ML20058A138
| ML20058A138 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 10/12/1990 |
| From: | ROCHESTER GAS & ELECTRIC CORP. |
| To: | |
| Shared Package | |
| ML17262A198 | List: |
| References | |
| NUDOCS 9010250295 | |
| Download: ML20058A138 (8) | |
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l ATTACIONNT A i
Revise the Technical Specification pages as follows:
I Remove Insert 3.5-6 3.5-6 i
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9010250295 901oj2 i
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TABLE 3.5-1 (CONTINUED)
PROTECTION SYSTEM INsTMUMENTATION 1
2 3
4 5
6 OPERATOR ACTION H)TAL NO. of MIN.
PERMISSIBLE IF CONDITIONS OF CHANNEL NO. of CHANNELS OPERABLE BYPASS COLUMN 1 OR 3 OPERABLE NO. FUNCTIONAL UNIT CFANNELS TO TRIP CHANNELS CONDITIONS CANNOT BE MET ABOVE 11.
2 2
5 50% Power 12.
Deleted 13.
Lo Lo Steam 3/ loop 2/ loop 2/ loop 5
Hot Shutdown Generator Water Level 14.
Undervoltage 4 KV 2/ bus 1/ bus 2/ bus 6
5% Power Bus (both busses)
(on either bus) b
'E 15.
Underfrequency 4 KV 2/ bus 1/ bus 2/ bus 6
5% Power Bus (both busses)
(on either bus) 16.
Quadrant power tilt 1
NA 1
Log individual Hot Shutdown upper & lower monitor (upper &
ion chamber lower ex-core currents once/hr neutron detectors)
& af ter a load change of 10% or after 48 steps of control rod motion 7eaa
- m. missus
ATTACIDENT B The Analog Steam Generator Fcedwater Control System is being replaced with a Digital Foodwater Control System.
The digital system uses throo steam generator (SG) narrow range level signals vs. one used by the analog system.
The three narrow rango SG level signals are processed by the computer and the computer rejects any signal that is faulty.
The software that does this processing is referred to as the "Modian Signal Selector" (MSS).
The MSS is described in more detail in Attachment C (WCAP-12347).
The MSS design and sof tware is the same as installed in Prairic Island (WCAP-11931).
Attachment D summarizes the differences between WCAP-12347 and WCAP-11931.
As stated in the attached WCAP the only purpose of the low feedwater flow reactor trip (steam flow /fcod flow mismatch reactor trip) is to satisfy the requiromonts of IEEE-279-1971 paragraph 4.7.3.
Since the digital feedwater controller uses three level signals to the MSS vs. one in the existing analog system, there is no single random failure that can generate a condition requiring protective action.
Thereforo, the requirements of IEEE-279-1971 are satisfied without the steam flow /fcod flow mismatch reactor trip.
Also, no credit is taken for steam flow /fcod flow mismatch reactor trip in any UFSAR Chapter 15 accident analysis.
No limiting conditions of operation are required if the MSS should f ail because failuro of the MSS would not preclude protectivo action on SG level.
Also, f ailure would be annunciated and the foodwater control would be switched to the backup computer.
Failuro of the backup computer woub_ also be required before the system transferred to manual. This is similar to the current, less redundant system where one f ailure could require control to be transferred to manual.
Software of the MSS is verified prior to use and administrative procedures control any softwarc modifications.
In accordance with 10CFR50.91, this change to the Technical Specifications as specified on Tabic 1 has been evaluated to determine if the operation of the facility in accordance with the 1
proposed Amendment would:
1.
Involve a
significant increase in the probability or consequences of an accident previously evaluated; or 2.
Create the possibility of a new or different kind of accident from any accident previously evaluated; or 3.
Involvo a significant reduction in a margin of safety.
Removing the steam flow /fcod flow mismatch reactor trip does not increase the probability of an accident previously cvaluated because the trip does not cause an accident; therefore, the trip can not offect' the probability of an accident. The consequences are not of fected because no credit is taken for the trip when the accidents are evaluated.
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h Removal cf th3 Ctcam flow / ford flow micantch trip do30 n3t croat3' the - possibility of 'a new or. dif ferent kind.of accident ' than-previously evaluated.because the trip can not create an accident.
