ML20096G258

Special Rept 92-05:on 920502,listed Locs Entered Due to Leak in High Pressure Fire Protection Piping Sys.Caused by Misalignment of Pipe in Slip Joint Bell Connector.Line Repaired & Sys Realigned to Normal on 920509

ML20096G258
Person / Time
Site:	Sequoyah
Issue date:	05/18/1992
From:	Joshua Wilson TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
92-05, 92-5, NUDOCS 9205260005
Download: ML20096G258 (4)

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l J L Wdson vo eres,am-t. Se rr i:Afbeemrunt May 18, 1992 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Centlemen:

In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority )' 50-328 SEQUOYAH NUCLEAR PLANT (SQN) - UNITS 1 AND 2 - FACILITY OPERATING LICENSES DPR-77 AND DPR HIGH-PRESSURE FIRE PROTECTION (HPFP) SYSTEM INOPERASILITY - SPECIAL REPORT 92-05 The enclosed special report provides details concerning the inoperability of the fire suppression water system in the condenser circulating water intake pumping station. This condition was initially reported by telephone notification at 1930' Eastern daylight time on May 2,1992, and by f acsimile i dated May 4, 1992. This report is being made in accoriance with Techni,. cal Specification 3.7.11.1 Action Statement (b)(2)(c).

If you have any questions concerning this submittal, please telephone

.M. A. Cooper at (615) 843-8924.

Sincerely.

(p)L~

L. Wilson Enclosure cc: See page 2 i

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,9205260005.920518

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ADOCK 05000327 PDrt k[ f

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-U.S.-Nuclear Regulatory Commission Page-2 May 18, 1992 cc (Enclosure):'

Mr. D. E. LaBarge, Project Manager- l U.S. Nuclear Regulatory Commission  !

One White F11. , North 11555 Rockvilla like '

Rockville, Maryland 20852  !

i NRC Resident Inspector  ;

Sequcyah Nuclear Plant 2600 Ig9u'rerry Road Soddy-Daisy, Tennessee 37379 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission-Region-II 1101 Mariette Street, NW, Suite- 2900 1 Atlanta, Georgia 30323

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ENCLOSURE SEQUOYAH NUCLEAR PLANT (SQH)

SPECIAL REPORT 92-05 14-DAY FOLLOW-UP REPORT Description of Condition On May 2, 1992, at 1930 Eastern daylight time (EDT), with Unit 1 in Mode 2 returning to power from a forced outage, and Unit 2 in Mode 5 recovering from a Cycle 5 refueling outage, SQN entered Limited Conditions for Operation (LCO) 3.7.11.1 and 3.7.11.4.

LCOs 3.7.11.1 and 3.7.11.4 were entered because of a leak in the high-prassure fire protection (HPFP) piping system, causing the fire-hose stations required by technical specification (TS) in the condenser circulating water (CCW) intake pumping station to be declared inoperable.

The leak was detected when water was noticed flowing out of the ground in front of the CCW intake puniping station. The site Fire Protection supervisor and the Technical Support engineer were notified, and they subsequently concluded that the leak was originating from a 10-inch, cast-iron HPFP line. Isolation of the leak disrupted the supply of HPFP water to the CCW intake pumping station fire-hose stations, which are listed in fire-hose station LCO 3.7.11.4 as being required to be operable. The line was isolated to stop the leak and to permit maintenance personnel to repair the leaking pipe joint. The normal supply flow paths for the remaining fire suppression water system were also affected because of the off-normal alignment. LCO 3.7.11.1 was therefore appropriately entered, pause of Condition The pipe leak was determined to be in a supply line slip joint connection and has been attributed to the misalignias.7t of the pipe in the slip joint bell conncetor. The reason fr>r the pipe misalignment is indeterminate. The cast-iron pipe is connected from one section to another by simply inserting the male end into the bell or hub end of the next section. A rubber gasket inserted in the bell seals the joint, and a seal ring and tie rod arrangement mainta!.ns the joint. The fire protection piping in general is systeratically anchored by means of concrete kickers at the turns and mechanical connecting rods at the valves and

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I hydrants to prevent movement and disconnection because of water hammer and the normal force of high pressure and high volume of ,

water necessary for fire protection. Ilowever, it was found that the affected section of piping was not installed according to the general installation requirements. The piping was installed in the 1977-78 time frame and, for this reason, it could not be datormined why the piping was not installed in accordance'with general installation requirements.

This-particular section of pipe was installed approximately 15 yrara ago and was buried less than the recommended 3-foot depth.

T1.e pipe was approximately 18 inches under the surface of the ground. Ileavy equipment has periodically been moved in this area and is suspected to have contributed to the pipe becoming misaligned to the point that the gasket was not effective in containing the high-pressure water surges. The pipe van also not adequately inserted into the bell end of the adjoining pipe, as normally required and recommended by construction practices.

It could not be determined if the potential for a similar situation exista elsewhere in the llPFP piping. No additional similar cases were identified from review of in-house experience and maintenance history. Further, the condition is self-revealing.

Corrective Actions Actions were immediately taken to isolate the leaking portion of the piping and to establish a backup suppression system for the inoperable TS hose stations within one hour, as required by Action Statement 3.7.12. 4(a). This was accomplished by routing fire hoses into the CCW intake pumping station from a nearby charged yard hydrant. A backup fire suppression system, as required by TS Action Statement 3.7.11.1(b) (1), was established within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to augment the off-normal alignment of the remaining fire suppression system by positioning a fire pumper at the plant discharge station and tying into the yard fire protection piping. The pumper was capable of taking suction from the discharge canal.

The line was repaired, the system was realigned to normal, and LCOs 3.7.11.1 and 3.7.11.4 were exited at 2300 EDT on May 9, 1992.

Commitmenta None.

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