Information Notice 1992-15, Failure of Primary Systems Compression Fitting
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C.
20555
February 24, 1992
NRC INFORMATION NOTICE 92-15: FAILURE OF PRIMARY SYSTEM COMPRESSION FITTING
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice
to alert addressees to problems that could result from the inadequate installa- tion of compression fittings. It is expected that recipients will review the
information for applicability to their facilities and consider actions, as
appropriate, to avoid similar problems. However, suggestions contained in this
information notice are not NRC requirements; therefore, no specific action or
written response is required.
Description of Circumstances
On November 23, 1991, operators at the Oconee Nuclear Station, Unit 3, detected
unidentified leakage of approximately 70 gallons per minute (gpm) from the
reactor coolant system (see licensee event report 50-287/91-008). The licensee
shut down the reactor in an orderly manner. The licensee observed a maximum
leak rate of approximately 130 gpm.and found that a total of 87,000 gallons of
reactor coolant was discharged to the containment before the reactor coolant
system could be depressurized.
On November 25,1991, personnel entered the
Unit 3 containment building and determined that the source of the leak was a
separated compression fitting on a 3/4-inch diameter instrument line. The
instrument line is part of the reactor vessel level indication system (RYLIS).
The leak occurred where the line connects to the top of the "An steam generator
hot leg. The tubing separated from the fitting next to a 3/4-inch flow
restriction valve.
The licensee inspected the fitting and determined that the probable cause of
the tubing separating (or pulling out) was that the nut had not been suffi- ciently tightened onto the compression fitting. The nut on the fitting
appeared to have been tightened approximately 1/2 turn less than was recom- mended by the fitting manufacturer, the Parker-Hannifin Corporation. The gap
between the nut and the fitting was greater than the maximum nominal value
furnished by the vendor.
The licensee inspected the tubing at the failed
fitting and determined that the diameter reduction at that location was much
less than the diameter reduction for the tubing in another fitting that had not
failed. Based on these inspections the licensee determined that the ferrule
9202190038 2).
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IN 92-15 February 24, 1992 was not adequately compressed into the tubing. The licensee reconfigured the
instrument line and replaced the valve, the 3/4-inch instrument tubing, and the
fittings on the hot legs of both steam generators.
The licensee inspected all of the fittings on instrument tubing connected to
the Unit 3 primary system. The licensee examined the 264 Parker-Hannifin
fittings in the primary system using nominal expected gap values furnished by
Parker-Hannifin as an acceptance criteria.
However, Parker-Hannifin does not
consider the gap to be a critical dimension. The licensee also inspected the
191 Swagelock fittings in the primary system using gap inspection gages fur- nished by Swagelock. The licensee found that approximately 27 percent of both
types of fittings appeared to have gaps outside of the nominal range. The
licensee attempted to tighten these fittings to reduce the gaps to the values
recommended by the manufacturers. However, a small percentage of the
Parker-Hannifin fittings could not be tightened to meet the vendor's nominal
gap values.
The licensee accepted these fittings as-is based on the judgement
of the instrument technicians that the connections could not be tightened
further without damaging the tubing or connections, and on an engineering
evaluation made after disassembling and inspecting one of the questionable
fittings.
Discussion
This event reemphasizes the importance of making successful connections in
instrument tube lines.
Fitting-nuts-on compression-fittings-must-be tightened- sufficiently to ensure that the fitting has been adequately seated. According
to the licensee, they have previously experienced problems with inadequate
assembly of 3/4-inch fittings due to the high torque required to properly seat
the fittings. The licensee's modifications to the RVLIS eliminated the use of
3/4-inch fittings on these lines.
While conducting inspections at other facilities, the NRC and licensees have
noted other problems with the installation of compression fittings, including
the following:
°
Interchanging hardware from different manufacturers
o
Installing the ferrules backwards in fittings, or omitting the ferrules
Failing to bottom the tubing on the shoulder of the fitting
o
Using tubing that is not cut square or that is burred, scratched, deformed, or contaminated with dirt, oil, or other contaminants
o
Failing to adequately tighten the fitting to the finger-tight position
before making additional turns from the finger-tight position
o
Failing to ensure that the tubing has not moved back out of the fitting
when the nut is tightened
These problems indicate that licensees' procedures for installing compression
fittings may not provide adequate guidance to avoid improper assembly of the
IN 92-15 February 24, 1992 fittings. Procedures may also fail to address the vendor's installation
recommendations, not only for the initial installation of connections, but also
for disconnecting and retightening fittings during normal maintenance activities.
