Information Notice 1986-81, Broken Inner-External Closure Springs on Atwood & Morrill Main Steam Isolation Valves
| ML031250220 | |
| Person / Time | |
|---|---|
| Issue date: | 09/15/1986 |
| From: | Jordan E NRC/IE |
| To: | |
| References | |
| IN-86-081, NUDOCS 8607110318 | |
| Download: ML031250220 (6) | |
86-81
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C.
20555
September 15, 1986
IE INFORMATION NOTICE NO. 86-81:
BROKEN INNER-EXTERNAL CLOSURE SPRINGS ON
ATWOOD & MORRILL MAIN STEAM ISOLATION VALVES
Addressees
All nuclear power reactor facilities holding an operating license or a construc- tion permit.
Purpose
This notice is provided to inform recipients of a potentially significant safety
problem that could result from broken inner-external closure springs on main
steam isolation valves (MSIVs) manufactured by Atwood & Morrill Co., Inc.
The
springs that failed were manufactured by Duer Spring and Manufacturing Co.
Quench cracks, which apparently developed during the manufacturing process, caused the springs to fail.
It is expected that the recipients review the information for applicability
to their facilities and consider actions, if appropriate, to preclude a similar
problem from occurring at their facilities.
However, suggestions contained in
this information notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
Description of Circumstances
During an inspection of MSIVs following low-pressure seat leakage tests at
Enrico Fermi Unit 2 in May 1986, the licensee observed that four inner-external
closure springs were broken into two-to-seven pieces.
The licensee analyzed two
of the broken springs and determined the failure to be quench cracking caused by
the heat treatment process during manufacturing.
There are eight MSIVs with
eight inner-external and eight outer-external closure springs per valve.
All
outer-external closure springs were found intact and undamaged.
All 64 external
springs were from the same heat number (#8067703).
The external closure-spring
assemblies (inner and outer) perform a safety function to close the MSIVs.
Discussion:
Springs from Duer Spring and Manufacturing Co. were supplied to PWR and BWR
nuclear power plants on MSIVs manufactured by Atwood & Morrill.
The external
closing springs that failed at Fermi 2 were the inner springs around the valve
yoke rods.
The following effects on valve operation could occur with one or
more springs failing:
8607110318
IN 86-81 September 12, 1986 1.
Slower closing time with steam in the normal forward flow direction.
For
BWRs, General Electric estimates the closure time would increase from the
Technical Specification requirements of 3 to 5 seconds but will remain
under 10 seconds.
2.
Increased difficulty in meeting low-pressure seat leakage test requirements
in BWR units.
3.
Valve closure with steam in the reverse flow direction in PWR units could
be adversely affected since the springs provide the only external closing
assistance.
Internal closing assistance is provided by the use of a pilot
poppet design in these valves.
The spring manufacturer also performed laboratory metallographic examination of
the failed springs and verified that the failure was the result of quench
cracking.
Atwood & Morrill and Duer Spring have recommended that at the first
available opportunity all the external closing springs on all MSIVs be cleaned
and magnetic particle testing be performed.
Duer has provided an inspection
procedure.
Atwood & Morrill is issuing a letter to all affected customers concerning this
event which recommends that the above actions be taken.
The Atwood & Morrill
list of affected units is attached.
In addition, General Electric has issued
a service information letter, SIL No. 442 dated July 18, 1986, to owners of
affected BWRs recommending a visual inspection and, in some cases, load tests.
The NRC has reviewed the two procedures and has determined that either
recommendation is adequate for BWRs.
For PWRs, only the Atwood & Morrill
recommendations are appropriate.
However, consideration should be given to
visual inspections of the springs following any cycling of the valve until
completion of the Atwood & Morrill recommended inspection.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional Admini- strator of the appropriate regional office or this office.
.dwardt
Jordan, Director
Divisi
and Engineering Response
Office of Inspection and Enforcement
Technical Contact:
J. C. Stone, IE
(301) 492-9044 Attachments:
1.
List of affected plants as identified by Atwood & Morrill
2.
List of Recently Issued IE Information Notices
Attachment 1
IN 86-81 September 15, 1986 ATWOOD & MORRILL CO., INC.
