ML13330B362
| ML13330B362 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/25/1988 |
| From: | Morgan H SOUTHERN CALIFORNIA EDISON CO. |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 8808110014 | |
| Download: ML13330B362 (6) | |
Text
REC ED REGION V Southern California Edison Company SAN ONOFRE NUCLEAR GENERATING STAT ON P. 0. BOX 128 SAN CLEMENTE, CALIFORNIA 92672 H.E. MORGAN TELEPHONE STATION MANAGER (714) 368-6241 July 25, 1988 U. S. Nuclear Regulatory Commission Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Attention:
Mr. J. B. Martin, Regional Administrator
Subject:
Docket No. 50-206 Design and Implementation Review Unit 1 Safety Injection System
Reference:
Letter, Mr. H. E. Morgan (SCE) to Mr. J. B. Martin, dated March 17, 1988 The Reference documented a discussion between Mr. Charles B. McCarthy and yourself on March 8, 1988 in which SCE committed to perform a Design and Implementation Review (DIR) of the Unit 1 Safety Injection System (SIS). Upon completion of the DIR, SCE indicated that a summary report would be provided to the NRC. The subject DIR has been completed. This letter with enclosure constitutes the summary report as committed to by the Reference.
The DIR consisted of an overall system review over an eight week period by two engineers (one from the Station Technical Division and one from the Nuclear Generation Engineering Division of the Engineering and Construction Department), and a limited evaluation of selected system components by the Independent Safety Engineering Group (ISEG).
Within the scope of the DIR, the objectives were to: 1) verify that the design bases of the SIS have been preserved throughout the design change process so that the system can perform the safety injection function (recirculation and long term decay heat removal were not included); 2) assess the operational readiness of the portions of the SIS that are required for this safety function; and 3) verify that operations, maintenance and testing of system components reasonably assure system operability to perform this function under normal and postulated accident conditions. The DIR methods of investigation were modeled after those typically utilized by NRC teams involved with Safety System Functional Inspections (SSFI). Given the time schedule and resources devoted to this effort, however, the breadth and depth of the resulting review could not be as comprehensive as an SSFI.
8SOS110014 880725 PDR ADOCK 05000206 P
PDC I~
Mr. J. B. Martin 2
Although documentation deficiencies were identified which require correction, it was determined that within the scope of the DIR, the current as-built configuration of the injection portion of the SIS satisfies the existing design bases with the exception of previously identified single failure susceptibilities (reference LER 87-015) and environmental qualification deficiencies (reference LER 88-001). In addition, within the scope of the DIR, the system was found to be operated, maintained, and surveilled such that the injection portion of the SIS will function under normal and postulated accident conditions.
A more detailed synopsis of the DIR scope, methodology, conclusions, findings, and planned corrective actions is contained in the Enclosure. A copy of the DIR, including the ISEG evaluation, has been provided to the resident inspectors.
If you require any additional information, please so advise.
Sincerely, cc:
F. R. Huey (USNRC Senior Resident Inspector, Units 1, 2 and 3)
ENCLOSURE Page 1 of 4 I. Scope and Methodology The DIR assessment boundaries encompass the injection portion of the SIS up to the point at which interfacing systems and signals identified as being required to adequately support the functional requirements of the SIS were determined to exist. The methods of investigation were modeled after those typically utilized by NRC teams involved with Safety System Functional Inspections (SSFI). It is recognized that the resources devoted to this effort (two engineers during an eight week period) would not result in as comprehensive a review as would occur with a multi disciplined inspection team over an extended period of time (typical SSFI inspection teams contain 6 - 10 multi-disciplined inspectors who devote approximately 6 weeks to the effort).
However, the DIR scope was sufficient to perform a general assessment of the present design and operability of the injection portion of the SIS. The major DIR effort targeted the SIS itself and not its support systems. For example, the electrical support systems review was not intended to entail a review of sufficient depth or breadth that would have disclosed the recently identified problem with Diesel Generator loading (reference LER 88-009).
This review assessed the operational readiness of the injection portion of the SIS by determining whether:
- 1) the as-built system is capable of performing the safety injection function required by its design bases,
- 2) testing is adequate to demonstrate that the system will perform its required safety injection function,
- 3) system maintenance is adequate to ensure system operability under normal and postulated accident conditions,
- 4) operator training is adequate to ensure proper operation of the system, and
- 5) supporting procedures for the system are adequate to ensure proper system operation under normal and postulated accident conditions.
To establish the SIS functional requirements and design bases, the following types of documents were reviewed:
- 1. Correspondence
- 2. Technical Reports
- 3. Safety Analysis and Criteria
- 4. Codes and Standards
- 5. Regulatory Documents
- 6. Design Criteria
- 7. Licensing Documents
ENCLOSURE Page 2 of 4 To define the as-configured status and material condition of the SIS, the following design implementation documentation was reviewed:
- 1. Technical Specifications
- 2. Piping and Instrument Diagrams
- 3. Electrical Elementary Diagrams
- 4. Process Diagrams
- 5. Logic Diagrams
- 6. Control Loop Diagrams
- 7..Piping Isometric Drawings
- 8. Miscellaneous Drawings
- 9. Design Change Packages II. Major Conclusions and Findings A. System Design Within the scope of the DIR, the current as-built configuration of the injection portion of the SIS was found to satisfy the existing design bases with the exception of previously identified single failure susceptibilities and environmental qualification deficiencies (these items are discussed in LER 87-015 and LER 88-001).
