05000263/LER-1977-030

LER 77-30:on 771010,discovered Leak from B RHR Loop Relief Valve 2005 2 Boss Connection.Caused by Excess Cyclic Moment Induced by Unrestrained Vibration During Shutdown Cooling Operation.Relief Restraint installed.W/771109 Ltr

ML20056B860
Person / Time
Site:	Monticello
Issue date:	11/09/1977
From:	Mayer L, Tilly D NORTHERN STATES POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
LER-77-30, NUDOCS 9102130500
Download: ML20056B860 (2)

LER-2077-030,

Event date:
Report date:
2632077030R00 - NRC Website

text

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LICENSEE EVENT REPORT ]

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1 6 LtCENSE NuveER E DE

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7 89 14 15 tvtNT DATE RfP0nY CATE

'IP T S$a$ DoCari NuusER l 015 l 0 l-l 0 l 216 l3 l l1 l 0l1 l0 l 7 l747] 75 l1l1l 0l 9l7 l780l CAY 1GDRV

@ CONT 7 8 S7 I I58I U59 Lt_J 60 61 68 69 l f

EVENT DESCRIPTION E8 l Durinst shutdown cooling operation discovered leak from B RHR loop relief valve 2005l 80 7 89

@ l 2" boss connection. Further inspection revealed crack in RHR line at point of boss60l ,

7 89

!. $ l connection. Crack did not affect operability of system. One previous similar re-80l 7 89 EE l portable occurrence (A0 75-22). 2" boss and crack ground out and replaced with 3" l l gg 7 89 BG l u,iani o,- ana anon reauc e r. netter valve rest raint installed. (M-RO-77-30) l SUPPL R uA R votATow '

DE CODf couPoNENT CODE 3E l ClF l d 7 89 10 11 lP lI l P] EjX jX l 12 17 W 43 44 lZ l9 l 9l 9l 47

[NJ 48 l CAUSE DESCAIPTION UE lThe branch connection to RV 2005 failed due to excess cyclic moment induced by theggl 7 89 32 l unrestrained vibration during shutdown cooling operation. 2" boss and crack ground l gg ,

7 89 UE l out and replaced with 3" weldolet and 3"x2" reducer. The relief restraint insta11ep,  ;

7 89 METHOD OF

• ACUTv

% POWER OTHER STATUS DISCOVERY DISCOVERY DESCR* TON STATUS 1

7 8 d

9 l0 l 0l 0l l NA 10 12 13 l

44 W45 l KA 46 80 l l FDRu OF RE E$5[o OF REL ASE AMDuNT OF Activity LoCATON DF RELEASE BE LzJ trJ l NA I I NA l .

7 8 9 10 11 44 45 80 FEASONNEL EXPOSURES NuusEn TvPE DESCRATON DE l 0l0 l 0 l12[

7 89 11 l NA 13 _ eO l ,

PEASONNEL INJUA ES NUMBE R DESCRjpTON DE l0 l0 l 0 l l NA l 7 89 11 12 80

.j OFFSITE CONSEQUENCES lis l NA l 7 89 .

80 i

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LOSS OR DAMAGE TO FACILITY i vPE DESCRsPTON '

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7 89 10 PUBLICITY j 3 DE l NA -'

gg 7 89 ADDITIONAL FACTORS 18 l (cause Description Cont'd) ]!elief valve connection on A loop inspected and found l .

7 89 80 l ' satisfactory. l

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w NAME: D D Tilly 9102130500 772109 CF e ~g.612/295-5151 .. ......T .

ADOCK 05000263 '

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i NORTHERN STATES POWER COMPANY l u ~ ~ capou s, u s w u c sotA ss4os

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November 9, 1977 -

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Mr J G Keppler, Director, Region III Office of Inspection 6 Enforcement 6 -

' N , j "y U S Nuclear Regulatory Cor:nission ,

, 799 Roosevelt Road Glen Ellyn, IL 60137

Dear Mr Keppler:

MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Crack in B Loop LPCI Relief Valve Line The Licensee Event Report for this occurrence is reproduced on the back of this letter. Enclosed are three copies.

Yours very truly, s

L 0 Mayer, PE Manager of Nuclear Support Services LQ4/MHV/deh cc: Director, IE, USNRC (30)

Director, MIPC, USNRC (3)

G Charnoff MPCA Attn: J W Ferman f!OV 141977 "r '

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