W3P87-2006, Application for Amend to License NPF-38,revising Allowable Containment Pressure Operating Range Based on Reanalysis of Limiting Peak Containment Pressure Event (Main Steam Line Break).Fee Paid

Application for Amend to License NPF-38,revising Allowable Containment Pressure Operating Range Based on Reanalysis of Limiting Peak Containment Pressure Event (Main Steam Line Break).Fee Paid

ML20236H202
Person / Time
Site:	Waterford
Issue date:	07/29/1987
From:	Barkhurst R, Barkhusrt R LOUISIANA POWER & LIGHT CO., NEW ORLEANS PUBLIC SERVICE CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20236H204	List: ML20236H212 W3P87-2006, Application for Amend to License NPF-38,revising Allowable Containment Pressure Operating Range Based on Reanalysis of Limiting Peak Containment Pressure Event (Main Steam Line Break).Fee Paid
References
W3P87-2006, NUDOCS 8708050097
Download: ML20236H202 (7)

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. f LOUISIANA POWER & LIGHT COMPANY e Post Office Box 6008 New Orleans. louisiana 70174 .J 1

i N%i Mu NEW ORLEANS PUBLIC SERVICE INC.

• Post Office Box 60340 = New Orleans. Louisiana 70160

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July 29, 1987 W3P87-2006 I A4.05 '{

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I U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

SUBJECT:

Waterford SES Unit 3 Docket No. 50-382 Technical Specification Change Request NPF-38-62 Gentlemen:

Louisiana Power & Light hereby files an application for an anendment to the Waterford 3 Technical Specifications. The amendment involves a revision to the allowabic containment pressure operating range based on a reanalysis of the limiting peak containment pressure event - a main steam line break (MSLB).

The containment pressure analyses are described in the text, figures and tables of FSAR Section 6.2. Those changes necessary to reflect the MSLB reanalysis will be incorporated in an FSAR update following approval of the proposed change by the NRC Staff.

As described in the enclosure, LP&L is proposing this change to alleviate the undue attention placed on containment pressure control as a result of 1 the overly conservative operating pressure range presently in the Technical Specifications. We would appreciate your assistance in obtaining a timely review of this submittal. q 1

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"AN EQUAL OPPORTUNITY EMPLOYER'8 l

Page 2 W3P87-2006 July 29, 1987 The proposed change does not involve an unreviewed safety question nor a significant hazards consideration. Should you have any questions or i require additional information, please contact Mike Meisner at I (504) 595-2832.

i Yours very truly,

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R. . Barkhurst Vice President-Nuclear Nuclear Operations RPB/MJM/pim Enclosures NPF-38-62 Filing fee, LP&L check - $150.00 cc: E.L. Blake, W.M. Stevenson, J.A. Calvo, J.H. Wilson, R.D. Martin, Administrator Nuclear Energy Division (State of Louisiana),

American Nuclear Insurers, NRC Resident Inspector's Office (W3)

UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the matter of )

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Louisiana Power & Light Company ) Docket No. 50-382 Waterford 3 Steam Electric Station )

AFFIDAVIT R.P. Barkhurst, being duly sworn, hereby deposes and says that he is Vice President, Nuclear of Louisiana Power & Light Company; that he is duly authorized to sign and file with the Nuclear Regulatory Commission the attached Technical Specification Change Request; that he is familiar with the content thereof; and that the matters set forth herein are true and correct to the best of his knowledge, information and belief.

1 c OJ R.P. Barkhurst Vice President-Nuclear STATE OF LOUISIANA)

) ss PARISH OF ORLEANS )

Subscribed and sworn to before me, a Notary Public and for the Parish and State above named this td 7 YL day of ' mas #

1967. #

fu aLL Notary Public f My Commission expires ((( (If(CClb .

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DESCRIPTION AND SAFETY ANALYSIS OF PROPOSED CHANGE NPF-38-62 This is a request to revise Technical Specification 3.6.1.4, Containment Systems Internal Pressure.

Existing Specification See Attachment A.

Proposed Specification See Attachment B.

Description The change is requested to increase the maximum allowable internal containment pressure based on a reanalysis of the limiting Main Steam Line Break (MSLB) event. Technical Specification Figure 3.6-1 presently defines the maximum containment pressure for Modes 1-4 as a curve from 15.4 psia at 80 F to 14.9 psia at 120 F. The proposed change will replace the curve with a single pressure value to account for a lower analyzed peak containment pressure and revise the measurement units from " psia" to." inches water gauge" to facilitate performance of the surveillance requirements.

As noted in the Bases, the maximum containment pressure allowed under Technical Specification 3.6.1.4 ensures that the containment peak pressure resulting from either a LOCA or MSLB event will not exceed the containment design pressure of 44 psig. To satisfy this condition, LP&L conducted a series of analyses for LOCAs (a spectrum of break sizes) and MSLBs (a spectrum of break sizes and initial power levels) to determine the event which would produce the peak pressure in containment. These analyses, summarized in FSAR Tables 6.2-1 and 6.2-2, demonstrated that the peak i containment pressure of 43.76 psig occurred for a 7.4765 ft2 MSLB from 75%

power with the concurrent failure of a containment cooling train. The i containment design pressure of 44 psig, therefore, allowed a margin of 0.2 psig over the calculated peak pressure. Because the allowable pressure j range was small and, in anticipation of operational difficulties in maintaining containment pressure in such a narrow band, LP&L proposed (and the NRC accepted) Technical Specification 3.6.1.4 to define the maximum 3 allowable containment pressure as a function of containment temperature, f thereby allowing an operating pressure range slightly larger than 0.2 psig for containment temperatures below 120 F. (

Although some operational flexibility was afforded through expressing  :

maximum allowable containment pressure as a function of containment L temperature, the narrow pressure range has placed undue operator attention 1 on maintaining containment pressure within Technical Specification limits. l To resolve this concern, LP&L has reanalyzed the limiting MSLB event.

