ML19340D927
| ML19340D927 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry, Hartsville, Phipps Bend  |
| Issue date: | 12/05/1980 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Parris H TENNESSEE VALLEY AUTHORITY |
| References | |
| NUDOCS 8101050588 | |
| Download: ML19340D927 (1) | |
Text
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o UNITED STATES NUCLEAR REGULATORY COMMISSION
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101 MARIETTA ST., N.W., sulTE 3 500 j'
ATLANTA, GEORGIA 30303 DEC 5 1980 In Reply Refer To:
RII:JP0 50-259, 50-260
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50-519, 50-520 W
50-521, 6'Q55C 59 N
Tennessee Valley Authority l-ATTN:
H. G. Parris
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Manager of Power 500A Chestnut Street Tower II C
055 Chattanooga, TN 37401 O
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Gentlemen:
The enclosed Information Notice is provider *. as an early notification of a possibly significant matter. Recipients of this notice should review the information for possible applicability to their facilities. However, no specific response is requested at this time. After further NRC evaluations we expect a bulletin will be issued to recommend or request specific licensee actions. If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, w \\ ( v Q +. ( fi D
3 ames P. O' Reil.ly Ilirector
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Enclosures:
1.
IE Information Notice No. 80-43 2.
List of Recently Issued IE Information Notices l
cc w/ encl:
cc w/ encl:
I H. L. Abercrombie, Plant Superintendent W. P. Kelleghan, Project Manager R. E. Rogers, Project Engineer J. E. Wills, Project Engineer H. N. Culver, Chief, Nuclear Safety J. F. Cox, Supervisor, Nuclear Review Staff Licensing Section R. T. Hathcote, Project Manager 31010 5088T h
r SSINS NO.:
6835 Accession No.
8008220279 D\\
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UNITED STATES NGCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 December 5, 1980 IE Information Notice No. 80-43: FAILURES OF THE CONTINUOUS WATER LEVEL MONITOR FOR THE SCRAM DISCHARGE VOLUME AT DRESDEN UNIT NO. 2 Description of Circumstances:
On December 2,1980, following a reactor scram at Dresden Nuclear Power Station Unit 2, the licensee discovered that the recently installed scram discharge volume (SDV) continuous water level monitoring system had failed to respond as expected. The continious water level monitoring system was designed and supplied by Nortec Corporation, and utilizes a single transmit /
receive transducer for each of the four level monitoring channels. Following installation of the continuous level monitoring system, the licensee verified its operability by tripping each alarm channel while its sensor was connected to a calibration standard consisting of a section of 4 inch pipe identical to the SDV piping. No in situ test of the equipment was accomplished.
The expected high level annunciator alarms were not received in the control room following scram whea the SDV filled with water. An investigation to determine the cause was initiated and once per shift checks of the SDV level on both Units 2 and 3 were re-instituted. The reactor scram system functioned normally and post scram manual ultrasonic tests on the SDV verified proper system drain.
Investigations by the licensee determined that the ultrasonic detectors were inadequately coupled to the SDV piping. The coupling was improved and testing performed to show that the system could detect water flow into the SDV during single control rod scram tests. The unit was taken critical and was heating up on December 4, 1980, at approximately 400 l
psig when a reactor scram occurred. The expected SDV high level annunciator alarms were not received in the control room immediately following the scram, but were received about 10-15 minutes later when the SDV was draining.
Following an additional scram at approximately 20 psig with control rods inserted these alarms were received properly.
Investigation identified level detection system operability problems as evidenced by a low signal l
l to noise ratio. Arrangements at:e being made for replacement components I
(including transducers) to improve the signal characteristics and reduce system noise. Until the improvements are installed and demonstrated adequate by in situ testing, use of the ultrasonic detection system is l
being augmented with manual ultrasonic checks of level in the SDV, using I
the previously required once per shift check. A manual check will be performed after each.eactor scram. At Dresden Unit 2 the licensee will I
i IN 80-43 December 5, 1980 Page 2 of 2 complete the system improvements and required testing within 7 days in accordance with the Immediate Action Letter issued by Region III on December 4, 1980.
The above operating experience indicates the need for a demonstration of the operability of ultransonic systems recently installed to continuously monitor for water in the SDV. Until demonstrated operable by in situ
'ng, these systems should not. be solely relied on for detection of water in the SDV. Usc of new ultrasonic detection systems shoulJ be augmented by manual checks for water in the SDV each shift and af.ter reactor scram until in situ testing is performed.
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It is important that a high degree of reliability be establisAed in operability of these continuous water level monitoring systems in order to support plant operations in the interim until final scrfm discharge system modifications are performed.
This IE Information Notice is provided as an early notification of a possibly significant matter that is still under review by the NRC staff.
Recipients should review the information for possible applicability to their facilities. No specific response is requested at this time.
Pending further NRC evaluations, we expect licensee actions will be requested or required.
No written response to this IE Information Notice is required.
If yon tave any questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
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f IN 80-43 3
December 5,1980 RECENTLY ISSUED IE INFORMATION NOTICES Info rmation Date of Notice No.
Subject Issue Issued to 80-43 FAILURES OF THE CONTINUOUS 12/5/80 All BWR and power reactor WATER LEVEL MONITOR FOR THE facilit ies with an OL or SCRAM DISCHARGE VOLUME AT CP DRESDEN UNIT NO. 2 80-42 Effect of Radiation on 11/24/80 All power reactor Hydraulic Snubber Fluid facilities with OL or CP 80-41 Failure of Swing Check 11/10/80 All power reactor Valve in the Decay Heat facilities with an OL Removal System at Davis-or CP Besse Unit No. I 80-40 Excessive Nitrogen Supply 11/10/80 All nuclear power Pressure Actuates Safety-facilities with Relief Valve Operation to OL or CP Cause Reactor Depressur-ization 80-39 Malfunctions Of Solenoid 10/31/80 All light water reactar Valves Manufactured By farilities holding Valcor Engineering Corporation pe wer reactor OLs or C's 80-38 Cracking In Charging Pump 10/30/80 All.PWR facilities Casing Cladding with an OL or CP 80-37 Cont inment cooler leaks 10/24/80 All nuclear power and
'er cavity facilities holding flooo... at Indian Point power reactor OLs Unit 2 or cps 80-36 Failure of Steam 10/10/80 All nuclear power Generator Support Bolting reactor facilities holding power reactor OLs or cps 80-35 Leaking and dislodged 10/10/8G All categories G and Iodine-124 implant seeds G1 medical licensees 80-34 Boron dilution of reactor 9/26/80 All pressurized water c:olant during steam reactor facilities generator decontamination holding power reactor OLs 80-33 Determination of teletherapy 9/15/80 All teletherapy timer accuracy (G3) licensees
- Opere ing Licenses or Constructica Permits