ML20154R580

Proposed Tech Spec Changes,Revising Measurement Range of Triaxial Acceleration Sensors in Seismic Monitoring Sys

ML20154R580
Person / Time
Site:	Byron
Issue date:	03/18/1986
From:	COMMONWEALTH EDISON CO.
To:
Shared Package
ML20154R577	List: ML20154R573 ML20154R580
References
1429K, NUDOCS 8603310090
Download: ML20154R580 (4)

Text

ATTACHMENT A PROPOSED CHANCE TO APPENDIX A 4

TECHNICAL SPECIFICATIONS OF FACILITY OPERATING LICENSE NPF-37 l

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Revised Page: 3/4 3-45 i l

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8603310090 860318 i PDR ADOCK 05000454 - 1 P PDR 1429K i

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TABLE 3.3-7 SEISMIC MONITORING INSTRUMENTATION MINIMUM MEASUREMENT INSTRUMENTS INSTRUMENTS AND SENSOR LOCATIONS ~ RANGE OPERABLE

1. Time - History Accelerographs.

a. Aux. Elect; Rm, OPA02J N.A. I

b. Byron River Screen House N.A. 1

2. Triaxial Peak Accelerographs

a. Cont./ Reactor Eq. Accumulators -2 g to +2 g 1

.b. Cont'./ Reactor piping -2 g to +2 g -- 1

-c. Aux. Bldg./ Cat. I piping -2 g to +2 g 1

3. Response-Spect' rum Analyzer

' Aux Elect Rm, OPA02J. None . 1

4. ' Triaxial Acceleration Sensors

a. Cont./10W - 377' g to +2 1

b. Cont /10W - 502' -2 to + g - 'l

c. Cont./10X - 426' -2 g +2 g 1

->" -2

~

d. Free Field /41 + 00E, 27 + 00N o 2g 1

e. Aux. Bldg./18N - 426' -

g to + 1

f. Byron River Screen. House 2 g to +2 g 1 d[ -l g to +1 g g -l g to +1 g

-l g to +1 g

-l g to +1 g

-l g to +1 g

-l g to +1 g .

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BYRON - UNITS 1 & 2 3/4 3-45 O

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ATTAC191ENT 5 l

REASONS FOR PROPOSED CHANGE i .

i This change is requested because the seismic instrumentation has been alarming with no indication of a seismic event. It has been determined that this problem is a result of the low alarm setpoint (0.023) being.only-

'j 1% of the full scale range (2.0g) of.the sensors. If the full scale range of the sensors is reduced while maintaining the same alarm setpoint of 0.02g, a larger signal will be required to reach the same. alarm setpoint.

i With the proposed change of the measurement range, the' seismic-monitoring system will still be capable of detecting a 0.02s event'as described in section 3.7.4.3 of the Byron /Braidwood FSAR. The system will still detect an operating basis earthquake (0.09g) and a safe shutdown earthquake (0.2g) as described in sections 2.5.2.6 and 2.5.2.7 of the FSAR.

Also, the seismic monitoring system will still meet the requirements of ANSI N18.5 and NRC Regulatory Guide 1.12.

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SIGNIFICANT HAZARDS CONSIDERATIONS .

1 Commonwealth Edison has evaluated this proposed amendment and i determined that it involves no significant hazards considerations. According l to 10 CFR 50.92(c), a proposed amendment to an operating license involves no - -

significant hazards considerations if operation of the facility in accordance with the proposed amendment would not: I (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 l accident previously evaluated; or j i

(3) Involve a significant reduction in.a margin of safety. '

This proposed amendment revises the measurement range of~ instruments I used to measure the acceleration of a seismic. event. These instruments do not perform any protective function. With~ respect to the first standard, the probability of accidents.previously evaluated is not'affected by a change to the measurement range of these monitoring instruments. Since

! .these instruments do not perform any protective function, the consequences of accidents previously evaluated remains the same.

The sole purpose of these instruments is to perform a monitoring function. Therefore, a revision to the range of these instruments will not create the possibility of a new or different kind of accident contemplated l by-the second standard.

With respect to the third standard, there is no margin of safety associated with these seismic monitoring instruments.

Based on the preceeding assessment, Commonwealth Edison believes this proposed amendment involves no significant hazards considerations.

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