ML13309A296
| ML13309A296 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/07/1992 |
| From: | Rosenblum R SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M69351, NUDOCS 9208110278 | |
| Download: ML13309A296 (12) | |
Text
70 Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 R. M. ROSENBLUM TELEPHONE MANAGER OF August 7, 1992 (714) 454-450 NUCLEAR REGULATORY AFFAIRS U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Relief Request, Ten-Year Inservice Inspections San Onofre Nuclear Generating Station, Unit 1
Reference:
- 1)
Letter dated October 5, 1988, from C. M. Trammell (NRC) to K. P. Baskin (SCE), Inservice Inspection Interval (TAC No. 69351)
This letter requests schedular relief for certain second ten-year interval Inservice Inspections (ISI's) for San Onofre Nuclear Generating Station Unit 1 (SONGS 1).
These inspections are required by the plant Technical Specifications (TS) and the ASME Code.
This letter also requests relief from the reporting requirements for the second interval ISI and discusses our plans for the third interval ISI program. We are making these requests in anticipation of the proposed permanent shutdown of SONGS 1 at the end of the present fuel cycle.
Background
Technical Specification 4.7, "Inservice Inspection Requirements," requires that Class 1, 2 and 3 pressure retaining components and supports meet the ISI requirements of Section XI of the ASME Code.
The second ten-year ISI interval for SONGS 1 expired on November 30, 1991; however, the inspection period has been extended to November 30, 1992.
SONGS 1 is committed to implement the 1974 edition of the ASME Code, including Addenda through summer of 1975, for the second ten-year interval.
The ten year ISI interval is divided into three periods.Section XI allows a one year extension to permit the last period inspection of the ISI interval to be concurrent with a plant outage. By Reference 1, the NRC informed us that this one year extension applied only to the last period inspection and not to the interval.
Therefore, the second ten-year interval ended on November 30, 1991, although the inspections may be completed by November 30, 1992.
9208110278 920807 T_
PDR ADOCK 05000206 O
Document Control Desk
-2 The ASME code also includes a provision to extend the ten-year inspection interval to account for periods when the unit is shutdown and not operating at design pressure or temperature. The November 30, 1991 expiration date for the second interval ISI included an allowance for outages with a duration of greater than one year, as allowed by the 1974 edition of the ASME code. The code was later amended in the 1977 edition to permit an extension for outages exceeding six months in duration. Collectively, SONGS 1 has had approximately 29 months total outage time among four outage periods that may not be credited under the 1974 edition of the Code. Two of these outage periods were longer than six months and could have qualified under the newer edition of the code.
Following the Cycle 11 refueling/thermal shield repair outage we had planned to complete the remaining second interval ISI's during the succeeding outage, scheduled to start in November, 1992. However, the proposed permanent shutdown of SONGS 1 toward the end of this year makes it necessary for us to request relief from some of the inspection requirements to avoid any conflict with the ASME code, and to avoid unnecessary inspections of systems that will not be needed during and after the shutdown.
ISI Interval Extension Request Our current plan is to shut down SONGS 1 at the end of November 1992, barring any unplanned equipment outages. We plan to reach Mode 5 shortly thereafter and complete core offloading by February, 1993.
We are presently requesting a six month extension to the inspection interval, extending the final period to May 31, 1993.
The extension is being requested to avoid any conflict with the ASME code or Technical Specifications during the time we are defueling the reactor and shutting down systems not required to support fuel storage, and to avoid having to perform any unnecessary inspections. However, it would also allow us to slightly extend the permanent shutdown date for best fuel utilization should we have an unexpected outage before November 30, 1992.
To manage the status of the remaining inspections, we have divided the systems and components that are subject to TS 4.7 requirements into 3 groups:
Group 1 - Systems and components required beyond core offload for long term spent fuel cooling.
Group 2 - Systems and components required until core offload.
Group 3 - Systems and components required until Mode 5 is reached.
With the exception of four (4) Component Cooling Water System (CCW) hydrostatic tests, we intend to complete the remaining third period inspections on the Group 1 systems and components by November 30, 1992. A relief request regarding CCW will be submitted separately. We do not plan to perform the remaining inspections on the Group 2 and Group 3 systems and components. These systems will be permanently removed from service within several months after plant shutdown and will no longer have any safety function. Therefore, there would be little benefit in continued ISI on the
Document Control Desk
-3 Group 2 and Group 3 systems and components. provides a status of those systems by Groups with justification for the requested relief.
Approval of this relief request will enable us to implement our ISI plan as described without having to declare any uninspected components inoperable under the Technical Specifications because the ISI had not been performed. It is requested that you approve this relief request by October 31, 1992 so that we may plan our shutdown schedule.
