ML17296B231
| ML17296B231 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 01/27/1981 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| NUDOCS 8102280549 | |
| Download: ML17296B231 (16) | |
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II>UCLEAR REGULATORY COMMISSION
,iEGION V l990 N. C" LIFORNIABOOL vARO SUITE "92, '."IALNUTCREEI<?LAZA iVALNUTCR E!C, CALIFORNIA94596 January 27, 1981 Docket Nos. 50-528, 50-529 50-530 Arizona Public Service Comoany P.
0.
Box 21666 Phoenix, Arizona 85036 Attention:
IMr.
E.
E.
I/an Brunt, Jr.
I!ice President, nuclear Projects Gentlemen:
The enclosed BulIetin 8l-Ol is forwarded to you for information.
No written response is required.
I> you desire additional information regarding this
- matter, please con~act this office.
SincereIy, R.
H. Engelke'n Director Encl osures:
l.
Recently issued IE Bulletins cc w/enclosures:
F.
M. Hartley, APS
(. nsae9549
II
SSINS No.:
6820 Accession No.:
8005050075 IEB 81-01 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT MASHINGTON, D.C.
20555 January 27, 1981 IE Bulletin No. 81-01:
SURVEILLANCE OF MECHANICAL SNUBBERS Description of Circumstances:
Several instances of failures of mechanical snubbers supplied by International Nuclear Safeguards Corporation
( INC) have been identified that indicate possible deficiencies in these snuobers.
A summary of the failures that have occurred is orovided below:
l.
On August 9, 1974, the Tennessee Valley Authority submitted event report BFAO-50-260/74lll identifying ll of 14 INC Model MSVA-1A snubbers thai were found inoperable on Browns Ferry Nuclear Power Station Unit 2 and subsequently identified 5 of 14 inoperable units on Browns Ferry Nuclear Power Unit No 3.
All of these units were found to be frozen, and the cause was attriouied to a failure to lubricate the paris during assembly.
The failed snubbers were replaced with new units produced by the same manufac turer'.
2.
On April '2, 197C, ihe St.. Lucie Plant Unit 1 facility,of Florida Power and Light Corporation submitted event report No. 50-335-76-,9 wherein five INC Model MSVA-1 snubbers were identified as inoperable because they were found to be frozen.
The failures were caused bv oxidation on the internals and by improper assembly.
All INC mechanical snubbers were replaced with units produced by another manufacturer.
3.
On April 8,
- 1977, Iowa Electric Liaht and Power Company submitted event report No. 77-23 for the Duane Arnold Energy Center facility that identi-fied 13 INC Model 1MSVA-1 Type AS snubbers to be frozen; the cause of failure was attributed to large amounts of interior oxidation.
Tge units were replaced with those produced by another manufacturer.
4.
On December 5, 1979, personnel from the Nuclear. Regulatory Commission visited Department of Energy (DOE) facilities at Richland, Washington, to obtain information on DOE experience with INC snubbers at the Fast Flux Test Facility (FFTF).
The DOE-owned FFTF was equipped with more than 4,000 mechanical pipe restraints (snubbers) supplied by INC.
In 1978, FFTF examined more than 800 of these mechanical snubbers by removing them from their installation and found that 43, or about 5X of those
- examined, were frozen.
The plant was still under construction so the snubbers had seen no service and had been subjected to only normal construction environments for 1 to 2 years.
IEB 81-01 January 27, 1981 Page 2 of. 6 Tests were conducted on three operable snubbers by installing them on a
Hanford Engineering and Development Laboratory (HEDL) process line.
The three snubbers were subjected to flow-induced low-amplitude vibration (0.003 inches or less).
These snubbers were of both the combined carbon steel and stainless steel construction and the all stainless steel con-struction.
Detailed test data are not available to the NRC at this time.
However, all three snubbers froze after beina subjected to the vibration for periods of 3 to 30 days.
The failure modes on all units inspected and tested'involved a number of different mechanisms leading to the freezing of the snubbers.
Following disassembly of some of the snubbers, inspections showed the failures were caused by improper assempl,y; overneatina of internal components caused by welding (durina fabrication);
and sensitivity of the desian to diri, corrosion, ana inadeauate or excessive lubrication.
