ML20044A522

Mgt Meeting Rept 50-219//90-37 on 900430.Violation Noted. Major Areas Discussed:Augmented Insp Team Findings Re Sys Response Due to Flow Dynamics,Instrument Drift Problem & Adequacy of Testing to Address Operability

ML20044A522
Person / Time
Site:	Oyster Creek
Issue date:	06/08/1990
From:	Contel R, Easlick T, Gallo R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20044A517	List: ML20044A519 ML20044A522
References
50-219-90-37-MM, NUDOCS 9006290157
Download: ML20044A522 (26)

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{{#Wiki_filter:_ _ i I J U. S. NUCLEAR REGULATORY COMMISSION REGION I Meeting No.: 90-37 Report No.: 50-219/89-81 Docket No.: 50-219 License No.: DPR-16 Licensee: GPU Nuclear Corporation i P. O. Box 388 Forked River, New Jersey 08731 Facility Name: Oyster Creek Nuclear Generating Station Meeting At: NRC Region 1 Office, King of Prussia, Pennsylvania Meeting Date: April 30, 1990 ' Prepared by: fleM [p 1 [oML 6!P 90 Iheodore A. Easlick! Oper~ations Engineer, D6te Division of Reactor Safety Reviewed by: dndd Md A. [. C013o 6/F[9O ^ Richard J. Conte, Chfef, BWR lection, Da~te Division of Safety A (_ hhb Approved by: Rob ~erVM.Gallo, Chir,kerationsBranch Date Division of Reactor Safety Meeting Summary: A significant licensee neeting (Meeting No. 90-37) was conducted on April 30, 1990, at the NRC Region I office, King of Prussia, to discuss the findings and conclusions of an Augmented Inspection Team (AIT) inspection conducted at the Oyster Creek Nuclear Generating Station on December 8-12, 1989. The discussion included issues documented in Section 1.4 of Inspection Report 50-219/89-81: (1) system response due to flow dynamics; (2) instrument drift problem and its continuing study; (3) testing adequately addressing operability; (4) adequacy of Technical Specification (TS) and setting found contrary to TS requirements; (5) "A" and "B" condenser vacuum trip function operability; and (6) operator and management performance during and after the event, h[iO $$h f Q

4 t 2 ( P The licensee provided their corrective actions which included a change in the vacuum trip setpoint to account for instrument drif t and a review of the TS requirements for the low vacuum scram function for adequacy as it reflects on i the as-built design of the trip system. (Unresolved Item No. 219/89-82-01, see l Paragraph 3). Corrective actions which were still in progress were also e discussed, which' included revision of the operations plant manual and the submittal of a licensee event report on the TS non-compliance for protective instrumentation. (Unresolved Item No. 219/89-81-02, Paragraph 3). After the meeting,Me st 'f deliberated and determined that the licensee was in non-compliance w ' h Tec', cal Specification 3.1 (Violation No. 219/89-81-03,- c paragraph 6). W1 ' t " condenser vacuum instrumentation set at the low vacuum

limits of T.S., th eensee provided no margin for instrument drift resulting

'in a violation of t..# T.S. This occurred despite the identification of a _ generic instrument setting problem identified by NRC in November 1988. The violation demonstrated a need for the licensee to enhance their corrective action process. f I + e r ? 4 1

