ML19273B756
| ML19273B756 | |
| Person / Time | |
|---|---|
| Issue date: | 05/03/1979 |
| From: | Pappas H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Wright G ILLINOIS, STATE OF |
| References | |
| NUDOCS 7906120222 | |
| Download: ML19273B756 (2) | |
Text
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MAY 3 1979 State of Illi,o'_s Department of Public Health ATIN:
Mr. Gary N. Wright, Chief Division of Nuclear Safety 535 West Jef ferson Street Springfield, IL 62761 Genticmen:
The enclosed IE Circular No. 79-07 titled " Unexpected Speed Increase of Reactor Recirculation MG Set Resulted in Reactor Power Increase" was sent to the following licensees on May 2, 1979, for information:
Cincinnati Gas & Electric Company Zimmer (50-358)
Cleveland Electric Illuminating Company Perry 1, 2 (50-440, 50-441)
Commonwealth Edison Company Dresden 1, 2, 3 (50-10, 50-237, 50-249)
La Salle 1, 2 (50-373, 50-374)
Quad-Cities 1, 2 (50-254, 50-265)
Consumers Power Company Big Rock Point (50-7.55)
Dairyland Power Cooperative LACBWR (50-409)
Detroit Edison Company Fermi 2 (50-341)
Illinois Power Company Clinton 1, 2 (50-461, 50-462)
Iowa Electric Light & Power Company Duane Arnold (50-331) 2351 301 790612 h 5
State of Illinois Northern Indiana Public Service Company Bailly (50-367)
Northern States Power Company Monticello (50-263)
Sincerely, A
Helen Pappas, Chief Administrative Branch
Enclosures:
1.
IE Circular No. 79-07 2.
List of IE Circulars Issued in Last Twelve Months cc w/encls:
Central Files Reproduction Unit NRC 20b Local PDR NSIC 2351 302 TIC D. W. Kane, Sargent and Lundy
U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMEhT REGION III May 2, 1979 IE Circular No. 79-07 UNEXPECTED SPEED INCREASE OF REACTOR RECIRCULATION MG SET RESL1TED IN REACTOR POWER INCREASE Description of Circumstances:
On November 24, 1978, an unexpected rapid speed increase was experienced on the 'B' Reactor Recirculation MG set (RRMG) at the Cooper Nuclear Station. Prior to the event, the RRMG set had been inadvertently tripped during the performance of routine maintenance. Upon restart, the MG set would not respond to a speed increase signal.
Licensee personnel co=-
menced trouble shooting this problam in accordance with the instructions in the manufacturer's technical matual.
One step of these instructions suggested removing the fuse from the Bailey scoop tube actuator circuit (a blown fuse would de-energize the actuator and not permit the scoop tube to move). When the ter=inal panel cover was removed, licensee perscanel noted two fuses instead of one as shown on the vendor drawings. When licensee personnel remeced the second fuse to verify fuse integrity, a rapid speed increase of the MG set occurred. This increase was terminated by replacement of the fuse or tripping of the MG set by the control roo= operator (both actions took place almost simultaneously).
The input signal to the scoop tube actuator is received from the speed controller via a function generator. This signal is a scoop tube posi-tion demand signal. As the actuator drives the scoop tube in or out of the fluid coupler, a position followup signal is generated to null the input signal and stop scoop tube motion at the required position. The vendor's drawings of the scoop tube actuator circuit showed only one fuse in the circuit. The licensee contacted the vendor regarding the second fuse and was informed that this fuse had been added as a change in the initial circuit design to provide protection for certain elec-tronic co=ponents in this circuit. This additional fuse is located in
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the position followup circuit. Removal or loss of the fuse would result in a loss of the nulling signal and would cause the scoop tube to drive to the maximum speed position.
2351 503
IE Circular No. 79-07 May 2, 1979 The licensee examined the circuit for the 'A' RRMG set scoop tube actuator and discovered that it contained only the single fuse as indicated on the vendor's drawings.
At the time of the speed increase, the reactor was operating at 27 percent power. The speed increase on the RRMC set caused power to increase rapidly to 75 percent until terminated by the manual trip of the RRMG set.
The short term reactivity increase corresponded to a reactor period of less than 5 seconds.
A check of reactor parameters after this event verified that no core limits were exceeded. The FSAR contains an analysis of a similar transient which is failure of a speed controller causing one RRMG set to drive to the maximum speed condition. This analyzed transient starts fron a 100 percent power rod pattern, whereas the observed transient coc=enced from a lower power rod pattern.
Therefore, this observed transient falls within the bounds of the FSAR analysis.