DOE concl,uded that there were generic aeficiencies in ihe desian of the snubbers of this specific manufacturer for applicaiion to the FFTF facility and for pipes subjected to vioration.
All INC mechanical snubbers in FFTF.have been replaced with snubbers produced by anoiher manufacturer.
5.
On Hay 31, 1980, Georaia Power Company reported eight INC snubbers located on instrument and drain lines at Edwin I. Hatch Nuclear Plant Unit 1 were identified as inoperable (LER 321-80-55).
The cause of the failures was identified as internal'orrosion ihai caused a frozen condition.
In an attempt to free a snubber (750-pound capacity),
forces up to 1500 pounds were applied in boih ihe "exiend" and "retract" directions and the snubber did noi move.
The inspeciion of INC snubbers was completed at the Hatch facility and, on June 30,
- 1980, NRC received a supplemental repori ihai 45 of the 61 snubbers thai had been inspec ed on Unit 1 had,been identi-fied as inoperable and three of the 42 snubbers that were inspecied on Unit 2 were inoperable.
All inoperable snuboers were replaced prior to startup of the affected unit.
Some were replaced with mechanical units produced by another manufacturer, some were replaced with. later-model INC
- snubbers, and three were replaced with rigid restraints.
Plans are being made to replace all INC snubbers during upcoming refueling outages.
Analyses are also being performed on the pipina affected by the locked up snubbers.
In addition to INC snubber failures, failures of mechanical snubbers by another manufacturer are identified below:
1.
On September 7, 1979, Public Service Electric and Gas Company reported the failure of three tlodel PSA-3 mechanical snubbers manufactured by Pacific Scientific Company that were located on a main feedwater line of Salem Nuclear Generatina Station Unit 1 (LER 79-54).
These three snubbers could not be rotated around their spherical rod end bearings.
The snubbers were removed and inspection revealed that the lead screw and traveling nut
'ssembly, which translates linear to rotational motion, had failed.
The snubbers no longer provided seismic shock restraint under this condition.
These snubbers are directly upstream of the nuclear Class II piping boundary and are included in the stress calculations for the seismic analysis of the nuclear portion of the main feedwater piping.
Failure of the snubbers
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I B 81-01 January 27, 1981 Page 3 of 6 aopeared to result from a force many tim s greater than the design load of the snubbers.
This force was either an extreme shock load or occurred when the snubber was in +he fully retracted condition.
The snubbers were replaced with units oroduced by the same manufacturer.
2.
Qn April 10, 1979, Consumers Power Comoanv reported a failure of eight ilodel PSA-3 Pacific Scientific snubbers at their Big Rock Point Nuclear Plant facility (LER 79-017/03L-0).
The cause of the failure was improper installation in that a spherical washer~ias omitted from the transition tube.
3.
On March 15 and June ll. 1979, Florida Power and Light reported failures of Pacific Scientific Comoanv mecnanicai snubbers on main steam and feedwater systems ai Turkey Point Plant Units 3 and 4
(LER 79-006/03L-0 and 79-009/03L-0 resoectiveiyj.
The cause in ooth cases was attributed to excessive loaaina.
The nature of ihe above mecnanicai snubber failures is io prevent, the piping
- systems, io wnicn iney are arzacned, from moving freely during ihe normal thermal heat up ana cooi aown associated with plant operations..-
Restraining this thermal moiion resuiis in nigher than normal stresses which, if high enough and repeai:ed frequenv.iy enough, can lead io a premature fatigue failure of ine piping system.
These mechanical snuobers have been installed for a.number of years without any NRC requirements for periodic surveillance to determine.their condition.
As a resul t, ihei r curren L condi t i on is unknown io NRC. and therefore HRC i s requesting a prompt examination of all mecnanical snubbers installed.io date.
Because of the high percentage of failures discovered with ihe INC snubbers, the time frame for tneir examination is the shortest and additional opera-bility tests are called.or.
Actions to be Taken b
Licensees of 0 eraiin Reactors:
1.
>Iithin 30 days of ihe issuance date of this bulletin, all normally accessible*
INC mechanical snubbers installed on safety-related systems or in storage shall be visually examined and tested as follows:
a ~
b.
Perform a visual examination for damage and, without causing the system to be inoperable except as permitted by the facility technical specifications, verify that the snubbers have freedom of movement by performing a manual test over the range of the stroke in both com-pression and tension.