In addition, personnel who make compression fitting connections may not be
adequately trained.
Related Generic Communications
The NRC staff has previously issued Information Notice 84-55 (including Supple- ment 1), "Seal Table Leaks at PMRs," to address problems associated with
compression fitting failures.
This information notice requires
you have any questions about the
of the technical contacts listed
Reactor Regulation (NRR) project
no specific action or written response. If
information in this notice, please contact one
below or the appropriate Office of Nuclear
manager.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical contacts:
Joseph J. Lenahan, RII
(404) 331-4190
John R. Fair, NRR
(301) 504-2759 Attachment: List of Recently Issued NRC Information Notices
\\ch ent
-'11192-15
February 24. 1992
Page I of I
LIST OF RECENTLY
ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice ho.
Subject
Issuance
Issued to
92-14
92-02, Supp. 1
92-13
92-12
92-11
92-10
92-09
Uranium oxide Fires at Fuel
Cycle Facilities
Relap5/1od3 Computer Code
Error Associated with the
Conservation of Energy
Equation
Inadequate Control Over
Vehicular Traffic at
Nuclear Power Plant Sites
Effects of Cable Leakage
Currents on Instrument
Settings and Indications
Soil and Water Contamina- tion at Fuel Cycle Facil- ities
Irachytherapy Incidents
Involving Iridium-192 Wire
Used In Endobronchial
Treatments
Overloading and Subsequent
Lock Out of Electrical
Buses During Accident
Conditions
02/21/92
All fuel cycle and uranium
fuel research and development.
licensees.
02/18/92
All holders of OLs or CPs
for nuclear power reactors.
02/18/92
All holders of OLs or CPs
for nuclear power reactors.
02/10/92
All holders of OLs or CPs
TCA rucatar power reactors.
02/05/92 All uranium fuel fabrica- tion and conversion facil- ities..
01/31/92 All Nuclear Regulatory Cco.
mission (NRC) licensees
authorized to use
Iridium-192 for brachy- therapyl manufacturers and
distributors of irldium-192 wire for use in brachy- therapy.
01/30/92
All holders of OLs or CPs
for nuclear power reactors.
CL
- Operating License
- Construction Permit
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 2055
OFFICIAL BUSINESS
PENALTY FOR PRIVATE USE, $300
MAGS D MUS PAID
PERMIT No. 047
IN 92-15 February 24, 1992 fittings.
Procedures may also fail to address the vendor's installation
recommendations, not only for the initial installation of connections, but also
for disconnecting and retightening fittings during normal maintenance activities.
In addition, personnel who make compression fitting connections may not be
adequately trained.
Related Generic Communications
The NRC staff has previously issued Information Notice 84-55 (including Supple- ment 1), "Seal Table Leaks at PWRs," to address problems associated with
compression fitting failures.
This information notice requires no specd
you have any questions about the informat
of the technical contacts listed below or
Reactor Regulation (NRR) project manager.
fic action or written response. If
ion in this notice, please contact one
the appropriate Office of Nuclear
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical contacts:
Joseph J. Lenahan, RII
(404) 331-4190
John R. Fair, NRR
(301) 504-2759 Attachment:
List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
D/ ,P.y4R
- C/OGCB:DOEA:NRR
C0 o5s,')
CHBerlinger
0277491 02/13/92
- OCBtDOEA:N R*RII
AJKugler
JJLenahan
01/31/92
02/06/92
- RPB:ADM
TechEd
01/30/92
- RII
AFGibson
02/06/92
- D/DET: NRR
JERichardson
02/12/92
- EMEB:DET:NRR
JRFair
02/11/92
- C/EMEB:DET:NRR
JANorberg
02/11/92
- EMEB:DET:NRR
TLChan
02/11/92 DOCUMENT NAME: IN 92-15
IN 92-XX
February XX, 1992 fittings. These procedures may also fail to address the vendor's installation
recommendations, not only for the initial installation of connections, but also
the limitations in disconnecting and retightening fittings during normal
maintenance activities. In addition, the personnel who make the compression
fitting connections may not be adequately trained.
