B16385, Submits Changes to & Identifies Errors in ECCS Evaluation Models or Applications of Models for Unit 3

Submits Changes to & Identifies Errors in ECCS Evaluation Models or Applications of Models for Unit 3

ML20140D776
Person / Time
Site:	Millstone
Issue date:	04/14/1997
From:	Brothers M NORTHEAST NUCLEAR ENERGY CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B16385, NUDOCS 9704240109
Download: ML20140D776 (9)

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Northeast 1%, Ferry iu (iwote 336), watersra, er 06383  :

l. UU 00I "UU @ M& tone Nuclear Power Station Nonheast Nuclear Energy Company 1 .

' P.O. Ibn 128

', Waterford, CT 06385-0128 i (IM,0) 447-1791 Fax (860) 444-4277 j

i The Northeast Utilities System

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, APR I 41997 Docket No. 50-423 ,

E1EME I

f l Re: 10CFR50.46(a) j

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U. S. Nuclear Regulatory Commission  !

, Attention: Document Control Desk i

Washington, DC 20555 i

l Millstone Nuclear Power Station, Unit No. 3 Annual Reporting cf Changes to, and Errors in,

Emeroency Core Coolma System Models or Apolmations i,

i in accon$ance with 10CFR50.46(a)(3)(ii), Northeast Nuclear Energy Company I

! (NNECO) hereby submits changes to, and identifies errors in, the emergency core ,

4 cooling system (ECCS) evaluation models or applications of those models for  !

Millstone Unit No. 3.

This report covers the penod from January 1,1996, through Dec&v.ber 31,1996,

i. and identifies changes in peak cladding temperature (PCT) based on changes to, or

errors identified in, the ECCS evaluation models, and changes in the applications of 1

the models beyor,d the range that was intended, The last annual update was

! submitted to the NRC Staff on March 21,1996.

l The following is a breakdown of the information provided in Attachment 2: i i- 4 i 1. Attachment 2 reports the Westinghouse modifications in the ECCS models s applicable to Millstone Unit No. 3. NNECO has previously reported the significant changes to the NRC in a letter dated November 27,1996, to meet the 30-day reporting criterion of 10CFR50.46(a)(3)(ii). These modifm' ations have resulted in permanent PCT margin allocation for Unit 3.

NNECO's commitments klentified in this letter are contained in Attachment 1.

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9704240109 970414 $ i p DR c I c

053422-5 REY.12-95

'U S Nuclear Regul: tory Commission

- i B16385\Page 2 We believe that this information satisfies the reporting requirements of l i

10CFR50.46(a)(3)(ii). N you have any questions, please contact J. M. Peschel at  !

l (860) 437-5840.

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Very truly yours, )

i l NORTHEAST NUCLEAR ENERGY COMPANY l i

i AfNI '~

M. H. Brothers 4 Vice President - Millstone Unit No. 3 I l

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cc: H. J. Miller, Region i Administrator l W. D. Travers, Dr., Director, Special Projects A. C. Corne, Senior Resident inspector, Millstone Unit No. 3 l J. W. Andersen, NRC Project Manager, Millstone Unit No. 3 1

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Docket No. 50-423 B16385 4

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Attachment 1 Millstone Nuclear Power Station, Unit No. 3 Annual Reporting of Changes To and Errors in Emergency Core Cooling System Models or Applications NNECO'S Commitments April 1997

'U.S. Nuclear Reguictory Commission

- - 816385%ttachment 1\Page 1 Enclosure  !

List of Regulatory Commitments

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The following table identifies those actions committed to by NNECO in this document. Any other actions discussed in the submittal represent intended or planned actions by NNECO. They are described to the NRC for the NRC's {

information and are not regulatory commitments. Please notify the Manager -

l Nuclear Licensing at the Millstone Nuclear Power Station, Unit No. 3 of any questions regarding this document or any associated regulatory commitments. j e

i Committed Date or Commitment Outage NONE N/A

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Docket No. 50-423 B16385 ,

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Attachment 2 Millstone Nuclear Power Station, Unit No. 3 l

Annual Reportina of 10CFR50.46 Marain Utilization i

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I April 1997 l

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, ,. 'U.S. Nucl:ar R gulator / Commission B16385\ Attachment 2V' age 1 Annual Reporting of 10CFR50.46 Margin Utilization Small Break LOCA PLANT NAME: Millstone Unit No. 3 Clad Temperature Notes

