ML13333A360

Forwards List & Brief Description of Design Changes Approved During 1978

ML13333A360
Person / Time
Site:	San Onofre
Issue date:	03/30/1979
From:	Ottoson H SOUTHERN CALIFORNIA EDISON CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
NUDOCS 7904030340
Download: ML13333A360 (13)

Text

Southern California Edison Company P.O. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 March 30, 1979 U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Attention: R. H. Engelken, Director Docket 50-206 San Onofre Unit 1

Dear Sir:

Provided herewith as an enclosure to this letter is a listing containing a brief description of design changes completed during 1978. Submittal is pursuant to directives contained in 10CFR50.59(b) and includes a summary of the safety evaluation of each. An original and two copies are provided.

Should you have any questions regarding this submittal, please contact me.

H. L. Ottoson Manager, Nuclear Generation

Enclosure:

Design Changes Approved During the Year 1978, San Onofre Nuclear Generating Station Unit I

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eiTTector, Office of Inspection and Enforcement (40) 7904030<'

ENCLOSURE DESIGN CHANGES APPROVED DURING THE YEAR 1978 SAN ONOFRE NUCLEAR GENERATING STATION UNIT 1 SOUTHERN CALIFORNIA EDISON COMPANY SAN DIEGO GAS & ELECTRIC COMPANY DOCKET NO. 50-206 LICENSE NO. DPR-13

PAGE I DESIGN CHANGES The following design changes were approved for implementation by the On-Site Review Committee in 1978. Except as noted, the design changes were fully implemented as of the end of calendar 1978.

This listing fulfills the reporting requirements of 10 CFR 50.59(b) and Environmental Technical Specification 5.6.1.b. With respect to the latter requirement, none of the 1978 changes resulted in a condition which significantly altered the impact of the Station on the environment as described in the NRC Final Environmental Statement and did not involve a change in the Environmental Technical Specifications incorporated in the San Onofre Unit 1 Provisional Operating License DPR-13.

DESIGN CHANGE 76-14 (Revision 1):

RELOCATION OF THE COMPONENT COOLING WATER RADIATION DETECTOR. (In Progress)

The component cooling water system radiation detector is to be moved from its original location in the suction header of the component cooling water pumps to a newly installed liquid-radioactive sample pig due to high background radiation.

The new sample pig obtains a representative sample from the component cooling pump minimum recirculation line.

The installation of the channel sample pig and detector in the pump minimum recirculation line provides a continuous survey of component cooling water radioactive material content without disrupting the minimum recirculation function. The pressure boundary associated with this change is safety-related and is to be installed accordingly. The additional delay time associated with the piping run to the new detector location was evaluated to be about four seconds which is considered to be insignificant.

DESIGN CHANGE 77-07 (Amendment No. 1): MODIFICATION OF STANDBY POWER ADDITION SYSTEM PIPING SUPPORTS This design change added piping supports to the auxiliary skid piping of the standby power addition 4160 volt/6000 KW diesel driven generators. The addition of the supports to the auxiliary skid piping was accomplished to bring the piping systems into conformance with ANSI B 31.1, "Power Piping".

PAGE 2 DESIGN CHANGE 77-08 (Revision 1 and Amendment No. 1):

REPLACE A CONTROL VALVE IN THE COMPRESSED AIR SYSTEM WITH A MANUALLY OPERATED NORMALLY CLOSED ISOLATION VALVE.

This design change replaced a l(one) inch control valve which was installed in a 3 inch line between the compressed air system and the portable diesel-powered air compressor, with a manually operated normally closed 3 inch isolation valve.

The 3 inch valve was installed to enable the portable air compressor to provide greater back-up capability to the plant compressed air system. No safety related equipment was involved in this design change and postulated failure of the 3 inch valve would not adversely affect plant safety.

DESIGN CHANGE 77-10: MANUAL ALIGNMENT SWITCHES IN THE CHARGING PUMP STOP CONTROL CIRCUITS This change was previously reported as having been approved for implementation in 1977.

