IR 05000369/1989005

Forwards Summary of Enforcement Conference on 890428 Re Insp Repts 50-369/89-05 & 50-370/89-05.Issues Discussed Re Instrument Air Sys Interface W/Diesel Generator Starting Air Sys.List of Attendees & Handout Also Encl

ML20247D241
Person / Time
Site:	McGuire, Mcguire
Issue date:	05/15/1989
From:	Ebneter S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:	Tucker H DUKE POWER CO.
References
NUDOCS 8905250279
Preceding documents:	ML20248D589 (20 September 1989)
Download: ML20247D241 (31)

Text

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MAY 151989 Docket Nos. 50-369, 50-370 License Nos. NPF-9, NPF-17 Duke Power Company ATTN: Mr. H. B. Tucker, Vice President Nuclear Production Department 422 South Church Street Charlotte, NC 28242 Gentlemen:

SUBJECT: ENFORCEMENT CONFERENCE SUMMARY NRC INSPECTION REPCRT NOS. 50-369/89-05 AND 50-370/89-05 This letter refers to the Enforcement Conference held at our request on April 28, 198 This meeting concerned activities authorized for your McGuire facilit The issues discussed at this conference related to the Instrument Air (VI)

system interface with the Diesel Generator Starting Air (VG) syste A' list of attendees, a summary, and a copy of your handout are enclose We are continuing our review of these issues to determine the appropriate enforcement actio In accordance with Section 2.790 of the NRC's " Rules of Practice," Part 2, Title 10, Code of Federal Regulations, a copy of this letter and its enclosures will be placed in the NRC Public Document Roo Shou?d you have any questions concerning this letter, please contact u

Sincerely,

/W Stewart D. Ebneter Regional Administrator l

Enclosures:

List of Attendees  ; Enforcement Conference Summary Handout

REGION II 0FFICE - ATLANTA

• • • AGENDA * * *

H. B. TUCKER OPENING REMARKS T. L. MCCONNELL P. R. HERRAN SYSTEM DESCRIPTION R. O. SHARPE ,

SEQUENCE OF EVENTS ,

P. R. HERRAN l

' SAFETY SIGNIFICANCE / ROOT CAUSE/

CORRECTIVE ACTIONS J. T. FULLER OPERATIONS RESPONSE TO THE EVENT T. L. MCCONNELL SUMMARY STATEMENT H. B. TUCKER CLOSING REMARKS

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DESIGN BASES 0~ START EMERGENCY D/G AT LEAST TWICE, CONSECUTIVELY.

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EACH START LESS THAN OR EQUAL TO 11 SE O SUPPLY CONTROL AIR TO DIESEL CONTROLS AND INSTRUMENTATION " START" AND "RUN" CONDITION

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supply Note 1. Opens on a L'oss of Offsite Power, remains closed on LOC _

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8 NOT SAFETY RELATED 8 MCGUIRE IS " HOT STANDBY" PLANT 0 LOSS OF 0FFSITE POWER WITH & WITHOUT CONTROL ROOM EVACUATION 0 OPERATING PROCEDURES SUPPORT OPERATOR ACTION REQUIREMENTS 8 REVISE FSAR SECTION 9.3.1.3 TO CLARIFY HOT STANDBY AND COLD SHUTDOWN BASIS

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@"coId shMoM specification 288.1, Type I, Class 0 air qualit After the filters, air from both compressors dircharge into a common receiv'ar tank. .

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From the'd tank,' breathind air is suppl.ed to various locations in he Auxiliary; .and'inside the Containment. Isolation valves locsted outsids ther neont are installed in series with check valves located inside the Containment for each breathing air containment penetratio 'In addition to the screw compressors, two low pressure Itquid ring compressors can be used as backup. Each of these compressors discharges to a water separator and then to a receive tan .3. Safety Evaluation The compressed air systems are designed to provide a dependable source of compressed and' cooled air for station serv.f ce, breathing testing, and instrum sentation requirements. Sufficient redundancy is provided to give e M $ -

degree of reliability of air supply at all times. Sufficient air resolver .n capacity is provided to meet system high ir demand transient 4 ,,.. %.]

