ML13303A911

Forwards Request for Addl Info Re Implementation of 10CFR50.62.Response Requested within 60 Days of Ltr Date

ML13303A911
Person / Time
Site:	San Onofre
Issue date:	08/25/1988
From:	Hickman D Office of Nuclear Reactor Regulation
To:	Baskin K, Cotton G San Diego Gas & Electric Co, Southern California Edison Co
References
TAC-59139, TAC-59140 NUDOCS 8809010345
Download: ML13303A911 (9)

Text

August'25, 1988 Docket Nos.: 50-361 and 50-362 Mr. Kenneth P. Baskin Mr. Gary D. Cotton Vice President Senior Vice President Southern California Edison Company Engineering and Operations 2244 Walnut Grove Avenue San Diego Gas & Electric Company Post Office Box 800 101 Ash Street Rosemead, California 91770 Post Office Box 1831 San Diego, California 92112.

Gentlemen:

SUBJECT:

10 CFR 50.62 (ATWS RULE) REQUEST FOR ADDITIONAL INFORMATION (TAC NUMBERS 59139 AND 59140)

During the course of our review of your implementation of 10 CFR 50.62 (ATWS Rule), we find that additional information is needed. The requested information is described in the Enclosure. Please forward this information within 60 days of receipt of this letter.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under Pub. L.96-511.

As you know, the rule requires prompt implementation of modifications to achieve compliance. These modifications do not require prior staff approval.

Sincerely, original signed by 8609010345 860825 PDR ADOCK 05000361 P

PNU i

Donald E. Hickman, Project Manager Project Directorate V Division of Reactor Projects - III, IV, V and Special Projects Enclosure As stated cc:

See next page DISTRIBUTION DOCKET FILE OGC EJORDAN BGRIMES ACRS (10)

NRC & LPDRs PDV RDG DCrutchfield DHickman OFC :DRSP/PDV/PM :DRSP/D:PDV:

NAME :D

GWKnightonP::

DATE :08/2/88

08/,/88 OFFICIAL RECORD COPY (I

August 25, 1988 Docket Nos.:

50-361 and 50-362 Mr. Kenneth P. Baskin Mr. Gary D. Cotton Vice President Senior Vice President Southern California Edison Company Engineering and Operations 2244 Walnut Grove Avenue San Diego Gas & Electric Company Post Office Box 800 101 Ash Street Rosemead, California 91770 Post Office Box 1831 San Diego, California 92112 Gentlemen:

SUBJECT:

10 CFR 50.62 (ATWS RULE) REQUEST FOR ADDITIONAL INFORMATION (TAC NUMBERS 59139 AND 59140)

During the course of our review of your implementation of 10 CFR 50.62 (ATWS Rule), we find that additional information is needed. The requested information is described in the Enclosure. Please forward this information within 60 days of receipt of this letter.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under Pub. L.96-511.

As you know, the rule requires prompt implementation of modifications to achieve compliance. These modifications do not require prior staff approval.

Sincerely, original signed by Donald E. Hickman, Project Manager Project Directorate V Division of Reactor Projects -

III, IV, V and Special Projects Enclosure As stated cc:

See next page DISTRIBUTION DOCKET FILE OGC EJORDAN BGRIMES ACRS (10)

NRC & LPDRs PDV RDG DCrutchfield DHickman OFC :DRSP/PDV/PM :DRSP/D:PDV NAME :DE,

GWKnighto DATE :08/25/88

08/,)/88 OFFICIAL RECORD COPY

++.

0 UNITED STATES NUCLEAR REGULATORY COMMISSION o

WASHINGTON, D. C. 20555 August 25, 1988 Docket Nos.: 50-361 and 50-362 Mr. Kenneth P. Baskin Mr. Gary D. Cotton Vice President Senior Vice President Southern California Edison Company Engineering and Operations 2244 Walnut Grove Avenue San Diego Gas & Electric Company Post Office Box 800 101 Ash Street Rosemead, California 91770 Post Office Box 1831 San Diego, California 92112 Gentlemen:

SUBJECT:

10 CFR 50.62 (ATWS RULE) REQUEST FOR ADDITIONAL INFORMATION (TAC NUMBERS 59139 AND 59140)

During the course of our review of your implementation of 10 CFR 50.62 (ATWS Rule), we find that additional information is needed. The requested information is described in the Enclosure. Please forward this information within 60 days of receipt of this letter.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under Pub. L.96-511.