Relief from Reporting RequirementsSection XI, Article IWA-6000, requires an extensive report be prepared and submitted for each inspection. These reports represent a major effort to prepare, review, and submit to the NRC. Since we are permanently shutting down SONGS 1, the majority of the plant systems will not be operated or inspected under a Section XI ISI program in the future. Therefore, we are requesting relief from preparing and submitting the NIS-1 report for the remaining inspections. We will retain the inspection results for Group 1 systems and components on file for NRC inspection or review in accordance with our document control procedures.
Third Interval ISI Program Our third ten-year ISI interval began on December 1, 1991.
The ASME Code requires that the ISI program be filed with the NRC.
Since we are planning to permanently shut down SONGS 1 following the current fuel cycle, we do not expect to perform any third interval inspections, or submit our revised program for the third interval.
Should our plans to permanently shutdown SONGS 1 change, we will revise our request accordingly.
If you have any questions or need more information, please call me.
Very truly yours, Enclosure cc:
J. B. Martin, Regional Administrator, NRC Region V George Kalman, NRC Senior Project Manager, San Onofre Unit 1 J. 0. Bradfute, NRC Project Manager, San Onofre Unit 1 C. W. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2&3
ENCLOSURE 1 RELIEF REQUEST REGARDING SIX MONTH ISI EXTENSION This relief request is organized by Group 1, Group 2 and Group 3 systems.
These are:
Group 1 - Systems and components required beyond core offload for long term spent fuel cooling. (This list is under review and may change according to the status of fuel storage at SONGS 1.)
Group 2 - Systems and components required until core offload.
Group 3 - Systems and components required until Mode 5 is reached.
Each system is identified, its function described, and its major components listed. The status of the ISI applicable to the system is described. All first and second period inspections have been completed. The justification for not completing all required tests/examinations on the system is presented as applicable. Systems that are not safety-related, but are included in our ISI program, such as Turbine Plant Cooling Water, are not discussed.
GROUP 1 SYSTEMS - REQUIRED TO BE OPERABLE LONG TERM BEYOND CORE OFFLOAD Spent Fuel Pool System SFP function:
Cool and store in a safe configuration spent fuel removed from the reactor until it can be shipped offsite for disposal.
Spent Fuel Pool major components: Spent fuel pit pump, spent fuel pit pump heat exchanger,piping and supports.
ISI Status:
All required first, second and third period inspections completed.
Inspections that will not be done:
None Justification for Extension:
None is needed.
Component Cooling Water System (CCW)
CCW function:
(1) serves as an intermediate cooling system to transfer heat to the salt water cooling system from both safety-related and non-safety-related components that receive heat from the RCS. (2) provides an intermediate Page 1 of 9
CCW CONT'd barrier between potentially radioactive systems and the salt water cooling system. (3) provides spent fuel pit heat removal.
CCW system major components: CCW pumps, CCW heat exchangers, CCW surge tank, RCP thermal barrier pump, piping and piping-supports.
ISI Status:
All first, second and third period inspections, except for 4 hydrostatic pressure tests, will be completed.
Inspections that will not be done:
4.hydrostatic pressure tests.
Justification for Extension:
A separate relief request is being submitted for the 4 hydrostatic tests that will not be done. These tests cannot be completed with the system in service because of the physical arrangement of the CCW isolation valves, and operability requirements for the system. In accordance with the code, the relief request specifies in-service leak tests in lieu of the hydrostatic tests.
During normal full-power operation, one CCW pump connected to either of the two CCW heat exchangers can accommodate the heat removal loads. Either one of the two standby pumps along with the standby heat exchanger provides 100%
backup. During cooldown operations, one of the three available CCW pumps can remove one half of the heat load when the RHR loop is first placed in service.
The CCW system is also used for heat removal during post accident conditions (loss of coolant accident, main steam line break accident, seismic events and fires). Scenarios associated with the loss of a portion of the CCW system under various plant conditions are analyzed in the UFSAR and covered in plant emergency operating instructions.
The two heat exchangers and the surge tank are protected against overpressurization by relief valves. The surge tank is at atmospheric pressure. The RCP thermal barrier pump protects the integrity of the reactor coolant pump seals and this equipment will not be required after plant shutdown.
For spent fuel pool heat removal purposes, the capacity of each CCW pump and each CCW heat exchanger exceeds the capacity of the spent fuel pool pump and spent fuel heat exchanger. Additionally, the CCW system has more redundancy than the spent fuel pool system and therefore the CCW system is not the primary risk factor in a loss of spent fuel pool cooling incident.
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Saltwater Cooling System (SWCS)
SWC function:
(1) provide salt water from ultimate heat sink (Pacific Ocean) to CCW heat exchangers during normal plant operation and design basis accidents.