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A foss of instrument air due to a "Stacheut" during norms) operetten causes th. . *

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pneuestically operated valves in the station which are essential fem safe ,

shutdown to fail to the safe position. However, many of these valves requitte an air supply in the evint of Control Room evacuation coincident wgi normal electrical poweMD If this accident occurs, the plant can L2...tetw-J )gss of'

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""O i : M ;" condition from the auxiliary shutdown panel and the auxiliar l

the ry b ter panel. Therefore, air headers have been provided in the Auxiliary o Building and both ContainmentQgpply air to only those valves which are -

u .c. 2 2. The valves which pegweee a blackout air supply are listed in Table 9.3.1- These headers are protected against depressurization by check valves IV1122, IV1153, 2V1122 and 2V1153. Air storage for these headers are provided by the Instr nt Compressed Air Tanks. Since the diesel generator power during " " is not available for the Instrument Air Compressors, the blackout air supply headers are aligned to the Diesel Gaperator Starting Air System headers through a normally closed solenoid valv & Thoth solenoid valves must receive a "S4eehowt" and a " Diesel Running" signa 13to ope 'OP w a. LOCA s;gncd An ASME,Section III, Class 3 air reservoir is provided o/o n the instrument air piping to each main steam isolation valve operator. Redundant ASIE,Section III, Class 3 check valves are provided upstreas of each air reservoir for isolation free the remainder of the Instrument Air System. The interconnecting piping between the check valves, air reservoirs and the main steam isolation valve operators is Duke Class C. (Refer to Figure 9.3.1-2). These safety class air reserveles are provided as a redundant means of closure for each asin steam isolation valve. These valves are aise capable of being closed by spring action. Each reservoir has air capacity for a single closure of its respective main steam isolation valve. Air reservoir design

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i Past Operability of VG/VI ,

fwo Problems Identified: l designed-1

- Seismic - VI was not originally as a. seismic system Consumption by Blackout Header ,

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Air a-Information not generally available from vendors air consumption would b- Actual header of valves

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depend on operator cycling

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Operability Considerations 1 - Seismic - Due to small pipe size low mass, and adequate support, it was felt that the blackout header could be shown to be seismicly rugged

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2 - Air Consumption a -Preoperational testing had not identified any problems b -Previous short duration blackout had not indicated a problem with VG/VI ,

Conclusions 1) VG/VI interface capable of performing its design functio from a seismic standpoint 2) Past operability could not be determined without testing

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. 8 VG/VI Test Considerations 1.- Blackout header cannot be tested with the Unit above mode 5 .due to the impact on valves 2- Even with a unit in No-Mode (defueled) there are safety concerns with the potential impact i on the other unit because of the

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shared VI System 3- Test method (static test, dynamic test, number 'of compressors, etc)

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Unit 2 VG/VI Tests 6/28/88 2B VG to VI Blackout Header Test Test Method-2B VG compressors and receivers were aligned to 2B blackout header Results-Little or no change in VG or VI pressure (most loads were isolated from the header)

7/20/88 2A VG to VI Blackout Header Test Test Method-Same as 2B except that all loads were verified to be aligned to the header Results-Pressure in VI dropped to test termination

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point (approx. 80 psi); VG unaffected Conclusion at end of Unit 2 RFO 1) Regulator protected the VG system 2) Seistnic analysis of blackout header unnecessary  ;

3) Not reportable

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i Unit 1 VG/VI Testing 11/11/88 1A VG to VI Blackout Header Test

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Test Method-Same as 2 A except that a 30 cfm load was induced Results- 1) VG compressor w cs able to maintain VG pressure f 2) Check valve 1 VI- 12 2 did not seat Conclusion:

11/15/89 Due to leaking 1 -Test results were evaluated on check valve, test failed 2-With past condition of the check valve indeterminate, past operability of D/G 1 A could not be assured. Event was reported on 11./15/89 l

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Additional Testing January 1989 1- Focused attention on the filter regulator If this valve passed less air than the compressor could supply - would be no impact on VG if VI broke in a seismic event 2- By field testing and bench testing it was determined that:

a- D/G run/ shutdown cylinder needed 55 psig to remain open b- The filter regulator valve could pass greater than the compressor capacity at 20 psig l

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VG/VI Conclusions After identifying problem we moved quickly to:

1-a- Assure current operability b- Determine past operability 2- Develope a test program to determine operability refine method and test additional 3- Continued to test trains until we found an inoperable train 4- Kept Resident Inspectors informed l