Subsequently, it was determined that the issues addressed by this change would be considered within the Systematic Evaluation Program. Accordingly, Design Change 77-10 was cancelled in 1978.

DESIGN CHANGE 77-16:

SITE SECURITY MODIFICATION This design change describes site security project modifications. In accordance with 10 CFR 2.790 its contents are withheld from public disclosure.

For further information refer to letter dated December 19, 1978, entitled "Physical Security Plan for San Onofre Nuclear Generating Station" from Southern California Edison Company to the Nuclear Regulatory Commission, Director of Nuclear Reactor Regulation, Attention R. A. Clark.

PAGE 3 DESIGN CHANGE 77-17 (Addendum No. 1):

THE OVERPRESSURIZATION MITIGATING SYSTEM (OMS)

Design Change 77-17 established the overpressurization mitigating system (OMS) to prevent 10 CFR 50 Appendix G limits from being exceeded and protect the RCS from postulated overpressurization events. Addendum No. I completed the OMS installations by replacing the pressure switches used in the actuation of pressurizer power operated relief valves with two pressure transmitters and associated logic. Replacement of the pressure switches with the pressure transmitters provides for reactor coolant system pressure sensing while protecting against postulated single failure of sensing equipment. In addition to this change, Addendum 1 included modifications to the OMS control room annunciators to improve annunciation effectiveness.

These modifications resulted in overall improvement of the OMS and did not adversely affect plant safety.

DESIGN CHANGE 77-20: ADDITION OF STRAINERS IN THE FLASH EVAPORATOR DISTILLATE LINES This design change provided for the following:

1. A wye-strainer in both flash evaporator distillate lines;

2. A valve for blowdown to existing drain for each strainer;

3. Necessary valves and piping for each strainer.

This change was made to preclude carry-over from the flash evaporators, in the form of products, from entering the condensate system.

No safety related equipment was involved in the modification. Failure of the proposed strainers would not adversely affect the safety of the plant.

DESIGN CHANGE 77-21:

INSTALLATION OF AIR CONDITIONING IN DC SWITCHGEAR ROOM.

A five ton air conditioner was installed in the D/C Switchgear Room to lengthen the service life of inverter components.

The complete failure of this air conditioner would not degrade performance of the inverters or chargers. There are no direct connections between the air conditioner and structures of safety related components in the DC Switchgear Room.

9 PAGE 4 DESIGN CHANGE 78-02:

CONTROL ROOM EMERGENCY AIR TREATMENT SYSTEM The normal air intake damper to the Control Room was modified to allow manual closure from the Watch Engineers office. The change was accomplished by circuit revisions in the control room emergency air treatment system. Failure of the electrical contacts utilized for this modification would cause the dampers to go to or remain in the safety related position. Also, in the event of a radiological emergency requiring the control room emergency air treatment system, manual control of the normal dampers would be overridden and.the dampers would close automatically to their safety related positions.

DESIGN CHANGE 78-04: MODIFICATIONS TO THE REGION 9 FUEL ASSEMBLIES The modifications of this design change consist of 29 Engineering Change Notices (ECN's) processed by Westinghouse concerning Region 9 fuel assemblies loaded into the reactor for Cycle 7. The ECN's were implemented to facilitate the design and manufacture of Region 9 fuel assemblies by Westinghouse.

They included changes associated with drawing notations, manufacturing specifications, engineering tolerances and material specifications. The ECN's did not result in any changes to thermal-hydraulic, nuclear design characteristics or reactor structural integrity.

DESIGN CHANGE 78-06:

RE-DESIGN OF THE UPPER INTERNALS LIFTING RIG SLING ASSEMBLY The original upper internals lifting rig sling assembly which used cables for the lifting members was replaced by a new assembly made of solid rods and thick walled pipes. The new assembly is less likely to experience unequal elongation of the lifting members which was suspected of causing binding during telescoping of the upper internal components following refueling operations.

The new assembly was designed and fabricated to meet or exceed the lifting capabilities of the original assembly without adversely affecting the safety functions of the lifting rig.

