ML17326A250

Forwards Addl Info Re Reinsertion of Two Previously Irradiated Westinghouse Fuel Assemblies in Place of Exxon Nuclear Co Assemblies Damaged During Refueling Outage. Discusses Decision Not to Perform Revised Accident Analysis

ML17326A250
Person / Time
Site:	Cook
Issue date:	09/07/1979
From:	Dolan J INDIANA MICHIGAN POWER CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
AEP:NRC:00263, AEP:NRC:263, NUDOCS 7909140313
Download: ML17326A250 (15)

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ACCESSION NBR:7909140315 DOC,DATE: 79/09/07 NOTARIZED:

NO DOCKET FACIL:50-315 Donald C,

Cook Nuclear Power Plant~

Unit li Indiana 8 '5000315 AUTH,NAME AUTHOR At-FILIATION OOLANgJ,E, Indiana 8 Michigan Power Co.

RECIP ~ NAME RECIPIENT AFFILIATION DENTONtH ~ RE Office of Nuclear Reactor Regulation

SUBJECT:

Forwar ds addi info re reinsertion of irradiated Hestinghouse fuel assembli Nuclear Co assemblies damaged during Discusses decision not to perform rev DISTRIBUTION CODE:

A001S COPIES RECEIVED: LTR TITLE: General Distribution for Af two previously es in place of Exxon refueling outage.

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INDIANA II MICHIGAN POWER COMPANY P. O. BOX 18 BO WL I N G G R E EN STAT ION NEW YORK, N. Y. 10004 September 7,

1979 AEP:NRC:00263 Donal d C.

Cook Nuc1 ear P 1 ant Unit No.

1 Docket No. 50-315 License No.

DPR-58 Revised Unit 1, Cycle 4 Core Loading Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.

20555 Dear Mr.

Denton:

This letter supplements our July 16, 1979 submittal (AEP:NRC:00212) which addressed the reinsertion of two previously irradiated Westinghouse fuel assemblies in place of two Exxon Nuclear Company (ENC) assemblies which were damaged during the recent Unit 1 refueli'ng outage.

In the referenced letter we stated that we did not plan to perform any revised accident analysis with respect to this replacement.

The purpose of this letter is to discuss the bases for this decision.

The affected core locations are not high power regions.

The incore measured F

of the peak pin of the reinserted assemblies i's 1.073 as,com-pared, to tke core peak pin value of 1.633 (unpenalized values).

This is to be compared with the Fg limit of 1.90 established for Cycle 3 Westinghouse assemblies.

The 1.90 Timit is in fact conservative as discussed in our letter of January 24, 1979 (AEP:NRC:00136).'

A particular conservatism worthy of re-iteration is that the limit was established on the basis of as-built fuel parameters.

Therefore credit was not taken for the decrease in average pellet temperature due to burnup (reinserted assemblies had burnups of 16,400 MWD/MT).

In addition, there has been extensi've ECCS analysis of the ENC fuel as re-ported in References 1, 2, 3 and 4, in accordance with 10 CFR 50 Appendix K

requirements.

Z 0 09140+(p'g((

1 I y t

Mr. Harold R. Denton, Director AEP:NRC:00263 The core was reanalyzed to ascertain the effect of the reinsertion on

, the predicted core. power profile.

The results'of the neutronic reanalysis are reported in References 5 and 6 ~

Figure 1 of Attachment 1 presents the predicted relative power distribution for the original and modified cores at a burnup of 100 MWD/MT.

Figure 2 presents a similar map for a burnup of 10,200 MWD/MT.

As seen

-in these figures, there is a change of 2.5X in assembly relative power in regions surrounding the affected core locations and-power peak changes of less than 1% have been determined.

Figure 3

is a-map of the predicted and measured values of the power distribution at 212 MWD/MTU.

The measurements show good agreement with predictions.

Reactivity control parameters were reanalyzed.

The calculated critical boron concentration at Hot Zero Power (HZP) changed by about 1

ppm.

