ML20206T459
| ML20206T459 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 07/01/1986 |
| From: | Williams J TOLEDO EDISON CO. |
| To: | |
| Shared Package | |
| ML20206T455 | List: |
| References | |
| 1268, TAC-61937, NUDOCS 8607080137 | |
| Download: ML20206T459 (3) | |
Text
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Dscket No. 50-346 License No. NPF-3
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Serial No. 1268 June 30, 1986 APPLICATION FOR AMENDMENT TO FACILITY OPERATING LICENSE NO. NPF-3 FOR DAVIS-BESSE NUCLEAR POWER STATION UNIT NO. 1 Enclosed are forty-three (43) copies of the requested change to the Davis-Besse Nuclear Power Station Unit No. 1 Facility Operating License No. NPF-3. Also included are the Safety Evaluation and Significant Hazards Consideration.
The proposed change (submitted under cover letter Serial No.' 1268) affects:
Section 3/4.4, Reactor Coolant System, Limiting Condition for Operation, 3.4.1.2.
By Li 1A ~
e'nior'Vice Preside'ntf Nuclear Sworn and subscribed before me this 1st day of July, 1986.
hb Notary Public, State of Ohio My commission expires 5/18/91 pag 7Eu*'30$6 P
Dock:t No. 50-345 License No. NPF-3 Serial No. 1268
~
June 30, 1986 SAFETY EVALUATION This ameadment request is to. amend the Technical Specifications Section 3.4.1.2 to revise the reactor coolant system required subcooling margin during Modes 3, 4, and 5 from 10*F to 40*F.
1 Specifically addressed in _ the determination of a 40*F margin is an adequate subcooled margin at Reactor Coolant System (RCS) low range pressure, utilizing 1-0-500 psig pressure indicator PI-RC2A6 and the core exit thermocouples as monitored through the T-Sat Meter.
The safety function of Technical Specification 3.4.1.2 is to ensure.that means f
are provided to cool the decay heat from the reactor core during Modes 3, 4, and 5.
This is accomplished by maintaining proper subcooling margin in the system such that no steam voiding can occur given.all the uncertainties that may exist in the associated sensing instruments used to monitor the subcooling.
As directed per NRC letter, Log No. 1758 (attached) the adequacy of the current' subcooled margin has been reviewed and it is proposed to change the margin from 4
10*F to 40*F based on a calculation that estimates the instrument errors of the modules involved. The 40*F value is derived by considering (Based on calcul-ation C-HSA-64.00-001):
1.
All uncertainties associated with the electronic modules in sensing instrumentation.
2.
Errors are combined utilizing the square' roots of the sum of squares method of the individual components.
3.
No calibration errors are included.
1 4.
The following data' table shows a breakdown of the total temperature error associated with sensing instruments. As seen,Lan allowance l'
of 40*F is sufficient at all low range pressures to provide-adequate subcooling margin.
I
~
RCS Pressure Press.
Temp.
. Total (psig)
Error
, K*_
-Error Error 0
0.0 23.7 23.7 7
7.0 2.44 23.7 40.8 (240) 10 7.1 2.18' 23.7
.39.2 50 7.1 1.01 23.7 30.9 100 7.1
.65 23.7 28.32 150 7.1
.485 23.7 27.1 200 7.1
.394
- 23. 7.
.26.5' 250 7.1
.334 23.7
- 26.1 300 7.1
.294'
-23.7 25.8 i
350-7.1
.263 23.7 25.6-400 7.1
.238 123.7 25.4 500-7.1
.202 23.7.
25.1
. 2.
Docktt No. 50-346 License'No. NPF-3 Serial No. 1268 June 30, 1986
- K is a coefficient to account for the error in calculated saturation temperature due to the error in measured pressure 6T (K=gp).
The safety function of the Technical Specifications is not being degraded.
It is concluded that the change as proposed does not. constitute any-unreviewed safety question per the definition in 10 CFR 50.59.
