective Steos Which Hill be Taken to Avoid Further Violations The improvement in the safety review process discussed in C.3 above are considered sufficient to avoid the future recurrence of conditions similar to those leadi.1g to the event of November 21, 1985.

C.5 Date When Full Comoliance Hill be Achieved Full compliance was achieved on July 10, 1986 when a verification effort was completed to determine that restart commitments resulting from the event of November 21, 1985 either had been completed or would be compipted at the appropriate point in the start-up process. Mode 2 was entered oi July 15, 1986.

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