ML19340D884
| ML19340D884 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/05/1980 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| NUDOCS 8101050503 | |
| Download: ML19340D884 (1) | |
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UNITED STATES q
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NUCLEAR REGULATORY COMMISSION 3
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Arizona Public Service Company P. O. Box 21666 Phoenix, Arizona 85036 Attention: Mr. E. E. Van Brunt, Jr.
Vice President, Nuclear Projects Gentlemen:
The enclosed Information llotice is provided 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 fiRC evalu-ations 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 llRC Regional Office.
Sincerely, i
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R. H. Engelken Director
Enclosures:
1.
IE Information Notice I:o. 80-43 2.
Recently Issued IE Information Notice
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cc w/ enclosures:
F. W. Hartley,' APS l
8101050
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SSINS NO.-
6835 Accession No.
8008220279 IN 80-43 UNITED STATES gp NUCLEAR REGULATORY COMMISSION
- j OFFICE OF INSPECTION AND ErlFORCEMENT 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 Descrintion 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 continuous 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 operaoility 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 eauipment was accomplished.
The expected high level annunciator alarms were not received in the control roon folicwing scram when the SDV filled with water.
An investigation to deternine the cause was initiated and once per shif t checks of the SDV level cn both Units 2 and 3 were re-instituted. The reactor scram systen 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 inadenuately 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 psig when a reactor scram occurred.
The exoected 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 to noise ratio.
Arrangements are being made for replacement components (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 being augmented with manual ultrasonic checks of level in the SDV, using the previously required once per shift check.
A nanual check will be performed after each reactor scram. At Dresden Unit 2 the licensee will
IN 80-43 December 5, 1980 Page 2 of 2 ccmalete the systen inorovements and recuired testing within 7 days in accordance with the Inmediate Action Letter issued by Region III on December 4, 19S0.
The above coerating exnerience indicates the need for a demonstration of the operability of ultransonic systems recently installed to continuously monitor for water in the SD'/.
Until demonstrated coerable by in situ testing, these systems should not be solely relied on for detection of water in the SDV. Use of new ultrasonic detection systems should be augmented by manual checks for water in the SDV each shift and after reactor scran until in situ testing is performed.
It is imoortant that a hioh degree of reliability be established in operability of these continuous water level monitorino systems in order to support plant onerations in the interim until final scram discharge system modifications are performed.
This IE Infonnation ilotice 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.
Ho specific response is requested at this time.
Pendina furtner GRC evaluations, we expect licensee actions will be requested or required.
No written response cc tais IE Information notice is required.
If you have any auestions regarding this matter, please contact the Director of the appropriate !!RC Regional Of fice.
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IN 80-43 December 5, 1980 RECENTLY ISSUED IE INFORMATION NOTICES Information Date of Motice No.
Subject Issue Issued to 80 a2 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 Penoval System at Davis-or CP 2 esse Unit No. 1 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 licht water reactor
'!alves Manufactured By facilities holding Valcor Engineering Corporation power reactor OLs or cps 80-33 Cracking In Charging Punp 10/30/80 All PWR facilities "3 sing Ciadding with an OL or CP 80-37 Containment cooler leaks 10/24/80 All nuclear power and reactor cavity facilities holding flocaing at Indian Point power reactor OLs Unit 2 or cps l
80-36 Failure of Steam 10/10/80 All nuclear power l
Generator Support Colting reactor facilities holding power reactor O!s or cps 80-35 Leaking and dislodged 10/10/80 All categories G and Iodine-124 implant seeds G1 medical licensees 80-34 Boron dilution of reactor 9/26/8n All pressurized water coolant during steam reactor facilities generator decontamination holding power reactor OLs 80-33 Determination of teletherapy 9/15/80 All teletherapy i
timer accuracy (G3) licensees l
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- Operatina Licenses or Construction Pernits t
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