PAGE 5 DESIGN CHANGE 78-07: MANIPULATOR CRANE MODIFICATIONS The manipulator crane was upgraded by the performance of the following modifications:

1. Modified fuel assembly gripper to provide pressurized air supply to gripper mechanism in addition to the existing spring latch mechanism.

This modification enables more expeditious handling of fuel assemblies while providing more positive engagement by the gripper. As the existing latch mechanism is unchanged, loss of the air supply would not result in loss of gripper engagement.

2. Installed new circuitry to prevent hoist up-travel with gripper disengaged and load cell weight over 1200 pounds. This change reduces the likelihood of fuel handling problems arising from personnel error and thereby enhances plant safety.

3. Installed a re-designed gripper which relocated the finger locking plate to avoid possible interferences.

These modifications result in improved performance of the manipulator crane, and have no adverse impact on plant safety.

DESIGN CHANGE 78-08: WATER TRAP ADDITION TO HYDRAULIC VALVE AIR SYSTEM This design change added a drain trap to the station service air supply to four safety injection valve actuators to prevent water from entering the actuator pneumatic devices. The valves utilize self-contained accumulators to actuate to the safety related position. Service air is used to move the valves to their normal operating (non-safety related) position. Loss of service air due to a drain trap failure would only result in the loss of ability to move the valves from their safety related to their normal operating positions.

PAGE 6 DESIGN CHANGE 78-09:

IN-CORE INSTRUMENTATION PORT COLUMN MODIFICATION To confine a small reactor coolant system leak through an in-core instrumentation seal, a stainless steel cap was welded to the in-core instrumentation port flange. This modification was temporary until a permanent repair was made during the October 1978 refueling outage. The piping installation was designed to meet or exceed the design rating for the reactor pressure vessel.

ASME Code approved materials were used. Non-destructive testing was performed on all materials and welds.

Installation of the cap on 'the instrumentation port resulted in the unavailability of certain non-safety related in-core instrumentation. This condition was determined to be acceptable based on the number and geometry of the remaining similar instrumentation.

DESIGN CHANGE 78-10: MODIFICATION TO CONTROL CIRCUITS OF MOTOR OPERATED VALVES IN THE SAFETY INJECTION LINES To prevent possible valve stem distortion due to excessive applied torque, limit switch contacts were connected in series with a closing circuit torque switch for three motor operated valves in safety injection lines. The valves are required to open upon receipt of a safety injection signal.

This modification does not affect the opening circuitry of these valves and cannot result in the inadvertent closure of the valves during a postulated accident.

DESIGN CHANGE 78-11 (Revision 1):

CONTINUOUS AXIAL OFFSET MONITORING SYSTEM (CAOMS) MODIFICATION This design change installed a new axial offset calculating circuit to display true axial offset rather than delta flux. This modification simplified calibration procedures and resulted in the direct display of the parameter which must be monitored in accordance with Technical Specification requirements. The CAOMS does not perform a safety related function nor is it employed in systems required for safe shutdown of the plant.

9 PAGE T DESIGN CHANGE 78-12:

YARD DRAIN AND REHEATER SUMP PUMP CONTROL MODIFICATIONS (In progress)

In order to control and contain oil spills, this design change will add oil detection devices to the yard drain system sump and reheater pit sump.

The sumps and associated equipment are not safety related.

DESIGN CHANGE 78-14:

SUBSTITUTE STEM PACKING FOR FEEDWATER PUMP HYDRAULIC ACTUATED VALVES.

This design change allowed substitution of Grafoil ribbon packing for Crane 177A1 preformed split ring packing in the feedwater pump hydraulic actuated valves. This change was accomplished to facilitate valve maintenance.

The valve manufacturer provided written concurrence for use of the substitute packing material.

Following valve maintenance involving packing installation, the valves will be tested and the packing adjusted as necessary to maintain proper operating characteristics.

DESIGN CHANGE 78-15: MODIFICATION TO THE UPPER INTERNALS TELESCOPING INSTRUMENTATION SUPPORT COLUMNS.