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.Page 2 The peak containment pressure analyses (those presently in Section 6.2 of the FSAR and the MSLB reanalysis) are performed using a modified version of the CONTEMPT-LT Mod 26 computer code. A description of the computer code and modification is contained in FSAR Appendix 6.2B. In the Waterford 3 SER (Section 6.2.1.1) the NRC reviewed the modified computer code and found it acceptable for containment analysis.

Peak containment pressure is a sensitive function of the amount of passive containment heat sink. To support various Cycle 1 and 2 analyses, LP&L had updated the pre-licensing estimates of passive containment heat sink and exposed surface area to reflect final construction activities and other station modifications. This updated information was used in the reanalysis of the limiting 75% power MSLB. All other analysis assumptions and input f data described in FSAR Section 6.2.1.1.3 were unchanged from the original <

analysis. Due primarily to condensation on the increased surface area, the peak containment pressure for the limiting MSLB case was reduced from 43.76 i psig to 42.3 psig (see pressure plot in Attachment C).

I With this reduction of MSLB peak pressure, the worst peak LOCA pressure can q be considered as the limiting containment accident pressure. Referring to  !

FSAR Table 6.2-2, the new peak pressure of 43.2 psig occurs for the 9.82 ft2 J l DESLS LOCA with minimum safety injection. This value in conjunction with ]

the containment design pressure of 44.0 psig, defines a potential Technical J l Specification pressure range of 0.8 psig. -

The proposed change places a limit of 20 inches water gauge (INWG), or

! approximately 0.72 psig, on the maximum containment pressure during normal operating conditions. As described in the enclosed change to Bases Section 3/4.6.1.4, the calculated peak LOCA pressure margin of 0.8 psig (22.14 INWG) has been reduced by 1.20 INWG to account for potential instrument error and j 0.94 INWG for conservatism. Because of the increase in pressure margin  ;

operating range, the variation of initial containment pressure due to l i containment temperature has been ignored in the proposed change, providing )

additional conservatism.

l By using the peak LOCA pressure of 43.2 psig to define the allowable initial containment pressure range LP&L is introducing conservatism into Technical Specification 3.6.1.4 well beyond instrument error concerns. Unlike the limiting MSLB case, the LOCA events have not been reanalyzed utilizing the updated containment heat sink information, primarily because of the extended schedule necessary for the analyses. While the additional cases may be analyzed in the future, operational concerns with the narrow pressure range presently in Technical Specification 3.6.1.4, coupled with the lengthy NRC analyses required, dictate submittal of this proposed change based only on the limiting MSLB reanalysis. Should the LOCA cases be reanalyzed, LP&L expects the peak LOCA pressure to be reduced to less than or equal to the reanalyzed MSLB pressure of 42.3 psig, which would provide more.than double the pressure range requested by this proposed change.

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. 1 Safety Analysis The proposed change described above shall be deemed to involve a significant hazards consideration if there is a positive finding in any of the following areas: ,

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1. Will operation of the facility in accordance with this proposed j change significantly increase the probability or consequences of any 1 accident previously evaluated? l j

Response: No 1 1

The proposed change introduces no new effect into the previously l

evaluated accidents (MSLB/LOCA) other than updating the MSLB to reflect plant changes in passive heat sinks. The MSLB consequences

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(i.e. peak pressures) are reduced while still preventing overall j peak containment pressure due to the limiting LOCA from exceeding l containment design pressure. Therefore,.there is no increase in l probability or consequences for previously analyzed events.

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2. Will operation of the facility in accordance with this proposed l change create the possibility of a new or different kind of accident i from any accident previously evaluated?

Response: No.

The purpose of Technical Specification 3.6.1.4 is to prevent the maximum containment pressure during any MSLB/LOCA from exceeding the 1 l containment design pressure. The proposed change is the direct {

i result of incorporating as-built passive heat sink data into the MSLB analysis and thereby reducing the MSLB peak pressure. No new plant systems, modes of o P ation or setpoint changes have been introduced which could have an a fect on the course of an accident. Therefore, the proposed change will not create the possibility of a new or different accident from any previously evaluated. )

3. Will operation of the facility in accordance with this proposed change involve a significant reduction in the margin of safety?

Response: No.

Technical Specification 3.6.1.4 operates to prevent exceeding the containment design pressure. The proposed change ensures that design pressure is not exceeded by placing a limit on maximum containment  ;

pressure ciring Modes 1-4, based on the most limiting containment pressure event, thereby preserving safety margin. In fact, the margin from the limiting event peak pressure (calculated peak pressure plus maximum allowable containment pressure) to the containment design pressure increases from 0.04 psig under the existing Technical l Specification to 0.08 psig under the proposed change. Additionally, I reanalysis of the LOCA event would be expected to result in a peak l containment pressure much lower than that credited by the proposed l change. Therefore, the proposed change does not involve a reduction in a margin of safety.

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Safety and Significant Hazards Determination Based upon the above Safety Analysis, it is concluded that (1) the proposed change does not constitute a significant hazards consideration as defined by 10CFR50.92; (2) there is reasonable assurance that the health and safety of the public will not be' endangered by the proposed change; and, (3) this action will not result in a condition which significantly alters the impact of the station on the environment as described in the NRC Final Environ-mental Statement.

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