ML19340A247

Responds to Violations Noted in Insp Rept 50-269/74-04. Corrective Actions:Status Board Giving Sampling Schedule Prepared & Wastewater Handling & Collection Facility Enlarged.Control Rod Drive Cycle Records Encl

ML19340A247
Person / Time
Site:	Oconee
Issue date:	06/28/1974
From:	Thies A DUKE POWER CO.
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19340A248	List: ML19340A247 ML19340A249
References
NUDOCS 8001310538
Download: ML19340A247 (7)

Text

AEC DISTRIELTCN FOR PART 50 DOCEET MATERIAL (TEMPORARY FCF.M)

CONTROL TO: 6170 6

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DATE OF LOC DATE REC'D LTR TWX RPT CT;-2R uuce Power Company Chnrlotte, N.C. 28201 Mr. A.C. Thics b 28-74 7-8-74 X

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CRIG CC CTrER SENT AEC PER N

SENT LOCAL PLA "

N.C. Moseley none CLASS UNCLASS PROP INFO INPUT NO CYS REC'D DOCKET NO:

XXX 1

50-269 DESCRIPTION:

ENCLOSUP2S:

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Ltr trans the following....

Response to AEC/RO Report No. 50-269/74-4 concerning the problem with the control rod drive absolute position indication (ASI) system........

ACKNOWLEDGED (1 ev enel ree'd)

DO NOT REMOVE PN M -

Oconee FOR ACTIC'.. ; INPC72' t.TICN 7-10-74 JB BUTLER (L)

SCHWENCER (L)

ZIEMANN (L)

REGAN (E)

W/ CYS W/ CYS W/ CYS W/ CYS CLARK (L)

STOLZ (L)

DICKER (E)

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W/ CYS W/ CYS W/ CYS W/ CYS (gy in a c c a r i g,,i_ y vuw ten unuo W/ CYS W/ CYS W/ CYS W/ CYS l

KNIEL (L)

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YOUNGBLOOD (E)

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1. HENDRIE GRDiES DIGGS (L)

ERAITMAN C

/CHROEDER GAMMILL GEARIN (L)

SALTZMA';

MUNTZING/ STAFF J

CCARY KASTNER GOULBOURNE (L)

B. HURT

/ CASE IGHT BALLARD KREUTZER (E)

GIAMBUSSO AWLICKI SPANGLER LEE (L)

PLANS BOYD HA0 MAIGRET (L)

MCDONALD MOORE (L)(LWR-2)

STELLO ENVIRO REED (E)

CHAPMAN DEYOUNG (L)(LWR-1) dy0USTON MULLER SERVICE (L)

DUSE w/ input SKOVHOLT (L)

J OVAK DICKER

/SHEPPARD (L)

E. COUPE

/GOLLER (L)

OSS KNIGHTON SLATER (E)

P. COLLINS PPOLITO YOUNGBLOOD SMITH (L)

D. THol'PSON (2)

DENISE TEDESCO PIGAN TEETS (L)

/KLECTER

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/ ONG PROJECT MGR WILLIAMS (E)

/EISENHUT FILI & REGIO 5 (3)

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/ MORRIS BENAROYA HARLESS eT

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DUKE. POWER COMPANY Powra Buttoiwo 422 SouTu Cnuncu STutzt, GnAa!DTTE, N. C. asaoi A. C. Tu rcs sr w c p.ics.oca, P. O. Box 298 Peooverem a o Ta4=smisseon June 28,~1974 '

Mr.. Norman C. Moseley, Director l

Directorate.of Regulatory. Operations

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U. S.' Atomic Energy Commission Region II - Suite 818 230 Peachtree Street, Northwest Atlanta, Georgia 30303 i

Re:

RO:II:TNE

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50-269/74-4 l

Dear Mr.'Moseley:

Please find attached our responses.to Items I.A.l.a and I.A.3.a and b l

contained in RO Inspection Report 50-269/74-4.

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Duke Power Company does not consider any information contained in l

RO Inspection Report 50-269/74-4 to be proprietary.

Very truly yours,.

s/A. C. Thies A. C. Thies ACT:vr w

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DUKE POWER COMPANY OCONEE UNIT 1 RLSPONSE TO AEC/R0 REPORT 30. 50-269/74-4 I.A.l.a Asymmetric Red Monitoring System 10CFR50.59 requires that proposed changes to the facility involving an un-reviewed safety question shall not be carried out unless authorized by the Atomic Energy Commission.

Contrary to the above, during the period from January 18, 1974 to April 26, 1974, Unit 1 was operated with as many as six asymmetric rod monitors for individual control rods turned off.