Perform an operability iesi to confirm that (I) activation (restraining action) occurs in both compression and tension and (2) the drag forces are within the specified range. in both compression and tension.
The tests shall be performed on all snubbers in storaae and on a representative samnle (105 of the total of this type of snubber in use in the plant or 35, which ever is less) of the
<<"Normally accessible-refers to those areas of the plant that can be entered during reactor operation.
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IE8 81-01 January 27, 1981 Page 4 of 6 normally accessible snubbers that are in service and can be indiv-idually removed without causing the system to be inoperable, except as permitted by the facility technical specifications.
for each snubber that does not meet the test acceptance
- criteria, an additional representative sample (as defined above) of this type of snubber shall be tested.
For each of these additional snubbers that do not meet the test acceptance criteria, another representative sample of this type of snubber shall be tested.
This cycle shall be repeated until no more failures have been found or until all snubbers of this type have been tested.
The samples should be made up of snubbers representing the various sizes.
I
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d.
Snubbers wnich have been examinea ana tested in a manner comoaraole to I.ems la and lb above within the last six months may be exempted.
If any failures are identified in Items la or.lb above, take corrective action ana evaluate the effect of the failure on the system operability pursuant to me facility technical specifications for continued operation.
If failures are identified in Items la and lb above, and, i= INC snubbers are'nown io be located in any inaccessible
- areas, a plant shutdown shall be performed wichin 30 days after the discovery af the first inoperable snuboer and inspections conducted in accordance with Item 2a and 2b oelow, unless justification for continued operation has been pro'vided to tne i~RC.
2.
'Iisually examine and desi ail inaccessible Ii'IC mechanicai snubbers installed on safety related systems at the next outage of greater than five days duration as follows:
a
~
'lisually examine and manually test all inaccessible snubbers as described in Item la above.
b.
Perform an operability test on a representative sample of inaccessible snubbers as described in Item lb above.
c
~
d.
Snubbers which have been examined and tested in a manner comparable to Items 2a and 2b above within the last six months may be exempted.
If anv failures are identified in Items 2a or 2b above, take corrective action to evaluate the effect of the failure on system operability pursuant to the facility technical specifications for resuming operation.
3.
Provide a schedule ror an inspection program covering mechanical snubbers produced by other manufactures.
As a minimum, this inspection program shall:
a.
b.
Include all snubbers installed on safety-related systems; Include the visual examination and manual test described in Item la above for all snubbers;
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IEB 81-01 January 01, 1981 Page 5 of 6 c.
Snubbers which have been examined and tested in a manner comparable to Item 3b above within the last twelve months may be exempted:
d.
Reaui re the corrective action and evaluations described in Items ld and 2d above; and e.
Be completed prior to the completion of the next refueling outaae.
Plants which are currently in a refueling outage should perform the visual examination and manual Wsts of inaccessible mechanical snubbers before resumption of ooerations unless some other basis for assurance of snubber operability is provided to the NRC.
Submit a reoort of tne results of the insoeciions, testing and evaluation reaueszea in item 1 io NRC within 45 days of rhe issuance date of ihis bulletin.
Repori the resuits of ihe inspections, testing and evaluation reauested in irem 2'iihin 30 days after ihe inspecuon and testing have been comp I crea.
The resoonse io item 3 shall be submi tted within 60 days of the issuance aaie of inis Bulletin.
The results or ihe inspections performed ror item 3 snail be submitted wiihin 60 days afier the completion of the inspection.
The reporis snail contain
@he following:
a.
C.
d.
A descripiion or the visual examinaiions and tests performea.
Number or snuooers examined and tesied.
Grouping by manufacturer name moaei nuiTioer and s 1 ze i s accepra bi e.
Number o-Failures idenrified; manufacturer
- name, model number, size, mode or Failure, cause oF failure, corrective action, snubber location, effeci of failure on plant and system safety, and justjfication ror continuing or resuming operation.
The above information shall also be provided for the snubbers exempted by Items,lc, 2c, and 3c above.
Actions to be Taken by ihe Followinq Licensees Holdin Construction Permits:
Diablo Canyon Nuclear Power Plant Unit 1; San Onofre Nuclear Station Unit 2; watts Bar Nuclear Plant Units 1 and 2; and 'lirail C.