(

l t f 5

y L DETAILS 1.0 Introduction On April 30, 1990, at the NRC Region I Headquarters, the beiow listed personnel participated in a management meeting to discuss the findings and conclusions of an Augmented Inspection Team inspection of an event involy-ing a main condenser low vacuum transient without scram, either automati-cally or manually. The NRC management introduced the topic and asked the licensee to present its position, perspective and proposed corrective actions. 2.0 Meetina Attendees 2.1 GPU Nuclear Corporation (GPUNJ G. Bush, licensing Manager, O.C. A. Rone, Plant Engineer Director /GPUN J. Barton, Deputy Director /GPUN W. Popow, Site Services M. Heller, Licensing Engineer A._Agarwal, E&D/GPUN R. Ezzo.E&D/GPUN P. Hansen, SAPC/GPUN N. Trikouros, Manager SAPC/GPUN 2.2 U.S. Nuclear Regulatory Commission W._Hodges, Director, DRS W. Johnston, Deputy Director, DRS J. Wiggins, Deputy Director, DRP E. Wenzinger, Branch Chief, DRP R. Gallo, Chief Operation Branch, DRS R. Conte, Chief BWR Section,DRS J. Stewart, Acting Section Chief, DRP E. Collins, Resident Inspector. 0.C. A. Dromerick, NRR License Program 'T. Eas11ck, Operations Engineer 3.0 Licensee Presentation The' text of the licensee presentation is included in this report as. The licensee began the presentation with a brief descript-ion.of the low condenser vacuum trip system and how it is related to the three condensing chambers. The description also included an explanation of the reactor trip logic associated with the condenser low vacuum signals. The licensee discussed the function of the low vacuum scram and presented the results of a RETRAN (licensing model) computer analysis. FSAR transient analysis was also discussed. The licensee concluded from -their analysis _that the low vacuum scram does not have a safety function

1. '

<1 4 l and that fuel cladding integrity and reactor coolant pressure boundary safety limits are not affected by a low vacuum scram. The review of the FSAR transient analysis indicated that the low vacuum scram was not considered. Additionally, a review of the operational design of the trip system shows that any one of the six bellows instrument channels can cause a reactor scram. The licensee stated that it had changed its position on 1 the adequacy of the TS concerning the low vacuum trip system and agreed with the NRC staff that the TS requirements do not consider the bellows sensor arrangement (as-built design) in the minimum required system and j channel operability. The issue of instrument drift was discussed with the licensee confirming that it is an ongoing problem previously identified in NRC Inspection Report 50-219/88-202, issued on November 16, 1988. An instrument setpoint review program status is expected to be submitted to j the NRC, May 1990, and is part of the corrective actions by licensee. 3 The licensee discussed corrective actions completed prior to the meeting l and additional corrective actions which are still in progress (see Attach-ment 1, pages 12, 13). The presentation indicated that a review and evaluation of the Technical Specification requirements for the low vacuum scram function was currently in progress. This evaluation will address a revision or possible elimination of the requirements to correct the TS adequacy problem. The licensee's continuing review of the low vacuum scram function is considered to be an unresolved item (219/89-81-01)..The i corrective actions in progress included submittals of a status report on the instrument setpoint review program and a licensee event report (LER) on the TS non-compliance. These submittals and other corrective actions will require further NRC follow-up and, therefore, are considered to be an unresolved item (219/89-81-02). t 4.0 Additional Discussion i The NRC staff questioned the licensee on the philosophy behind the " Conduct of Operations," Station Procedure 106 which requires the operators to verify indications using related instrumentation. The concern was whether the operators were instructed to believe an indication until it is determined to be false or to believe an indication is false until it is determined to be true. The licensee was requested to review Station Procedure 106 and look for any conflicts in the guidance given to operators on instrument i verification. The licensee committed to review of Station Procedure 106 and upon completion of the review, forward the results to the Senior Resident Inspector. The licensee's decision to change their position on the adequacy of the TS requirements. for the low vacuum scram function was discussed. The licensee concluded the TS were inadequate after a review of the system design was completed. A better understanding of the system led them to change their interpretation of a questionable area. l t h L

i 5 i 5.0 Meetina Conclusion The major findings and conclusions of the Augmented Inspection Team inspection were discussed during this meeting. The licensee agreed with. the findings of the team and stressed their conclusion that the' low vacuum scram doth not have a safety function, it was intended to protect the main j condenser by reducing the steam load. When asked if there was any differ - I ence in operator training between a safety scram and a non-safety scram i ~ he licensee stated that there was no difference. l t 6.0 Post-Meetina Summary- } After the meeting NRC management determined that the inadequate control over the low vacuum reactor trip setpoints was a Severity Level IV t violation of NRC requirements. Accordingly, a Notice of Violation will [ be issued (219/89-81-03, Paragraph 3). Attachments: Copy of the Licensee's Presentation Slides b .iI, l . I t + i i f f I ..w e .._.g.,.. 7 t 9 a f

y A LA ueb 1. i .i I l l 1 4 1 i l O b 4 OYSTER CREEK NUCLEAR GENERATING STATION GENERAL PUBLIC UTILITIES NUCLEAR l GPUN .m:: ,... J::"l. h /' i f I I I I i i I I I I I I I I I I i i I I l / V t L l GENERAL PUDLIC UTILITIES NUCLEAR RESPONSE TO NRC AIT REPORT 89-81 l APRIL 30,1990 t I