RESPONSE

In a February 28, 1974 letter to Mr. Angelo Giambusso, Deputy Director for Reactor Projects, Duke Power Company reported problems with the control rod drive absolute position indication (API) system at Oconee Nuclear Station.

As identified in that report, most of the problems with the API have con-sisted of fluctuating or erratic indications.

The effect of the erratic indications is to give an asymmetric rod signal to the integrated control system (ICS) which initiates a runback in power as long as the indicated fault exists provided the ICS is operated in the automatic mode.

In order to avoid spurious runback due to erratic position indication signals, station personnel switched out of service the cignal from the asymmetric rod monitoring bistable in the control rod drive system (CRD).

Records indicate that six of these bistables were placed in the inoperative position.

Switching off the bistables had the following effect on the operation of the unit:

1.

For those bistables switched off a runback in power would not have been initiated if those rods were asymmetric.

However, in many cases, if a bypcssed rod were dropped, runback would be initiated by other rods in the group due to the change in group average.

2.

Rod withdrawal inhibit was bypassed on the particular rods for which bistables were switched off.

3.

The statalarm vindow indicating " asymmetric rod" would have been in-operable for those rods which had the bistable switched off. However, position indication on the control rod drive PI panel would be available to the operator as well as an asymmetric alarm light on the control rod drive station.

This light indicates a seven-inch asymmetric rod.

It should be noted when the control rod drive station is in manual, the reactor runback and rod withdrawal inhibit features of the control rod drive and integrated control systems are blocked.

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_2-

'The'effect of a dropped' control rod, assuming no ICS or control rod drive system action, has been analyzed and reported in BAW-1387, "Oconee 1 Fuel Densification Report," January, 1973.

Referring to Page 33, "The rod drop analysis results in a decrease in power initially after which the power returns'to 100 percent.

It has been shown previously that neither the withdrawal nor' the drop of a single control element will cause perturbation of the flux shape sufficient-to exceed design conditions at 112 percent.

Therefore, this occurrence still does not present any thermal problems."

AEC/ Directorate of Licensing (DOL) in Supplement 3 to the Oconee Nuclear Station Unit 1 Safety Evaluation issued July 10, 1973 stated in Section 3.3 that the results of the control rod drop incident have been reviewed by the staff and this transient, "taking into account.the effects of fuel densifi-cation concludes that they_would not result in a reduction of core thermal

margin, i.e., a DNB, less than 1.3."

Consequently, although the words of Section 14.1.2.-7 of the Final Safety Analysis Report have not been revised af ter the analysir, was completed for fuel densification, the effect of a dropped rod with no credit being taken for the rod withdrawal inhibit or asymmetric rod runback features of the control rod drive and integrated control systems had been analyzed by B&W and confirmed by AEC/ DOL in 1973.

Also, Section 7.2.3.3 of the FSAR states the following:

Failure of the.ICS does not diminish the safety of the reactor.

-None of the functions provided by the ICS are required for reactor protection or for actuation of the ESPS.

The recetor protection criteria, used in the analysis of the accidents presented in Section 14, can be met irrespective of ICS action.

In May of 1974, B&W was requested by Duke Power Comp ny to reconfirm by analysis that core protection limits are not exceeded assuming no control system action.

The results of that analysis are as follows.

The maximum increase in peaking for a dropped control rod is 22.3 percent with an incore detector quadrant power tilt of 14.9 percent.

Startup test analysis for Oconee 1 of the worst-case dropped rod observed an incore detector tilt of 15 percent and consistent peaking relationships.

The analysis indicates'that if a dropped rod occurred during' normal operation the' center fuel line melt and DNER criteria would not be exceeded.

The following is a list of assumptions for the analysis:

1.

The dropped rod is the worst case

2. - Initial' power level is 102 percent 3.

Central fuel melt limit is 20.1 kW/ft 4.

Fuel densification is included 5.

Power peaking is at the highest' level for normal equilibrium operation during life (BOL)-

6.

There is-no initial quadrant tilt

7. ' Af ter the dropped rod, the tilt increases to 15 percent (peaking increases:by 22.4~ percent)

With the preceding assumptions, the initial heat rate is 15.0 kW/ft. After

'the rod drop, the linear heat rate would increase to 18.4 kW/ft assuming no control reactivity compensation and a return to 102 percent power.

If powcr

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_3 remains constant at.102 percent and the ~ control ' rods compensate for the K

reactivity. decrease,' linear heat rate increases to 18.0 kW/f t.

