ML20028D229
| ML20028D229 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 01/07/1983 |
| From: | Caba E, Melstad K TOLEDO EDISON CO. |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20028D226 | List: |
| References | |
| LER-81-045-03X, LER-81-45-3X, NUDOCS 8301170248 | |
| Download: ML20028D229 (4) | |
Text
NRC FORM 666 U.S. NUCLEAR REGULATORY COMMISSION 17 77)
- LICENSEE EVENT REPORT CcNTROL BLOCK: l l l l l 1 l@ (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) lo l14 l3l 0 l LICENSEE H l D COOE l B l S 14l 1 l@l 0 l 0 l - lLICENSE 15 0 l 0N.M8ER l0l0l0l-l0 25 l 0 26 l@lUCENSE 4 l 1TYPE l 1 S3 ! 1 l 517 Llhll A T Sd l@
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bu 61 DOCKET NUvaER 6d 63 EVENT DATE 74 75 REPORT D ATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h I o 121 l (NP-33-81-57) After the unit trip on 7/30/81, three action statements were entered. l
- gy3; , Auxiliary Feedwater Pump (AFP) 1-2 did not operate properly. Shield building inte- l
- g,,, lgrity was lost when Mechanical Penetration Room #4 blowout panel was inadvertently l f
g9,3j g blown out due to ventilation system problems. Main Steam Safety Valve SPl7A3 was l
- oieglfound later to have lifted at too low of a setpoint. The applicable technical speci- l
[g;,i lfications were 3.7.1.2, 3.6.5.2, and 3.7.1.1. There was no danger to the health and l
,g,g; ; safety of the public or station personnel. I SYSTEV CAUSE CAUSE COYP. VA LV E COCE COCE SUBCODE COVPONENT CODE SU8COCE SU9 CODE l0l9]
7 6 l Cl Hl@ Wh lB lh l Ml El Cl Fl Ul Nlh l Zl@ l Zlh 9 to 11 12 ?? 18 59 20 SEQUENTI AL OCCURAENCE REPORT REVISION
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l36 Zl@ 3/ 40 44 42 44 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l i j o l l AFP l-2 did not operate properly due to a defective governor. The governor was sent !
[ilil l to the manufacturer for investigation and a spare was installed. The blowout panel I
,,,,,;was repaired. It had blown out when the containment purge exhaust fan tripped with l
]the containment purge supply fan still running. (Facility Change Requests81-191 and l
- ,y3;
,,,,,i ;81-226 were written to resolve this problem). Safety valve SPl7A3 was reset. 80 l
7 8 9
% POWER OTHER STATUS IS O RY DISCOVERY DESCRIPTION ST S l l1 l5* l l X ]@ l' 0l 0l 0l@l nNA l l Al@l Operator observation l 12 44 4s 48 s0 A!TiviTv cO0 TENT LOC ATroN OF RELE ASE RELE AsEo es RELEASE AVOuNT OF Activity hl l NA l l t l6a l9 W @ lZ10 l@l NA 7 11 44 45 80 PERSONNEL EXPOSLRES NUY8ER TYPE DESCRIPTION l
l i 171 1010 l 0 l@l Z l@l NA *
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~uveER oEsCR,. TION @
l 81010101@l 7 8 9 11 NA 12 80 LOSS OF CA DWAGE TO FACILITY TY8E DESCR PTf 0N l
l i l 9 l l Z l@l NA PueSTv 0301170248 830107 NRC USE ONLY esufo PDR ADOCK 05000346 l l l l l l l l 1 1 1 l l ;;
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DVRs81-106, 10#.,g Lll, g g g-159 Erdal Caba/Kevin Melstad pygyg 419-259-5000. Ext. 196/23,0
. _ . ~ _ _ _ _ _ . . . - _ _
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TOLEDO EDISON COMPANY
! DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-81-57 DATE OF EVENT: July 30,1981 (second event determined to be reportable 1 December 8, 1982)
FACILITY: Davis-Besse Unit 1 4
1 IDENTIFICATION OF OCCURRENCE: Reportable occurrences caused by the unit trip of July 30, 1981 Conditions Prior to Occurrence: The unit had been operating at approxi-
- mately 100% of full power prior to the trip. The unit was in Mode 3 with i
l Power (MWT) = 0 and Load (Gross MWe) = 0 at the time of the entries into the action statements.
