ML20024A345

LER 83-018/03L-0:on 830506,reactor Protection Sys Channel a, Low Steam Generator Pressure Bypass Removal Setpoints Found Out of Spec.Caused by Instrument Drift Due to High Sensitivity to Changes in Input resistance.W/830602 Ltr

ML20024A345
Person / Time
Site:	Millstone
Issue date:	06/02/1983
From:	Deslandes K, Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
LER-83-018-03L, MP-5088, NUDOCS 8306170042
Download: ML20024A345 (2)

Text

r NRC F ORM 366 U. S. NUCLEAD HEGULATO2Y COMMf S$10N LICENSEE EVENT REPORT CONTROL BLOCK: l 1

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(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

R lClTlMlNISI2l@15l 7 8 9 LICENSEE CODE 14 0101 -l O l LICENSE 0 l 01010 NUMBER l- 1010 l@l 4lLICENSE 25 26 ll ll TYPE ll 1l@lJO l

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CON'T Lo_Lt.J V E C l Li@l 60 0l 635 l 0 l 0DOCKET  ! 0 NUMBER l 3 i 316 l@l 88 0

89 l 510 l 6 l 813 74l@l7b016REPORT EVENT DATg l 0lQATE2l 81380l@

EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l During a monthly surveillance test, the Reactor Protection System Channel A, Low I o 3 l Steam Generator Pressure Bypass removal setpoints were found to be out of specifica- l m l tion in a non-conservative direction. The bistable setpoints were immediately l pgTsl I adjusted in accordance with Technical Specifications 2.2.1, Table 2.2.1, Item 7, I ioisl l Note 2 and operation continued. There were no consequences of this event because the l FT l I setpoints were found to be correct in the previous monthly check and there were no l o 3 i operations requiring bistable functioning (auto bypass removal). l DE CO E SU8C E COMPONENT CODE SUS DE S E 8 I I I A l@ [,B_J@ LA_J @ l Il N I S l T l R l U l@ [J_j@ [Lj @

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33 34 3b 36 40 42 43 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i O l The cause of the high setpoints was instrument shift caused by high sensitivity to l 3 i l changes in input resistance, a condition that will be resolved by the future planned I

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gl replacement of the auctioneered input bistable trip units. The bistable card is a l lgl Gulf General Atomic, model NT-4. Previous occurrences: LER 75-36, 12/14/75; I l

gl LER 80-16, 5/1/80; and LER 82-15,6/11/82. 80 1

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Keith . Deslandes ,ggy, w-lm p WO g NAVE OF PREPARER

NORTHEAST UTII.ITIES

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S,u w mc<m.m P O BOX 270 HARTFORD, CONNECTICUT 06101 en e n u, a n m.ow" (203) 666-6911 k ' J C:=';l': =.l"r" June 2,1983 MP-5088 Dr. 'Ihmas E. Murley Regional Administrator, Region I U. S. Nuclear Regulatory Cmmission 631 Park Avenue King of Prussia, Pennsylvania 19406

Reference:

Facility Operating License No. DPR-65 Docket No. 50-336 Reportable Occurrence RO 50-336/83-18/3L-0

Dear Dr. Murley:

This letter forwards Licensee Event Report 83-18/3L-0 required to be sulnitted within thirty days pursuant to Millstone Unit 2 Appendix A Technical Specifications, Section 6.9.1.9.a, reactor protection syst s instrument settings found to be less conservative than those required in the Technical Specifications but which do not prevent the fulfillment of the functional requirements of the effected systs. An additional three copies of the report are enclosed. , ,

t Yours truly, NORIHEAST NUCLEAR ENEfE CCMPANY l

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! E J. Mroczka Station Superintendent l Millstone Nuclear Ptwer Station EJM/KDD:mo

Attachment:

LER RO 50-336/83-18/3L-0 l

l cc: Director, Office of Inspection and Enforcement, Washington, D. C. (30)

Director, Office of Maragment Information and Program Control, Washington, D. C. (3)

U. S. Nuclear Regulatory Cmmission, c/o Document Management Branch, Washington, D. C. 20555 l

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