As you know, the rule requires prompt implementation of modifications to achieve compliance. These modifications do not require prior staff approval.

Sincerely, Donald E. Hickman, Project Manager Project Directorate V Division of Reactor Projects -

III, IV, V and Special Projects Enclosure As stated cc:

See next page

Mr. Kenneth P. Baskin San Onofre Nuclear Generating Southern California Edison Company Station, Units 2 and 3 cc:

Mr. Gary D. Cotton Mr. Hans Kaspar, Executive Director Senior Vice President Marine Review Committee, Inc.

Engineering and Operations 531 Encinitas Boulevard, Suite 105 San Diego Gas & Electric Company Encinitas, California 92024 101 Ash Street Post Office Box 1831 San Diego, California 92112 Mr. Mark Medford Southern California Edison Company Charles R. Kocher, Esq.

2244 Walnut Grove Avenue James A. Beoletto, Esq.

P. 0. Box 800 Southern California Edison Company Rosemead, California 91770 2244 Walnut Grove Avenue P. 0. Box 800 Mr. Robert G. Lacy Rosemead, California 91770 Manager, Nuclear Department San Diego Gas & Electric Company Orrick, Herrington & Sutcliffe P. 0. Box 1831 ATTN:

David R. Pigott, Esq.

San Diego, California 92112 600 Montgomery Street San Francisco, California 94111 Richard J. Wharton, Esq.

University of San Diego School of Alan R. Watts, Esq.

Law Rourke & Woodruff Environmental Law Clinic 701 S. Parker St. No. 7000 San Diego, California 92110 Orange, California 92668-4702 Charles E. McClung, Jr., Esq.

Attorney at Law Mr. S. McClusky 24012 Calle de la Plaza/Suite 330 Bechtel Power Corporation Laguna Hills, California 92653 P. 0. Box 60860, Terminal Annex Los Angeles, California 90060 Regional Administrator, Region V U.S. Nuclear Regulatory Commission Mr. C. B. Brinkman 1450 Maria Lane/Suite 210 Combustion Engineering, Inc.

Walnut Creek, California 94596 7910 Woodmont Avenue, Suite 1310 Bethesda, Maryland 20814 Resident Inspector, San Onofre NPS c/o U. S. Nuclear Regulatory Commission Mr. Dennis F. Kirsh Post Office Box 4329 U.S. Nuclear Regulatory Commission San Clemente, California 92672 Region V 1450 Maria Lane, Suite 210 Mr. Sherwin Harris Walnut Creek, California 94596 Resource Project Manager Public Utilities Department Mr. Dennis M. Smith, Chief City of Riverside Radiological Programs Division City Hall Governor's Office of Emergency Services 3900 Main Street 2800 Meadowview Road Riverside, California 92522 Sacramento, California 95832

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RREG&j 0

UNITED STATES 0

NUCLEAR REGULATORY COMMISSI N o

WASHINGTON, D. C. 20555 SAN ONOFRE UNITS 2 AND 3 10 CFR 50.62 (ATWS RULE)

REQUEST FOR INFORMATION TACS 59139 AND 59140

1.0 INTRODUCTION

AND DISCUSSION On July 26, 1984 the Code of Federal Regulations (CFR) was amended to include the ATWS rule (Section 10 CFR 50.62, "Requirements for Reduction of Risk from Anticipated Transients Without Scram (ATWS) Events for Light-Water-Cooled Nuclear Power Plants"). An ATWS is an expected operational transient (such as loss of feedwater, loss of condenser vacuum, or loss of offsite power) which is accompanied by a failure of the reactor trip system (RTS) to shutdown the reactor. The ATWS rule requires specific improvements in the design and operation of commercial nuclear power facilities to reduce the likelihood of failure to shutdown the reactor following anticipated transients, and to mitigate the consequences of an ATWS event. Paragraph (c)(6) of the rule requires that information sufficient to demonstrate compliance with the requirements of the rule be submitted to the Director, Office of Nuclear Reactor Regulation. The ATWS rule requires Combustion Engineering (CE) plants such as San Onofre Units 2 and 3, to provide a diverse (from existing RTS) scram system (DSS),

diverse (from the existing RTS) auxiliary feedwater system (AFWS) actuation, and diverse (from the existing RTS) initiation of turbine trip (DTT) system.