Related Generic Communications
The NRC staff has previously issued Information Notice 84-55 (including Supple- ment 1), "Seal Table Leaks at PWRs," that addressed problems associated with
compression fitting failures.
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact one
of the technical contacts listed below or the appropriate Office of Nuclear
Reactor Regulation (NRR) project manager.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical contacts:
Joseph J. Lenahan, RII
(404) 331-4190
John R. Fair, NRR
(301) 504-2759 Attachment: List of Recently Issued NRC Information Notices
Document Name: COMPRESSION FITTING IN/2
- SEE PREVIOUS CONCURRENCEI
D/DOEA:NRR
C/OGCB/
E
CERossi
CHBerl~t'dr
02/ /92
02/1 j92
- OGCB:DOEA:NRR*RII
AJKugler
JJLenahan
01/31/92
02/06/92
- RPB:ADM
TechEd
01/30/92
- RI I
AFGibson
02/06/92
- D/DET:NRR
JERichardson
02/12/92
- EMEB:DET:NRR
JRFair
02/11/92 C/EMEB:DET:NRR
JANorberg
02/11/92
- EMEB:DET:NRR
TLChan
02/11/92
IN 92-XX
February XX, 1992 Related Generic Communications
The NRC staff has previously issued Information Notice 84-55 (including
Supplement 1), "Seal Table Leaks at PWRK' that addressed problems associated
with compression fitting failures.
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation project manager.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts:
Joseph J. Lenahan, Region II
(404) 331-4190
John R. Fair, NRR
(301) 504-2759 Attachments:
1. List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
D/DOEA:NRR
CERossi
2/ /92 EMEB:DE :R
JRFair
2/ l /92 C/OGCB:DOEA:NRR
CHBerlinger
2/ /92 EMEB:DE, NRR
TLChant'@\\-
2/ i /92
- OGCB:DOEA:NRR
AJKugler
1/31/92 AP
-NRR
JA loerg
2/1t /92
- RPB:ADM
TechEd
1/30/92 v
/
D/D E
f
WOK
{-,dyvERic
5o
- RI I
JJLenahan
2/6/92
- RI I
AFGibson
2/6/92
IN 92-XX
February XX, 1992 This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation project manager.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts:
Joseph J. Lenahan, Region II
(404) 331-4190
John R. Fair, NRR
(301) 504-2759 Attachments:
1. List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
D/DOEA:NRR
CERossi
2/ /92 C/OGCB:DOEA:NRR
CHBerlinger
2/ /92 OGCB:DOEA:NRR
AJKug lerIAK
1/'&t /92
- RPB:ADM
TechEd
1/30/92 EMEB:DET:NRR
JRFair
2/ /92 RII fi i:
JJLenahan
2/ ( /92 EMEB:DET:NRR
TLChan
2/ /92 RII
AFGibso k"
2/6/92 C/EMEB:DET:NRR
JANorberg
2/ /92 D/DET:NRR
JERichardson
2/ /92
IN 92-XX
February XX, 1992 This information notice requires no specific action or written response.
If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation project manager.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: Joseph J. Lenahan, Region II
(404) 331-4190
John R. Fair, NRR
(301) 504-2759 Attachments:
1.
List of Recently Issued NRC Information Notices
D/DOEA:NRR
CERossi
2/
/92 EMEB:DET:NRR
JRFair
2/
/92 C/OGCB:DOEA:NRR
CHBerlinger
2/
/92 EMEB:DET:NRR
TLChan
2/
/92 OGCB:DOEA:NRR
AJKugler
2/
/92 C/EMEB:DET:NRR
JANorberg
2/
/92 RPB:AEC1
TechEd 11man 97
)130Pl
D/DET:NRR
JERicharcison
2/
/92 RII
JJLenahan
2/
/92 RII
AFGibson
2/
/92