05000346/LER-1979-130-01, Revised 79-130/01T-1:on 791227,clearance Between RCS Hot Leg & Four Large Shims of Pipe Whip Restraints R-4 Determined to Be Insufficient.Caused by Design Error.Pipe Whip Restraints R1 & R4 Modified & R3 Shim Removed

Revised 79-130/01T-1:on 791227,clearance Between RCS Hot Leg & Four Large Shims of Pipe Whip Restraints R-4 Determined to Be Insufficient.Caused by Design Error.Pipe Whip Restraints R1 & R4 Modified & R3 Shim Removed

ML19344D225
Person / Time
Site:	Davis Besse
Issue date:	03/06/1980
From:	Dieterich K TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19344D222	List: 05000346/LER-1979-130-01, Revised 79-130/01T-1:on 791227,clearance Between RCS Hot Leg & Four Large Shims of Pipe Whip Restraints R-4 Determined to Be Insufficient.Caused by Design Error.Pipe Whip Restraints R1 & R4 Modified & R3 Shim Removed
References
LER-79-130-01T, LER-79-130-1T, NUDOCS 8003110562
Download: ML19344D225 (3)

LER-1979-130, Revised 79-130/01T-1:on 791227,clearance Between RCS Hot Leg & Four Large Shims of Pipe Whip Restraints R-4 Determined to Be Insufficient.Caused by Design Error.Pipe Whip Restraints R1 & R4 Modified & R3 Shim Removed

Event date:
Report date:
3461979130R01 - NRC Website

text

TiPC."O N.t %G U. S. NUCLE AR HEGUt ATORY COW *1tSSIO;4 11 771, LICENSEE EVENT REPORT

(

k/

CO,'!THOt 3LC,C:e l l

l l

l l

l@

(PLE ASE PRINT OR TYPE ALL REQUIRED INFORT1ATION) 1 6

[ lo l 3 ) [0JI1D l B l S l 1 [gl1b0 l0 l-l0 l0 lN lP lF l-l0 l3 l g 4l 1l 1l 1l 1l g l

j 7

8 9 LtGU.Sts CODE le LIChNSE NV".*d% H 2$

26 LICLNhk T YPE JO b i b A T bd CO?J'T ZITITl' s'S I L !@l 0 5;9; 1 0 l3 4l6jgl1l2l2l7l7l9 gj l

l l

l l g 7

6 6J 61 00CAET*.9'.M R tA b)

EVENT DATE 14 6

PEPORT DATE t!J l

EVENT DESCRIPilON AND PROBABLE CONSEQUENCES h [ll 0121 l On 12/21/79 it was discovered there was insufficient clearance between the Reactor l

{ g3J l Coolant System (RCS) hot leg and the four large shims of pipe whip restraints R-4.

On j o l4 l l 12/27/79, it was determined this was in conflict with the reactor supplier's RCS pip-l l o 151 l ing seismic analysis assumptions that there be no contact between RCS hot leg piping j o is 1 Land whip restraints during a seismic event. This became immediately reportable under g

] l o l 71 l T.S. 6.9.1.8.h.

There was no danger to the public or station personnel. These pipe whip restraints do not affect normal operation.

(NF-32-79-14) l Z lf o l a i i sa T

en l

SYSTENI

CAUSE

CAUSE COVP.

VALVE CODE CODE SUECODE CO*.1PONENT CODE SusCODE SuscCOE

{['oT9'l I Cl Bl@ W@ W@ IS ju ir 10 lR IT lg l x ig l z l g 7

8 9

10 Il 12 13 la 19 2J SEQUENTI AL OCCUR R E NCE REFCRT REVIS40N I.'ENTYEAR REPCHT NO.

CODE TYPE No.

E

@,"L E R A 3 17 19 I l-1 11 13 10I l/l 10 11 I I Tl b

W jt,j,S 2'

22 23 24

6 27 28 29 3J 31 32

^ U sit U U F SnT,$u's. "C7Ptii7 mS$f72TNEn 10 l o I e I o @I e I lY l@

l N l@

lA lh l Bl 1l 3 l 0lg NE! '$rY5!

C[e't2NT SeS $'

s HOuns (1}@[._7)@

Lz_J@

k 3J 44 33 ab 31 40 el 42 43 44 47 CAUSE DESCRIPDON AND CORRECTIVE ACTION 3 h

] li lo l l The cause was design error by the architect / engineer, Bechtel. The condition was j

._l_ 11 I i i l discovered by TECo personnel' while performing RCS hot leg RTD modification work.

g Under Facility Change Request 79-441 Supplement 1, pipe whip restraints R1 and R4

!il7j l I

jlil3l l were modified by removing the adjustable portion of the shims. R3 had the shim com-y 1tTTTTIl pletely removed.