MEETING TO DISCUSS NRC INSPECTION REPORT 89 81 CONCERNING LOW CONDENSER VACUUM SCRAM FUNCTION j 1. INTRODUCTION / OVERVIEW MR. GEORGE BUSCH OYS?ER CREEK LICENSING MANAGER 2. VACUUM TRIP SYSTEM MR. RANDY EZZO DESCRIPTION INSTRUMENTATION ENGINEER 3. CONDENSER PERFORMANCE ANALYSIS MR. PAUL HANSEN SAFETY ANALYSIS ENGINEER 4. CORRECr!VE ACTIONS / CONCLUSION MR. GEORGE BUSCH OYSTER CREEK LICENSING MANAGER L.. 1 i b l' {' l

j 1 CHRONOLOGY OF EVENTS 12/7/89 (0155 HOURS) VACUUM TRANSIENT INITIATED DUE TO OPERATOR ERROR. DURATION OF TRANSIENT APPROXIMATELY 2 MINUTES 12/7/89. (0312 HOURS) GPUN CONFERENCE CALL HELD WITH GSS, STA, OPERATIONS MANAGEMENT AND A CORPORATE ENGINEER 'IU DISCUSS CONCERNS WITH PLANT RESPONSE. DECISION MADE TO CONVENE POST TRIP REVIEW GROUP (P'IRG) I l' 12/7/89 (0440 HOURS) 10CFR50.72 FOUR HOUR NOTIFICATION. POSSIBLE FAILURE OF RPS TO ACIVATE UPON LOW CONDENSER VACUUM. 12/7/89 (0600 HOURS) PTRG CONVENED 12/7/89 (1430 HOURS) GPUN/NRC CONFERENCE CALL L F 12/7/89 (1615 HOURS) REACTOR SHUTDOWN COMMENCED. (COLD S/D ACHIEVED WITHIN 30 HOURS OF 0155 HOURS) l i 12/8/89 NRC AUGMENTED INSPECTION TEAM (AIT) ARRIVES l, 12/12/89 AITINSPECTION EXIT MEETING I 2/14/90 AITINSPECTION REPORTISSUED. MANAGEMENT t MEETING REQUESTED TO DISCUSS l FINDINGS / CONCLUSIONS I e e

._.. _ _ - ~ _ _. _. _ _.. _ _. _ 1 '~ i REVIEW OF IR 89 81 SECTION 1A TWO SYSTEMS. DIFFERENT FUNCTIONS l ! . DIFFERENCE DUE TO FLOW DYNAMICS i INSTRUMENT DRIFT PROBLEM NOT NEW/ CONTINUING STUDY (SSOMI) i TESTING ADEQUATELY ADDRESSED OPERABILITY I ADEQUACY OF TECH SPEC (AS. BUILT DESIGN) l . STANDARD TECH SPEC DEFINITION I SE1 TINGS FOUND CONTRARY TO TECH SPEC REQUIREMENTS 'A' AND *B' CONDENSER VACUUM TRIP FUNCTION INOPERABLE OPERATOR PERFORMANCE. AGREE WITH ALL CONCLUSIONS t MANAGEMENT PERFORMANCE. AGREE,WILL BE DISCUSSED IN FOLLOWING p PRESENTATION 1 I i e -F I

t FIGURE 1 . SIMPLIFIED CONFIGURATION OF VACUUM TRIP BELLOWS 'B' AND W.25 SENSING LINES LOOKING EAST 1 1 / \\ ~ Turbine f Elev. 50'-0* l I d p FT-25 l I I { i ,,,,,,Elev. 46'-6* sy,,,,, I (operating g sensing line giong3 , for PT-25 h (Indicition) l -lev. 40'-3"' d (. l \\ l 12'-5* l Crossover-- ' sensing line Elev. 32' for "B" bellows j [Elev.27'-10" b g (scram) - [-

