ML19338C999
| ML19338C999 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/21/1975 |
| From: | Stephenson B COMMONWEALTH EDISON CO. |
| To: | |
| References | |
| 259-75, NUDOCS 8009150572 | |
| Download: ML19338C999 (2) | |
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Commom.. Ith Edison i
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/ One First Natawat Plaza. Chicago Illinois
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BBS Ltr. #259-75 I-Dresden Nuclear Power Station 0
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April 21, 1975 n
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Mr. James G. Keppler, Regi5dsl Director
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Directorate of Regulatory Operation-Region III U. S. Nuclear Regulatory Coumission 799 Roosevelt Road Glen Ellyn, Illinois 60137 SUILTECT: REPORT OF ABNORMAL OCCURRDJCE PER SECTION 6.6.A OF THE TEHNICAL SPEIFICATIONS CORE SPRAY VENT LINE LEAK
References:
- 1) Regulatory Guide 1.16 Rev.1 Appendix A
- 2) Notification of Region III of U. S. Nuclear Regulatory Comission Telephone:
P. Johnson, April 94, 1975 at 1045 hours0.0121 days <br />0.29 hours <br />0.00173 weeks <br />3.976225e-4 months <br /> Telegram:
J. Keppler, April 14, 1975 at 1325 hours0.0153 days <br />0.368 hours <br />0.00219 weeks <br />5.041625e-4 months <br /> Report Nu=ber: 50-10/1975-6 Report Date: April 18, 1975 Occurrence Date: April 12, 1975 Facility: Dresden Nuclear Power Station, Morris, Illinois IDENTIFICATION OF OCCURRENCE This occurrence constitutes an abnomal degradation of a boundary designed to contain radioactive materials, in which the three quarter (3/4) inch core spray systect vent line to the poison system primary steam header developed a pin-hole leak in a socket weld at a pi p -coupling, joint.
CONDITIONS PRIOR TO OCCURRENCE l
Prior to the occurrence the unit was in the RUN mode at a themal power of 50 MWt, preparing to roll the main turbine. The sphere was in an airborne condition.
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. 'Nr. James G. Keppler April 21, 1975 DESCRIPPION OP OCCURRENCE At 0030 on April 12, the Unit 1 sphere was placed on an airbcrne status, with fitl1 face mask requirements. At approximately 0730 a sphere inspection was begun to detemine the source of the airborne condition. At 0930 the leak in the core spray system vent line was discovered and innediately isolated. At 1 45 on April 15, the sphere was removed from the airborne status.
DESIGNATION OF APPARENP CAUSE OF OCCURRENCE (Eqnignent Failure)
The cause of the occurrence was failure of the pipe-to-coupling socket weld, resulting in a pinhole leak. The caitse of the failure was detemined to be a slag inclusion in the weld and poor adhesion of the weld material.
ANALYSIS OF OCCURRENCE The health and safety of the public and plant personnel were not endangered as a result of this occurrence. All leakage resulting from this occurrence was contained within the primary containment boundary, monitored, and released only through the facility radwaste system or ventilation stack. During the occurrence no release limits were exceeded. Additionally, the sphere air was continuously monitored for airborne radioactivity concentrations and respiratory protective equipnent was prescribed in a timely manner for personnel protection.
CORRECTIVE ACTICE On April 17, the affected coupling cnd short sections of pipe on each side -
of the coupling were removed and replaced. Since the weld failure was strictly mechanical in nature and not related to stress or corrosion cracking, no additional corrective action is required.
PAILURE DATA A review of Unit 1 incident reports indicate that.this is the first failure of a socket weld in small diameter (< 2") piping. The failed weld was in line CS-116-3/4
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B. B'."Ste son Superintendent BBS:RFJ smp
?ile/NRC
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