B13321, Informs of Inability to Submit plant-specific Analyses for Util as Planned,Due to Delays Encountered in Completing Sensitivity & Break Spectrum Analysis.Meeting Between NRC & Util Representatives Arranged for 890810

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Informs of Inability to Submit plant-specific Analyses for Util as Planned,Due to Delays Encountered in Completing Sensitivity & Break Spectrum Analysis.Meeting Between NRC & Util Representatives Arranged for 890810
ML20248C098
Person / Time
Site: Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date: 08/01/1989
From: Mroczka E
CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST UTILITIES
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B13321, TAC-66958, NUDOCS 8908090435
Download: ML20248C098 (3)


Text

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NORTHEAST UTILITIES cenerei Omces . seiden street. seriin. Connecticut l

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= arwanawomac wa" P.O. BOX 270 l HARTFORD. CONNECTICUT 06141-0270 k k J NN,NEfw~a.o 6 03) 665-5000 August 1, 1989 Docket No. 50-213 i B13321 Re: Zircaloy Clad Conversion ISAP Topic 2.17 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Gentlemen:

Haddam Neck Plant Large Break LOCA Topical Report Zircalov Clad Fuel Conversion (TAC No. 66958)

In letters dated January 31, 1989,III and February 17, 1989,(2) Northeast Utilities Service Company (NUSCO) on behalf of Connecticut Yankee Atomic Power Company (CYAPC0) submitted to the NRC Staff two topical reports describing the methodology to be used for the reanalysis of large break loss of coolant accidents (LOCAs) for the Haddam Neck Plant with Zircaloy clad fuel. The methodology was based on the NULAPS-LB transient thermal hydraulic blowdown and reflood code, the NUFRAP-T6 hot rod thermal and mechanical response code, and the NUCOM core oxidation and hydrogen generation code. The referenced submittal s also committed to submit the plant-specific large break LOCA I analysis for the Haddam Neck Plant in July 1989.

Dwing recent months, as discussed with the NRC Staff in telephone conver-sations, NUSCO has encountered delays in completing the sensitivity studies and the break spectrum analysis due to excessive conservatism in the code models and the plant specific model. As a result, CYAPC0 will be unable to submit the plant . specific analyses for the Haddam Neck Plant as planned.

In anticipation of schedule delays, NUSCO initiated a parallel effcr?. with Westinghouse (W) to perform LOCA analyses for the Haddam Neck Plant using the (1) E. J. Mroczka letter to the U.S. Nuclear Regulatory Commission, "Large ,

Break LOCA Topical Report - Zircaloy Clad fuel Conversion (TAC No.

66958)," dated January 31, 1989.

(2) E. J. Hroczka letter to the U.S. Nuclear Regulatory Commission, "Large Break LOCA Topical Report-Zircaloy Clad Fuel Conversion (TAC No. 66958),"

dated February 17, 1989.

8908090435 890801 3 f. g PDR ADOCK 0500 P -

i U.S. Nuclear Regulatory Commission B13321/Page 2 August 1, 1989 NRC-approved WCOBRA/ TRAC methodology for upper plenum injection (UPI) plants.

The original intent of this effort was to establish a basis for comparison l with our NULAP5-LB results and to demonstrate the licensability of Zircaloy clad fuel. Preliminary W calculations have demonstrated that Zircaloy clad fuel is licensable for Haddam Neck and that the two-loop methodology is applicable to the four-loop plants. The thermal hydraulic effects at the

, Haddam Neck Plant under a postulated large break LOCA event are the same as in the two-loop plants with UPI. Comparisons with the Westinghouse analysis have also enabled NUSCO to eliminate some of the excessive conservatisne in the NUL APS-LB models. Preliminary analysis with NULAP5-LB now show acceptable results for a large break LOCA at the Haddam Neck Plant with Zircaloy clad fuel.

CYAPC0 has determined that we will be unable to submit the large break LOCA analysis based on the NULAPS-LB methodology without unduly compressing the proposed NRC review interval to support the upcoming Cycle 17 reload. CYAPC0 evaluated the alternatives while taking into consideration what would be a realistic review schedule for the NRC Staff. With that in mind, CYAPC0 has opted to have H perform the large break LOCA licensing analysis using their approved WCOBRA/ TRAC methodology to support the Zircaloy clad conversion i

schedule for Cycle 17. The submittal date for the documentation is scheduled for mid-1990 in support of a planned Cycle 17 start-up of February 1991. The

report will include justification of applicability of the methodology to four-loop (UHI) plants, results of the break spectrum analysis, plant model sensitivity studies, fuel performance and hot rod analysis.

We plan to continue efforts to develop our in-house large break LOCA analysis capability culminating in submittal of our plant specific analyses. To that end, we are prepared to interact with the NRC Staff and their contractor in facilitating the review of our topical reports submitted in the referenced letters. This LOCA methodology is planned to be used in future licensing submittals.

In the interest of ensuring a mue thorrugh understanding of our plans and schedules for NRC review cf the documentation cf the large break LOCA analy-ris, we have arranged to meet with the NRC Staff on August 10, 1989. Repre-untatives from CYAPC0 r.nd M will participate iro the meeting. 4 The purpose of this :aettina Wii bn to provide the NRC Staff with an update an the development of NUSCO's capability to perform the large break [0CA analysis l for the Haddam Neck Plent. Also presented will to the y efforts and schedule l for auspting the WCOBRA/ TRAC methodology for the Haddam Neck Plant. One 1 important objective of this meeting ~will be for the NRC St&ff to confirm the i acceptability of the proposed scope and schedule for obtaining an NRC approved large break LOCA analysis for Cycle 17 with Zircaloy clad fuel.

1 CYAPC0 wishes to emphasize that the only change in methodology and schedule )

for licensing Cycle 17 is with respect to the large break LOCA analysis for

b . ,,. _. . . '

U.S. Nuclear Regulatory Commission B13321/Page 3 August 1, 1989 Haddam Neck. The . methodology for. analyzing' the small break LOCA and the non-LOCA transients and accidents remains unaffected.

If you have any questions in . advance' of the August 10, 1989 meeting, please-contact us.

Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY E. J.'Ep6czka f l- Senior Tice President cc: W. T.' Russell, Region I Administrator A. B. Wang, NRC Project Manager, Haddam Neck Plant J.-T.'Shedlosky, Senior. Resident. Inspector, Haddam Neck Plant 1.

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