ML20244E480

Proposed Tech Specs Providing Alternate Method for Determining Position of Nonindicating Rod Described in Action a.1 of Tech Spec 3.1.3.2, Position Indication Sys - Operating

ML20244E480
Person / Time
Site:	Sequoyah
Issue date:	06/16/1989
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20244E478	List: ML20244E476 ML20244E480
References
NUDOCS 8906200363
Download: ML20244E480 (8)

Text

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ENCLOSURE 1 PROPOSED TECHNICAL SPECIFICATION CEANGE in S2QUOYAH NUCLEAR PLANT UNIT.1 DOCKET NO. 50-327 (TVA-SQN-TS-89-31)

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LIST OF AFFECTED PAGES Unit 1 3/4 1-17 I

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REACTIVITY CONTRCL SYSTEMS N

P0,SITION INDICATION SYSTEMS - OPERATING j

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3.1,3.2 The shutdown and control rod posid on indication system end the derrand position indication system shall be OPERABLE and capabie of determining

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the control rod positio6s with h + 12 steps.

e APPLICABILITY: MODES 1 and 2.

SION:

With i maximum of ew rrd position indicator per bank inoperable a.

either:

I 1.

Determine the position of trie non-inoic.ating rod (s) indirectly by the movable incore detectors at least oncts per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and immediately after any motion of the non-inaicating rcd which exceeds 24 steps in one direction since the last determination of the rod's positica, or 2.

Reouce THERMAL POWER to less than 50% of RATED THERMAL POWER F$

within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

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With a maximum of cne deinand position indicater per bank inope able either:

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Verify that all rod position indicators for the affected bank f

are OPERABLE and that the most withdrgwn rod and the least withdrawn rod of the bant are within a maximum of 12 steps of each.other at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, or 2.

Reduce THERMAL MVER to less than 50% of RATED THERMAL POWER within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

9 SURVEILLANCE REQUIREMENTS

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4.1.3.2 Each rod position indicator shall be determined to be OPERABl.E by verifying that the demand position indication system and the red position indication system agree within 12 steos at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> except l

during time intervals when the Rod Position Deviction Monitor is inoperable, then compare the demand position indication system and the rod position inoica-tion system at least once per 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

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INSERT FOR ACTION a.1 o

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Initial,1yld5termine the position of the non-indicating red (s) indirectly.

..by.the moveable'.incore. detectors and;>at'least'once every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereaf ter, verify by alternate Leethods that the non-indicating' rod (s)

'have'not. moved.

If:there is' indication-that the subject rod (i) m y have moved,3 thenlimmediately;initiste action te determine the new position (by

' the moveable incore detectors),of any non-indicating rod (s).that have

' moved since the last' determination of,the rod (s) position.

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'T!w provicious of 3.0.4'are not app 1! cable-for Action a.1 for the remainder of Unit 1 Cycle 4.

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' ENCLOSURE 2" lp o.,

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-PROPOSED TECR'TICAL' SPECIFICATION CHANGE' g.

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SEQUOYAH NUCLEAR' PLANT UNIT l.

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' DOCKET NO. 50-327 s

.'(TVA SQN-TG-89 -31) ~

DESCRIPTION AND JUSTIFICATION FOR o

CHANGING THE METHOD OF M6NITORING THE POSITION' b,;,

FOR FULL-LENGTH, SHUTDOWN ROD (S)'WITH IWOPERABLE ROD POSITION INDICATORS e

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ENCLOSURE 8 Description of thsnge Tennensde Vallef Authority proposes to modify the Sequoyah Nucicar Plant (SQN) Unit 1 technical specification (TS) to revise Specification 3.1.3.2, "Positien Indication Systems - Operating." The proposed change pro' rides an alternative method of determining rod position. The proposed change will be applicable for the remainder of Unit 1 Cycle 4 and will af fect only the shutdown rois. An exemption from Specification 3 0.4 for this change is also requested.

Reason, fter Change SQN Unit 1 E-13 (shutdown bank D) rod position indicator (RPI) has been declattd inoperabl.e becaase of voltage fluctuations in the anatog RPI instrumentation channef.. Action a.1 of Specification 3.1.3.2 currently requires determination of thn position of the nenindicating rod indirectly by the aoveable incore detectors at least once every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> while the RPI is inopercble. Use of the incore monitoring system to comply with this action would increase the use of the incore detector system from once each month to 90 times each month, significantly increasing the wear on the associated thimble tubes.

