ML20063K622
| ML20063K622 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 02/14/1994 |
| From: | Fenech R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9403010245 | |
| Download: ML20063K622 (6) | |
Text
_m l/.
'I IUA
....z.-_
Tennessee Vancy Auttenty. Post Othce Box 2(XX), Soddy Dasy. lennessee 37379-2000 Robert A. Fenech Vce Presdent, Sequoyah Nuclear Plant February 14, 1994 U.S. Nuclear Regulatory Commission ATIN: Document Control. Desk
[
Washington, D.C. 20555 Gentlemen:
- l' In the Matter of
)
Docket No. 50-327 Tennessec Valley Authority
)
SEQUOYAll NUCLEAR PLANT (SQN) - REQUEST FOR RELIEF FROM THE REQUIREMENTS OF-THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) CODE SECTION XI -
HYDROSTATIC PRESSURE TEST REQUIREMENTS
.[
Enclosed'is a request for relief from the ASME Code,Section XI, hydrostatic test requirements involving SQN's main steam system for Unit 1.
This exemption is associated with a plant modification to replace a flow control valve (1-FCV-1-17) in the steam supply piping to the turbine-driven auxiliary feedwater pump.
The enclosed request for relief concerns a postmodification testing requirement contained in paragraph IWA-5214-(Item c) of the ASME Boiler' and Pressure Vessel Code,Section XI, 1977 Edition, Summer 1978 Addenda.
TVA has determined that conformance with this code requirement would result'in hardship and unusual difficulties with no compensating increase in_the level of quality and safety. TVA proposes to perform alternative testing that is considered to be an adequate demonstration of leak.
tightness for the modified main steam piping.
Consequently, the proposed i
code exemption is being submitted in accordance with 10 CFR 50.55a(a)(3)~
and 10 CFR 50.55a(g)(5)(iii)-.
f 230041 1
9403010245.940214'
'i
/
PDR ADOCK 05000327:
y{
(.
P PDR A
1 i
e 1
t U.S. Nuclear Regulatory Commission Page'2 February 14, 1994 provides a description of the modification. Enclosure 2 provides the request for relief. Enclosure 3 provides a TVA commitment.
associated with a proposed alternative test.
The modification to the main steam piping was performed during the Unit 1-Cycle 6 refueling outage. TVA requests that the NRC response be provided before the start of the Unit 1 Cycle 7 refueling outage (this will be the
- last opportunity for scheduling and scoping test activities before the end of the first 10-year in-service inspection interval for Unit 1).
The Unit 1 Cycle 7 refueling outage is currently scheduled to begin September 1, 1995.
Please direct questions concerning this issue to D. V. Goodin at
{
(615) 843-7734.
Sincerely,
,I,#}$h Ab b pf - h I' Robert A. Fenech j
Enclosure cc (Enclosure):
Mr. D. E. LaBarge, Project Manager
- U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 l
NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Regional Administrator U.S. Nuclear Regulatory Commission Region II j
101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711
-,, - -.. =
v 5
h ENCLOSURE 1
[
Degnt;iption of_the Modificatlan A four-inch-diameter, flow control valve (FCV-1-17) located in the steam-supply piping to the turbine-driven auxiliary feedwater pump was replaced with a new valve because of valve bonnet leakage. The piping on either side of Valve FCV-1-17 is An rican Society of Mechanical. Engineers, Code l
Class 3 piping. This modification involved four new welds; two on the upstream side of Valve FCV-1-17 and two on the downstream side.
s
)
+
I t
I 6
l
'i
.]
l j
l
b ENCLOSURE 2 REQUEST FOR RELIEF System:
Main steam Drawings:
47W803-2 and Final Safety Analysis Report Figure 10.4.7-12 Component:
Valve 1-FCV-1-17 and main steam supply piping to the turbine-driven auxiliary feedwater pump (TDAFWP)
American Society of Mechanical Engineers Class:
3 Function:
Valve 1-FCV-1-17 and the associated piping provide a flow path from the main steam header to the TDAFWP.
Subject of Relief:
Hydrostatic pressure testing following repair or replacement.
Code Requirements: The test pressure and temperatures, subsequent to the component repair, replacement, or the alteration of a system, shall conform with the system test pressure and the temperature specified in IWB-5000, IWC-5000, and IWD-5000 as applicable to the_ system that is altered or that contains the repaired or replaced, or altered components (IWA-5214[b]).
Basis for Relief:
Following the replacement of Valve 1-FCV-1-17 and a small length of piping on both sides of the. valve, a hydrostatic pressure test was-attempted.
It was discovered that the hydrostatic pressure testing of the downstream portion of the piping is not possible because of the inability to establish adequate test boundary isolation.
The trip and throttle valve, Valve 1-FCV-1-51, is the only isolation j
valve in the pressure test boundary. The piping-configuration and design of Valve 1-FCV-1-51 consist of four leak-off lines, two high pressure, which are routed j
to the turbine, and two low pressure that'are routed to a
~
drain tank.
These. leak-off lines provide an unisolable flow path from within the valve body to the turbine and drain tank, preventing the establishment'of the required v
hydrostatic test pressure boundary. Additionally, test-equipment is not available that has the capacity to make up the amount of leak-off loss for maintaining a ' constant i
P v
r e
a we r we
- n test pressure.
Even if additional capacity were i
available, it would not be prudent to attemptLto achieve hydrostatic test pressure since the high pressure leak-off lines discharge to the turbine. Discharging water into the turbine would result in corrosion to the turbine j
internals.
In addition, the configuration of the piping I
to Valve 1-FCV-1-51 does not permit the installation of a temporary blank.
A nondestructive examination (NDE) was performed on each weld.in accordance with ANSI B31.7 Construction Code requirements. The NDE included pre-and post-welding visual exams and a liquid penetrant exam of the final welds. These exams provide assurance of weld integrity.
In addition, the welds on the upstream side-of Valve FCV-1-17 have received a hydrostatic pressure test-and VT-2 examination in accordance with the ASME code requirements. The piping-welds on the upstream side were found to be acceptable.-
Al te rna te Testing:
In lieu of a hydrostatic pressure test, an in-service system pressure test at nominal operating pressure I
(approximately 1,005 pounds per square inch gauge) and temperature (approximately 547 degrees Fahrenheit) in I
conjunction with a VT-2 visual examination will be performed on the downstream welds associated with the replacement of Valve 1-FCV-1-17.
This test will be performed during Unit I restart while the unit is in Mode 3.
i i
l I
i i
1 1
i j
1
~u
~
I i
y- -
j ENCLOSURE 3
~
TVA Commitment In lieu of a hydrostatic pressure test, a system in-service pressure test at nominal operating pressure and temperature in conjunction with a VT-2 visual examination will be performed on the downstream welds associated
- i with the replacement of Valve 1-FCV-1-17.
This test will be performed-during. Unit i restart while the unit is in Mode 3.
.J
. f I
i k
1
' l i
i i
4 i
- )
6
. I P
.. ~..
_,.,s.
,,