Summer Nuclear Station Unit l.
l.
After preoperational and/or hot functional testing and precedina fuel loading, visually examine and test the mechanical snubbers installed on safety-related systems as follows:
a.
For ail snubbers perform a visual examination for damage and verify that the snubbers have freedom of movement by performing a manual test over the range of the stroke in both compression and tension.
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IEB 81-01 January 27, 1981 Page 6 of 6 b.
For Ii'(C snubbers, perform an ooerability test to confirm that (1) activation (restrainina action) occurs in both compression and tension and (2) the draa forces are within the specified range in both compression and tension.
The tests shall be perrormed on a representative sample (10~ of the total of this iype of snubber in use in the olant or 35, which ever is less).
For each snubber that does not meet the test acceptance
- criteria, an additional representative sample (as defined above) of this type of snubber shall be tested.
For each of these additional snubbers that do not meet the test acceotance criteria, another representative sample of this tyoe of snuboer snail be tested.
This cycle shall be repoatea until no more r'ailures have been found or until all snubbers or this ryoe have been tesred.
The samoles should be made up of snuobers ihat represen~
tne various sizes.
c
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Ir any railures are identified in Items a or b above, take corrective acti on prior to r'uel 1 oaai ng.
2.
The schedule ror ihe inspections and tests requesied in Item 1 above, shall be submiiied wiihin 60 days of ihe issuance date of this bulletin.
The resulis of ihe inspeciions,
- iesiing, ana evaluaiion requested in Item 1
shall be reported io iiRC within 30 days arier ihe inspeciion and testing nave been compleied.
The reoorcs shall coniain cne following:
a.
A descripiion or ihe visuaI examinaiions and tests performed.
b.
!umber or snuobers examinea and iesied.
Grouping by manufacturer
- name, model
- number, and size is acceptable.
c.-
Humber Gr failures identified; manufacturer
- name, model
- number, size, mode of failure, cause oi failure, corrective action, and snubber location.
- Reports, signed under oath or affirmaiion, under the provisions of Section 182a of the Atomic Energy Act of 1954, shall be submitted to the Director of the appropriate HRC Regional Office and a copy shall be forwarded to the Director of the fiRC Office of Inspection and Enforcement, Mashington, D.
C.
20555.
If you desire additional information regarding this matter, please contact the IE Reaional Office.
Approved by GAO B-180225 (S81003) expires December 31, 1981.
RECENTLY ISSUED IE BULLETINS IES 81-01 January 27, 1981 Bulletin'o.
Sub'ect Date Issued Issued To 80-25 Supplement 4
to 80-17 80-24 80-23 80-22 Oper ing Problems with T rget Rock Safety-Relief
~!allies at BtjRs Failure of Control Rods to Insert Durino a Scram Bt.jR Prevention of Damage Due zo Water LeaKage Inside Conzainmenz (October 17, 1980 Indian Poinz 2
E'/ent)
Failures of Solenoid
'!al ves jlanufaczured by
'!al cor Engineering Corpora r.i on Automation inouszries, "odei 200-520-008 Sealed-
.ource Connectors 12/19/80 12/18/80 11/21/80
>>/14/80
-/11/80 All BHR facilities with Ol jm specified near term OL BWR facilities 8 a'il BWRs with a CP To specified BWRs with an OL 8 All BljRs with a CP All oower reacior facilities with OL or CP All power reacior facilities with OL or CP All radiograpny licensees 80-21.
Supplement 3
to 79-01B Supplement 2
to 79-01B 80-22
.al'/e yohes supp I leo oy 11/5/80 Malcolm Foundry Company',
Inc.
Automation Industries, Hodel 200-520-008 Sealed-source Connectors 9/11/80 Environmenral gualificat:ion 10/20/80 of Class 1E Equipment Envi ronmenia 1
equal ifi ca tion 9/30/80 of Class 1E Equipment All light water reactor facilities with OLs or CPs All power reactor facilities with an OL All power reactor facilities with an OL All radiography licensees 79-26 Revision 1
Boron Loss rom "';lR Conirol Blades 8/29/80 All BljR power facilities with an OL OL = Operating License CP
= Construction Permit
4 Ii I