ML20040H049
| ML20040H049 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 01/25/1982 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Hancock J FLORIDA POWER CORP. |
| Shared Package | |
| ML20040H050 | List: |
| References | |
| NUDOCS 8202170060 | |
| Download: ML20040H049 (1) | |
Text
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Docket No. 50-302 19925[3 n
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!!r. John A. Ilancock N
Vice President, fluclear Operations c)
Florida Power Corporation ATTN: Manager, fluclear Licensing P. O. Dox 14042, M.A.C. H-2 St. Petersburg, Florida 33733
Dear !!r. ilancock:
From our review of the information you provided with regard to Degraded Grid Protection for Class lE Power Systems for Crystal River Unit 3 Nuclear Generating Plant we find your proposed electrical system design nodification acceptable. Our Safety Evaluation Report (SER) and the Technical Evaluation Report (TER) prepared by EG&G are enclosed.
In your letter dated October 30,1981 you stated that you will not be able to propose Technical Specifications for the second level of under-voltage protection until you have received our complete concurrence with your design. He now have appmved your proposed design. Therefore, within 30 days-of receipt of.this letter provide pmposed changes and additions to the Crystal River. Unit.3 Nuclear Generating Plant Technical Specifications for the Degraded Grid Protection. Sample Technical Specifications were included in our June _6,1977 letter.
The reporting and/or recordkeeping mquireaents contained in this letter affect fewer than ten respondents; therefore 0!E cicarance is not required under P.L.96-511.
Sincerely,
'ema:a, si m yg J0iniJ.SIOLZe John F. Stolz, Chief Operating Reactors Branch #4 Division of Licensing
Enclosures:
1.
SER 2.
TER cc w/ enclosures:
See next page 8202170060 820125 PDR ADOCK 05000302 P
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION
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%,,,,, *#g SAFETY EVALUATION CRYSTAL RIVER NUCLEAR GENERATING PLANT UNIT 3 DOCKET NO. 50-302 DEGRADED GRID VOLTAGE PROTECTION FOR THE CLASS lE SYSTEM i
INTRODUCTION AND
SUMMARY
The criteria and staff positions pertaining to degraded grid voltage protection were transmitted to Florida Power Corporation (FPC) by NRC generic letter dated June 6,1977.
In response to this by letters dated July 21,1977, July 25,1977, April 3,1980, December 22, 1980, October 30, 1981 and telephone conversation on November 12,1981, the licensee proposed certain design modifications. A detailed review and technical evaluation of these proposed modifications was performed by EG&G, under contract to the NRC, and with general supervision by NRC staff. This work is reported by EG&G in " Degraded Grid Protection for Class lE Power Systems Crystal River Nuclear Generating Plant Unit 1 (attached). We have reviewed this technical evaluation report and concur that the proposed electrical design modifications are acceptable.
Technical Specification to cover the surveillance requirement, allowable limits for setpoint and time delay, and limiting conditions for operation for the second-level undervoltage relays have not been submitted by FPC.
l Upon receipt, review and approval of the Technical Specification, a SSER l
will be issued.
l l
l j
. EVALUATION CRITERIA The criteria used by EG&G in its technical evaluation of the proposed changes include GDC-17 (" Electric Power Systems') of Appendix A to 10 CFR 50; IEEE Standard 279-1971 (" Criteria for Protection Systems for Nuclear Power Generating Stations"); IEEE Standard 308-1974 (" Class lE Power Systems for Nuclear Generating Stations"); ANSI Standard C 84.1-1977 (" Voltage Ratings for Electrical Power Systems and Equipment - 60 Hz"); and staff positions defined in NRC generic letter to FPC dated June 7, 1977.
PROPOSED CHANGES, MODIFICATIONS AND DISCUSSION The following electrical system design modifications were proposed by FPC:
a.
Installation of a second level of undervoltage relays on each of the 4160 volt Class lE buses. The second level, degraded grid undervoltage modification consist of three relays per bus, arranged in a l
l l
1 three-out-of-three logic, a seven second timer, a thirteen second timer and a three second timer. 'If the bus voltage should fall to less than 3744(+ 2%) volts, it ill activate the seven second timer which starts the diesel generator 'for' the effected bus and activates the thirteen second timer.
If the voltage recovers,before the total of twenty seconds has elapsed, the circuit will reset.
If the voltage remains below the setpoint'for greater than twenty seconds, the circuitry will activate the three second timer, trip the incoming breakers to the Class lE bus, and initiates load shedding. After 23 seconds has elapsed, the diesel generator output breaker will clcse if adequate frequency and voltage output has been achieved. Generation of a safety injection signal at any time during the twenty-second sequence will star't' the diesel generator, if not already started, activate three second imer, and bypass the thirteen second timer.
Therefore, if a safety in'jection signal is received at any time during a degraded grid condition, the diesel generator will be connected to the emergency buses within ten seconds after the signal is received.
Actuation of any one'of the second level undervoltage relays will be j
annunciated in the control room.
l l
b.
The blocking of load shedding when the diesel generator is supplying the Class lE loads and reinstatement of this feature on a diesel I
generator trip is presently incorporated in the Crystel River l
l design.
l
4-c.
Technical Specification additions and changes have not been provided by the applicant.
CONCLUSIONS We have reviewed the EG&G Technical Evaluation Report and concur in its findings that:
(1) The proposed degraded grid modifications will protect the Class lE equipment and systems from sustained degraded voltage within the expected range of grid voltage variations analyzed.
(2) The existing load-shed circuitry prevent load shedding while the diesel generator is supplying the emergency load. This feature is reinstated upon a diesel generator. trip.
(3) Upon receipt, review and approval of the required Technical Specification additions and changes, a final SSER will be issued.
Datsd$
January 25, 1982
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