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4-SAFETY SIGNIFICANCE OF ORIGINAL CONFIGlJRATION

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EVENT LOOP W/LOCA

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I NO SAFETY ISStJE 8 VG S0LEN0ID VALVES REMAIN CLOSED FOR LOCA

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SAF~.TY SIGNIFICANCE OF ORIGINAL CONFIGURAT EVENT - LOOP W/0 SEISMIC DIESELS 8 NON-SAFETY INSTRUMENT AIR RtMAINS 8 DIESELS SUPPLY Alit TO SEPARATE BLACK 0UT HEADERS WHICH ARE SEPARATED BY CHECK V 8 NORMAL & BLACK 0UT HEADERS INSTRUMEN AVAILABLE

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8 LIMITED AIR USEAGE SIMULATION OF THE AIR HEADER HAVE BEEN INCONCLUSIVE DIESEL ALTERNATIVES 8 STANDBY SHUTDOWN FACILITY IS CAPABLE TAINING HOT STANDBY CONDITIONS

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SAFETY SIGNIFICANCE OF P11GINAL CONFIGURATION EVENT - LOOP W/ SEISMIC DIESELS 8 BLACK 0UT AIR HEADER SEISMICALLY RUGGED (SQuG)

N0 UNACCEPTABLE INTERACTIONS 0 DIESEL STARTING AIR COMPRESSORS, AFTERC00LERS, DRYERS AND PIPING COMPRESSORS SEISMICALLY QUALIFIED OTHER COMPONENTS SEISMICALLY RUGGED (SQUG) ,

NO UNACCEPTABLE INTERACTIONS 8 THEREFORE, CONCLUSIONS STATED FOR LOOP W/0 SEISMIC ALSO APPLY

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DIESEL ALTERNATIVES

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8 TURBINE DRIVEN AUXILIARY FEEDWATER PUMP IS SEISMICALL

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QUALIFIED e THE SSF IS NOT SEISMICALLY QUALIFIED.BASED ON A SEISMIC REVIEW, THE SSF WOULD BE EXPECTED TO REMAIN FUNCTIONAL FOLLOWING AN SS :

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i ROOT CAUSE

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8 AT THE TIME THE VG/VI INTERFACE WAS DESIGNED, THERE WAS INSUFFICIENT DESIGN BASIS DOCUMENTATION THAT THE DIESEL GENERATOR CONTROLS REQUIRED CONTINUED AIR PRESSURE TO BE MAINTAINED AFTER THE ENGINE !!AD STARTED IN ORDER FOR THE ENGINE TO CONTINUE TO OPERATE

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LONG TERM CORRECTIVE ACTIONS SPECIFIC CORRECTIVE ACTIONS 8 SEISMICALLY QUALIFY DIESEL GENERATOR ENGINE STARTING AIR AFTERC00LERS, DRYERS AND PIPING 8 UPDATE FSAR TO CLARIFY HOT STANDBY VERSUS COLD SHUTDOWN BLACK 0UT AIR HEADER BASIS 8 PURSUE ALTERNATE SOURCE OF AIR FOR THE BLAC GENERIC CORRECTIVE ACTIONS 0 TOPFORM (DESIGN INPUTS, SITA, IDRs, ETC.)

e DESIGN BASIS DOCUMENTATION

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Operations' Response to the Event to

- Implemented CONSER VA TIVE measures FUTU2?E operability ensure PRESENT and

.of the Diesel Generators, regardless of test results ACTION Shut manual VG-VI isolation valv . , .

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Procedure changes: -

-Loss of Instrument Air (Abnormal Procedure 22)

-Loss of Control Room (Abnormal Procedure 17)

- Training / Required Reading involvement in test development

- Continuing

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Pre-Isolation Review

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The effect would have been dependent on fault location and operator actio Mitigating factors:

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On Diesel start, Operator automatically inspects D/G

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Control Room trouble annunciator

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2 annunciator alarms

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System reserve and tank blowdown time .