• - 10'-5" e.

l l - Elev. 22'-5" South North 7 CW Line CW Line i i I t 1 - Elev. 2'-5" R3ference Dwgs: S= =N E 1. GU 3D-411-22-1002 Note: Alt eensing line location ) 2. Wo SL-71762 dimensinns are approximate 3. GU 3D-151-02-007 4

1 .- ~ FIGURE 2 VACUUM *IltIP SYSTEM NO.1 FUNC110NAL DIAGRAM (System No. 2 Similar) spare low vacuum alarm Lwa_ turbine trip switch set at collar set to trip g 24.9" Hg vacuum at 2" hg vacuum lascs-11.12)--.e-letTS-1 J a cam reactor scram switches-set at 23.65" Hg vacuum '\\ W Peratingf H s p g C1 7 iston f tp torque g A g ngop p a shaft ,e C,3 from "C. I I MSOP E dMg ischarge d y condenser-l C2 I( h drainh 3 r 225 psig

• B2 I

"N I B1 gj3 I bellows o fr m back-up %Ap b 8,3 I i f rom "B" -- - - I B2 overspeed trip j I N 'I condenser vent T A2 drain f ; [ floating Al A ' I supply am [ to emergency governor

• a A31 L

Notes l A2 _

1. System shown at normal vacuum:

28" Hg Vac

2. All components located in front standard drain 1 P MSOP E

discharge-e' from "A. 25 ps19 f Ref. GE 233R309 sh 2 pilot valve condenser supply ~

i ] I 1 FIGURE 3 1 CONDENSER LOWVACUUM REACTOR TRIP LOGIC I condenser condenser condenser I A B C i i l o o p o o o bellows instrument th 18 1C 2A 28 2C channel } Y f p h h U h U g vacuum vacuum trip trip system system one two N RSCS-11 RSCS-21 RSCS-12 RSCS-22 ,_,o ~o .n o (orj (or } reactor N/ N / reactor protection protection system system div 1 div II o o signal Key and U sensing line Mechanical / Hydraulic p Electric ,,, ego, scram Ref. CE 237E566 Sh. lA GE 233R309 Sh. 2

4 i CONCLUSIONS THE BELLOWS SENSING THE LOWEST VACUUM IS IN CONTROL. A TEST WAS PERFORMED TO DEMONSTRATE TO THE AIT THAT THE LOWEST OF THE THREE BELLOWS WILL ACTUATE 'lilE 1 -{ SCRAM SWITCHES. ANY ONE OF SIX BELifeWS INSTRUMENT CHANNEIE CAN CAUSE A REACTOR SCRAM h.4 7 1 l i i i _ 7_

i l l-LOW CONDENSER VACUUM SCRAM FUNCTION 'l i SCRAM ANTICIPATES LOSS OF HEAT SINK l PROTECT CONDENSER .I l SCRAM DOES NOT HAVE SAFETY FUNCTION r LOSS OF CONDENSER VACUUM EVENT IS BOUNDED BY W 1. TURBINE 'IRIP WITHOUT BYPASS FOR INSTANTANEOUS gs. LOSS OF VACUUM 2. TURBINE TRIP WITH BYPASS - FOR RAPID TO SLOW LOSS OF VACUUM r '( i l' .l l ~&

.. o FSAR "'RANSIENT ANALYSIS CONSIDERATIONS RAPID PRESSURI7ATION EVENTS FOR OC INCLUDE TURBINE TRIP WITHOUT BYPASS TURBINE TRIP WITH BYPASS 1 LOSS OF CONDENSER VACUUM i { EVALUATION OF FSAR TRANSIENTS I i EVENTS ' EVALUATED FOR i i I 1. FUEL CIADDING INTEGRITY h 2. REACTOR COOIANT PRESSURE BOUNDARY SAFETY LIMITS ASSUMPTIONS AND METHODS i I 1. RETRAN LICENSING MODEL USED 2. 'IWO RATES OF VACUUM LOSS ASSUMED 2' Hg/SEC AND 0.5" Hg/SEC 3. SCRAM SETPOlNTS OF 23" Hg AND.<_22" lig EVALUATED 4 l _9

