ML20247D241

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
Download: ML20247D241 (31)

See also: IR 05000369/1989005

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, 1989. This meeting concerned activities authorized for your McGuire

facility.

The issues discussed at this conference related to the Instrument Air (VI)

system interface with the Diesel Generator Starting Air (VG) system.

A' list of attendees, a summary, and a copy of your handout are enclosed. We

are continuing our review of these issues to determine the appropriate

enforcement action.

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 Room.

Shou?d you have any questions concerning this letter, please contact us.

Sincerely,

/W

Stewart D. Ebneter

Regional Administrator l

Enclosures:

1. List of Attendees  ;

2. Enforcement Conference Summary

3. Handout

cc w/encls:

T. L. McConnell, Station Manager

Senior Resident Inspector - Catawba

State of North Carolina

bcc w/encls: (See page 2)

8905250279 890515 I I

PDR ADOCK 05000369

Q PDC

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ENCLOSURE 1

LIST OF ATTENDEES

U.S. Nuclear Regulatory Commission

S. D. Ebneter, Regional Administrator

C. W. Hehl, Deputy Director, Division of Reactor Projects (DRP)

E. W. Merschoff, Deputy Director, Division of Reactor Safety (DRS)

G. R. Jenkins, Director, Enforcement and Investigations Coordination Staff

(EICS)

A. R. Herdt, Branch Chief, DRP

M. B. Shymlock, Section Chief, DRP

P. K. VanDoorn, Senior Resident Inspector, McGuire, DRP

Duke Power Company

H. B. Tucker, Vice President, Nuclear Production

T. L. McConnell, Station Manager, McGuire

D. W. Murdock, McGuire, Design Engineering Manager

R. L. Gill, Regulatory Compliance Manager

P. R. Herran, Design Engineer

R. O. Sharpe, McGuire Compliance

B. Travis, Superintendent of Operations

J. T. Fuller, McGuire Operations

J. S. Warren, Regulatory Compiionce

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ENCLOSURE 2

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ENFORCEMENT CONFERENCE SUMMARY

On April 28, 1989, representatives from Duke Power Company (DPC) met with the

NRC in the Region II office in Atlanta, Georgia to discuss (.oncerns regarding

the Instrument Air (VI) system interface with the Diesel Generator Starting Air

(VG) system.

Following opening remarks by S. Ebneter, NRC RII Regional Administrator, DPC

gave a presentation (Enclosure 3) on the subject identified above. The DPC

presentation covered a system description, sequence of events, safety

significance, root cuse, corrective actions, and operations response to the i

event. T. McConne*,6, Station Manager, McGuire summarized the presentation

followed by H. Tucker, Vice President, Nuclear Production, directing closing

remarks.

DPC stated that the deficiency was identified during a Self-Initiated Technical

Audit (SITA) of the VG system. The deficiency involved automatic alignment of

VG to VI and that a portion of VG was not clEssified as seismic. DPC discussed

corrective actions and an operability determination of the diesel. They also

concluded that their was no safety issue even durirg a LOCA with a seismic

event.

The NRC closed the meeting by stating that it had served to enhance Region II's

understanding of the issues and DPC's corrective actions.

I

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _

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ENCLOSURE 3

ENFORCEMENT CONFERENCE

DUKE POWER COMPANY

MCGUIRE NUCLEAR STATION

,

DIESEL GENERATORSYSTEM STARTING (VI)

AIR SYSTEM (VG)/ INSTRUMENT

APRIL 28, 1999

NRC' REGION II 0FFICE - ATLANTA

• • • AGENDA * * *

H. B. TUCKER

1. OPENING REMARKS T. L. MCCONNELL

P. R. HERRAN

2. SYSTEM DESCRIPTION

R. O. SHARPE

3.

,

SEQUENCE OF EVENTS ,

P. R. HERRAN l

'

4. SAFETY SIGNIFICANCE / ROOT CAUSE/

CORRECTIVE ACTIONS

J. T. FULLER

5. OPERATIONS RESPONSE TO THE EVENT

T. L. MCCONNELL

6. SUMMARY STATEMENT

H. B. TUCKER

7. 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 SEC.

