ML20237H367
| ML20237H367 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 08/06/1987 |
| From: | Bailey J GEORGIA POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| GN-1392, NUDOCS 8708170167 | |
| Download: ML20237H367 (4) | |
Text
"
Georgia Power Company Post Office Box 282 Waynesboro, Georgia 30830 Telephone 404 554 9961 1
404 724 8114 Southern Company Services, Inc.
l Post Office Box 2625 Birmingham, Alabama 35202 Telephone 205 870-6011 VOgtle Project Augs.;t 6, 1987 i
U. S. Nuclear Regulatory Commission Document Control Desk File:
X7BC35 Washington, D.C.
20555 Log:
GN-1392 I
Reference:
Letter GN-1379, dated July 1,1987 i
I NRC DOCKET NUMBER 50-425 CONSTRUCTION PERMIT NUMBER CPPR-109 V0GTLE ELECTRIC GENERATING PLANT - UNIT 2 EVALUATION OF REACTOR C0OLANT SYSTEM FOR
]
STEAM GENERATOR UPPER SUPPORT DESIGN j
l Gentlemen:
Attached is the additional information requested by your staff during a telephone conversation held on July 29, 1987, on the reliability of Paul-Munroe snubbers used in the steam generator upper support.of Vogtle Unit 2.
The attachment defines the visual inspection, functional testing and maintenance programs to be implemented for Vogtle Unit 2 l
and provides service history information of Paul-Munroe snubbers for nuclear plant applications.
It should be treated as supplemental l
information to the above referenced letter.
j f
Should you have ar,y questions on the enclosed information please advise.
l Sincerely, 4
4
,k-J. A. Bailey Project Licensing Manager JAB:jc Attachment xc: NRC Regional Administrator B. W. Churchill, Esquire NRC Resident Inspector M. A. Miller (2)
R. E. Conway G. Bockhold, Jr.
J. P. O'Reilly R. Goddard, Esquire P. D. Rice D. Feig L. T. Gucwa R. W. McManus R. A. Thomas Vogtle Project File
\\
%)
J. E. Joiner, Esquire 8708170167 870006 g
PDR-ADOCK 05000425 O.
PDR Lm___ _ _ _ _ _. _ _ _ __
fo n.
RELIABILITY OF PAUL'-MUNR0E STEAM GENERATOR HYDRAULIC SNUBBERS The reliability of the Paul-Munroe hydraulic snubbers that are.. used on Vogtle Unit 2 has been demonstrated.by their effective' performance (over 1900 snubber years without impact to plant operation).
Westinghouse - has primarily used Paul-Munroe hydraulic snubbers in the
- Westinghouse reactor. coolant. loop support system.
To'date, Westinghouse j
plants have accumulated over 1000 snubber years of trouble-free. operating experience with Paul-Munroe snubbers in Westinghouse - designed reactor i
coolant loop support systems.
Throughout this operating service life, l
Westinghouse is not aware of any instance in which a Paul-Munroe steam generator hydraulic snubber was found to be inoperable or cause. for a plant shutdown.
Inoperability'is ' defined as the snubber not being able to perform the minimuim plant specific functional requirements of locking-up and bleeding (translating under load).
To update and q
confirm Westinghouse knowledge.of Paul-Munroe' snubber operating experience, Westinghouse recently conducted a limited survey of domestic l
operating plants with a Westinghouse reactor coolant loop support. design and Paul-Munroe steam generator snubbers.
In every case the Paul-Munroe.
snubbers were reported to have experienced no operational problems.
.j 1
Additionally, Georgia Power Company contacted INP0 to perform a sort i
on the INP0 Licensing Event Report (LER) data base to identify all
')
reported failures of Paul-Munroe hydraulic snubbers.
The INP0 report identified only three LERs referencing Paul-Munroe hydraulic snubbers.
l 1.
Diablo Canyon Unit 1
'On 9/13/86, with Unit 1 in mode 5, during inservice inspection one steam gonerator snubber was found to-be unpinned at the blind end.
All other snubbers were found to be functional.
The cause of the pin movement is unknown.
A design change which provided the pins with locking devices was implemented to prevent repetition.
1 The Vogtle steam generator snubbers are provided with pins which feature a positive locking device, cotter pins.
2.
Calloway Unit 1 - On 3/8/86, during inservice testing of one steam l
generator snubber, one hydraulic control valve failed causing the snubber to lock-up.
The cause of the failure was attributed to the in-place test equipment creating an. unnatural -high rate of cycling on the control valve and thereby causing the valve stem to shear.
The snubber was replaced and sent to Paul-Munroe for refurbishment.
The Vogtle steam generator snubbers have the same control valve used on the Calloway snubbers.
However, Paul-Munroe has isolated the problem that caused the control valve failure and have modified their in-place test-equipment to-prevent any recurrence.
