ML18018B222

LER 77-023-00 for Dresden Unit 2 Regarding Discovery of the 12% APRM Upscale Rod Block Trip Setting to Be at 12.5% for APRM Channel One

ML18018B222
Person / Time
Site:	Dresden
Issue date:	07/05/1977
From:	Stephenson B Commonwealth Edison Co
To:	James Keppler NRC/RGN-III
References
BBS Ltr. #77-600 LER 77-023-00
Download: ML18018B222 (8)

Text

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~e U.S. NUCLEAR REGULATORY Co)sisssISSION DOC~ET NUMBER NRC FORMi195 I2-76) WO

, r /go) '7 FILE NUMBER NRC DISTRIBUTION FQR PART 60 DOCKET MATERIAL FROM: DATE OF DOCUMENT TO:

Commonwealth Edison Company 7/5/77 Mr. James G. Keppler Morris, Illinois DATE RECEIVED B B, Stephenson 7/19/77 QNOTORIZED PROP INPUT FORM NUMBER OF COPIES RECEIVED ETTER RIGINAL

/UNCLASSIFIED COPY DESCRIPTION ENCLOSURE Licensee Event Report (RO 50-237/1977-23) on 6/5/77 concerning the 12% APRM upscale rod RFM0'lE block trip setting (refuel & start-up/hot Po Ng standby mode-TeS 3 '.C.1)

~ being at 12 '%

for APRM channel one. ~ . ~

Dresden Unit Ne, rdrs-pl~QVPm R JL 7/20/77 I+~ ( 1<<P ) (2-P)

NOTE: IF PERSONNEL EXPOSURE IS INVOLVED SEND DIRECTLY TO KHEGER/J. COLLINS L .C FOR ACTION/INFORMATION INTERNAL DISTRIBUTION T T EXTERNAL DISTRIBUTION CONTROL NUMBER 7 2010206 CRS 16 SENT AS AT B NRC FORM 196 I2-76)

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Commonw Edison Dresden Nuctea wer Station R.R. g1 Morris, illinois 60450 Telephone 815/942-2920 XO IS BBS LTR //77-600 JUL $ 9 1977

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Mr. James G. Keppler, Regional Director Directorate of Regulatory Operations Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 Enclosed please find Reportable Occurrence, Report //50-237/1977-23.

This report is being submitted to your office in accordance with the Dresden Nuclear Power Station Technical Specifications, Section 6.6.B.

tep enson Station Superintendent Dresden Nuclear Power Station BBStkc Enclosure cc: Director of Inspection il Enforcement Director of Management Information & Program Control File Copy/NRC 7720l0206

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LICENSEE EVENT REPORT CONTROL BLOCK: t'PLEASE PRINT ALL REQUIRED INFORMATION)

UCENSEE LICENSE EVENT NAME LICENSE NUMBEA TYPE TYPE

[gg I I D R S 2 0 0 0 0 0 0 0 0 4 I 1 1 1 ~03

~

7 89 14 15 25 26 30 31 32 REPOAT REPORT CATEGORY DOCKET NUMBER EVENT DATE REPORT OATS

~a~ corn 0 5 0 0 2 3 7 0 6 '0 57 7 0 7 015 7I 7 7 8 57 58 59 60 61 68 69 74 75 80 EVENT OESCRIPTION I

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7

~04 7

2 8 9 During routine start-up surveillance, 89 for

'89 block APRM trip setting (refuel channel one.

and The two remaining

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it was start-up/hot standby APRMS discovered that the mode-T.S.

in the trip 12% APRM 3.2.C.l) was system were operable, upscale rod at 12.5%

thuP 0 80 80 gg the LCO requiring one operable APRM rod block per trip system (T.S. section

~

3.2.C.l) 7 8 tOOI 9

was not violated and the event had little safety significance. This particular 7 8 9 SYSTEM CAUSE FAME COMPONENT COMPONENT (Continued)

[oa7] ~IB CODE CODE

~E I N B I COMPONENT CODE R o SUPPUER N G MANUFACTURER 0 8 0 N 7 8 9 10 11 12 17 44 47 CAUSE OESCRIPTION

[oas] The setpoint being found out of calibration was attributed to minor instrument drift.

7 8 9 IOOI APRM channel one was placed in bypass until the reactor mode switch was in run, at 80 which time the 12% rod block was no longer required. On June 7, 1977, the setpoint 80

~~10 7 89 FACAITY METHOD OF (Continued) 80 STATUS POWER OTHER STATUS DISCOVERY DISCOVERY DESCRIPTION P~g 7 8 9

~D ~oo o NA B Start-up Surveillance 10 12 13 44 45 46 80 FOAM OF ACTIVITY COATENT RELEASEO OF RELEASE AMOUNT OF ACTIVITY LOCATION OF AELEASE Q~g z z NA NA 7 8 9 10 11 44 45 80 PERSONNEL EXPOSURES 7 89 11 12 13 80 PEAS'ONNEL INJURIES DESCRIPTION NA 7 8 9 11 12 OFFSITE CONSEQUENCES Q~g NA 7 8 9 80 LOSS OR OAMAGE TO FACILITY 7 8 9 '0" PUBLICITY

[i>~]

7 89 AOOITIONAL FACTORS NA 7 89 80 7 89 80 NAME:

Thomas Rausch 432 PHONE:

OP 0 I II I ~ 6 II 7

e EVENT DESCRIPTION (Continued) setpoint drift . was 'ound to have occurred only once in the past two years of Unit 2/3 operation. (~>5O-237/1977-23)

CAUSE DESCRIPTION Continued) was returned to 11.5 +.5%. Based upon the very small setpoint error observed, and upon the infrequent nature of this occurrence, no further corrective action is deemed necessary.

RECEIYEO DOCUMEtlT PROCESSING UHI i 19'll JUL l8 phd l2 29