O SUPPLY CONTROL AIR TO DIESEL CONTROLS AND

INSTRUMENTATION " START" AND "RUN" CONDITION

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

on LOCA.

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BLACK 0UT CONTROL AIR HEADER q

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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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specification 288.1, Type I, Class 0 air quality. After the filters, air from

both compressors dircharge into a common receiv'ar tank. .

_

'

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 penetration.

'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 tank.

9.3.1.3 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 .ne.

capacity is provided to meet system high ir demand transient 4 ,,..  %.]

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Los.s J W jhu- (s_ cop') .

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

.

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'

j

""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

9.3.1-3. 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 open.

'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

.

.

A

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.

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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 ,

2 -

Air

a-Information not generally available

from vendors

air consumption

would

b- Actual header

of valves

!

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

.

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 function.

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

,

shared VI System

3- Test method (static test, dynamic

test, number 'of compressors, etc)

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e

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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

'

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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Unit 1 VG/VI Testing

11/11/88 1A VG to VI Blackout Header Test

.

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

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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

l

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.

,e , en - ,

e--

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4-

SAFETY SIGNIFICANCE OF ORIGINAL CONFIGlJRATION

.

-

EVENT LOOP W/LOCA

.

.

I NO SAFETY ISStJE

8 VG S0LEN0ID VALVES REMAIN CLOSED FOR LOCA

.

.

6

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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

.

8 LIMITED AIR USEAGE SIMULATION OF THE

AIR HEADER HAVE BEEN INCONCLUSIVE

DIESEL ALTERNATIVES

8 STANDBY SHUTDOWN FACILITY IS CAPABLE

TAINING HOT STANDBY CONDITIONS

l

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a.

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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

'

DIESEL ALTERNATIVES

,

8 TURBINE DRIVEN AUXILIARY FEEDWATER PUMP IS SEISMICALL

'

QUALIFIED

e THE SSF IS NOT SEISMICALLY QUALIFIED.BASED ON A SEISMIC

REVIEW, THE SSF WOULD BE EXPECTED TO REMAIN FUNCTIONAL

FOLLOWING AN SSE.

_ _ _ _ _ - _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ - _ - . _ _ _ _ - _ _ _

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ROOT CAUSE

.

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

,

e

W

G

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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

,

e

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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 . , .

,

-

-

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

-

The effect would have been

dependent on fault location

and operator action.

- Mitigating factors:

-

On Diesel start, Operator

automatically inspects D/G

-

Control Room trouble

annunciator

-

2 annunciator alarms

-

System reserve and tank

blowdown time .

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Post-Isolation Review

-

VG allowed to supply VI

Ble.ckout Header only under

carefully controlled

1

conditions.

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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, 1988.

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'S.

CONSERVATIVE AND IMMEDIATE ACTION TO ASSURE CURRENT AND

FUTURE OPERABILITY.

(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 OPERABILITY.

(3) TESTING ON UNIT 2 IN JUNE AND JULY 1988 SUPPORTED PAST

OPERABILITY AND WE COULD HAVE STOPPED THE INVESTIGATION A

THAT POINT. HOWEVER, FURTHER REVIEW OF THE TEST INDICATED

IT WAS INCONCLUSIVE AND WE PROCEEDED WITH PLANS TO TEST

1 DURING UPCOMING REFUELING.

(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 NRC.

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ee se p

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(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 RISK.

(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 TESTING.

(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 1988.

(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 SYSTEM. THIS WAS TESTED IN JANUARY 1989 AND

FAILED.

(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 COMPRESSORS.

(10) WE FEEL THAT OUR ACTIONS WERE CLEARLY PRUDENT, BASED ON WHAT

PLANT SAFETY WAS A

WE KNEW AT THE 11ME OF OUR DECISIONS.

TOP PRIORITY THROUGHOUT THE EVALUATION PERIOD AND WAS

EVIDENT IN THE DECISIONS MADE.

.

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