ML20058K190
| ML20058K190 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 11/30/1990 |
| From: | Peterson S Office of Nuclear Reactor Regulation |
| To: | Carns N ENTERGY OPERATIONS, INC. |
| References | |
| NUDOCS 9012130210 | |
| Download: ML20058K190 (6) | |
Text
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November 30, 1990 Docket No. 50 368 Mr. Neil S. Carns Vice President, Operations ANO Entergy Opeations, Inc.
Roi.3 3 P'x 137G Russe...ille, Arkansas 72801
Dear Mr. Carns:
SU2 JECT: CLARIFICATION REGARDING THE SAFETY EVALUATION FOR ARKANSAS NUCLEAR ONE, UNIT 2 (ANO-2) COMPLIANCE WITH THE ATWS RULE, 10 CFR 50.62.
By letter dated June 21, 1989, tht.: NRC forwarded to Arkansas Power and Light Company (AP&L) the Safety Evaluation (SE) regrading ANO-2 desi Diverse Scram System (DSS) and the Diverse Turbine Trip (DTT) gns for the stating that the
~ proposed DSS and DTT conformed to the requirements of 10 CFR 50.62 (the ATWS Rule),
in addition,' revised pages to the SE were issued on August 16, 1990,
'which incorporated clarifications identified by AP&L. ' Subsequent to further.
. review of the revised pages. Entergy Operations, by. letter dated November 16, 1990, identified additional items included in the staff's SE which needed Jfurther clarification.
V-This. letter provides the enclosed additional revised pages to the' June 21, 1989 SE.which incorporates the additional clarifications identified by Entergy Operations. These clarifications-do not alter our previous conclusion that AP&L's proposed modifications to ANO-2; as discussed in the SE, conform to the requirement of the~ATWS Rule.
, Pleas'e contact me if you have any questions concerning'this issue.
. Sincerely, a + * '7 y
ORIGINAL SIGNED BY:
[s oneri Peterson, Project Manager 7
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' Project Directorate IV-1 L
Division of Reactor Projects III -IV,'and Y
?,u Office of: Nuclear Reactor Regulation t,
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DISTRIBUTION
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~ Docket No. 50-333 Mr. Neil S. Carns
~
Vice President, Operations ANO Entergy Operations, Inc.
Route 3 Box 137G Russellville, Arkansas 72801
Dear Mr.,
Carns:
SUBJECT:
- CLARIFICATION REGARDING THE SAFETY EVALUATION FOR ARKANSAS NUCLEAR ONE,' UNIT 2 (ANO-2) COMPLIANCE WITH THE ATWS RULE, 10 CFR 50.62.
By. letter dated June 21, 1989, the NRC forwarded to Arkansas Power.and Light Company (AP&L)theSafetyEvaluation(SE)regradingANO-2desi DiverseScramSystew(DSS)andtheDiverseTurbineTrip(DTT)gnsforthe proposed DSS and DTT conformed:to the requirements of 10 CFR 50.62 (g that the statin the ATWS I
Rule)~..In addition,' revised pages to the SE were issued on August 16, 1990,
- which incorporated clarifications identified by AP&L.
Subsequent to further l
review of-the revised pages, Entergy Operations, by letter dated November 16, l
1990,; identified additional items included in the staff's SE which Meded L,
further riarification.
i L
L This letter provides the enclosed additional revised pages to the June 21,-
I'989 SE'which incorporates the additional clarifications identified by Entergy 1:
Operations. These clarifications do not alter our previous conclusion that 1
L AP&L's proposed modifications to ANO-2, as discussed in the SE, conforir to the
?
- requirements of the ATWS Rule.
j
, Please contact me if you hwe any questions concerning,this issue.
Sincerely, a
h h
I.
1 Sheri'Peterson, Project Manager.
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Project Directorate IV-1 Dfvision of Reactor Projects III, IV, and.V Office of Nuclear Reactor Regulation.
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Enclosure:
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.As stated h(
!cc w/ enclosure:
See'next page'
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1 Mr'. Neil S. Carns Entergy Operations, Inc.
Arkansas Nuclear One, Unit 2 cc:
Mr. Donald C. Hint 7 Mr. Gerald Muench Executive Vice President Vice President Operations Support and Chief Operating Officer Entergy Operations, Inc.
Entergy Operations, Inc.
P. O. Box 31995
.P. O. Box 31995 Jackson, Mist'ssippi 39286 Jackson, Mississippi 39286 Mr. Robert B. McGehee
.Mr. Jerry Yelverton Wise, Carter, Child & Caraway Director Nuclear Operations P. O. Box 651 Arkansas Nuclear One Jackson, Mississippi 39205 Route 3 Box 137G
'. Russellville, Arkanses 72801 Mr. Charles B. Brinkman, Manager Washington Nuclear Operations Mr. Nicholas S. Reynolds Combustion Engineering, Inc.