Information in addition to that provided in the Southern California Edison Company (SCE) letter dated June 6, 1986 is needed to allow the staff to determine whether San Onofre Units 2 and 3 comply with the hardware diversity, electrical independence, reliability and testability at power requirements of the ATWS rule. The information identified below is required by the staff to complete the review of implementation of the ATWS rule requirements at San Onofre Units 2 and 3. It should be noted that the requested information concerns the DSS and DTT designs only. Compliance of the San Onofre Units 2 and 3 designs to the ATWS rule requirement for diverse actuation of the AFWS will be reviewed following receipt of the SCE response to the staff's letter dated January 11, 1988 (G. Knighton, NRC to K. P. Baskin, SCE).

1. It is the staff's understanding that the San Onofre, Units 2 and 3, diverse scram system (DSS) design uses inputs provided by the four existing reactor protection system (RPS) pressurizer pressure transmitter instrument channels. The DSS input signals will be generated in the existing RPS process instrument cabinets and transmitted to the DSS through qualified isolation devices. A reactor trip will occur when power to the motor-generator (MG) set output contactors is interrupted which de-energizes the control element drive mechanism (CEDM) holding coils. This action is independent of the existing reactor trip breakers.

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a. Please provide electrical schematic/elementary diagrams for the DSS and DTT designs that clearly show all instrument channels (including bistables), logic, actuation circuits, test circuits, interlocks, bypasses, alarms and indications. Also, provide electrical one-line diagrams showing the CEDM MG sets, DSS actuated output contactors, and power distribution to the RPS, DSS, and DTT circuits, including vital buses, inverters, batteries and chargers, etc.

b. For all DSS and DTT instrument channel components (excluding sensors and signal conditioning equipment upstream of the bistables) and logic channel components, and DSS actuation devices, provide information sufficient to demonstrate compliance with the ATWS rule diversity requirements. The information should include a diversity comparison of the DSS and DTT components with the components used in the existing RPS, e.g.,

manufacturer, model number, design principle (electromechanical, solid state, etc.) mode of operation (energize/deenergize to actuate), power source (AC/DC), etc. The similarities and differences in the physical and operational characteristics of these components must be analyzed to determine the potential for common mode failure mechanisms that could disable both the RPS and ATWS prevention/mitigation functions. The evaluation of the adequacy of the diversity provided must be performed at a detailed level to include hardware design considerations and diversity aspects that might not be apparent from a cursory/audit review. For example, two electromechanical relays from the same manufacturer and having the same voltage/current ratings and energize-to-actuate/deenergize-to-actuate trip status, and therefore, which appear to be unacceptable for satisfying the diversity requirements of the ATWS rule, may actually be acceptable if different materials and different manufacturing processes are used. Conversely, two printed circuit cards from different manufacturers, and therefore, which appear to be acceptable for satisfying diversity requirements of the rule, may not be acceptable if they both use identical components.

c. Please provide information necessary to explain how the DSS and DTT will remain operable to perform their intended functions given a loss of offsite power.

d. Please describe in detail the indications and alarms used to alert the control room operators to DSS and DTT inoperable conditions (e.g., when a channel/system or equipment is placed in a bypass or test status). Include a discussion of all operating and/or maintenance bypasses that will be used in conjunction with the DSS or DTT.

e. Explain the specific operator actions required to manually initiate a DSS and/or DTT protective action. Also, following manual or automatic initiation, is the protective action sealed in at the system level to ensure completion of the ATWS prevention/mitigation function?

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2. Electrical independence of the DSS from the existing RPS should be provided from the sensor output up to and including the final actuation device. Electrical independence of the DTT system from the existing RPS should be provided from the sensor output up to the final actuation device.

It is the staff's understanding that the proposed San Onofre Units 2 and 3 DSS and DTT power supply design is such that all power will be supplied from the non-Class 1E uninterruptible power supply (UPS) and that the non-Class 1E UPS is independent of the Class 1E power supply to the RPS.

a. Identify all DSS and DTT system components that receive power from sources that are also used to provide power to the existing RPS. If RPS power supplies are used, information must be provided to demonstrate that: 1) faults within the DSS or DTT circuits cannot degrade the reliability/integrity of the existing RPS below an acceptable level, and 2) that a common mode failure affecting the RPS power distribution system (including degraded voltage and/or frequency conditions, e.g., overvoltage and undervoltage; the effects of degraded voltage/frequency conditions over time must be considered if such conditions can go undetected) cannot compromise both the RPS and ATWS prevention/mitigation functions. If alarms are relied on to provide early detection of degraded voltage/frequency conditions, the information should include the specific alarm(s) and their setpoint value(s), and the limiting voltage/frequency values for which the affected circuits/components have been analyzed/demonstrated to still be capable of performing their intended functions. A discussion of the periodic surveillance/testing performed to verify operability of the alarm circuits should also be provided.

b. Electrical independence of nonsafety-related ATWS circuits from safety related circuits is required in accordance with the guidance provided in IEEE Standard 384, "IEEE Standard Criteria for Independence of Class 1E Equipment and Circuits," as supplemented by Regulatory Guide 1.75, Revision 2, "Physical Independence of Electrical Systems."

