ML19257B676
| ML19257B676 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 12/20/1979 |
| From: | Reid R Office of Nuclear Reactor Regulation |
| To: | Cavanaugh W ARKANSAS POWER & LIGHT CO. |
| References | |
| NUDOCS 8001180087 | |
| Download: ML19257B676 (2) | |
Text
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wAsmuaTom. o.c. 20ssa December 20, 1979 Docket No. 50-313 Mr. William Cavanaugh, III Vice President, Generation and Construction Arkansas Power & Light Company P. O. Box 551 Little Rock, Arkansas 72203
Dear Mr. Cavanaugh:
SUBJECT:
PRELIMINARY DESIGN APPROVAL FOR THE SAFETY-GRADE ANTICIPATORY REACTOR TRIP (ART) ON LOSS OF FEEDWATER AND TURBINE TRIP We have reviewed your submittals of May 21 and October 8,1979, in which you forwarded a preliminary design for upgrading the present control-grade ART for loss of feedwater and turbine trip to safety-grada. A copy of the staff safety evaluation (SE) approving your preliminary design is included as an enclosure to this letter.
As summarized in Attachment 1 of this evaluation, additional infonration will need to be submitted prior to the final design approval. Therefore, insure that this infonration is submitted for staff review in sufficient time to allow staff approval prior to system operation.
If you have any questions in this matter, please contact the NRR Operating Reactor Project Manager, Mr. Guy Vissing at (301) 492-7435.
Sincerely, Al.
7 Robert W. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors
Enclosure:
SE cc w/ enclosure:
See next page 1768 121
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Arkansas Power & Light Conpany ccw/ enclosure (s):
Phillip K. Lyon Esq.
Director, Technical Assessment House Holms & Jewell Division 1550 Tower Building Office of Radiation Programs Little Rock, Arkansas 72201 (AW-459)
U. S. Environmental Protection Agency Mr. David C. Trimble Crystal Hall #2 Manager, Licensing Arlington, Virginia 20460 Arkansas Power & Light Company P. O. Box 551 U. S. Environmental Protection Agency Little Rock, Arkansas 72203 Region VI Office ATTN: EIS COORDINATOR Mr. James P. O'Hanlon 1201 Elm Street General Manager First International Building Arkansas Nuclear One Dallas, Texas 75270 P. O. Box 608 Russellville, Arkansas 72801
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Mr. William Johnson Director, Bureau of Environmental U. S. Nuclear Regulatory Commission Health Services P. O. Box 2090 4815 West Markham Street Russellville, Arkansas 72801 Little Rock, Arkansas 72201 Mr. Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 420, 7735 Old Georgetown Road Bethesda, Maryland 20014 Troy B. Conner, Jr., Esq.
Conner, Moore & Corber 1747 Pennsylvania Avenue, N.W.
Washington, D.C.
20006 Arkansas Polytechnic College Russellville, Arkansas 72801 Honorable Ermil Grant Acting County Judge of Pope County Pope County Courthouse Russellville, Arkansas 72801 N
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SAFETY EVALUATION BY THE OFFICE OF. NUCLEAR REACTOR REGULATION OF PRELIMINARY DESIGN FOR SAFETY-GRADE ANTICIPATORY REACTOR TRIPS (ARTS) ON LOSS OF MAIN FEEDWATER AND/OR TURBINE TRIP FOR DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS NOS 1, 2 AND 3 DOCKETS N05. 50-269, 270 AND 287 SACRAMENTO MUNICIPAL UTILITY ')ISTRICT RANCHO SECO NUCLEAR GEtiERATING STATION DOCKET N0. 50-312.
ARKANSAS POWER & LIGHT COMPANY ARKANSAS NUCLEAR OflE, UNIT 1 DOCKET NO. 50-313 FLORIDA POWER CORPORATION CRYSTAL RIVER NUCLEAR GENERATING STATION UNIT NO. 3 DOCXET NO. 50-302 I.
BACKGROUND Following the accident at Three Mile Island Unit 2, an assessment of feedwater transients in the Babcock and Wilcox (B&W) designed pressurized water reactors was performed. The results of that review were reported in NUREG-0560. This report highlighted a concern regarding the challenges to the power-operated relief valves (PORV) in the B&W design.
In response to I&E Bulletin 79-05B, the licensees lowered the existing setpoint for the high pressure reactor trip and raised the setpoint of the PORV. By inverting these setpoints the challenge rate to the PORY and thus the chance of it not reseating following actuation was reduced.
To provide additional margin to the automatic opening setpoint, the licensees proposed design provisions for direct reactor trip on loss of main feedwater or turbine trip. This design modification was approved and incorporated as part of the required actions of the Comission's Confirmatory Shutdown Orders
. issued in May 1979.
In order to achieve a timely implementation it was deter-mined that a " control-grade" design was sufficient for the short-term.
In the short-tenn the licensees implemented harh_ trips inde-pendent of the reactor protection system were to be upgraded to safety-grade and DUPLICATE DOCUMENT As part of the long-term requirements, e designs for safety-grade reactor trips t Entire document previously entered into system under:
llY d8 1768 123 No. of pages:
These submittals are listed as References 1 through 8 of Attachment 2 to this evaluation. The following evaluation is applicable to Oconee Units 1, 2 and 3; Arkansas Nuclear One, Unit 1, Rancho Seco and Crystal River Unit 3.
II. EXISTING RPS The existing plant RPS includes four redundant and independent channels.
Each channel has its own independent input sensors that are physically and electrically separated from the sensors of the other channels. The present trip conditions that are monitored by these sensors and channels include:
1.
Nuclear power / flux (high) 2.
Nuclear power based on flow (high) 3.
Nuclear power based on reactor coolant pump status (high)*
4.
Reactor coolant system pressure (high) 5.
Reactor coolant system pressure (low) 6.
Reactor coolant system pressure based on temperature (low) 7.
Reactor coolant temperature (high) 8.
Reactor building (containment) pressure (high)
Within the RPS cabinets each of the four channels contain a logic string of the above inputs. Any individual actuation will cause the logic string to trip and actuate a trip relay. The trip relays of the four channels form a two-aut-of-four coincident logic to open the reactor trip breakers.
III. DESCRIPTION OF PROPOSED DESIGN The licensees have proposed ARTS which will actuate on turbine trip anti /nr main feedwater pump trip. These anticipatory trips provide additional protection and conservatism beyond that provided by the existing RpS.
No credit is taken for these trips in the FSAR Chapter 15 analyses. Pre-viously existing and diverse parameters will cause a reactor trip should these proposed trips fail to function.
The proposed trips are to be incorporated into the existing RPS. They each contain four redundant and independent inputs to interface with the four RPS channels.
The turbine trip is to be sensed by four independent pressure switches.
The feedwater pump trip is similarly sensed (for each pump) by four inde-pendent pressure switches. The logic is arranged such that both main
.e-feedwater pumps must be tripped to cause reactor trip.
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- The trip system in Crystal River 3 does not monitor for this condition.
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