ML18038B512
| ML18038B512 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry, Sequoyah  |
| Issue date: | 06/24/1988 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML18038B503 | List: |
| References | |
| NUDOCS 9511080203 | |
| Download: ML18038B512 (4) | |
Text
5N 157B Lookout Place JUICE 24 1%9 8+
pe U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Vashington, D.C.
20555 Gentlemen:
Zn the Hatter of Tennessee Valley Authority SEQUOYAH NUCLEAR PLANT (SQN)
SAFETY VALVES
)
Docket Nos. 50-327
)
50-328
- PERFORMANCE TESTING OF REACTOR ELK~~
AND
Reference:
TVA letter from J. A. Domer to E. Adensam, NRC, dated March 18, 1985 Enclosed is an update to the referenced lee.cer for SQN unit 2 as requested in the NRC/TVA April 29, 1988 meetin TVA vill evaluate t eva ua e
he effectiveness for unit 2 through compliance vith the technical specifications for'eactor coolant t
1 aka an sys em e
ge.
Enclosure cc:
See page 2
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Zf you have any ques ions, please telephone Kathy S. thitaker at (615) 870-7748.
Very truly yours, maize~
~l~'/'"
TENNESSEE VALLEY AUTHORIT J'Ju 3 ~ V..<
Original Signum >7 R.L. Gr'dhX R. Cridiey, Director Nuclear Licensing and
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i aegulatary AEEaic ~,i.=.. m i
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95ii080203 95ii03 PDR ADOCK 0500025'P P
ENCLOSURE PERFORCE TESTXHC OF.REACTOR RELXEF AND SAFETY VALVES SEQUOYAH (SQM) UNIT 2 The original design foc SQN included water-filled loop seals on bith the povec'-operated relief valves (PORV) and the safety/relief valves
(':./RV).
Reanalysis of the discharging piping loads after completion of the El esearch Institute (EPRI) relief valve test program indicated that n
o e
ectrxc caused b
th y
e discharge of the loop seal slug vere excessive.
TV/L decided to xca e
a loads eliminate the PORV loop seals (by rerouting of the piping), to drain the S/RV loop seals, and to install steam trim in the S/RVs.
The e modifications were implemented on unit 1 ducing the refueling outage aftec'uel cycle 2.
Subsequent to this modification on unit 1, high S/RV tail pipe temperatures vere observed that vere interpceted to indicate valve leakage past the seat.
To eliminate the leakage, TVA ceestablished the S/RV loop seals.
Aftec'valuating the options available to resolve the issue.
TVA implemented the changes (removing the PORV loop seals, d~ing the S/RV loop seals, and installing the steam trim in the S/RVs) on unit 2 during the refueling outage after fuel cycle 2.
modifications and additions vere mad t
th d
the discharge piping to reduce the S/RV flange loads in order to ceduce the likelihood of valve seat leakage.
As a contingency, modifications were installed to allow operation with a heated loop seal to reduce the t d
~
~
e ce e magna ude s ug xscharge pxpxng loads, heat t:.:ing and insulation were installed on the loop seal to maintain elevated fluid temperatures; and supports on the discharge piping vere added or modified to accommodate t.".e s1ug discharge loads.
The piping was qualified to loads predicted with the RELAPSIHO01 d
XP computec'odes.
Seat leakage during startup necessitated the cefilling an of the loop seals.
Xn August 1985, SQM units 1 and 2 entered ex ended shutdowns.
Unit 1 vas nearing completion of the refueling outage at the end of fuel cycle 3, and unit 2 vas in fuel cycle 3.
Duc'ing the extended shutdown, water trim vas installed in the unit 1 and unit 2 S/RVs in keeping vith the heated loop seal operation.
During heatup of unit 2 af tee the extended
- outage, S/RV seat leakage and pcoblems vith the loop seal temperature control occurred.
TVA then decided to reevaluate the options.
TVA nov plans to operate unit 2 vith drained loop seals and steam trim in the S/R s.
The piping vas designed for a heated loop seal discharge and is moce than adeouate for the steam discharge.
The piping ha" also b
a so een rigorously qualified to loads generated vith RELAP5/MOD1 and REPXPK for discharge of.
steam fcom the S/RVs (without PORV actuation) and foc steam discharge from the PORVs.
To eliminate the pcoblems with valve seat leakage, supports have been modified to reduce the S/RV flange loads to vithin those specified by Crosby Valve and Gauge Company (the valve manufacturer).
The valves have also been serviced and tested by Pyle Laboratories before installation.
1'