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pus No A85-431B M
ong Nuctoar Licensing /
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UNITED STATES cc. R. P. Crouse g
NUCLEAR REGULATORY COMMISSION y $ Q, j
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WASHINGTON. D. C. 20555 L. A. Gorne
!4 C. T. Dctt O,
June 3, 1985 N Ecy.[.'efger I LRS Consultants Docket No. 50-346 Ea. Johnson A
SAR-Up RECEIVED SdeNL S. M. Quennoz Mr. Richard P. Crouse JUN 5 1985 M. t. stewart PR Vice President, Nuclear Toledo Edison Company TOLEDO EDISON G
A. staaiey Edison Plaza - Stop 712 300 Madison Avenue Toledo, Ohio 43652
Dear Mr. Crouse:
SUBJECT:
SUBC00 LING MARGIN IN TECHNICAL SPECIFICATION As part of the staff's review of Multiplant Action (MPA) number B-57, dealing with technical specifications for decay heat removal, we identified a possible nonconservatism in the standard technical specifications regarding the required subcooling margin that must be established when reactor coolant pumps are to be secured in modes 3, 4 and 5.
The required subcooling margin is stated to be 10 F.
However, when instrument uncertainties and elevation head effects are taken into account, this subcooling margin may not be sufficient to prevent flashing in the higher elevation of the hot legs and steam accumulation at the top of the hot leg U-bends with consequent interruption of natural circulation, the very condition the subcooling margin was designed to prevent.
You are therefore requested to evaluate the adequacy of the subcooling margin specified in Technical Specification 3.4.1.2 that must be established for natural circulation conditions, and ensure that a sufficient margin exists such that void formation is precluded when instrument error and elevation effects are accounted for.
If you conclude that the margin specified is inadequate, you should propose a revised subcooling margin which will ensure that void formation does not occur when decay heat removal is-through natural circulation only. Please confirm the adequacy of the specified subcooling margin or submit a proposed revision to your technical specifications no later than July 15, 1985.
Sincerely, o n F. Stolz, Chief rating Reactors Branc 4
Division of Licensing
/75/
u,g Numeer E Nocfm Engr. Lead cc: See next page 5il Staren toad C Nuc' ear Sendcas Lead O O A Lead C Other r,/jy,1ce-Dee Date fTo6t on3 i
-Rash-6
Dockst No 50-346 License No. NPF-3 Serial,No. 1268 June 30, 1986 SIGNIFICANT HAZARDS ~ CONSIDERATION Technical Specification 3.4.1.2 provides that a reactor coolant subcooling margin of 10*F must be maintained when reactor coolant pumps are secured in Modes 3, 4, and 5.
Subcooling margin is designed to prevent flashing in the higher elevations of the hot legs and the accumulation of steam at the top of the hot leg U-ben'ds consequently leading to interruption of natural circulation.
On June 3, 1985 the NRC requested (Log-No. 1758) that Toledo Edison verify the adequacy of the subcooling margin specified in Technical Specification 3.4.1.2.
This request.was based on the staff identification-of possible.nonconservatism in the Standard Technical Specification.
regarding the required subcooling margin that must be established when reactor coolant pumps are to be secured in Modes 3, 4, and 5.
Toledo Edison has reviewed the instrument uncertainties and determined that the'subcooling margin in Technical Specification.3.4.1.2 would be revised from 10*F to 40*F.
This change will ensure sufficient subcooling margin in the system such that void formation is precluded.
The granting of the request would not:
1)
Involve a significant increase in the probability or consequences of an accident previously evaluated (10CFR50.92(C)(1)).
The revised subcooling margin does not increase the probability or consequence of an accident previously evaluated,,but, rather, ensures that an adequate subcooling margin is maintained.
2)
Create the possibility of a new or different kind of accident from any accident previously evaluated (10CFR50.92(C)(2)).
The -revised subcooling margin does not create a new or different.
kind of accident from any accident previously evaluated, but, rather, ensures that an adequate subcooling margin ~ is maintained.
3)
Involve a significant reduction in a margin of safety (10CFR50.92(C)(3)).
The margin of safety is not reduced by this Technical Specification change, but, rather, is maintained by' ensuring an adequate subcooling margin.
On the basis of the above, Toledo Edison has determined that the amendment request does not involve a significant hazards: consideration.
_