05000237/LER-1976-053, Updated LER 76-053/01T-1:on 760803,util Advised by GE That MAPLHGR Limits in Effect No Longer Considered Sufficiently Conservative at Low Core Flow Rates.Problem Thought to Be ECCS Models Used to Determine Rates

Updated LER 76-053/01T-1:on 760803,util Advised by GE That MAPLHGR Limits in Effect No Longer Considered Sufficiently Conservative at Low Core Flow Rates.Problem Thought to Be ECCS Models Used to Determine Rates

ML20083R502
Person / Time
Site:	Dresden
Issue date:	01/03/1977
From:	Dolter J, Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
77-2, LER-76-053-01T, LER-76-53-1T, NUDOCS 8304040295
Download: ML20083R502 (4)

LER-2076-053, Updated LER 76-053/01T-1:on 760803,util Advised by GE That MAPLHGR Limits in Effect No Longer Considered Sufficiently Conservative at Low Core Flow Rates.Problem Thought to Be ECCS Models Used to Determine Rates

Event date:
Report date:
2372076053R00 - NRC Website

text

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Update Report I

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x LICENSEE EVENT PgORT Previous Report Date: 8/17/c CONTROL DLUCK:( l l l l l l ULIACE PRINT ALL REQU: RED INFCRMATION) 1 0 t E L'ctNSE NtNDER YPE YPE

{ ll lL lD l Rl Sl 2l 7 U9 14 l 0l 0l-l0 l 0 l 0 l 0 l 0l-l 0l 0l l4 l1 l1 l1 ll l l0 l1 l 15 25 PS 30 31 32 CATEC04f T7P 5 COCrET NUMDER FVENT CATE REPORT CATF 01 CON 7 l l l 7 8 57 68 lTl 59 W60 l 0l 5l 0l-l 0l21317 l 61 60 l 0 l 8 l 0 l 317 l6 l 69 74 l0 75 l1 lo l317 l 7l 00 EVENT DESCRPTION gg l Formal notification was received on 8/3/76 from General Electric company advising l 7 09 eo Ql that, in light of low-flow ECCS analyses that had been recently conducted, the 1 7 89 90 Q l maximum average planar linear heat generation rate (MAPLUGR) limits then in effect l 7 00 60

@ l could no lonner he considered sufficiently conservative at low core' flow rates. l 7 89 00 gl General Electric recommended that the MAPLHGR limits be reduced by 5% for core j

'SS" '^C SOY COMPONENT COOE M C A VOLATON ME [Rl Cl @j lZ lZ lZ l Zl Zl Zl l Zl lZ l9 l9 l9 l W 7 00 10 11 12 17 43 44 47 40 CAUSE DFSCn!PTION gg l Gcneral Elect ric considered the proble ; to be in the ECCS models used to determinc l 7 89 EO O

l the' MAPLHGR l imi t s at low core flow rates: acco rd i ng l y , theECCSanalysiswasreeval-)

7 00 LO

$l ua t hd . a rni t h e rasults were submitted to t hc_l!RC (ref. O.

7 UU Based on thn results nf l F AtiUT y 5fATUS  % POWER OTHER STATUS METHOD OF D;SCOVERY DISCOVERY DESCR;PTON (Continued) 8 7 0 9 (t_j 10 10l 9l 7l l 12 13_

NA 44 l [Dj 45

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46 NA l 80 LEAS OF F LF SE AMOUNT OF ACTivrTV LOCATCN OF RELEASE H Ld L7J l na l I nA I 7 U D 10 11 44 45 80 PERSONNEL EXPOSUALS NoVDEH fyrF DESCAf CN H 10101 of LZJ l "A I 7 00 11 12 13 00 PERSONNEL INJun1FS NUMUER DE SC4.PT ON i 10101 01 I nA l 7 09 11 12 ag OffGITE CONSEQUENCES 39 l NA l

7 UU '

80 LOSS OR DAMAGE TO FACILITY TYPE OC SCthPT ON 8 I zj l "^ I 7 o0 10 00 PUDLICITY 8l 7 08 H^

_ l G304040295 770103 c5 ADDITIONAL FACTORS DR ADOCK 05000 1 l NA l

7 89 gg 8I 7 0D nA 80 i

NAME: J. M. Dolter pyggg; EXT. 443

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EVENT DE9CRIPTl0N (Continued)

' flew rates of 85% or less. Operating order no. 25-76 was issued to ensure prompt corrective action in the event MAPLHGR values rose to 95% of the limit during low core flow conditions. This was the first reported occurrence of this nature at Dresden. (50-237/1976-53)

CAUSE DESCRIPTION (Continued) this reevaluation, Commonwealth Edison has determined (with General Electric's concurrence) that no reduction in MAPLHGR limits is appropriate for either Dresden Unit 2 or 3 at low core flow rates (ref. 4). Conequently- the operating order restricting MAPLHGR values to 95% of the limit at core flow rates of 85% or less has been rescinded.

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ADililllSTRATIVE TROCEDURES Q.C.P. 15-52.2

/; (APPLi; DIX B) ( i- Revision 0 n/

Septernber 1974 s

) SUPPLEt!ENT TO DVR DVR !!0. .E FILE 00Ek

- STA UNIT. YEAR 1:0.

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PART I j TITLE CF EVLliT OCCURRED

?-3-?$ 04&O Ct2/?OF' DISCDVtD.'ED (f) GCCS f,NA LVSl5 R'/ GE. DATE T ittE liEA50:1 F OR SUPPLEtiEtiTAL REP 0ftT

(').r:l.? N.n +d A:s tmf Mrmas Ah s') h) n supt oa u nukoJ tv&f- i PART 2 l ACCEPTANCE BY STATIO!! REVIEW _(# .I . 4,5 ih new e y DATE w1 u ,7 l- 0 37 SUPPLEttEllTAL REPORT APPROVED . ;,_ f[ [.

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corhonwea:th Edison 7f' Dresden Nuctcar Power Station lj ~, n n, ll1 h(- ' .

Morris. ;ttinok 00150 N J'd Tetephone 815/942-2920 CBS Ltr. #77-2 January 3, 1977 Mr. James G. Keppler, Regional Director Directorate of Regulatory Operations - Region 111 U. S. Nuclear Regulatory Commission 799 RooseveIt Road Glen Ellyn, Illinois 60137

REFERENCES:

1) NRC Docket Nos. 50-237/249

2) Reportable Occurrence report no. 50-237/1976-53, dated August 17, 1976

3) Letter from A. J. Levine .(G.E.) to Z. R. Rosztocy (NRC)

- dated August 24, 1976

4) Letter from G. A. Abrell to D. L. Ziemann dated November 10, 1976 Enclosed please find an update report to Reportable Occurrence report number 50-237/1976-53 This report is being submitted to your office in accordance with the Dresden Nuclear Power Station Technical Specifications, Section 6.6.B.

m d' /

,jf'f9?his.'.

' B.' B. 'S tephenson i.v Station Superintendent Dresden Nuclear Power Station BBS:Jo Enclosure cc: Director of Inspection & Enforcement Director of Management Information & Program Control File /NRC J'

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