Main Steam Isolation Valves
Furnished With External Closing Springs
Manufactured by Duer Spring & Manuf. Co.
PWR UNITS
Utility
Duke Power Co.
Duke Power Co.
Duke Power Co.
Duke Power Co.
Houston Lighting
& Power
South Carolina
Elec & Gas
Station
Catawba 1 & 2 i
McGuire 1 & 2 Perkins 1, 2, & 3 Cherokee 1, 2, & 3 South Texas
Project 1 & 2
Virgil Summer 1
Quantity and Valve Size
8 34-inch
8 32-inch
12 32-inch Units Cancelled
12 32-inch Units Cancelled
8 32-inch
3 32-inch
Bellefonte 1 & 2 Sequoyah 1 & 2 Watts Bar 1 & 2
8 32-inch
8 32-inch
8 32-inch
Attachment 1
IN 86-81 September 15, 1986 ATWOOD & MORRILL CO., INC.
Main Steam Isolation Valves
Furnished With External Closing Springs
Manufactured by Duer Spring & Manuf. Co.
BWR UNITS
Utility
Boston Edison
Cleveland Elec.
Illuminating
Detroit Edison
Georgia Power
Gulf States Util.
Houston Lighting
& Power
Illinois Power
Jersey Central
Power & Light
Mississippi Power
& Light
Niagara Mohawk
Power Corp.
Northern States
Power Co.
Pennsylvania
Power & Light
Philadelphia
Electric
Philadelphia
Electric
Public Service
Elec & Gas
Station
Pilgrim 1!
Perry 1 &12
Enrico Fermi 2
Hatch 1
River Bend 1
Allens Creek 1 Clinton 1
Oyster Creek 1
Grand Gulf 1 & 2
Nine Mile Point 1
Monticello
Susquehanna 1 & 2 Limerick 1 & 2 Peach Bottom 2 & 3 Quantiy & Valve Size
8 20-inch
16 26-inch
8 26-inch
8 24-inch
8 24-inch
8 24-inch
Unit cancelled
8 24-inch
4 24-inch
16 28-inch
2 24-inch
8 18-inch
16 26-inch
16 26-inch
16 26-inch
16 26-inch Unit 2 cancelled
Hope Creek 1 & 2
Attachment 1
IN 86-81 September 15,
1986 ATWOOD & MORRILL CO., INC.
Main Steam Isolation Valves
Furnished With External Closing Springs
Manufactured by Duer Spring & Manuf. Co.
BWR UNITS
Utility
Station
Browns Ferryl1, 2,
& 3i
Hartsville AX, A2, B1 & B2
%
Quantiy & Valve Size
24 26-inch
32 26-inch Units B1 & B2 Cancelled
Phipps Bend 1 & 2
16 26-inch
Units cancelled
4 I%1-1
Attachment 2
September 15, 1986
LIST OF RECENTLY ISSUED
IE INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issue
Issued to
86-80
86-79 Unit Startup With Degraded
9/12/86
High Pressure Safety Injection
System
Degradation Or Loss Of
Charging Systems At NWR
Nuclear Power Plants!Using
Swing-Pump Designs l
Scram Solenoid Pilot'Valve
(SSPV) Rebuild Kit Problems
9/2/86
9/2/86
86-78
86-77 Computer Program Error Report 8/28/86 Handling
86-76
86-75
86-74 Problems Noted In Control
8/28/86
Room Emergency Ventilation
Systems
Incorrect Maintenance
8/21/86
Procedure On Traversing
Incore Probe Lines
Reduction Of Reactor Coolant 8/20/86 Inventory Because Of Misalign- ment Of RHR Valves
Recent Emergency Diesel
8/20/86
Generator Problems
Failure 17-7 PH Stainless
8/19/86
Steel Springs In Valcor
Valves Due to Hydrogen
Embrittlement
All power reactor
facilities holding
All power reactor
facilities holding
All BWR facilities
All power reactor
facilities holding
nuclear fuel man- ufacturing facilities
All power reactor
facilities holding
All power reactor
facilities holding
All BWR facilities
All power reactor
facilities holding
All power reactor
facilities holding
86-73
86-72 OL = Operating License
CP = Construction Permit