As part of the corrective action for this event, the licensee has placed a warning sign on the control panel cover to remind technicians of the effect of recoving the second fuse.
Recom=cnded Actions for Licensee's Consideration:
All holders of operating licenses for BWR plants employing variable speed Reactor Recirculation Motor Generator sets should be aware of the potential for occurrences of the type indicated above.
It is recom-mended that this area be reviewed at your facility in the following respects:
1.
A review of the scoop tube actuator circuit should be conducted to verify that the circuit diagra= indicates the actual nu=ber of fuses installed.
2.
Where the actual circuit configuration contains the second fuse (in the scoop tube pcsition follow-up circuit) a warning statement describing the consequences of its removal when the unit is opera-ting should be incorporated into the troubleshooting guides.
A permanent label to the same effect should be placed on the control panel cover which houses the fuse. In addition, operating personnel and maintenance technicians should be apprised of the effect of renoving the fuse from the circuit.
2351 304
IE Circular No. 79-07 May 2, 1979 3.
Review procedural controls for troubleshooting systems and components that have the potential to affect significant plant parameters such as power level, water level pressure etc. Ensure that when a vendor's technical manual is being used in lieu of a detailed procedure, all personnel are sensitive to differences between the actual equipment and the manual description. When discrepancies are identified, resolution should be obtained before proceeding.
This circular is being forwarded to all holders of BWR construction perr.its for information.
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.
Enclosure:
List of IE Circulars Issued in the Last Twelve Months 2351 305 s
IE Circular No. 79-07 May 2, 1979 LISTING OF IE CIRCULARS ISSUED IN LAST TWELVE MONTES Circular Subject Date Issued To No.
of Issue 78-03 Packaging Greater Than 5/12/78 All Holders of Type A Quantities of Reactor OLs, cps, Low Specific Activity Fuel Cycle, Radioactive NM erial 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 Cooldown Reactor OLs or cps 78-06 Potential Co==en Mode 5/23/78 All Holders of Flooding of ECCS Equipment Reactor OLs or Rooms at BWR Facilities cps 78-07 Da= aged Co=ponents 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 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 OLa or cps 2351 106 Enclosure Page 1 of 3
IE Circular No. 79-07 May 2, 1979 LISTING OF IE CIRCULARS ISSUED IN LAST TWELVE MONTHS Circular Date of No.
Subject Issue Issued To 78-12 HPCI Turbine Control 6/30/78 All Holders of Valve Lift Rod Bending EWR OLs or cps for plants with HPCI Terry Turbine 78-13 Inoperability of Multiple 7/10/78 All Holders of Service Water Pumps Reactor OLs and cps except for plants located in: AL, AK, CA, FL, GA, LA, MS,
SC 78-14 HPCI Turbine Reversing 7/12/78 All Holders of Bk'R Chamber Hold Down Bolting OLs or cps for plants with a HPCI Terry Turbine excepting Duane Arnold and Monticello 78-15 Checkvalves Fail to 7/20/78 All Holders of Close In Vertical Reactor OLs or cps Position 78-16 Limitorque Valve 7/26/78 All Holders of Reactor OLs or Actuators cps 78-17 Inadequate Guard Training /
10/13/78 All Holders of Qualification and Falsified and applicants Training Records for Reactor OLs 78-18 UL Fire Test 11/6/78 All Holders of ReactorOLsoryPs 78-19 Manual Override (Bypass) 12/28/78 All Holders of of Safety Actuation Signals cps 79-01 Administration of 1/12/79 All Medical Unauthorized Byproduct
" Licensees except Material to Humans Teletherapy Medical Licensees and each Radiopharmaceutical Suppliers 2351
.507 Enclosure Page 2 of 3
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IE Circular No. 79-07' May 2, 1979 LISTING OF IE CIRCULARS ISSUED IN LAST TWELVE MONTHS Circular Date of No.
Subject Issue Issued To 79-02 Failure of 120 Volt Vital 2/16/79 All Holders of AC Power Supplies Reactor OLs and cps 79-03 Inadequate Guard Training-2/23/79 All Holders of Qualification and Falsified and applicants Training Records for Special Nuclear Material Licenses in Safeguards Group I 79-04 Loose Locking Nut On 3/16/79 All Holders of Limitorque Valve Reactor OLs or cps Operators 79-05 Moisture Leakage In 3/20/79 All Holders of Stranded k' ire Conductors Reactor OLs or cps 79-06 Failure to Use Syringe 4/19/79 All Holders of and Battle Shields in Medical Licensees Nuclear Medicine except teletherapy licensees 2351 308 Enclosure Page 3 of 3