Description of Occurrence: On July 30, 1981, Davis-Besse Unit I was operating at approximately 100% of full power when the rubber expansion joint between Low Pressure Turbine #1 and the high pressure condenser failed. Due to the subsequent loss of condenser vacuum, the operators began an immediate load reduction to take the turbine / generator off the line. At 0812 hours0.0094 days <br />0.226 hours <br />0.00134 weeks <br />3.08966e-4 months <br />, the reactor tripped at approximately 14% of full power on low Reactor Coolant System (RCS) pressure following the rapid reduction in reactor power.
At 0839 hours0.00971 days <br />0.233 hours <br />0.00139 weeks <br />3.192395e-4 months <br />, the Main Feedwater Pump Turbine (MFPT) #2 automatically tripped on low condenser vacuum, MFPT #1 was already shutdown per station procedures. Both Auxiliary Feedwater Pumps (AFP) were manually started to restore the dropping steam generator levels to avoid a Steam and Feedwater Rupture Control System (SFRCS) trip. When both pumps were placed in automatic on a half SFRCS trip, which led eventually to a full SFRCS trip on #1 actuation channel, AFP #2 did not respond properly. This placed the unit in the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> action statement of Technical Specification 3.7.1.2.
i At 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br />, it was noted that the blowout panel in Mechanical Penetra-tion Room #4 was loosened due to events following the reactor trip and had a gap equivalent to approximately 200 square inches. This placed the unit in the action statement of Technical Specification 3.6.5.2, which requires shield building integrity to be restored within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
l By 1640 hours0.019 days <br />0.456 hours <br />0.00271 weeks <br />6.2402e-4 months <br />, the ventilation system was returned to normal, and the I blowout panels were refastened using standard 1-3/4" x 1/4" all thread l
aluminum bolts. On December 8,1981, it was discovered by a QC Inspector that " explosion" release fasteners should have been installed as required y
by drawing 7749-A66.
An analysis by Bechtel was then requested in which it was determined that the blowout panels for Mechanical Penetration Room #4 in their modified condition could not be considered to be completely functional. This event is being reported under Technical Specification 6.9.1.9.c, which requires the reporting of events due to observed inadequacies in the implementation l
I
i TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-81-57 PAGE 2 1
of administrative or procedural controls which threaten to cause reduction 1, of degree of redundancy provided in the Reactor Protection System (RPS) or Engineered Safety Features System (ESFS).
Following the reactor trip, Main Steam Safety Valve (MSSV) SP17A3 lif ted.
Since no conclusive information was available as to the exact lift pressure (the transient monitor data is eva11able three seconds apart which might not show a pressure spike), the valve was hydro-tested during startup at 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br /> on August 15, 1981. The test results showed that safety valve SP17A3 had a lift point which was out of specification low. The conditions of the action statement of Technical Specification 3.7.1.1 were met when the lift setpoint was reset and proven repeatable at approximately 1230 hours0.0142 days <br />0.342 hours <br />0.00203 weeks <br />4.68015e-4 months <br /> per Surveillance Test ST 5070.01.
The trip recovery was completed without any unusual RCS transients. The plant was placed in Mode 4, Hot Shutdown, (and eventually entered Mode 5) to repair the rubber expansion joint which had failed.
Designation of Apparent Cause of Occurrence: The cause of the AFP 1-2 improper response appears to be a problem internal to the turbine governor.