Completed SIS design changes have not resulted in any violation of the existing design bases; however, the safety evaluations of several design changes contain technical discrepancies and/or are incomplete.
These discrepancies and omissions, however, do not invalidate the overall conclusions of the safety evaluations with respect to the adequacy of the design changes.
The ECCS flow calculation, which estimates the time for effective full ECCS flow to reach the core after initiation of a safety injection signal, was found to have deficiencies that were later determined not to affect the safety conclusion. The calculation contains input for feedwater and safety injection pump performance that was obtained from an uncontrolled document. The calculation also contains ambiguous statements, unreferenced assumptions, and unverified design input, which precluded an independent verification by the engineer performing the DIR. However, discussions with personnel familiar with the calculation provided enough additional information to allow a review of the calculation, and the results indicate that effective full ECCS flow will reach the core within the required time.
The DIR evaluations concluded that the SIS interfaces with auxiliary systems support the requirements of the SIS. These support systems, whose detailed review was outside the scope of the DIR, were assumed to be functional.
ENCLOSURE Page 3 of 4 Design documents were noted to have errors in them (e.g., the Technical Specifications referenced the wrong document for a design basis parameter; Loop Diagram 451356 shows incorrect pressurizer low level setpoints, although Instrument Calibration and Data Collection cards, to which work in the plant is done, show the correct setpoints). In addition, not all historical design change documentation could be recovered from Corporate Document Management (CDM).
Sufficient documentation did exist, however, to confirm system operability.
Most of the deficiencies noted above were made under the provisions of earlier forms of the design change program. Although SCE believes that the present design change control program corrects many of the programmatic weaknesses that led to these deficiencies, SCE continues to review this program to determine what enhancements, if any, are necessary.
B. Testing On a selective sample basis, surveillance and functional test procedures and results were evaluated to determine the adequacy of the testing programs.
Post modification testing and inservice testing were also evaluated. It was concluded that within the scope of the DIR, SIS components have been adequately tested to demonstrate that they will perform their intended safety injection function as defined in the design bases.
C. Maintenance On a selective sample basis, the programs which control deficiency identification, work requests, corrective and preventive maintenance, and instrument calibration were reviewed to determine if the system is being maintained in a functional state. Within the scope of the DIR, no deficiencies in these programs were noted.
D. Operations and Training A review was performed of operationally oriented documentation to verify that procedures adequately address appropriate operating and emergency conditions. In some of the areas where procedures did not provide detailed guidance, a verification of the training program was performed to ensure that the operators have been made knowledgeable in these areas. Documentation reviewed included:
- 1. Operating, Emergency, Abnormal, and Alarm Response Procedures
- 2. Administrative Controls Procedures
- 3. Surveillance Test Procedures Within the scope of the DIR, no major deficiencies were noted.
ENCLOSURE Page 4 of 4 III. Corrective Actions:
The following activities will be performed to correct the deficiencies identified in the DIR:
A. An integrated safety evaluation of the injection portion of the SIS will be prepared to "baseline" the present configuration of the SIS.
B. As stated at the exit interview on June 10, 1988, an SCE task force is evaluating the overall adequacy of engineering and technical support provided for the San Onofre Nuclear Generating Station. When this evaluation is complete, the NRC will be advised of the specific actions to be taken to ensure the requisite quality of engineering and technical support.
C. All identified items, including the aforementioned calculation and documentation deficiencies will be corrected by December, 1988.
IV. Independent Safety Engineering Group Findings and Corrective Actions:
A. Binding of the solenoid operated bonnet vent valves SV-2900 and SV 3900 (Main Feed Pump Safety Injection Discharge Isolation Valves HV 851A and HV-851B, respectively), has occurred more frequently than expected for a typical solenoid valve. Also, SV-3900 was found to have a crack in the main disc sleeve, which is thought to have been caused by a manufacturing defect (reference LER 88-004). An enhanced testing and inspection program has been established to monitor valve performance. Should additional data become available that indicates a possible misapplication of this type of valve or design deficiencies, appropriate corrective.action will be initiated.
B. The solenoid operated oil dump valves SV-1 and SV-2 (internal components of the actuators which operate the safety injection pump suction and discharge valves) were found to be degraded by rust corrosion of iron components in the valve housing. Action has been taken to protect the SV-1 and SV-2 valves from moisture intrusion which caused the corrosion. Additionally, these valves have been added to the repetitive maintenance program and, as such, will be inspected and cleaned as necessary every refueling outage.