05000338/LER-1981-035-03, /03L-0:on 810429,20 Unacceptable Pipe Hangers Not Meeting Operability Criteria Due to Overstressed Conditions Were Identified.Caused by New & Larger Accelerations on Pipe Sys.Affected Hangers Were Modified

/03L-0:on 810429,20 Unacceptable Pipe Hangers Not Meeting Operability Criteria Due to Overstressed Conditions Were Identified.Caused by New & Larger Accelerations on Pipe Sys.Affected Hangers Were Modified

ML19352A965
Person / Time
Site:	North Anna
Issue date:	05/28/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19352A962	List: 05000338/LER-1981-035, Forwards LER 81-035/03L-0 05000338/LER-1981-035-03, /03L-0:on 810429,20 Unacceptable Pipe Hangers Not Meeting Operability Criteria Due to Overstressed Conditions Were Identified.Caused by New & Larger Accelerations on Pipe Sys.Affected Hangers Were Modified
References
LER-81-035-03L-01, LER-81-35-3L-1, NUDOCS 8106020436
Download: ML19352A965 (5)

LER-1981-035, /03L-0:on 810429,20 Unacceptable Pipe Hangers Not Meeting Operability Criteria Due to Overstressed Conditions Were Identified.Caused by New & Larger Accelerations on Pipe Sys.Affected Hangers Were Modified

Event date:
Report date:
3381981035R03 - NRC Website

text

a U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT h CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

/0/1/

/V/A/N/A/S/1/ (2)

/0/0/-/0/0/0/0/0/-/0/0/ (3)

/4/1/1/1/1/ (4)

/ / / (5)

LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

/0/1/

REP [X/ (6)

/0/5/0/0/0/3/3/8/ (7)

/0/4/2/9/8/1/ (8) /0/5/2/8/8/1/ (9) 9UR DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

/0/2/

/

On April 29, 1981, the ongoing multiple structure ARS evaluation effort identi-/

/0/3/

/

fled 7 pipe support arrangements in various Unit I systems which did not meet /

/0/4/

/

the operability criteria due to overstressed conditions. On May 19, 1981, a to-/

/0/5/

/

tal of 13.nacceptable pipe hangers on Unit 2 were identified. This additional /

/0/6/

/

analysis does not change the original design basis selection of ARS for appli- /

/0/7/

/

cation to bounded piping problems. Therefore, the public health and safety were/

/0/8/

/

not affected by the results.This event is reportable pursuant to T.S.6.9.1.9.b./

SYSTEM

CAUSE

CAUSE COMP.

VALVE -

CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

/0/9/

/S/B/ (11) [X/ (12) [Z/ (13) /S/U/P/0/R/T/ (14) [D/ (15)

[Z/ (16)

SEQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REPORT NO.

CODE TYPE NO.

(17) REPORT NCMBER

/8/1/

. [-/.__ /0/3/5/

/\\/

/0/3/

[L/

[-/

[0/

ACTION FUTUPE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP.

COMPONENT TAKEN ACTIO4 ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER [F/ (18) [Z/ (11) [Z/ (20) [Z/ (21) /0/0/0/0/ (22) [Y/ (23) [N/ (24) [A/ (25) /G/2/5/5/ (26)

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

/1/0/

/

Tite requested seismic stress reanalysis of piping sections spanning multiple

/

/1/1/

/

buildint, structures imposed new and larger accelerations on the pipe systems

/

/1/2/

/

causing the overstressed conditions to arise. Each of the affected hangers

/

/1/3/

/

were m,dified by Design Change 80-S46 to meet the new operability criteria.

/

/1/4/

/

/

FACILITY METHOD OF STATUS

% POWER OTHER STATUS DISCOVERY DESCRIPTION (32)

/ (30) DISCOVERY

/1/5/

[E/ (28)

/1/0/0/ (29) /

NA [D/ (31)

/ Pipe Stress Reanalysis By A/E/

ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36)

/1/6/

LZ/ (33)

[Z/ (34) /

NA

/

/

NA

/

PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

/1/7/ /0/0/0/ (37) [Z[ (38) /

NA

/

4 PERSONNEL INJURIES NUMBER DESCRIPTION (41)

/1/8/ /0/0/0/ (40) /

NA

/

LOSS OF OR DAMAGE TO FACILITY (03)

TYPE

DESCRIPTION

/1/9/

[Z[ (42) /

NA

/

PUBLICITY ISSUED DESCRIPTION (45)

NRC USE ONLY

/2/0/

[N[ (44) /

NA

/////////////

NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 8196 GH2 O 4 3 6

P Virginia Electric and Power Company North Anna Power Station, Unit #1 Attachment: Page 1 of 4 Docket No. 50-338 Report No. LER 81-035/03L-0

Description of Event

On April 29, 1981, Vepco was informed by stone & Webster that the ongoing multiple structure amplified response spectrum (ARS) evaluation requested by the NRC had identified 7 pipe support arrangements on Unit I which did not meet operability critieria due ta overstressed conditions.

On May 19, 1981, 13 pipe supports on Unit 2 were reported as not meeting the required criteria. This event is reportable pursuant to T.S. 6.9.1.9.b.

The hangers involved are as follows:

UNIT 1 Hanger No.