Winston & Strawn 12300 Twinbrook Parkway, Suite 330 1400'L Street, N.W.
Rockville, Maryknd 20852
' Washington, D.C.
20005-3502 AdmiralKinnairdR.McKee,USN-(Ret)-
Mr. Robert B. Borsum Post Office Box 41 Babcock & Wilcox 0xford, Maryland 21654 Nuclear Power Generation Division 1700 Rockville Pike, Suite'525 Mr. Tom Nickels
= Rockville,. Maryland 20852 Arkansas Nuclear One Route 3, Box 137G Senior Resident Inspector Russellville, Arkansas 72801 U.S. Nuclear Regulatory Commission 1 Nuclear' Plant Road Russellville, Arkansas' 72801 Regional Administrator,-Region IV U.S. Nuclear Regulatory anission Office of Executive Directo.-
for 0perations
.611 Ryan Plaza Drive, Suite.1000' LArlington, Texas '76011
' tionorable Joe W. Phillips County Judg2 of Pope, County Pope County Courthouse Russellville, Arkansas 72801 m
Ms. Greta Dicus, Director Division of Environmental Health
. Protection Arkansas' Department of Health 4815 West Mark 3m Street Little Rock, Arkansas 72201 L
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' (Revised)
Activation of both trip paths is required to initiate a reactor trip. Once the trip is actuated, it is sealed until manually reset at the DSS panel.
B.
DIVERSITY
' Hardware /comt
'nt diversity is required for all diverse scram system (DSS) equipment fron, sensor outputs to, and including, the components.used to interrupt control rod power. The use of circuit breakers from different manufacturers is not, by itself, sufficient to provide the required diversity
. for interruption of control rod power. The DSS sensors are not required to be diverse from the RTS sensors.
However, separate sensors are preferred to prevent interconnections between the DSS and the existing reactor protection system (RPS or RTS).
Th'e ANO-2 DSS design consists of four non-safety-related instrument channels, each of which_provides an input to four, separate, two-out-of-four, energize-to-acutate logic matrices. The output of each logic is used to open oneofthetwoRPSmotor-generator (MG)setoutputcontactors.
Both contactors must open to remove power from the control elemont assemblies (CEA), causing a reactor scram. The instrument channels consist of sensors, bistables, bistable relays, and actuation relays.
The sensors used in the DSS are separate from the existing RPS pressure L
transmitters. They do, however, share existing pressure sensing lines through i.
instrument valves. The DSS transmitter circuits are completely independent I
from the existing RPS instrument loops. Additionally, the DSS transmitters are' qualified for. Class 1E app 1_ication and are Seismic Category 1 in design.
This sensor design exceeds the requirements of the ATWS Rule.
The ANO-2 DSS design does not specifically use-bistebles or bistable relays in
.its design. The functions are performed by the Foxboro Spec. 200 Micro Control Module.
For this function, the RPS uses bistables manufactured by Gould and Electro-Mechanics and bistable relays manufactured by Electro-Mechanics. The DSS actuation devices are Foxboro output relay modules l
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' (Revised) dnd MG set trip relays, which open the MG set output load contactors. The actuation devices are powered from a non-Class 1E instrument AC-power panel.
The parallel device in the RPS is a mechanical circuit breaker powered by a Class 1E vital bus.
Based on the above, the staff concludes that the level of hardware / component diversity provided between the DSS circuits and the existing RPS circuits at ANO-2 is sufficient to comply with the requirements of 10 CFR 50.62 (the ATWS RJe)andis,therefore, acceptable, C.
DSS ELECTRICAL INDEPENDENCE / POWER SUPPLIES The purpose of the electrical independence requirements of the ATWS Rule is to prevent interconnections between the DSS and RPS (thereby reducing-the potential for CMFs that could affect both systern) and to ensure that faults within DSS _ circuits cannot degrade the RPS. Electrical independence of DSS circuits from RPS circuits should be maintained from sensor outputs up to the final actuation devices. The use of a common power source for the DSS and RPS sensors is acceptable because, in accordance with the ATWS Rule, the sensors
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can be shared between these two systems; The DSS at ANO-2 receives power from two, separate, non-Class 1E' instrument AC power. sources, each of which feeds one Foxboro multi-nest power supply-which-is
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- operated in parallel with the other multi-nest power supply. Each power-t
- supply contains the capacity to supply all DSS cabinet loads. These power j.
supplies 'are provided with 24 VDC' batt' ry back-up inputs from an UPS.- The UPS e
for each power supply consists of a Power Conversion Products-battery charger-
- and a Johnson Controls battery set.
In addition to power i
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