The' circuitry can only create an-inadvertent trip which is bounded
'r by a required trip or failure to' trip which is. acceptable because-no credit is taken for the trip in accident evaluation.
Removal of the trip does not reduce the margin of safety because no:
credit is taken-for the trip in the UFSAR Chapter 15 accident
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Detailed Techn$ cal specification chances 1
~ Description of Change Reason For Change '
Location 1
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- Page.'3.5-6~ item 12
. Item 12 has been deleted Removal-of the' i
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and the word. DELETED in-steam flow / feed j
serted-flow reactor trip y-3 4
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A'PFACHNENT C WCAP-12347
" Advanced Digital Feedwater Control System Median Signal Selector for R.E. Ginna"
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ATTACHMENT D
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Westinghouse Energy Systems ex m Electric Corporation remwenena mao em RGE-90-606 August 16, 1990 5
Mr. R. Baker Rochester Gas & Electric Corporation 49 East Avenue Rochester, NY 14649 ROCHESTER GAS & ELECTRIC CORPORATION R E GINNA STATION RG&E P.O. NO. NQ 11641 B RD/(W)G.0. NO. SY 00026 NRC Action item Resoonse
Dear Mr. Baker:
following a presentation to the NRC ey representatives of RG&E and I.
Westinghouse on July 24, 1990, on the Ginna Advanced Digital Feedwater Control System (ADFCS) program, an action was defined for Westinghouse to provide the NRC with a summary of the differences between the WCAPs j
i on the ADFCS Median Signal Selector (MSS) for the Prairie Island units and Ginna (WCAPs 11931 and 12347, respectively).
WCAP 11931 was submitted to the NRC in the Fall of 1988 as part of the licensing documentation for the Prairie Island ADFCS program.
The MSS design and the actual MSS software is the same for both the Prairie Island units and Ginna.
Furthermore, the MSS implementation in the respective ADFCSs as described in the WCAP documents is the same.
The following is a summary of the differences between the respective documents to assist the NRC in their review of WCAP-12347 for Ginna.
l The Median Signal Selector (MSS) is used in both the Prairie Island and l
Ginna ADFCS designs on the three narrow rangs steam generator level inputs per loop to justify elimination of the Low Feedwater flow (i.e.,
low steam generator level coincident with steam flow >feedwater flow) reactor trip function in addition to enhancing fault tolerance to input signal f ailures.
WCAPs 11931 and 12347 are very similar and include descriptions of 1) the basis for the diverse trip function,
- 2) MSS Iv $, testing, and implementation,
- 3) justification of elimination of the Low Peedwater Flow trip based on MSS operation and 4) reliability 4
of the ADFCS hardware / software system.
Use of the MSS to justify Low Feedwater flow trip elimination is the same for both Prairie Island and i
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Ginna ADFCS designs.
Changes incorporated in WCAP-12347 are minor and l
were made to
- 1) include editorial revisions and delete unnecessary
- text,
- 2) add detail to some sections, and 3) respecify bracketing of some text.
The more significant of these are described further, below.
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o Mr. Baker 2
RGE-90-606 August 16, 1990 1
Editorial Revisions (1):
Section 1.2 in WCAP-11931 has been relocated to Section 2.3 in WCAP 12347.
Section 3.1 in WCAP 11931 which describes protection logic for plants with four narrow range level channels per loop has been deleted.
Additional Text (2):
A Section 4.4 has been added to describe the capabilities of the ADFCS to withstand input channel overrange conditions.
Subsections 6.2.1 and 6.2.2 have been added to describe the MSS Configuration Certification process.
I..
Bracketing (3):
The bracketing of proprietary information throughout the text has been
- revised, in most cases, this was done to eliminate the bracketing on some text that was protected in WCAP-11931.
Other changes have been made to include clarification, revisions in terminology, and simplifications in specific sections of text.
l-Please contact Mr. J. Pepka or myself if you have any questions.
Very truly yours, WESTINGHOUSE ELECTRIC CORPORATION J
F. Hofscher Project Engineer New York Area
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~R. Eliaszi Dc1.ewis"(W)
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