ML20210C175

Proposed Tech Specs,Clarifying Table 3.3-9, Remote Shutdown Monitoring Instrumentation. Description & Justification for Proposed Change & NSHC Determination Encl

ML20210C175
Person / Time
Site:	Sequoyah
Issue date:	02/03/1987
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20210C151	List: ML20210C146 ML20210C175
References
NUDOCS 8702090336
Download: ML20210C175 (7)

Text

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TABLE 3.3-9 REMOTE SHUTDOWN HONITORING INSTRUMENTATION i

S, 2

'

• MINIMUM READ 0UT MEASUREMENT CHANNELS

=

l [ LOCATION RANGE OPERABLE .

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- 1. Source Range Nuclear Flux . NOTE 1 1 to 1 x 10 cps 1

! 2. Reactor Trip Breaker Indication' at trip switchgear OPEN-CLOSE 1/ trip breaker I/ lo6 P

3. Reactor Coolant Temperature - NOTE 1 0-650*F l g.

I

~

Hot Leg

4. Pressurizer Pressure NOTE 1 0-3000 psig 1 f o- too 9 j ,

5. Pressurizer Level NOTE 1 ,

0-525 '- 1 "R i' ) 6. Steam Generator Pressure NOTE 1 0-1200 psig 1/steamgeperator f 7. Steam Generator Level NOTE 2 or l

near Auxilary F. W. 0-100%

Pump 1/ steam generator ,

8. Full Length Control Rod Position Auxilary Instrument 1 insertion limit Limit Switches Room: Racks R41-44 On-off switch / rod

9. RHR Flow Rate NOTE 1 0-4500 gpa 1 i 10. RHR Temperature NOTE 1 50-400*F 1 o - <4 4 0 eyp w s f shw o,c a n.sk + E

- 11. Auxiliary Feedwater Flow Rate NOTE 1 0-200 ;;-  ?

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ENCLOSURE 2 PROPOSED TECHNICAL SPECIFICATION CHANGE SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS. 50-327, -328 (TVA SQN TS 79)

DESCRIPTION AND JUSTIFICATION FOR PROPOSED CLARIFICATION OF TABLE 3.3-9, REMOTE SHUTDOWN MONITORING INSTRUMENTATION 2

O

DESCRIPTION OF CHANGE This change revises Table 3.3-9, Remote Shutdown Monitoring Instrumentation, on page 3/4 3-51 of unit 1 technical specifications and page 3/4 3-52 of unit 2 technical specifications. The shown measurement range of the pressurizer level (item 5) is changed from 0-525 inch to 0-100 percent, and the shown measurement range of the auxiliary feedwater flow rate (item 11) is changed from 0-880 gpm to 0-440 gpm. The required number of minimum channels operable is clarified by changing the description given for the reactor coolant temperature-hot les (item 3) from 1 to 1/ loop and the description given for the auxiliary feedwater flow rate from 1 to 1/ steam generator.

REASON FOR CHANGE Sequoyah has reviewed the instrument ranges specified in the technical specification. This review identified the two discrepancies in the measurement ranges given in table 3.3-9.

The pressurizer level gauge in the auxiliary control room is calibrated to display percent full from 0 to 100 percent. While the measurement range presently shown in table 3.3-9, 0-525 inches, is used to calibrate the pressurizer level transmitter for a cold system, the pressurizer level gauge of the remote shutdown monitoring instrumentation displays units of percent full. Changing the measurement range to that actually displayed in the auxiliary control room will preclude any possible operator confusion.

The other measurement range discrepancy is the range shown for the auxiliary feedwater flow rate. Each nuclear unit at Sequoyah has two motor-driven auxiliary feedwater pumps (MDAFWP) with a capacity of 440 gpm each and one turbine driven auxiliary feedwater pump (TDAFWP) with a 880 gpm capacity.

This pumping capacity corresponds to 440 gpm of auxiliary feedwater to each of the four steam generators (S/G) per unit. The 0-880 gpm measurement range given in table 3.3-9 is the range for the flow indicator on the discharge of the TDAFWP. Flow indicators on the auxiliary feedwater inlets to the S/G have a range of 0-440 gpm. Since the amount of auxiliary feedwater flow to each S/G is the important parameter, the given measurement range should reflect the 0-440 gpm range of the feedwater inlet indicators. The related surveillance instructions which have been used to satisfy this surveillance requirement calibrate the 0-440 gpm flow indicators. The current range shown is not appropriate.

The two remaining changes which are in the " Minimum Channels Operable" column of table 3.3-9 are for clarification purposes only. These changes will explicitly show what has been assumed in past interpretations.

JUSTIFICATION FOR CHANGE Changing the pressurizer level measurement range from 0-525 inch to 0-100 percent will have no adverse ramifications on nuclear safety. It does not affect the method of calibration for the pressurizer level indicator; however, it will enhance the clarity of table 3.3-9 by establishing a consistency between the units shown on the table and the units shown on the level gauge.

Changing the auxiliary feedwater flow rate range which is indicated in the table from 0-880 gpm to 0-440 gpm will also have no adverse ramifications on nuclear safety. The 0-880 spm is only appropriate for measuring the discharge from the TDAFWP. The parameter which is important'~to nuclear safety is the amount of feedwater flowing into the S/G. The flow indicators for this parameter have a range of 0-440 gpm. The measurement range shown on this table should be appropriate for the flow instrumentation on the auxiliary feedwater inlet to the S/G.

The two changes in the descriptions for the number of minimum channels operable are only editorial in nature and explicitly state previous interpretations. Reactor coolant temperature-hot leg (item 3 in table 3.3-9) has an indicator for each of the four primary loop's. As appropriate, the number of minimum channels has always been interpreted as 1/ loop; however, this was not explicitly shown in table 3.3-9. Since it is important that the temperature in each hot leg is indicated, this requirement should be clearly stated. Likewise, the minimum channels operable for the auxiliary feedwater flow rate (item 11 of table 3.3-9) has always been interpreted as 1 per S/G.

These changes do not alter the intent or the historical interpretation of table 3.3-9 and are justified by the resulting clarity enhancement.

e.

ENCLOSURE 3 PROPOSED TECHNICAL SPECIFICATION CHANGE j SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS. 50-327, -328 (TVA SQN TS 79)

DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATIONS FOR PROPOSED CLARIFICATION OF TABLE 3.3-9, REMOTE SHUTDOWN MONITORING INSTRUMENTATION m.

SIGNIFICANT HAZARDS EVALUATION

1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

No. The proposed amendment only clarifies table 3.3-9 and it does not alter the operation of the plant. The pressurizer level measurement range shown in the table is revised to establish consistency with the units shown on the pressurizer level gauge. The auxiliary feedwater flow measurement range shown in the table is revised to establish consistency with the auxiliary feedwater flow range to each of the steam generators.

The two changes under the " Minimum Channels Operable" column are editorial and explicitly state previously accepted interpretations.

2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

No. The proposed amendment is basically editorial and it is requested for clarification purposes. The plant design is not affected.

3. Does the proposed amendment involve a significant reduction in a margin of safety?

No. The proposed amendment can only enhance ' safety since it reduces the probability of misinterpretation or confusion.

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