O l 0 CASES EVALUATED WITH RETRAN 4 VACUUM TRIP SETPOINT RESULTS PEAK TURBINE BYPASS PEAK DOME NORMALIZED EYEy[ SCRAM TRIP CLOSURE PRESSURE HEAT FLUX l TURBINE TRIP WITHOUT BYPASS NA NA NA 1271.46 PSIA 1.36 l 1 TURBINE TRIP WITH BYPASS NA NA NA 1153. PSIA 1.28 LOSS OF COND VACUUM (2' - Hg/SEC) CASE 1 23' Hg 22' Hg 10' Hg 1136. PSIA 1.15 l r LOSS OF COND l VACUUM (2* Hg/SEC) h CASE 2 22' Hg 22' Hg 10' Hg 1151. PSIA 1.27 1 LOSS OF COND j VACUUM (2' Hg/SEC) CASE 3 IS' Hg 22" Hg 10' Hg 1153. PSIA 1.28 l LOSS OF COND l VACUUM (0.5' Hg/SEC) CASE 4 23' Hg - 22' Hg 10' Hg 1072.4 PSIA 1.0 ) l l l ii '

i CONCLUSIONS i i ) 1 l LOW VACUUM SCRAM DOES NOT HAVE SAFETY FUNCTION f LOW VACUUM SCRAM PROTECTS CONDENSER BY REDUCING LOAD i i FSAR ANALYSES DO NOT USE LOW VACUUM SCRAM \\ l FUEL CLADDING INTEGRITY AND REACTOR COOLANT PRESSURE BOUNDARY SAFETY LIMITS ARE NOT AFFECTED BY LOW VACUUM SCRAM l l \\ I

i i CORRECTIVE ACTLQMS i COMPLETED t I 1. VACUUM TRIP SETPOINT CHANGED TO ACCOUNT FOR INSTRUMENT DRIIT 2. SURVEILLANCE PROCEDURE ENHANCEMENTS l 3. TRAINED OPERATORS ON THE EVENT LESSONS LEARNED l i 4. REVISED RELATED ABNORMAL PROCEDURE TO REFLECT THAT LOW ( VACUUM IN ANY ONE CONDENSER WILL CAUSE A SCRAM 5. INDEPENDENT REVIEW OF TECH SPEC SETPOINT PRACTICES CONDUCTED BY QA. IDENTIFIED DEFICIENCIES ADDRESSED BY INSTRUMENT SETPOINT REVIEW PROGRAM 6. COMPLETED HUMAN PERFORMANCE ENHANCEMENT SYSTEM (HPES) REVIEW OF OPERATOR ERROR RECOMMENDED CORRECTIVE ACI' IONS INCLUDED BELOW i 7. REVISED MAIN CONDENSER CIRCULATING WATER SYSTEM PROCEDURE i (HPES RECOMMENDATION) I-8. PREPARED NEW AS BUILT DRAW 1NGS TO SHOW SENSOR LOCATION / TUBING ISOMETRICS l e t

CORRECTIVE ACTIONS LN PROGRESS [ t 1. INSTRUMENT SETPOINT REVIEW PROGRAM (PROGRAM STATUS SUBMI' ITAL EXPECTED 5/90) l 2. EVALUATE TECH SPEC REQUIREMENTS FOR REVISION OR ELIMINATION OF LOW VACUUM SCRAM FUNCTION (5/90) 3. CONDUCT OPERATOR SELF VERIFICATION TRAINING (HPES RECOMMENDATION) (5/90 THROUGH 7/90) 4. REVIEW GUIDANCE FOR USE OF INFORMATION/ CAUTION TAGS (12/90) 5. SUBMIT LICENSEE EVENT REPORT IN ACCORDANCE WITH 10CFR50.73 (5/20/90) I 6. UPDATE SCRAM FUNCTION DESCRIPTION IN FSAR (AITER COMPLETION g .g-OF ITEM #2 ABOVE) I l 7. REVISE OPERATIONS PLANT MANUAL (HPES RECOMMENDATION) (7/90) 8. EVALUATE MERIT OF PROVIDING INTERLOCKS FOR MAIN CONDENSER VALVES (HPES RECOMMENDATION) (DUE DATE TO BE DETERMINED) i l [ -t>

