ML13309A159
| ML13309A159 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/19/1991 |
| From: | Ray H Southern California Edison Co |
| To: | Richards S NRC Office of Inspection & Enforcement (IE Region V) |
| References | |
| NUDOCS 9201070313 | |
| Download: ML13309A159 (4) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 HAROLD B. RAY TELEPHONE SENIOR VICE PRESIDENT 714-458*4400 December 19, 1991 Mr. S. A. Richards, Chief Reactor Project Branch U. S. Nuclear Regulatory Commission, Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596-5368
Dear Mr. Richards:
NC)
Subject:
Docket Nos. 50-206, 50-361 and 50-362 Response to Request for Maintenance Assessment C,
San Onofre Nuclear Generating Station Your letter dated October 18, 1991, included a request for Sothern California Edison (SCE) to provide our assessment of:
- 1.
The weaknesses in the maintenance program that contributed to the failures of valve CV-113 at San Onofre Unit 1, and
- 2.
The potential implications of making adjustments to other.
safety-related equipment without specific acceptance criteria for those adjustments.
The purpose of this letter is to provide our assessments of these two items. As discussed with Mr. Phil Johnson (NRC) on December 19, 1991, this response was delayed in order to provide a complete response.
Maintenance Program Weaknesses NRC Inspection Report (IR) 91-24 identifies on pgs. 12-19 eight weaknesses associated with maintenance and technical efforts on CV 113.
SCE's response to the Notice of Violation associated with failure of CV-113 was provided by my letter dated November 20, 1991.
The response identified the reasons for the violation and the corrective steps taken which are specific to work on CV-113.
As noted in NRC Management Meeting Report 91-33, which was forwarded by Mr. Martin's letter dated November 5, 1991, SCE agreed with the SALP assessment of our maintenance program, and is committed to a number of initiatives including:
Mr. S. A. Richards, Chief December 19, 1991 m
improvements in the quality of maintenance procedures a
multiple initiatives associated with improved craft, planner, and supervisor training, and a program directed toward improving the quality of the maintenance self-checking process.
With respect to the discussion in IR 91-24, SCE again agrees that strengthening is required in response to each of the maintenance program weaknesses identified. The following information in this regard is in addition to that provided either by my letter dated November 20, 1991 or summarized in your Management Meeting Report 91-33.
Engineering Role and Responsibility for Maintenance As briefly discussed at the management meeting in October, we recognize the need to better define and implement engineering's role and responsibility in the maintenance function. We have initiated an in-depth look into this area and will be prepared at the next Edison NRC management meeting to discuss our conclusions and action plans as a result of this review. Our review includes an evaluation of how to better utilize the IST program to provide predictive information to the maintenance program, improvements in the engineering diagnosis of apparently abnormal component performance, improved quality in documented operability assessments, and strengthening the role and authority of engineering in controlling the material condition of the plant.
Quantity and Quality of Maintenance Supervision In our evaluation of the weaknesses in the maintenance program, we have concluded that the quantity and the quality of supervision provided for individual maintenance tasks is insufficient. We are initiating actions to increase the number of first line supervisors in maintenance and, as previously discussed, are aggressively implementing training programs to improve the quality of maintenance supervision available in the field.
OA/QC Involvement IR 91-24 raises the question of whether there was adequate QA and QC involvement with work performed on CV-113 during the period of March-July 1991. We have evaluated this issue and concluded that both QA and QC field involvement were adequate, consistent with the SCE program and therefore were not contributors to the failures.
Specifically, we do not believe the use of a QC hold point for tightening the seal tube retaining nut is needed.
Mr. S. A. Richards, Chief December 19, 1991 Rather, performance of a second party check, as will now be required, is considered appropriate.
However, a Nuclear Oversite Division re-review of the CV-113 overhaul work package was performed and the level of detail provided in the package was identified as inadequate. Since this was not identified in the initial QC review of the work package prior to overhaul of the valve in February 1991, the initial QC review, in our opinion, was inadequate and represents a missed opportunity to avoid failure of CV-113. As a result of previous maintenance errors, which also had QC involvement, a Quality Action Team (QAT) was initiated between QC and Maintenance to better define QC support required. The QAT is evaluating the planning process, which includes work package review.
In addition, the QC Manager issued written guidance on November 1, 1991, to enhance the QC review of work packages. The guidance expands QC's criteria concerning when work packages need greater QC attention, such as inspection points, and when a higher level of detail should be expected in work packages.
Making Adjustments Without Specific Acceptance Criteria Adjustments to safety-related equipment can be categorized into two broad areas.
First, setpoints; and second, process control adjustments.
In this regard, setpoints are generally described as the actuation point at which a safety-related function is specified to occur. All,safety-related setpoints are adjusted in accordance with engineering controlled documents. We believe this level of control is appropriate and that it is unacceptable to adjust safety related setpoints, outside prescribed limits, without formal engineering review and approval.
Generally, process control adjustments can be described as those which effect the dynamic response of a component but do not control the actuation setpoint. Air pressure and adjustable spring tension settings on pneumatic valves, and gain settings on single element controllers are typical examples of process control adjustments.
These settings are often adjusted without specific acceptance criteria to obtain optimum system performance in response to changes in component or system parameters, such as valve packing friction.
We understand this second category of adjustments is the focus of your question.
Our assessment of the significance of making process control adjustments to safety-related equipment without specific acceptance criteria has reached the following conclusions:
- 1.
It is acceptable to make adjustments to safety-related equipment without specific acceptance criteria when the safety related function of the equipment is adequately
Mr. S. A. Richards, Chief December 19, 1991 verified by testing before returning the equipment to service.
For example, if the engine governor on the Diesel Generator fails, it is statically tested after replacement and adjusted to nominal settings. Subsequently, the diesel is started and the engine is tested and tuned both off and on line until the new governor's performance matches previous response.
2..
In those cases where the safety-related function of equipment or systems being adjusted cannot be verified by testing, an allowed adjustment range should be provided by engineering. We have identified a list of safety-related equipment for which we believe post-maintenance testing does not provide adequate verification of the acceptability of adjustments to the equipment. We will upgrade the requirements for engineering review and approval of MO work plans involving adjustments to these components such that the maintenance planner will be required to obtain acceptance criteria for these adjustments from engineering documents or approved procedures. If neither of these is available, an engineering review and approval of the MO work plan will be required.
- 3.
In those cases where the adjustments being made do not affect the safety-related function of the equipment or systems, engineering will not restrict the use of the entire adjustment span provided by the equipment design because acceptable safety-related equipment and system performance can be achieved with adjustments set at any point within the span.
If you have any questions or comments, or would like additional information, please let me know.
Sincerely, cc:
J. B. Martin, Regional Administrator, Region V C. W. Caldwell, Senior Resident Inspector, San Onofre