SWC system major components: SWC pumps (2), auxiliary SWC pump (1), piping and supports.
ISI Status:
First, second and third period inspections completed.
Inspections that will not be done: None Justification for Extension:
None is needed.
Refueling Water System (RWS)
RWS function:
The RWS provides borated water to the refueling cavity for normal, accident mitigation, and the containment fire suppression system. The RWS can be used for postaccident recirculation if the charging pumps become inoperable.
RWS system major components: refueling water storage tank (1), refueling water pumps (2),
piping, valves and piping supports.
ISI Status:
First, second and third period inspections completed.
Inspections that will not be done: None Justification for Extension:
None is needed.
GROUP 2 SYSTEMS - REQUIRED TO BE OPERABLE UNTIL CORE OFFLOAD Reactor Coolant System (RCS)
RCS Function (Reactor Shutdown):
(1) provide redundant paths to remove decay heat through steam generators via natural recirculation.
(2) provide RCS pressure control required for hot shutdown. The power operated relief valves CV-545 and CV-546 are required to be operable for overpressurization protection in accordance with the requirements of the Technical Specifications (TS).
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RCS CONT'd Major RCS components:
reactor vessel, reactor coolant pumps, pressurizer, pressurizer relief tank, steam generators, piping, and piping supports.
ISI Status:
First and second period inspections completed. All of the ISI reactor vessel inspections and the majority of all component support inspections applicable to the second ten year interval completed.
Inspections that will not be done: Third period inspections.
Justification for Extension:
The majority of the tests and exams required during the present inspection interval have been completed. During operating conditions, RCS leakage is monitored by an inventory balance, and instrumentation. Should there be an increase in leakage, action is taken in accordance with the Technical Specifications.
During most of the requested deferral period, the reactor will be shut down and the RCS will be depressurized. Under these conditions a failure of RCS structural integrity, or component supports, is highly unlikely. The overpressurization mitigating system (OMS) protects the RCS from overpressure transients at low temperatures as required by the Technical Specifications.
After the RCS has cooled sufficiently, an RCS vent is usually provided as an alternative to crediting the power operated relief valves for OMS. The RCS is vented by removing one of the pressurizer relief valves (RV-532 or RV-533).
The Technical Specifications require the operation of the pressurizer power operated relief valves for OMS, unless the RCS is vented. However, our new design basis for overpressure protection relies solely upon the operation of the Rsidual Heat Removal (RHR) system relief valve, RV-206 (see Amendment Application No. 194, May 13, 1991).
Valve RV-206 has met all of its ISI requirements and both RV-206 and the powered operated relief valves will be available, as required by the Technical Specifications.
Chemical and Volume Control System (CVCS)
CVCS function:
(1) maintain RCS inventory with charging flow. (2) provide alternate RCS pressure control via auxiliary spray to pressurizer through CV-305. (3) provide RCS recirculation and reactivity control.
(4) provide seal water for the reactor coolant pumps.
Major CVCS components:
regenerative heat exchanger, excess letdown heat exchanger, charging pumps, boric acid tank, boric acid injection pump, boric acid transfer pumps, piping and piping supports.
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First and second period inspections completed.
Inspections that will not be done: Third period inspections.
Justification for Extension:
Under operating conditions, leakage in the CVCS would be detected through the RCS inventory balance, or instrumentation. During most of the deferral period the plant will be in cold shutdown and the CVCS downstream of control valve FCV-1112 will operate at low temperatures and pressures. Should the normal charging path via control valve FCV-1112 fail, alternate charging flow paths are available which could be placed in service. These paths include the other charging pump, the seal injection flow path, and the refueling water pumps.
Residual Heat Removal System RHR System Function:
(1) provide long term heat removal required to achieve and maintain cold shutdown. (2) serve as decay heat removal path in Modes 4, 5, and 6. (3) Cool letdown flow to CVCS during normal plant operation.
Major RHR components:
RHR pumps, RHR heat exchangers, RHR Relief Valve.
ISI Status:
First and second period inspections completed.
Inspections that will not be done: Third period inspections.
Justification for Extension The RHR system was pressure tested during the last refueling outage. Only the portions of the RHR system required for letdown are in service during normal operation. The RHR system operates at low temperature (normally 350aF or less) and low pressure (normally 350 psig or less). It is designed to be isolated from the RCS on both the suction and the discharge sides by double valve interlocks whenever the RCS pressure exceeds approximately 400 psig.
During normal plant operation (Modes 1, 2 and 3), one heat exchanger is sufficient to cool the RCS letdown flow from 2640F to 1150F.
A pressure reducing orifice reduces the RCS pressure for the letdown flow. These features ensure the RHR system is not overpressurized by normal RCS pressure.