l APPENDIX l A. SIGNIFICANT FACTUAL ERRORS IN NRC INSPECrlON REPORT 89 81 l .} B. HANDOUTS FROM JANUARY 30,1989 GPUN/NRC MEETING I C. LOW CONDENSER VACUUM SCRAM HARDWARE AND LOGIC DESCRIPTION I I I l

!g F

i i, e 1 li !i t t ...a.

,, o ' Appendix A j Significant Factual Errors in NRC Inspection Report 89 81 1 1. Erren Page 2,1st paragraph,1st sentence reads 'On December 7, i 1989, at 4:40 a.m., the licensee made a four. hour notification to the NRC operations center in which they reported a main condenser vacuum 1 transient without scram, either automatically or manually.' Correction: GPUN eonservatively reported a possible failure of the reactor protection system to actuate upon low condenser vacuum, pending further evaluation. 2. Ermn Page 2,1st paragra >h,2nd sentence reads 'During the day shift on the same day, the I censee commenced a review of the event ) while power operations continued..' Correction: A formal review group (ITRG) was convened approximately 4 hours after the transient during the midnight shift. 3. Ermn Page 7,1st paragral>h,2nd sentence reads 'one sensing line provides only an analog indication in the Control Room through a 'Rosemont' pressure transmitter to a ' General Electric' indicator". Correction: A Rosemount pressure transmitter is utilized for the 'B' condenser. GE/MAC transmitters are utilized for the 'A' and 'C' condensers. 4. Erron Pa te 8,last sentence reads 'the sensing locations for both vacuum tr p systems are toward the west end of the condenser." Correction: These sensing lines penetrate on the east side of the { condensers. 5. Erron Page 9, section 3.3.2,1st paragraph reads 'this sensor

i consists of a halfinch outer diameter tube penetration into the condenser wall. It is located below the equalizing pipe openings and l

across from the feedwater low pressure heater". (. Cornetion: The sensing line is a 1/2' pipe (1/2' nominal inside diameter) and the heat exchanger identified is a drain cooler, not a feedwater low pressure heater. \\ lc 6. Erron Page 10,6th parrgraph,1st sentence reads "Another special l- { test was conducted to verify the independence of a vacuum sensor assembly to actuate the trip system". t Correction: This test was conducted to demonstrate to the NRC that each vacuum bellows operates independently.

~ - - 7. Error: Palte 10,6th paragraph,3rd sentence reads 'After simulating the norma, piston position for two bellows (representing normal vacuum at the two condenser bays), the vacuum was abasptly drupped in the i third bellows. This resulted in a full reactor trip signal within 30 seconds. 'Ihis test demonstrates that low vacuum in one condenser can actuste the reactor trip signal'. i Correction: The response time was approximately 0.35 seconds, well within 30 seconds. k a i 'I 9 f L ,t [ 't l F a t

Appendix B t i t 0C TECH. SPEC. INST M ENTS LOOP SU M 39 tech. spec. loops 1 GDP1 14functionalloopswithsupportingcalculations (10instruants) ) GEP2 8functionalloopswithgenericerrorevaluation 17 with engineering judgeant error evaluation GEP3 10Notech, spec. overlap GEP4 7Potentialtech, spec. overlap r Nosafetyconcerns ') l1 1 4 1 4

... -n -~ . - ~ ~. - ~ ^~* '~ ' ' TEOstlCAL SPECIFICATICIS INSTRIBIENT 140PS (EleGIliEERIIIG JUDGEleft IgEDICBTES T.S. Can SE EBCEEDED) GROUP IV Instr e t (Teg) Ieumte. of

• • ellb.

