ML17252A933

Letter Reporting a 01/01/1974 Condition Relating to Observance of Two 5 Inch Diameter Electrical Penetrations Through the Turbine Building to the Reactor Building Were Open - Dresden Units 2 and 3

ML17252A933
Person / Time
Site:	Dresden
Issue date:	01/11/1974
From:	Worden W Commonwealth Edison Co
To:	O'Leary J US Atomic Energy Commission (AEC)
References
WPW Ltr. #27-74
Download: ML17252A933 (3)

Text

Commo.Aalth Edison "'* Cy~

One First ~Za1 Plaza. Chicago. 111,inois Regulatorj FUe Address Reply to: Post Office Box 767 Chicago, Illinois 60690 WPW Ltr. 127-74 Dresden Nuclear Power Sta ti on R_. R. 41 Morris, IL

.January 11,

.J. F. O'Leary, Director Directorate of Licensing U.S. Atomic Energy Commission Washginton, D.c. 20545

SUBJECT:

LICENSES DPR-19 & 25, DRESDEN NUCLEAR POWER STATION, UNITS 2 & 3, SECTION 6.6.B.2 OF THE TECHNICAL SPECIFICATIONS

References:

1) Notification of Region Ill of AEC Regulatory Operations Telephone: Mr. Maura, 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />, January 2, 1974 Mr. Maura, 1445 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.498225e-4 months <br />, January 3, 1974 Mr. Maura, 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />, January 4, 1974 Telegram: Mr. Keppler, 1625 hours0.0188 days <br />0.451 hours <br />0.00269 weeks <br />6.183125e-4 months <br />, January 3, 1974

Dear Mr. O'Leary:

This letter is to report a condition relating to the operation of the units at about 2030 hours0.0235 days <br />0.564 hours <br />0.00336 weeks <br />7.72415e-4 months <br /> on January-1, 1974. At this time it was observed that two 5 inch diameter electrical penetrations through the turbine building to the reactor. building wall were open. This condition appeared to be contrary to section 3.7.C.l of the Technical Specifications which requires that the Standby Gas Treatment System be capable of maintaining a t inch of water vacuum on the reactor building. Subsequent testing, however, verified that during the period the penetrations were open the Standby Gas Treatment System would have been capable of meeting the requirements of section 3.7.C.l.

PROBLEM While conducting a plant tour on Unit #2 it was noted that a S inch diameter electrical penetration between the reactor building and turbine building was open. The penetration was opened to route one 3/8 inch cable for torus to drywell vacuum breaker "open" alarms in the control room. Inspection of the similar penetration on Unit D3 revealed the same situation. At the time of discovery both units were operating with power at 704 MWe and638MWe on Units U2 and 13 respectively. Operating Department personnel immediately made a temporary seal for both penetrations and at 2142 hours0.0248 days <br />0.595 hours <br />0.00354 weeks <br />8.15031e-4 months <br /> started ths Standby Gas Treatment System to verify the capability of maintaining secondary containment (\ inch of water vacuum). The test was successful.

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. J. F. O'Leary e *January 11. 1973 On January 3, 1973 secondary containment testing was conducted

• with the temporary seal on the electrical penetrations open to determine if secondary containment could have been maintained prior to the discovery of the open penetrations. Testing at this time indicated that a ~ inch of water vacuum could not be maintained. This test failure was reported in the referenced telegram to Mr. Keppler. Later the same day the two penetrations were pet111anently sealed with silicone sealant 11RTV. Further investigation into the testing problem revealed that the reactor building ventilation isolation valves had not been isolated as specified by the test procedure. Consequently, outside air was being drawn into the reactor building by the Standby Gas Treatment Syste~ This infiltration flow is not part of the secondary containment test.

Two similar spare penetrations were opened the following day, January 4, 1974, and another secondary containment test conducted. The ventilation isolation valves were isolated as would be the case if a high radiation level were monitored in the reactor building. This time the reactor building did maintain the required t inch of water vacuum. A test manometer was utilized on the four reactor building walls to determine the building D/P.

The readings were: north wall - 0.26" H20 east wall - 0.26" H20 south wall - 0.24" H20 west wall - 0.27" H20 avg - 0.2575" H20 INVESTIGATION Investigation*into the open penetrations revealed that the cables were routed by contractors July 1, 1973. At that time the* contractors did not have any silicone sealant 11 RTV11 avaliable. At that time, as a. temporary measure, Johns-Manville Duxseai was used. Somehow. during the six month interval, the duxseal became dislodged.

CORRECTIVE ACTIONS Off January 3, 1974, the two electrical penetrations were permanently sealed.

EVALUATIONS This situation did not endanger public health or safety.

Because it was initially believed that secondary containment could not be maintained with two open penetrations the deviation was reported as an abnormal occurrence requiring reporting in 10 days. However, upon additonal testing it was determined that secondary containment could still have been maintained, thus negating the reporting requirement.

Consequently this deviation is being reported as a 10 day letter even though it is not required.

J. P. O'Leary e ... Qi January 11, 1974 To minimize the possibility of a recurring situation, the respon-sible contractor has been made aware, in writing, of the seriousness of his failure to make a permanent seal or make periodic inspections of his tempor-ary seal. Also, the conpany's cognizant engineer following this particular job has bad the importance of secondary containment explained to him by station management. Continued operation during the six month interval has been justified and with the permanent sealing of the two penetrations the secondary containment has been restored to a normal condition.

Sincerely, w.~.w~.

w. P. Worden Superintendent Dresden Nuclear Power Station WPW/slb