This design change consisted of the removal of twenty radial support balls in each of the four telescoping instrumentation support columns on the reactor upper internals assembly. This modification was accomplished to eliminate the possibility of binding when re-installing the instrument plate in the reactor pressure vessel. A study was performed which verified that the stability of the columns and the fatigue life of critical areas without the balls was acceptable.

DESIGN CHANGE 78-16: MODIFICATIONS RESULTING FROM SINGLE FAILURE ANALYSIS REDUNDANT SIS BLOCK SWITCHES.

This design change proposed the installation of train-independent SIS override/block switches to prevent the unacceptable potential consequences of certain single failures. This modification provided redundancy such that one block switch could sustain an electrical or mechanical failure or operator error and not prevent SIAS from responding to an emergency signal.

Plant safety was enhanced as a result of this modification.

PAGE 8 DESIGN CHANGE 78-17: MODIFICATIONS RESULTING FROM SINGLE FAILURE ANALYSIS "LOSS OF OFFSITE POWER" UV RELAYS.

To prevent the unacceptable potential consequences of certain single failures, this design change provided independent and redundant "loss of offsite power" input signals by the addition of a second undervoltage relay in each 4160V bus. Plant safety was enjanced as a result of this modification.

DESIGN CHANGE 78-18: ADDITION OF THE TEMPORARY SHOO-FLY LINE.

This design change proposed the temporary installation of a shoo-fly line and its associated equipment between the Unit 1 switchyard and the Unit 2 reserve auxiliary transformer to provide power for startup and testing of the San Onofre Nuclear Generating Station Units 2 & 3. All components required for this design change are classified non-safety related and there is no adverse impact on plant safety as a result of this modification.

DESIGN CHANGE 78-19:

CONTROL ROOM EMERGENCY AIR TREATMENT SYSTEM CARBON CELL MODIFICATION.

In order to eliminate a potential leakage problem this design change replaced a neoprene rubber gasket on the front face of the carbon cell in the Control Room Emergency Air Treatment System with a new knife edge seal.

Following installation of the new seal the system was tested and certified satisfactory as required by Technical Specification 4.11.

DESIGN CHANGE 78-20: UNITS 2 & 3 STARTUP WASTE WATER DISCHARGE SYSTEM (TEMPORARY) INTO UNIT 1 CIRCULATING WATER OUTFALL SYSTEM.

This design change consisted of coring a penetration in the Unit I circulating water outfall tsunami structure along with piping installation to allow discharging Units 2 & 3 startup waste water. Except for the concrete coring effects on structural integrity of the existing structure, all aspects of the proposed temporary waste discharge system were non-safety related.

A structural analysis showed all effects on structural integrity to be acceptable.

In addition, the environmental effects associated with this change were found to be acceptable.

PAGE 9 DESIGN CHANGE 78-21:

INSTALLATION OF TEST PLATE-RACKS IN REACTOR CAVITY.

Two test-plate racks were temporarily installed in the lower reactor cavity during the October refueling outage in connection with an effort to develop a new cavity cleaning/decontamination process/system to reduce cavity decontamination time subsequent to refueling. The structural design of the racks and attachments was found to be acceptable. Adequate clearance was found to exist between all fuel transport equipment and the racks. The racks and test plates were removed for analysis at the conclusion of the refueling outage.

DESIGN CHANGE 78-23: MODIFICATION OF CONTAINMENT SPRAY ACTUATION SYSTEM (CSAS) INVERTER STATIC BYPASS SWITCH.

This design change deleted the function of the Silicon Controlled Rectifiers which provided uninterrupted power transfer upon sensing undervoltage at the primary inverter. This modification provides a momentary (less than 100 millisecond) power interruption to prevent the temporary loss of both inverters due to an internal fault in the primary inverter which would have been exposed to the secondary inverter via the original make-before-break transfer operation. The unavailability of one of the two redundant logic units for a period of less than 100 milliseconds during the revised break-before make transfer was determined to be insignificant. This modification increases the reliability of the CSAS by reducing the probability of a loss of power to the system.