The control valve failure at Calloway.is unique to the inservice testing performed on that snubber using original Paul-Munroe test equipment' and is no indication of any generic service life problem with the control valve.
a
RELTAB1LITY OF PAUL-MUNR0E
'PAGE 2 STEAM GENERATOR HYDRAULIC SNUBBERS i
1 3.
Arkansas Nuclear One Unit 1 - - On 11/9/86, during a surveillance shutdown, a 200 kip capacity reactor coolant. pump hydraulic snubber was found to be leaking fluid.
Examination of.the :nubber revealed i
arc strikes L on ~ the piston rod.
These. appeared to have been the result of-the snubber being used as a ground for' a welding machine.
The cause of the leak were. scratches on the TEFZEL piston rod seal apparently caused by the arc strikes.
The_ snubber was disassembled, cleaned, inspected, damaged. parts were rebuilt by Paul-Munroe and the snubber was reassembled with new seals.
The Vogtle steam generator snubbers also use. TEFZEL seals.
- However, the installation, maintenance, and inspection procedures at Vogtle will preclude-misuse of the snubbers and identify any abnormal 3
snubber leakage.
i As additional confirmation on the reliability of'. Paul Munroe hydraulic snubbers, Paul-Munroe Hydraulics was contacted and requested to. provide a summary of their knowledge of the operating service life of Paul-Munroe hydraulic snubbers similar in load capacity to the steam generator snubbers.
Paul-Munroe entered into the production of large bore (250 to 2000 kip capacity) snubbers in 1969.
Since that time, Paul-Munroe has become the major manufacturer of large bore snubbers world-wide with over 1400 snubbers supplied.
In addition, Paul-Munroe has been the main I
supplier of steam generator snubbers for botn Westinghouse and Combustion Engineering reactor coolant support systems.
Paul-Munroe has used advanced technology in its snubber
- seal, poppet-style control valve design, and in-place testing capability.
The Paul-Munroe TEFZEL seal has been an extremely reliable design ar.d is fully qualified for 40-year life performance.
The - poppet-style control valve provides consistent performance and is not subject to i
the problems experienced by conventional control valves.
The poppet-style control valve hr.s the bleed orifice in-line with the poppet thus eliminating silting or clogging conditions by nature of this 1
self-cleaning design.
The control valves are set in the factory and are not subject to field tampering.
The in-place testing capability -
allows the snubbers to be tested for operability in-place.
The Vogtle steam generator hydraulic snubbers incorporate all these advance design features.
The Paul-Munroe large bore snubbers have provided nuclear facilities with a total, effective performance of over. 1900 snubber years of' operating service without impact to plant operation.
Paul-Munroe has over 390 snubbers that-have been in operating service for over 4 years.
)
Paul-Munroe's statements are supported by EPRI's " Snubber Reliability Improvement Study", EPRI NP-2297, which : states that
...no generic problems have been reported for their (Paul-Munroe) snubbers due to
- storage, installation,- field adjustment, deterioration -in. service, inservice inspection, or maintenance."
)
i RELIABILITY.0F PAUL-MUNR0E PAGE 3 STEAM-GENERATOR HYDRAULIC SNUBBERS
~
In conclusion, the 1900 plus snubber:. years of operating experience with no. reports of_. inoperability demonstrate the reliability of the.
)
Paul-Munroe steam. generator hydraulic snubbers.
1 To ensure the continued operability of the steam generator. hydraulic snubbers, Vogtle has instituted a. number of plant specific procedures to maintain, inspect, and test the snubbers.
These documents. ' are tabulated below.
{
l 1.
Vogtle Plant Technical Specification 3/4.7.8
" Snubbers" 1
2.
Vogtle Electric Generating Plant Procedure No. 54171-C
" Inspection of Component Supports and Engineering Evaluation" 3.
Vogtle Electric Generating Plant Procedure No. 85410-C - " Visual l
Examination of Snubbers" f.
Vogtle Electric Generating Plant Procedure No. 28310-C
" Functional Testing 'of Mechanical and Hydraulic Snubbers" 5.
" Paul-Munroe Hydraulics' Installation, Operating, Maintenance j
Manual for Vogtle 1 & 2 Snubbers" - Document No. 1X6AB18-34-1 l
The steam generator hydraulic snubbers will be. inspected periodically in accordance with paragraph 4.7.8.b of Vogtle snubber. technical l
specification, document 1.
The inspections will be. performed in accordance with Vogtle specific documents 2 and 3.
a In addition to these visual inspections a minimum of 10% (ten percent) of the hydraulic snubbers will be functionally tested at every refueling l
outage per paragraph 4.7.8.e of document 1 and performance in accordance with the requirements of document 4.
i The maintenance of the hydraulic snubbers will be performed ~in accordance with the manufacturer's recommendations, document 5 and in compliance with paragraph 4.7.8.1 of the tech spec, document 1.
In conclusion, the demonstrated reliability of the Paul-Munroe steam generator hydraulic _ snubbers will be maintained and ensure through the plant specific-maintenance, inspection, and inservice testing i
procedures in-place at Vogtle.
i
{
l