The cause of the loosened blowout panel in Mechanical Penetration Room #4 was due to the tripping of the containment purge exhaust fan while the containment purge supply fan was still running. A routine penetration room purge was in progress prior to the trip. The containment purge exhaust fan tripped during the 13.8 KV fast transfer from the auxiliary transformers to the startup transformers. The microswitch relays in Honeywell control panels have such a fast dropout time that during the 13.8 KV fast transfer, the relays dropped out, tripping the corresponding fan.
i The cause of the installation of incorrect bolts was personnel error. The person responsible for preparing the Maintenance Work Order did not consult drawing 7749-A66 and consequently, was unaware of the explosion type bolt requirements.
1 The apparent cause of the slight variation in relief valve lift pressure is due to normal valve aging. The setpoint of any relief valve may vary I
over its life and therefore periodic tests are performed to verify these setpoints.
Analysis of Occurrence: There was no danger to the health and safety of the public or station personnel. AFP 1-1 operated properly supplying OTSG
- 1 while AFP 1-2 settled out while in manual and supplied OTSG #2.
The analysis performed by Bechtel has determined that an actual occurrence of a pipe rupture which would require the operation.of the blowcut panels in Room 314 is extremely remote. The portion of the pipe in Room 314 1
meets enat of the criteria established by NRC Branch Technical Position MEB 3- e qualify as a "no break zone", the exception being that the piping u.s designed to ANSI B31.1 instead of ASME Section III, Class 2.
____ ___ . .- - _ __ _ _-- _ _ _ _ _ _ _ -_= _ . _ . __ _ _ _ -
L E
TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE j SUPPLEMENTAL INF0PltATION FOR LER NP-33-81-57 PAGE 3 However, the Toledo Edison procurement and installation specifications 1 required the same material and installation documentation as is required under ASME Section III, Class 2.
l The safety valve apparently lifted only 4% lower than its setpoint. The l
valve would still have served its intended function of relieving pressure i had a trip from a higher reactor power occurred. The valve lift did not i affect the post trip response of the unit.
l Corrective Action: The AFP 1-2 governor was replaced with a rebuilt spare governor under Maintenance Work Order 81-2985. The AFP was successfully tested using auxiliary steam on August 2, 1981 and main steam on August i 14, 1981 per Surveillance Test ST 5071.01. The governor that was removed j has been sent to the manufacturer for inspection and analysis.
The blowout panel was repaired at 1640 hours0.019 days <br />0.456 hours <br />0.00271 weeks <br />6.2402e-4 months <br /> on July 30, 1981. Facility Change Request 81-191 has been written to install an interlock so that if either the containment purge exhaust fan or containment purge supply fan were to trip, the other will also trip. A change was also requested per Facility Change Request 81-266 to change the microswitch relays in the Honeywell control panels with relays that can ride out the fast transfers
- without dropping out.
Maintenance Work Order 81-4297 was written to remove the standard aluminum
( bolts and replace them with special " explosion" type bolts. These bolts y
were certified to break at 1 psi as required by drawing 7749-A66. Once the panels were correctly installed, all the seams were caulked to maintain the secondary boundary. The work was completed February 2, 1982. The 4 responsible person has been counseled by the Maintenance Engineer.
Under Maintenance Work Order 81-3127, the MSSV SP17A3 setpoint was adjusted
! in accordance with Surveillance Test ST 5070.02 on August 15, 1981.
?
During the 1982 outage, SP17A3 was rebuilt under Maintenance Work Order ,
81-3241, and was hydrotested prior to the unit startup in September 1982. '
Failure Data: Although there have been previous reportable occurrences of I Auxiliary Feedwater System failures, only Licensee Event Reports NP-33-80-02 (80-003) and NP-33-81-44 (81-037) appear to have a related root cause.
l There have been seven previous safety valva setpoint problems reporced in Licensee Event Reports NP-33-81-44 (81-037), NP-33-81-39 (81-034), NP-33-79-51 (79-049) , NP-33-79-34 (79-032) , NP-33-79-25 (79-020) , NP-33 23 (79-018) ,
j and NP-33-78-145 (78-124).
1 i There have been no previous reportable occurrences of the loss of shield
. building integrity with a related root cause, or the failure to install 1
the correct type of bolts in the blowout panels.
i LER #81-045 i
I
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