ML20041B881

LER 82-008/03L-0:on 820121,LPCI Sys & RHR Svc Water Sys a Declared Inoperable Due to Piping Stress in Excess of Code Allowables.Cause Unknown.Snubber GBC-1-SS-56 & RHR Sys Valve Replaced

ML20041B881
Person / Time
Site:	Duane Arnold
Issue date:	02/19/1982
From:	Varner D IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20041B876	List: ML20041B875 ML20041B881
References
LER-82-008-03L, LER-82-8-3L, NUDOCS 8202250291
Download: ML20041B881 (2)

Text

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NRC FORM 363 U.S. NUCLEA9 AECULATCRY CCMM103;CM (7 771 ,

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i 6J El C;04ET NLua A A (4 63 Ev2NT DATI 74 73 AEP Af gAf t da EVENT OESCRIPTION ANO PRQ3A3LE CCNSECUENCES la l 21 I During normal operation the LPCI system and the "A" RHR service water sv i

[o is i I stem were declareo inoperable as a result of an enaineerinq evaluation w I lo ! A I I bich concluded a portion of the "A" RHR '(t.PCi; system ninino mav he- Le I l o I s l t en stressed in excess of code allowables. The ovaluation was beino condo I la is l Icrod in acenrdanco with T.S. '4 6 H 7 H+ n r puow svstom ennhhnr Mr 1-s9 I l1 j 71 l -56 was found~ inoperable. A 7 day LCO was entered. There have been 3 pre I t o ia i I vious sim. events in a dif. section of RHR piping. (R0 77-8, 29, 79-25). I 7 8 9 80 CE CC E SU C ts CCMPCNENT CCCE SLS CC'E ~S C5 tol91 IC (F l@ J@ l Zl@ l Zli2Zi Zl Z! ZI Zl@- l Z l@ l Z J @

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43 44 47 CAUSE CESCRIPTICN AND CCRAECTIVE ACT!CNS 27 1i i o i I Exact cause. unknown. Water hanner is the most probahlo cause. Snubber I li t i i IGRC-1-SS-56 was replaced and an RHR svsten valve whic h was .fennd damaned 1 Iii2l lwas repaired. The "A" RHR and RHRSW systems were hydro testod with sat . I I i i 21 l resul ts. Selected welds outsida tha hydro boundarv enro lionid non e rw + ,,l

[i 14 i t examined with sat rosults. _Roth systers worn tested and declared nnerable.  !

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DUANE ARHOLD ENERGY CENTER

. Iowa Electric Light. and Power Company Licensee Event Report - Supplemental Data Docket No. 050-0331 Licensee Event Report Date: 2/19/82 Reportable Occurrence No.: 82-008 Event Description During normal operation, the low pressure coolant injection (LPCI) subsystem of the residual heat removal (RHR) system and the 'A' loop of the RHR service water system were declared inoperable whea an engineering evaluation identified a high stress point on the RHR injection line that may have exceeded code allowa bles. This engineering evaluation of the RHR and RHR service water systems was prompted by the discovery of both a failed snubber GBC-1-SS-56 and a failed yoke on control valve CV-2037 on January 19, 1982. The snubber and yoke are both located on a section of RHR service water piping which is connected to the RHR injection piping by a crosstie line.

As required by Technical Specification 3.5.A.5, a 7-day limiting condition for operation (LCO) was entered when LPCI was declared inoperable. Operability of both core spray subsystems, the containment spray subsystem, and the diesel generators required for operation of such components was demonstrated immediately and daily thereafter. There have been three previous similar occurrences of water hammer damsge to a different section of the RHR piping system (see R0 77-8, 7/-29, and 79-25).

Cause Description The exact cause of the snubber and yoke failures is unknown; however, possible causes include water hammer in the RHR and RHR service water systems and a high pressure surge from the RhR injection line during injection valve operability tests. ,

Corrective Action Both snubber GBC-1-SS-56 and the yoke on CV-2037 were replaced like for like and were functionally tested satisfactorily. The ' A' loops of the RHR and RHR service water systems were hydrostatically tested and inspected with liquid penetrant examination of selected. welds outside. the hydrotest. boundary. With satisfactory completion of these tests, the LpCI subsystem of the RHR system and the 'A' loop RHR service water system were declared operable 2.25 days into the 7-day LCO. To preclude recurrence, procedure changes have been made to ensure proper venting to reduce the penibility of water hammer, release of any high pressure following injection vahe operability testing, and manual operatier.

of the RHR service water pump discharge valves to initially fill the piping system slowly.

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