'A. Analysis of Record (6/90) PCT = 1891*F Eval. Model: NOTRUMP FO=2.6 Vendor: Westinghouso FdH=1.7 Fuel: VANTAGE SH SGTP=10%

B. Prior Permanent LOCA Model Assessment

1. Thru 12/1995 APCT= 56 F C. Current Permanent LOCA Model Assessments-Thru 12/1996 (Permanent Assessment of PCT Margin)

1. SBLOCTA Fuel Rod initialization Error APCT= 10 F (2)

2. MSSV 3% Setpoint Uncertainty APCT= 87 F (3)

D. 10 CFR 50.59 Safety Evaluations (Permanent Assessment of PCT Margin)

1. Increased Pressurizer Pressure Uncertainty APCT= 14*F

2. Effect of ZlRLO Fuel Cladding APCT= 24*F

3. Fuel Rod Crud APCT= 2*F -

4. Reduced Thermal Design Flow APCT= 12 F

5. Fuel Reconstitution APCT= 1F

6. Revised T-hot Average Scaling APCT= 2F E. Other Margin Allocations

1. Burst and Blockage / Time in Life APCT= 115*F (1)

2. Axial Offset Decrease to 20% APCT= -135 F ANALYSIS OF RECORD PCT + MARGIN ALLOCATIONS PCT = 2079'F

, ,,' N.S. Nuclear R::gulatcry Commission

• 1 B16385%ttachment 2\Page 2  ;

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Annual Reporting of 10CFR50.46 Margin Utilization Small Break LOCA (cont)  !

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Notes: )

(1) The base PCT used for calculating this penalty includes the Fud Rod Crud Safety Assessment performed to address the Cycle 4 axial offset ano'naly. The Fuel Rod Crud Evaluation penalty is found in item D, above. I (2) The 10 F penalty was reported by Westinghouse in July,1996 and is related to fuel rod initialization process in the SBLOCTA code. Specifically, an adjustment to the power, which is made to compensate for adjustments to the assumed pellet diameter, was incorrect. The 10 F penalty resulted in an increase in the Burst and Blockage / Time in Life penalty from 34 F to 40 F.

(3) The 87'F penalty resulted in a corresponding 75'F increase in the Burst and Blockage / Time in Life penalty, form 40 F to 115 F.  ;

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, U.S. Nuclear Regulatory Commission

• l B16385\ Attachment 2\Page 3 Annual Reporting of 10CFR50.46 Margin Utilization Large Break LOCA PLANT NAME: Millstone Unit No. 3 l

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Clad Temperature Notes j l

A. Analysis of Record (8/90) PCT = 1974*F (1) l l 1. Transition Core Penalty APCT= 50*F (2) 1 l Eval. Model: BASH 1 Vendor. Westinghouse j

Fuel

VANTAGE SH -

FQ=2.6 FdH=1.7 SGTP=10%

B. Prior Permanent LOCA Model Assessment l l 1. Thru 12/1995 APCT= -13*F (3)

C. Current Pymanent LOCA Model Assessments-Thru 12/1996 (Permanent Assessment of PCT Margin)

1. Translation of Fluid Conditions from SATAN to LOCTA APCT= 15'F l

D. 10 CFR 50.59 Safety Evaluations (Permanent Awassment of PCT Margin)

1. Increased Pressunzer Pressure Uncertainty APCT= 1*F

2. Effect of ZlRLO Fuel Cladding APCT= 6*F

3. Reactor Vessel Flange Radiation Shield APCT= 1*F i

4. Reduced Thermal Design Flow APCT= 12*F

5. Fuel Reconstitution APCT= 1*F

6. Revised T-hot Average Scaling APCT= 7'F 4

ANALYSIS OF RECORD PCT + MARGIN ALLOCATIONS PCT = 2054*F 4

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U.S. Nuclear Regulatory Commission

'- ' B16385%ttachment 2\Page 4 a

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Annual Reporting of 10CFR50.46 Margin Utilization Large Break LOCA(Continued) a i

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(1) Because the LOPAR fuel has achieved sufficient burnup to become non-limiting, i the VHS PCT of 1974*F will now be used instead of the LOPAR PCT of 2134*F. l 1

(2) A transition core penalty must be added to the Vantage 5 results until all the LOPAR fuelis removed from the core.

(3) This does not include the 193*F Hot Leg Nozzle Gap benefit reported by Westinghouse NNECO chooses to conservatively report this effect as a PCT benefit of 0.0*F until the NRC reviews and approves the hot leg nozzle gap methodology (WCAP-14404-P). 4