-The minimum

- margin occurs in the case without reactivity compensation and is 9.2 per-

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cent..The. loss in DNBR. peaking margin for the tilt at 15 percent is 17.8 percent. For the same conditionsias.the preceding, the minimum DNBR

. peaking margin is 19.5 percent at 102 percent power leaving an excess

- margin of.1.4 percent.

The above analysis.by B&W assumes no action by either the control systems t

or - by. the operator. However, Technical Specifier -ton 3.5.2.2e states the :

~ follo. wing:

If a ' control. rod in the ~ regulating.or safety rod groups is declared, inoperable per 4.7.1.2, power shall be reduced to 60 percent of the thermal power allowable for the reactor coolant -

pump combination.

This, in effect, requires the' operator to manually runback the plant to 60 percent power assuming no control system action. Appropriate action by the operator assures additional conservatism with regard to'the above analysis.

~

The violation.as issued alleged that an unreviewed safety question was involved. From 10CFR50.59, the definition of an unreviewed safety question is.as follows:

A proposed.cbange, test or experiment shall be deemed to involve I

an unreviewed safety question:

(1).if the probability _ of occurrence or consequences of an -

accident or a' malfunction of equipment important to safety.previously evaluated in the' safety' analysis report may be incretsed; or (2)lif'a possibility'for an accidentaor malfunction of a different type than that evaluated previously in the safety analysis report may be created; or (3) if the margin'of safety-as; defined in the bases of any 4

technical ~ specification is reduced.

In-view of the above_ analysis concerning a dropped control-rod without control ~ rod drive or integrated control system' action, Duke does not con-sider :that the bypassing of the control rod drive asymmetric rod bistable

monJtors to be an unreviewed. safety question.

LDuke,-however, is. concerned that appropriate station management personnel were not ' advised and did not have an opportunity.to review the bypassing

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of the bistables.- Mr. J. E. Smith, Oconee' Nuclear Station Superintendent, in a. letter dated June 14,;1974Etofall sapervisors and~ engineers stated.

m thaf.the bypassing!"of.these functions was performed without written pro-

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cedures and.without' proper review.".' Smith further writes, "while we do notl consider 1the' bypassing' of Lthese functions to be 'an unreviewed safety

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question. worthy 1of a. Category I: violation, it.does point iout the potential 4

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that a possibility exists in other areas for the bypassing of important functions which could result in a compromise of safety or the result in negating of important functions.

In the. future, such use of bypass switches is not to be permitted without proper review and a written approved. procedure."

While Duke does not consider the action performed to be an unreviewed safety question, it is realized that the description in Section 14.1.2.7 of the Final Safety Analysis Report may not lead one to the proper con-

.clusion concerning the required action of the control rod drive and inte-grated control systems:

specifically, that core protection criteria are met without asymmetric rod runback or control ~ rod drive inhibit.

There-fore, a revision to Section 14.1.2.7 has been forwarded to AEC/ DOL and is attached for information.

Duke is concerned that this matter was not identified to station manage-

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. ment as a violation during the exit interview by the RO inspectors on April 26, 1974.

Nor was Duke advised that RO considered this to be a violation prior to receipt of Inspection Report 50-269/74-4 dated May 28, 1974.. We believe that appropriate identification of apparent violations at the earliest possible date will provide sufficient opportunity for dis-cussion prior to written issuance of the apparent violation. We believe that a full discussion of this incident would not have resulted in'its l

being identified as a Category I violation.

Although Duke believes that proper procedural steps were not taken at the station, we respectfully request that the Category I nature of this violation be rescinded.

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I. A.3 ~ a : ' Specific Conductance and 'nH ' Monitorin g A'.noted'in the' details'section of the inspection report, there.was one day s

during the period from December 1,'1973 to April 18,1974 (and it, has -been subsequently verified.from. April 18, 1974. through June 1, 1974) when pH and e

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specific conductance. monitoring was 'not properly done.

It has not'been determined-why this sample was'notitaken..

fit is considered that appropriate action has already been taken to prevent recurrence-of this-violation. A status board.has been prepared which gi'.

the last date on which the-sample was taken and the date on which the next sample is due.. In'ad64 tion,-additional emphasis has been'given by the station chemist ' to the: regular gathering of these samples-for analysis or the re-

- porting of basin status JUE samples' cannot' be taken.

Since monitoring has been done regularly each~ day since December -2:2,1973,- no further corrective action 4

is~ anticipated.

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I.A.3.b--Haste Collection' Basin Effluent pH The propcaed revision to-Technical Specification 1.2B is under review bylthe

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' Directorate of Licensing.

Furthermore, work is in progress to-enlarge the wartewater: handling and collection facility ut Oconee.

Full compliance will requ$re satisfactory completion of _ both of these items.

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