DESIGN CHANGE 78-25:

FLASH EVAPORATOR SERVICE WATER SUPPLY.

This design change connected the service water supply line to the inlet side of the flash evaporator feed pumps to allow the flexibility of using service water as well as sea water. All compopents required for this design change are classified non-safety related and there was no adverse input on plant safety resulting from this change.

DESIGN CHANGE 78-26: ADDITION OF STRUCTURAL SUPPORTS TO CONTROL ROOM BOARDS.

This design change provided additional structural support to the control room board panels by welding angles at the base of the structural face plate (front side) of the panels. This modification will enable the control boards to withstand the effects of a 0.67g Housner horizontal ground acceleration spectra. The work for this modification was performed in accordance with quality assurance requirements for safety related installations.

PAGE io DESIGN CHANGE 78-28 (Revision 1):

FIRE PROTECTION PLANT MODIFICATIONS.

The following changes were instituted by this design change in order to maintain the plant in a safe shutdown condition underpostulated fire conditions.

1) Alternate source of power to the 480V switchgear No. 2.

2) D.C. Thermal Barrier Cooling Pump wiring modifications.

3) Additional power provisions for the pressurizer heaters.

4) Addition of local level instrumentation for the Volume Control Tank.

5) Concrete curb installation around the perimeter of the lube oil reservoir and conditioner area.

6) Fire door installation.

7) Drainage modifications under the turbine deck.

An interfacing design criteria was used such that failure of any structure, system or component required for this modification would not a) degrade the operation of the existing safety-related systems, b) adversely affect plant safety, and c) introduce potential common mode failures.

DESIGN CHANGE 78-29: ADDITION OF CIRCULATING WATER INTAKE SAMPLING SYSTEM.

This design change provided for a circulating water intake sampling system in order to comply with Environmental Technical Specification 4.3. That Technical Specification requires that circulating water conduit sampling studies be performed to establish levels of plankton entrainment within the SONGS-1 circulating water intake conduit. The change consisted of an access port installed in an intake tunnel manhole cover about 500 feet from the intake structure. This access port allows periodic installation of a sample nozzle with the circulating water pumps operating. This change was found to have no adverse impact on plant safety.

DESIGN CHANGE 78-31:

INSTALLATION OF REACTOR CAVITY FILTRATION SYSTEM.

A skid mounted reactor cavity filtration system was installed to improve reactor cavity water clarity and underwater visibility during refuelings.

The system was located and installed in such a manner as to have no adverse impact on plant safety.

PAGE 11 DESIGN CHANGE 78-32 (Revision 3): MODIFICATION TO THE OPERATORS ON TWO CONTAINMENT SPRAY ACTUATION SYSTEM VALVES.

Modifications were made to tubing, clamps, supports, and retaining devices on two hydraulic valve actuators installed in the containment spray actuation system (CSAS). Potential failure modes and operability problems were identified during seismic testing of a similar actuator by a testing laboratory for another utility. It was concluded that the test conditions resulted in excessive loads being imposed on the actuators which are not representative of loads expected at San Onofre Unit 1 in response to a design basis seismic event (DBE). However, despite this conclusion, the same modifications which were successfully employed to resolve the problems identified by the testing laboratory were incorporated in the two similar actuators which are required to function to perform their safety related function following a DBE.

DESIGN CHANGE 78-33:

FIRE PROTECTION MODIFICATION TO THE INSTRUMENT AIR HEADER The following modifications were implemented:

1) Installed a local air supply (accumulator) to the south salt water cooling pump discharge valve.

2) Installed new tubing connection for steam supply valve for the Auxiliary Feed Water Pump.

3) Installed a new tubing connection for the air supply to the Auxiliary Control Panel.

4) Rerouted air tubing from the Auxiliary Panel to the Steam Dump Valves.

5) Installed a new source of air for the Steam Dump Valves.

These changes provide an alternate supply of compressed air to equipment required to maintain the plant in safe hot and cold shutdown conditions.

These modifications were found to have no adverse impact on plant safety.