Information must be provided to demonstrate the adequacy of all isolation devices used to protect the integrity of safety related circuits from nonsafety-related ATWS DSS and DTT circuits.

The required information is identified in Attachment 1. If the isolation devices are identical to isolation devices used in other applications (e.g., to isolate the safety parameter display system from safety related circuits), and the requested information has been previously submitted for staff review, and the isolation devices have been approved for their applications, the related correspondence should be referenced, and no additional information need be provided.

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3. The equipment required by 10 CFR 50.62 to reduce the risk associated with an ATWS event must be designed to perform its function in a reliable manner. The DSS and DTT circuits must be designed to allow periodic testing to verify operability while at power. All bypass conditions should be automatically and continuously indicated in the main control room.

a. Describe the scope and intent of the various surveillance tests (e.g., sensor/channel checks, instrument channel functional tests, logic channel and actuation device tests, channel/system calibrations, overall system functional tests, etc.) that SCE intends to use to periodically verify operability of the DSS and DTT equipment/circuitry installed at San Onofre Units, 2 and 3.

Indicate the frequency for which each surveillance test is conducted. Also discuss the controls/programs (e.g., technical specifications) to be used to ensure that the equipment/circuitry installed in accordance with the ATWS rule will be properly tested and maintained in an operable condition. The controls/programs should provide positive assurance that the ATWS equipment/circuitry will perform its design functions when required, and therefore, satisfy the reliability requirements of the ATWS rule.

b. Please indicate whether the test procedures involve undesirable practices such as installing jumpers, lifting leads, pulling fuses, tripping breakers, blocking relays, or other circuit alternations.

4. During the life of a commercial light-water-cooled nuclear power plant many components reach their end of life and must be replaced, including components installed in the RTS, DSS, and DTT system.

Provide a description of the measures/programs implemented at San Onofre Units 2 and 3 to assure that the equipment diversity provided in accordance with the ATWS Rule will be maintained during component repair, replacement, modifcations and/or design changes etc.

throughout the life of the plant.

5. Discuss how good human factors engineering practices are incorporated into the design of ATWS prevention/mitigation system components located in the control room. Specifically address the coordination of displays used to provide the status of ATWS systems/equipment to the operator with existing displays.

ATTACHMENT ISOLATION DEVICE REQUEST FOR ADDITIONAL INFORMATION Each light-water-cooled nuclear reactor shall be provided with a system for the prevention and/or mitigation of the effects from anticipated transient without scram (ATWS) events. The Commission-approved requirements for the prevention/mitigation of ATWS events are defined in the Code of Federal Regulations (CFR) Section 10 paragraph 50.62. The staff has determined that the isolation devices used within ATWS prevention/mitigation systems (to provide isolation between class 1E and non-class 1E circuits or between redundant class 1E circuits) will be reviewed on a plant-specific basis. The following additional information is required to continue and complete the plant-specific isolator review:

Isolation Devices Please provide the following:

a. For the type of device used to accomplish electrical isolation, describe the specific testing performed to demonstrate that the device is acceptable for its application(s). This description should include elementary diagrams, when necessary, to indicate the test configuration and should describe how the maximum credible faults were applied to the devices.

b. Data to verify that the maximum credible faults applied during the test were the maximum voltage/current to which the device could be exposed, and define how the maximum voltage/current was determined.

c. Data to verify that the maximum credible fault was applied to the non-Class 1E side of the device in the transverse mode (between signal and return) and that other faults were considered (i.e., open and short circuits).

d. Define the pass/fail acceptance criteria for each type of device.

e. A commitment that the isolation devices comply with the environmental qualifications (10 CFR 50.49) and seismic qualifications that were the basis for plant licensing.

f. A description of the measures taken to protect the safety systems from electrical interference (i.e., Electrostatic Coupling, EMI, Common Mode and Crosstalk) that may be generated by the ATWS circuits.

g. Information to verify that the Class lE isolator is powered from a Class 1E source.