ML19262A519
| ML19262A519 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 07/10/1978 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| IEC-78-13, NUDOCS 7911120557 | |
| Download: ML19262A519 (5) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 July 10, 1978 IE Ci cular 78-13 IN0PERABILITY OF SERVICE WATER PUMPS Description of Circumstances:
On January 11, 1978, Salem Generating Station Unit No.1, a 4-loop Westinghouse PWR with once-through cooling located on the Delaware River, experienced high strainer differential pressures and the loss of four of six installed service water pumps within a period of approximately thirty minutes. At the time of this occurrence, the river surface was covered with a layer of frazil (slush) ice to an unknown depth.
Each service water pump discharge is equipped with an R. P. Adams VDWS-68 automatic self-cleaning strainer. The indication of failure was high strainer differential pressure. Subsequent investigation showed that each of the four strainers had broken shear pins in the backwash shaft which caused the self-cleaning feature to become inoperable. The internals of the strainers revealed no unusual debris which could have caused differential pressures high enough to shear the pins.
Each service water pump takes suction near the bottom of individual bays in the intake structure.
Examination of the bays revealed that silt had accumulated to significant heights between the traveling screen and pump The suctior in each of the bays associated with failed strainers.
combine. effects of high silt " walls," low river water level, and the surfacc. ice, probably caused the pump suction to receive only ice-entrained water. This mixture then caused the strainers to clog and shear the backwash shear pins due to the high differential pressures.
By the time the strainers were opened for inspection, the ice had melted.
The safety significance of this event stems from the potential, under a unique set of environmental circumstances, for a complete loss of service water.
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IE Circular No. 78-13 July 10,1978 Corrective actions included the establishment of a periodic surveillance program to ensure that silt levels in the service water bays do not reach a level sufficiently high to cause recurrence of this event.
Holders of operating licenses or construction permits for power reactors who receive this Circular should review the service water design and postulated conditions in the ultimate heat sink to ensure that a similar combination of surface ice, water level, and forebay silting could not If such condi-precipitate inoperability of the service water system.
tions are credible, a program to nonitor the conditions at the service water intake structure should be implemented and procedures established for corrective action to be taken under normal and emergency conditions.
No written response to this Circular is required.
If you require additional information regarding this matter, contact the Director of the appropriate NRC Regional Office.
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IE Circular No. 78-13 July 10, 1978 LISTING 0F IE CIRCULARS ISSUED IN 1978 Circular Subject Date Issued To No.
of Issue 78-01 Loss of Well Logging 4/5/78 All Holders of Source Well Logging Source Licenses 78 ';2 Proper Lubricating Oil 4/20/78 All Holders of for Terry Turbines Reactor OLs or cps 78-03 Packaging Greater Than 5/12/78 All Holders of Type A Quantities of Reactor Ols, cps, Low Specific Activity Fuel Cycle, Radioactive Material Priority I Material for Transport and Waste Disposal Licenses 78-04 Installation Error That 5/15/78 All Holders of Could Prevent Closing of Reactor OLs or Fire Doors cps 78-05 Inadvertent Safety Injection 5/23/78 All Holders of During Cooldoan Reactor OLs or cps 78-06 Potential Common Mode 5/23/78 All Holders of Flooding of ECCS Equipment Reactor OLs or Rooms at BWR Facilities cps 78-07 Damaged Components of a 5/31/78 All Holders of Bergen-Paterson Series Reactor OLs or 25000 Hydraulic Test cps Stand 78-08 Environmental Qualification 5/31/78 All Holders of of Safety Related Equipment Reactor OLs or at Nuclear Power Plants cps 78-09 Arcing of General Electric 6/5/78 All Holders of Company Size 2 Contactors cps Enclosure Page 1 of 2
IE Circular No. 78-13 July 10, 1978 LISTING 0F IE CIRCULARS ISSUED IN 1978 Circular Subject Date of Issued to No.
Issue 78-10 Control of Sealed 6/14/78 All Medical Sources Used in Licensees in Radiation Therapy Categories G and G1 78-11 Recirculation M-G 6/15/78 All Holders of Set Overspeed Stops BWR OLs or cps 78-12 HPCI Turbine Control 6/30/78 All Holders of Valpe Lift Rod Bending BWR OL's or cps I,r except as listed in Encl. 2 Enclosure Page 2 of 2
July 10, 1978
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IE Circular No. 78-13 INOPERABILITY OF MULTIPLE SERVICE WATER PUMPS Distribution MAIL STOP L. V. Gossick, ED0 MNBB-6209 J. R. Shea, DIR., 0IP MNBB-8103 J. J. Fouchard Acting Dir., PA MNBB-3709 N. M. Haller, Dir., MPA MNBB-12105 R. B. Minogue, Dir., SD NL-5650 C. V. Smith, Dir.. NMSS SS-958 S. Levine, Dir., RES SS-ll30 E. G. Case, Acting Dir., NRR Phil-428 R. S. Boyd, Dir., DPM:NRR Phil-268 V. Stello, Dir., DOR:NRR Phil-542 D. G. Eisenbut, Asst. Dir., S/P: DOR:NRR Phil-266 W. R. Butler, Chief, PSP:;!.90R:NRR Phil-416 B. K. Grimes, Asst. Dir., E/P:?OR:NRR Phil-370 R. J. Mattson, Dir., DSS:NRR Phil-202 H. R. Deeton, Dir., DSSEA:NRR Pnil-174 R. F. Fraley, ACRS H-1016 G. W. Kerr, Asst. Dir., SA:SP MNBB-7210A E. Volgenau, D:IE J. G. Davis, DD:IE E. L. Jordan, X00S:IE G. H. Smith, PAT:ROI:IE R. C. Paulus, X005:IE L. N. Underwood, X00S:IE (Orginal)
H. D. Thornburg, RCI:IE W. Reinmuth, RCI:IE
.. C. Moseley, ROI:IE R. W. Woodruff, ROI:IE J. H. Sniezek, ROI:IE L. B. Higginbotham, Acting Dir., FFMSI:IE L. J. Cunningham, Acting Asst. Dir., FFMSI:IE E. M. Howard, SI:IE L. I. Cobb, X0MA:IE R. W. Woodruff, ROI:IE IE Files NRC Central Files IE Reading Files Mike Atsalinos, DSB:TIDC:ADM Phil-050 U. S. Department of Energy ATTN:
R. S. Brodsky, Assistant Director for Reactor Safety and Computation Division of Naval Reactors Washington, D. C.
20545 U. S. Department of Energy ATTN:
H. Hollister, Director Division of Operational and Environmental Safety Washington, D. C.
20545