The cooldown capability of the RHR system under failure modes is provided in section 5.5.6.5.1 of the UFSAR. With either one pump or one heat exchanger not available, the time to cool the RCS from 3500F to 140OF is 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> or less.
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GROUP 3 SYSTEMS - REQUIRED UP TO REACHING MODE 5 Main Feedwater System (MFWS)
MFWS function:
(1) provide feedwater to secondary side of steam generators for production of steam (2) isolate sources of unborated water to RCS when feedwater pumps are being used for safety injection system operation.
MFW system major components: MFW pumps (2), valves, piping and piping supports.
ISI Status:
First and second period inspections completed.
Inspections that will not be done: Third period inspections.
Justification for Extension:
The MFWS was hydrostatically pressure tested during the last refueling outage.
This system is not needed to achieve and maintain cold shutdown conditions and will not be in use in Mode 5.
Auxiliary Feedwater System (AFS)
AFS Function:
(1) provide feedwater to steam generators during startup, normal shutdown and hot standby. (It does not have a safety function once RHR is established for decay heat removal.)
(2) provide feedwater to steam generators to cool RCS during abnormal and emergency conditions.
Major AFS components:
motor-driven pumps, turbine-driven pump, piping, piping supports and valves.
ISI Status:
First and second period inspections and Augmented ISI completed.
Inspections that will not be done: Third period inspections.
Justification for Extension:
The AFS is comprised of two redundant trains so that if one train fails or develops a leak the other can be placed in service. Each AFW pump can supply auxiliary feedwater to all three steam generators.
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Main Steam System (MSS)
MSS function:
Deliver saturated steam generated by the nuclear steam supply system to the main turbine and certain plant support systems and to dissipate this energy by other means under certain design transient conditions.
MSS major components:
valves, piping and piping supports.
ISI Status:
First and second period inspections completed. Also augmented inservice inspections for high energy line breaks have been completed for the first and second period.
Inspections that will not be done: Third period inspections.
Justification for Extension:
The major safety-related function of the MSS is to dissipate excessive energy from the nuclear steam supply system to the condenser or to the atmosphere under certain transient/load rejection conditions. This function is accomplished through the main steam dump system (MSDS). All required ISI's on the MSDS have been completed.
Another safety-related function of the MSS is to deliver steam for operation of the steam driven AFW pump turbine during shutdown and emergency conditions.
However, since the motor driven AFW pump is available as a backup to the steam driven pump, the plant is protected against single failure if the steam driven pump cannot be operated.
Safety Injection and Recirculation System (SIS)
SIS function:
(1) provide borated cooling water to reactor core promptly after a loss of coolant accident to limit core damage (2) recirculate spilled borated water in containment sump through reactor core for long term cooling (3) inject borated water into RCS after a steam line rupture.
SIS major components:
SI pumps (2), SI recirculation pumps (2), refueling water storage tank (1), valves, piping and piping supports.
ISI Status:
First and second period inspections completed.
Inspections that will not be done: Third period inspections.
Justification for Extension:
The SIS was subjected to a hydrostatic pressure test during the last refueling outage. This system is not required in low modes of operation.
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Gaseous Nitrogen System (GNS)
GNS function:
(1) provide backup nitrogen for operation of safety-related pneumatic equipment if instrument air is lost (2) supply gaseous nitrogen for corrosion control, testing of containment penetrations and piping, steam generator sparging etc.
GNS major components:
gaseous nitrogen bottles, valves, piping and piping supports.
ISI Status:
First and second period inspections completed.
Inspections that will not be done: Third period inspections.
Justification for Extension:
The system supplies back-up nitrogen to the pressurizer power operated relief valves. Although the power operated relief valves are required to be operable for OMS by the Technical Specifications, they are no longer credited in the design basis for OMS. Note that this system is not required by the Technical Specifications after the plant is shutdown and the RCS is vented.
Containment Spray System Containment Spray Function:
(1) spray borated water into upper containment sphere to reduce containment pressure after a loss of coolant or loss of secondary coolant. (2) Use hydrazine solution to wash down radioactive particulate matter and fission products released into the containment atmosphere by a LOCA. (3) assist in recirculation of spilled reactor coolant if charging pumps become inoperable.
Major components:
refueling water pumps (2), refueling water storage tank (1),
valves, piping, and piping supports.
ISI Status:
First and second period inspections completed.
Inspections.that will not be done: Third period inspections.
Justification for Extension:
This system is not required for plant shutdown.
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Liquid Radwaste System Function:
collect, process and store liquid radwaste generated during plant operation.
Major components:
piping, valves, filters, piping supports etc.
ISI Status:
First and second period inspections completed.
Inspections that will not be done: Third period inspections.
Justification for Extension:
This system is not required for safe plant shutdown.
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