~

Location Unacceptable Condition WFPD-H-1 Main Feedwater Header 26"-WFPD-6-901-Q2 Weld overstressed WFPD-H-2 Main Feedwater Header 26"-WFPD-6-901-Q2 Weld overstressed RS-H-206A and B "C" Recirculation Spray Cooler Snubbers stressed over Discharge Line 10"-RS-11-153A-Q2 rated allowable RS-N-208A and B "A" Recirculation Spray Cooler Snubbers stressed over Discharge Line 10"-RS-3-153A-Q2 rated allowable QS-H-207 "B" Quench Spray Header Laeply Snubber stressed over Line 8"-QS-39-153A-Q2 rated allowable QS-H-2C9A and B "A" Quench Spray Header Supply Snubbers stressed over Line 8"-QS-37-153A-Q2 rated allowable SHP-H-224 "A" Main Steamline 32"-SHP-57-601 Snubber stressed over rated allowable UNIT 2 Hanger No.

Location Unacceptable Condition WFPD-H-213 "C" Steam Generator Feedwater Brace plate Line 16"-WFPD-409-601 overstressed WFPD-H-214 "B" Steam Generator Feedwater Brace plate

,4 Line 16"-WFPD-413-601 overstressed WFPD-H-215 "A" Steam Generator Feedwater Brace plate Line 16"-WFPD-417-601 overstressed WGCB-H-161 "C" Steam Generasar Blowdown Hanger exceeds normal Line 3"-WGCB-403-601-Q3 upset stress allowable WGCB-H-513 "A" Steam Generator Blowdown Hanger exceeds normal Line 3"-WGCB-414-601-Q2 upset stress allowable i

e Attachment: Page 2 of 4 UNIT 2 (cont)

Hanger No.

Location Unacceptable Condition WGCB-H-514.

"C' Steam Generator Blowdown Hanger exceeds normal Line 3"-WGCB-416-601-Q2 upset stress allowable WGCB-H-515 "C" Steam Generator Blowdown Hanger exceeds normal Line 3"-WGCB-403-601-Q3 upset stress allowable WGCB-H-516 "B" Steam Generator Blowdown Hanger exceeds normal Line 3"-WGCB-415-601-Q2 upset stress allowable WGCB-H-517 "B" Steam Generator Blowdown Hanger exceeds normal Line 3"-WGCB-402-601-Q3 upset stress allowable WGCB-H-518 "A" Steam Generator Blowdown Hanger exceeds normal Line 3"-WGCB-414-601-Q2 upset stress allowable WGCB-H-608 "C" Steam Gener.ator Blowdown Hanger exceeds normal Line 3"-WGCB-4J3-601-Q3 upset stress allowable SI-H-56A High Head Safety Injection Weld size and bolt torque Lines 3"-Si-417-1502-Q1 and under required values 3"-SI-457-1502-Q1 for points 1 and 2 RP-H-4 Refueling Purification Pump Weld overstressed Discharge Header 6"-RP-41-152-Q3 Probable Consequences of Occurrence The additional analysis performed, due to the NRC request, does not change the original design basis selection of ARS for application to bounded piping problems. As a result, the health and safety of the general public were not affected by the results of the review. Also, all necessary pipe support modifications were implemented during unit shutdown and satisfactorily completed prior to startup.

Cause of Event

l The seismic stress reanalysis of piping sections spanning multiple l

building structures, by considering the appropriate accelerations from each of the independent structures to which the piping supports are attached, 4

imposed new and larger accelerations on the pipe systems resulting in the overstressed conditions.

I L

e v

Attachment: Page 3 of 4

Immediate Corrective Action

Each of the overstressed hangers were modified as follows by Design Change 80-S46 to meet the new operability criteria:

Hanger No.

Modification WFPD-H-1 Added stiffener plates to the support WFPD-H-2 Added stiffener plates to the support RS-H-206A and B Replaced existing snubbers with larger snubbers RS-H-208A and B Replaced existing snubbers with larger snubbers QS-H-207 Replaced existing snubber with larger snubbers QS-H-209A and B Replaced existing snubbers with larger snubbers SifP-H-224 Added an additional snubber to the i

support and replaced the existing snubber WFPD-H-213 Changed clamps on snubber and added stif fener plates to the support VFPD-H-214 Changed clamps on snubber and added stiffener plates to the support WFPD-H-215 Changed clamps on snubber and added ctiffener plates to the support WGCB-H-161 Removed portion of pipe trunnion from the support WGCB-H-513 Added -way strut to the support WGCB-H-514 Added sway strut to the aupport WGCB-H-515 Added sway strut to the support

- 4 WGCB-H-516 Added sway strut to the support WGCB-II-517 Added sway strut to the support i

WGCB-H-518 Added sway strut to the support

}

WGCB-H-608 Added a plate to the support SI-H-56A Added special clamp anchor to the support and changed welds

s

Attachment:

Page 4 of 4 Hanger No.

Modification RP-H

'4 Added tube steel stiffener plates and shim plates to the support.

Scheduled Corrective Action No scheduled corrective action is required.

Actions Taken to Prevent Recurrence No further actions required.

Generic Implications Potential generic implications exist on plants requiring multiple structure ARS evaluations or any other analysis which uses more severe seismic conditions as a. criterion.

i 4

l l