TVA believes that this increased use of the incore detector system and the resulting wear on the thimble tubes are nonconcervative with respect to the concerns similar to those identified in NRC Bulletin 88-09, "ThiAble Tube Thinning in Westinghouse Reectors."

Justification for Change As described in tr.a bases for Specification 3.1.3, the purpose of the full-length control rod system, of which the RPIs are an integyn1 part, is to ensure that: "(1) acceptable power distribution limits are mainthined, (2) the minimum SHUTDOWN MARGIM is maintained, tud (I) 11mit the potenti&1 sffects of rod misalignment on associated occident analyses. OPERABILITY of the control rod position indicatofs is required to determine control rod positions and thereby ensure compliance with the control rod alignment i

and insertion limits."

i TVA has determintd that these objectivas can be met with an inoperable RPI in a shutdown bank without subjecting the incore thimble tubes to unnecessary additional wear. TVA will install a strip chart recorder to track the output voltage of the stationery grfpoer coil on the nonindienting rod (s) and verify at least once every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> that the a,11 has not changed state.

This 8-hour surveillance period is consistent with the current operational requirements for position determination-If the coil has changed state, a determination of the sonindicating rod (s) position will be made by way of Surveillance Instruction (SI) 213, "Non-Indicating Rod Position Determination." If a better method of determining possible rod motion is identified. TVA will advise the NRC and Nuclear Safety Review Board of any intention to deviate from the method

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described above.

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At least once every 31 days, a full-core flux map will be pert'ormed, and SI-213 will be performed for any nonindicating rod (s) in conjunction with SI-11. " Reactivity Control Systems Moveable Control Assemblies," to i

determine operability of the full-length control rods as required by l

Surveillance Requirement 4.1.3.1.2.

Thosa periodic survenilances will provide additional assurance that the nonindicating rod (s) is in the i

expected positien.

f Ia sununary. TVA believes that the proposed change will ensure the inten!.

of Specification 3.1.3.2 is met for the remainder of Unit 1 Cycle 4 and will also minimize the potential for concerns similar to those identified in NRC Bulletin 88-09 with thimble tube wall thinning.

Environmental Impact Evaluation The proposed change request does not involve an 2nreviewe-d enviremental question because operation of SQN Unit 1 in accordar.cs with this change would not:

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Result in a significant increkse in any adverse environmental impact previously evaluated in the Final Enviranmerttel Statement (FES) as modified by the Staff's testimony to the Atomic Safety and 1.iccnsing Doerd, supplements to the FES, Environmental Impact Appraisals, or in any decisions of the Atomic Safety and Licensing Beard.

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Result in a significant change in effluents or power levels.

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liesult in matters not previonely reviewed in the licensing basis for SQN that may have a significant environmental impact.

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- o ENCLOSURE 3 PROPOSED TECHNICAL SPECIFICATION CHANGE l

.1 SEQUOYAH NUCLEAR TIANT UNIT ?

DCCKET NO. 50-327 (TVA-SQN-TS-89-31)

. DETERM M TION OF NO SIGNIFICANT tIA1ARDS CONSIDERATIONS I

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Lyo ENCLOSURE 3 M""

Significant Hazards Evaluation

~TVA has evaluated t'he proposed TS' change and has determined that it does 4

not represent'a significant hazards consideration based on criteria established inL10 CFR 50.92(c). Operation of SQN in accordance with the proposed amendment will not:

(1) Increase the probability or consequences cf any previously evaluated accident. The proposed change to the SQN Unit 1 TS is'to provide an alternative method for verifying shutdown rod position in the event the associated RPI becomes inoperable..The proposed change meets the intent of th'e current specification in that it ensures verification of position'of the shutdown rod (s) once every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The proposed change provides only an alternative method of monitoring shutdown rod position and does not change the assumption or results of any previously evaluated' accident. Therefore, the proposed change will not increase the probability or consequences of any previously evaluated accident.

(2) CrcSte the possibility of a new or different kind of accident from any previously analyzed.- As described above, the proposed change provides only an alternative method of determining shutdown rod (s) position. The proposed change does not affect the reactor protection system or the full-length rod control system. Therefore, the prc?osed change does not create the possibility-ofta new or different kind of accident from any previously analyzed.

(3) Involve a significant reduction in a margin of safety. The bases of Specification 3.1.3.2 state that the operability of the control RPIs is required to determine control rod positions and thereby ensure compliance with the control rod alignment and insertion limits. The proposed change does not alter the requirement to determine rod position but provides an alternative method for determining the position of the affected rod (s). Therefore, the proposed change does not reduce the margin of safety.

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