The work was completed by 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on 12/29/79.

l [7

8*9 80 l

F ACILITY METHOD OF STATV5

". PCM R OTHER STATUS DISCOVE R Y OtSCOVERY DESCRIPTION 32 NA l

l B [gl during FCR impicmentation l

J g l0l0l0l@l 80 ACTIVITY CCNTENT CEL EASE 3 OF RE LE ASE AMOUNT OF ACTivlTY LOCATION OF RELEISE

__li lo I I zi @ LZJ@l NA l

l NA l

7 8 9 10 11 44 45 80 PERSONNEL EXPO 3uRES NUP.*B E R TYPE DE SCRIPTION

,__l i I 7 I I 01 01 Ol@l Z l@l NA l

0 PER$C%EL INJURtES NU*.t 3 E R D E SCRIP TIO*J NA l

_iiIalI0101cl@l 7

8 9 t1 12 60 LOSS OF OR DAMACE TO F ACILITV Q 8008110.562 TYPE DEsCRiPitON

%,e t i l 91 L_zl@l NA 7

G 9 10 do NRC USE ONLY itSUEO DESCR9Pil0N t 2 l al ! N i@j NA l

llllllllllll l~

8 9 10 08. 69 60

• j h

DVR 79-203 Kennd L. Etedch aM 419-259-5000. Ext. 293 ugygoppngp3ngg

- PHONE:

m,.

.a r 3 a w n n em

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-79-14 DATE OF EVENT: Dec ember 27, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: A conflict between an assumption in the Reactor Coolant System (RCS) piping seismic analysis and six pipe whip restraints

' Conditions Prior to Occurrence: The unit was in Mode 5, with Power (MWT) = 0, and Load (Gross MWE) = 0.

Description of Occurrence: On December 21, 1979, while performing modifications under Facility Change Request 79-441 on RCS hot leg pipe whip restriants R-4, one on each hot leg, it was discovered that the large shims on the north and south side of the restraint could not be moved into their modified position without contacting the hot leg. This condition was reviewed to determine the minimum gap required be-tween these shims and the hot leg. On December 27, 1979, while performing this re-view, it was determine 1 that there was a conflict between the reactor supplier's RCS piping seismic analysis and the design of pipe whip restraints R-4.

The reactor supplier's seismic analysis assumed that during a design basis seismic event that there was unrestrained movement of the RCS pipe. During this review, it was dis-covered that the gaps between the large north-south shims and the RCS piping were not large enough to permit this unrestrained movemea*

This review also revealed the same conflict to exist between the large north th shims of pipe whip restraints R-3 and R-1 and the RCS piping.

All other shims o.

sese restraints are smaller and cict provide adequate gaps for seismic motion. This became immediately reportable under Technical Specification 6.9.1.8.h as a condition which conflicts with an 1

assumption of an accident analysis.

Being in cold shutdown (Mode 5), the unit remained down until corrections were made.

Designation of Apparent Cause of Occurrence: The cause of the occurrence was a design error by the architect / engineer, Bechtel Power Corporation, in that suffi-cient gap had not been provided between the large north-south shims of pipe whip res-traints R-1, R-3 and R-4 and the RCS hot leg to permit unrestrained movement during a seismic event as assumed by the reactor supplier's RCS piping seismic analysis.

Bechtel has reviewed all pipe whip restraints to determine if there are any other instances where large shims (i.e., larger than the other shims on the same restraint) have been used which could produce gaps that would conflict with the assumptions in

)

the seismic analysis. This review uncovered no other similar designs.

Based on this j

review, there is no reason to believe that these design errors were a result of any generic deficiency in the original design method.

Anal'ysis of Occurrence: There was no danger to the health'and safety of the public or to station perso'nnel. These pipe whip restraints' arc not required for normal operation.

LER #79-130 i

e l

.A

P TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-79-14 PAGE 2

Corrective Action

Under Facility Change Request 79-441 Supplement 1, pipe whip restraints R-1, R-3 and R-4 have been modified so that the gap between the north-l south shims and the hot leg piping is greater than the calculated seismic motion but does not exceed the gap used to verify the whip restraint design.

This was 1

accomplished on restraints R-1 and R-4 by removing the adjustable portion of the shims.

The shims on restraint R-3 were completely removed. There are no other shims on res-l traint R-3.

The gap between the pipe and the close fitting restraint ring of res-i

. traint R-3 was the gap used in the restraint design. All affected whip restraint l-modifications were completed by 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on December 29, 1979, prior to the unit l

returning to operation.

Failure Data: There are no previously reported conflicts between the pipe whip restraints and the assumptions of the seismic analysis.

LER #79-130 l

i i

l c

I l

l-l l

A si