Predicted Tech. Spec. Serve 11-8 Punction Onennele Ibanef. Range getsolet 1tpleresco Drift Limit lance Free. Demarke 1 Gen. Imed Sejection 4 Sy GE 30-300 183 pelg ' -2 pet -2.0 peng too peig geerterly Good nietory (PsL) ersas yeig 2 stein Conden. Im 4 By CE 0-30* IIg 23" IIg -0" tag -0.75* Iag 23* seg.

m. feel Good History vacuum (RSCE)

W wecuum +0.5* ne vacusan (Drift beood SCRAAB on historicot dete) 3 APfue lipecele (RIO2) e m S-1504 liet

• 1t

+3.4% 115.7% weehir/ Good nietory orsam nef e1 4 Argue specele (R102) e a 6-1504 1M.5%

• kt

+3.2% 10M meekly Cnod nietory Sod Block 5 Impe Upecele (pue01) S e 0-1254 11M

• 1.0%

+3.M 120%

insekly, Good M! story Schaft each etertup 6 Inge tspecele (anol) 8 GE 0-125%

IOM +1.04 +3.1M 1004

tesekly, Good History Rod Stock each etertup 7 Off Gee Mi Redletion 2

GE 1-10M aft /nr I.Suse +0 mm/Igr +.225mte 1.5mE4

tesekly, Goot nistory inw12) off-Gee um/ser

.3see en/ar um/ste em/ar nefuel isoletion i. I 4 -r ~ ~ a

e i l Appendix C 0 LOW CONDENSER VACUUM SCRAM i r HARDWARE OPERATION DESCRIPTION + f i DECREASE IN 8 CONDENSER VACUUM FROM 28* HG VACUUM (CONDENSERS A AND C CONSTANT l AT 28" HG VACUUM): I POINT B1 MOVES UPWARD; B2 MOVES DOWNWARD l ' FLOATING ARM" PIVOTS COUNTER-CIACKWISE ABOUT B3 I~

• ERROR" SIGNAL, ob, MOVES DOWNWARD MOVING B PILOT VALVE PISTON DOWNWARD I

B PILOT VALVE DRAINS HYDRAULIC FLUID ALLOWING OPERATING PISTON AND POINT D TO MOVE UPWARD TORQUE SHAFT AND POINT E MOVE COUNTER-CLOCKWISE POINT B3 (FEEDBACK) MOVES UPWARD UNTIL eb b IS EERO. ERROR SICNAL e WILL NOT BE EERO WHILE VACUUM CONTINUES TO DECREASE + ky POINTS A3 AND C3 MOVE UPWARD WITH B3 CAUSING e, AND s TO MOVE TO e l I "OFF-PORT" POSITION (A2 AND C2 DO NOT MOVE SINCE INPUT IS CONSTANT). THIS ALLOWS PILOT VALVE B TO BE THE ONLY PILOT VALVE IN CONTROL SINCE A AND C PILOT VALVES ARE NOT DRAINING OR CONTROLLING FLOW i CAMS ALLOW POSITION LIMIT SWITCH ARMS TO ROTATE CLOCKWISE AND, AT THE I REACTOR SCRAM SETPOINT, LIMIT SWITCHES OPEN 1 -} t t l-i l L i

L. O LOW CONDENSER VACUUM SCRAM LOGIC DESCRIPTION .i DECREASE IN B CONDENSER VACUUM IS SENSED BY BELLOWS IN BOTH VACUUM TRIP SYSTEM ONE (VTS-1) AND TWO (VTS-2) VTS-1 B BELLOWS ACTUATES REACTOR SCRAM SWITCHES (RSCS) 11 AND 12; VTS-2 B BELLOWS ACTUATEA RSCS 21 AND 22 l RSCS SWITCHES OPEN AND REACTOR PROTECTION SYSTEMS ONE AND TWO DE-ENERGIZE INITIATING A REACTOR SCRAM L. 1 i l' t i I I-L --}}