Even though the replacement assemblies do not contain control rods, the worths of control banks A, B, C, and D were recalculated(7)and the assembly re-placement is shown to change the rod worths by a maximum of 4.pcm.

Finally, the assembly infinite multiplication factors of the original and re-placement assemblies are illustrated in Figure 4 of Attachment l.

Very similar values of assembly.

K are evidenced (1.028 vs. 1.036).

The hydraulic and mechanical design compatibility of the Westinghouse and ENC fuel assemblies was also considered.

This led.to the conclusion that the assemblies are indeed compatible.

References 8,

9 and'10 provide technical justification for this conclusions In addition, Westinghouse performed a quality control review of the replacement assemblies and found them to be acceptable for Cycle 4 use.

The above facts, particular emphasis being made of the fact that the replacement assemblies are not peak power assemblies, in conjunction with our three years experience of operating with a mixed Westinghouse/ENC core loading, constitute our technical basis for not reperforming the existing safety analysis and for concluding that the current Unit 1, Cycle 4 safety

, analysis report (ll) remains valid.

Very truly yours, JE,D:em ohn E ~ Dolan ice President cc: (attached)

S o

,I 1

4

Mr. Harold R. Denton, Director AEP:NRC:00263 (2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

K. P. Galbraith et. al., "Donald C.

Cook Unit 1

LOCA Analyses Using ENC WREM - Based PWR ECCS Ev'aluation Model (ENC-WREM II), "

XN-76-51 Exxon Nuclear Company,

January, 1977.

K. P. 'albraith et. al., "Flow Blockage And Exposure Sensitivity Study for D.

C.

Cook Unit 1 Reload Fuel Using ENC WREM-II Model" XN-76-51, Supplement 1,

Exxon Nuclear Company,

January, 1977.

G.

C. Cooke, "Flow Blockage And Exposure Sensitivity Study for ENC D.C.

Cook Unit 1 Reload Fuel Using ENC WREM-II Model, "

XN-NF-76-51 (P)

Supplement 2, Exxon Nuclear Company, January, 1978.

R.

E. Collingham and G.C.

Cooke, "Flow Bloakage

. And Exposure Sensit-tivity Study for ENC D.C.

Cook Unit 1 Reload Fuel Using ENC WREM-II Model,"

XN-NF-76-51, Supplement 3 (NP), Exxon Nuclear Company, April, 1978.

R. L. Feuerbacher et. al.,

"D.C.Cook Unit 1, Cycle 4 Startup and Operations'eport,

" XN-NF-79-46, Exxon Nuclear Company, June 6, 1979.

M. R. Killgore, "D. C.

Cook Unit 1, Cycle 4 Modified Core Loading Pattern" Letter Report PWR-010-79, Exxon Nuclear Company, May, 1979.

M.

R. Killgore, "D.C. Cook Unit 1, Cycle 5 Final Core Loading,"

Letter Report PWR-011-79, Exxon Nuclear Company,

June, 1979.

J. Yates, "Single Phase Hydraulic Performance of Westinghouse and Exxon Nuclear H.B. Robinson, Fuel Assemblies,"

XN-74-44, Exxon Nuclear Company October 1974.

C. A. Brown, "Combined Seismic

-LOCA Mechanical Evluation for Exxon Nuclear 15 x 15 Reload Fuel For Westinghouse PWR's," XN-76-47 (P),

Exxon Nuclear Company, Apri'1 8, 1977.

L. T. Gesinski, "Fuel Assembly Safety Analysis for Combined Seismic And Loss-of-Coolant-Accident,"

WCAP-7950, Westinghouse Nuclear Energy

Systems, July, 1972.

M. R. Killgore, "D.C.Cook Unit 1 Cycle 4 Safety Analysis Report,"

XN-NF-79-10, Exxon Nuclear Company,'ebruary 23, 1979.

Nv. Ha,roid R. Denton,Di;rectory

,4 PEP(NPC;00263 cc:

R.

C. Callen G. Charnoff D. V. Shaller -Bridgman R.

S. Hunter R.

W. Jurgensen

ATTACHMENT l TO AEP: NRC: 00263

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