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Post-Isolation Review

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VG allowed to supply VI Ble.ckout Header only under carefully controlled

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DIESEL GENERATOR STARTING AIR (VG)/ INSTRUMENT AIR (VI) INTERFACE NRC ENFORCEMENT CONFERENCE APRll 28, 1989 SUMMARY STATEMENTS (1) McGUIRE EXPEDITIOUSLY INVESTIGATED THE WHEN VG/Vi INTERFACE RESULTS PROBLEM RAISED BY THE SITA IN MAY, 198 INDICATED THE POSSIBILITY OF INOPERABILITY UNDER CERTAIN CONDITIONS, IMMEDIATE. ACTIONS WERE TAKEN TO ISOLATE VG FROM THIS WAS VI AND ASSURE OPERABILITY OF THE D/G' CONSERVATIVE AND IMMEDIATE ACTION TO ASSURE CURRENT AND FUTURE OPERABILIT (2) IN MAY 1988 WE BELIEVED THAT PAST OPERABILITY COULD BE PROVEN FROM A SEISMIC AND AIR CONSUMPTION STANDPOINT; THEREFORE, WE DID NOT REPORT THE EVENT. WITH CURRENT OPERABILITY ASSURED, WE THEN DECIDED TO SYSTEMATICALLY TEST AND EVALUATE THE VG/VI INTERFACE TO PROVE PAST OPERABILIT (3) TESTING ON UNIT 2 IN JUNE AND JULY 1988 SUPPORTED PAST OPERABILITY AND WE COULD HAVE STOPPED THE INVESTIGATION A THAT POIN HOWEVER, FURTHER REVIEW OF THE TEST INDICATED IT WAS INCONCLUSIVE AND WE PROCEEDED WITH PLANS TO TEST 1 DURING UPCOMING REFUELIN (4) WHEN THE EVALUATION OF THE TESTING ON UNIT 1 INCAUSED NOVEMBER 1968 REVEALED THAT THE FAILURE OF VI-122 CHECK VALVE THE PAST INOPERABILITY OF D/G 1A WE EXPEDITIOUSLY REPORTED IT TO THE NR _ _ _ _ _ - - _ _ _ - _ _ _ - _ _ _ _ _ _ _ _ _ - - _ -

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i (5) THE REASON THE PAST OPERABILITY EVALUATION TOOK SO LONG WAS DUE TO THE FACT THAT TESTING COULD ONLY BE DONE UNDER CERTAIN CONDITIONS DURING REFUELING OUTAGES AND THEN IT WAS WITH A CERTAIN DEGREE OF RIS (6) BECAUSE OF ALL THE UNCERTAINTIES IN DETERMINING THE ACTUAL AIR LOADS ON THE BLACK-OUT AIR HEADER, ANY TESTING WE COULD POSTULATE WOULD NOT PROVIDE ABSOLUTE ASSURANCE OF PAST OPERABILITY. THEREFORE, DUE TO THE SAFETY RISK ASSOCIATED WITH A COMPREHENSIVE TEST AND THE LIMITED BENEFITS TO BE GAINED, WE DECIDED TO TERMINATE ANY ADDITIONAL TESTING THAT PLACED A TRANSIENT ON THE B. O. HEADER. CURRENT OR FUTURE PLANT SAFETY WOULD NOT BE ENHANCED BY FURTHER TESTIN (7) BECAUSE WE COULDN'T PROVE OPERABILITY ON THE OTHER 3 TRAINS (2A, 2B, AND 18) WITH SOLID EVIDENCE WE DECIDED TO REPORT THE D/G'S INOPERABLE UNDER CERTAIN CONDITIONS FROM STARTUP TO MAY 20, 1988. THE LER WAS SUBMITTED IN DECEMBER 198 (8) THE POSSIBILITY Dl0 EXIST THAT THE OTHER 3 TRAINS OF D/G'S COULD HAVE BEEN OPERABLE IF THE FILTER REGULATOR VALVES BETWEEN VG AND VI WOULD ACT AS AN ORIFICE TO PREVENT BLEED DOWN OF THE VG SYSTE THIS WAS TESTED IN JANUARY 1989 AND FAILE (9) IT IS STILL INCONCLUSIVE AS TO WHETHER OR NOT THE OTHER THREE TRAINS OF VG WERE INOPERABLE IN THE PAST, BECAUSE WE HAVE DETERMINED THAT THE PIPING WOULD WITHSTAND A SEISMIC EVENT AND ACTUAL AIR LOADS MAY BE WITHIN THE CAPABILITY OF THE VG COMPRESSOR (10) WE FEEL THAT OUR ACTIONS WERE CLEARLY PRUDENT, BASED ON WHAT PLANT SAFETY WAS A WE KNEW AT THE 11ME OF OUR DECISION TOP PRIORITY THROUGHOUT THE EVALUATION PERIOD AND WAS EVIDENT IN THE DECISIONS MADE.

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