ML18018B408

Forwards Responses to Requests for Addl Info Re Draft SER Open Items 63 & 67.Responses Verify Containment Pressure & Justify Operation of Normal Containment Purge Sys

ML18018B408
Person / Time
Site:	Harris
Issue date:	10/20/1983
From:	Mcduffie M CAROLINA POWER & LIGHT CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
LAP-83-493, NUDOCS 8310260147
Download: ML18018B408 (10)

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ACCESSION NBR: 8310260147 DOG ~ DATE! -83/10/20 NOTARI'ZED:." NO DOCKET' FACIL!50 400 'Shearon Har ris Nuclear Power 'Plantr. Unit 1< <Gai ol-ina 05000400

".50-401 'Shearon Harris'Nuclear Power -Plantr Unit-2i '-Carolina 05000401

'AUTH.NAME AUTHOR AFFILIATION MCOUFFIErMBA,

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8 Light>>Co>

'RECIP,NAME" RECIPIENT AFFILIATION DENTONrH ~ RE Office< of Nucl'ear Reactor<.Regulationr Direct'or SUBJECT!

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TITLE! Licensing 'Submittal: iPSAR/FSARi Amdts 8, Related Corr espondence'

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Carolina Power & Light Company SERIAL LAP 83 493 OCT. 8 0 'l983 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT UNIT NOS.

1 AND 2 DOCKET NOS.

50-400 AND 50-401 RESPONSES TO REQUESTS FOR ADDITIONAL INFORMATION CONTAINMENT SYSTEMS BRANCH

Dear Mr. Denton:

Carolina Power 6 Light Company hereby transmits one original and forty copies of additional information requested by the NRC as part of the safety review of the Shearon Harris Nuclear Power Plant.

This information is being submitted in response to the Draft Safety Evaluation Report Open Items 63 and 67.

We will be providing responses to other requests for additional information shortly.

Yours very truly, PSA/lcv (8254PSA)

Enclosure M. A. McDuffie Senior Vice President Nuclear Generation Mr. Wells Eddleman Dr. Phyllis Lotchin Mr. John D. Runkle Dr. Richard D. Wilson Mr. G. 0. Bright (ASLB)

Dr. J.

H. Carpenter (ASLB)

Mr. J. L. Kelley (ASLB) 411 Fayetteville Street

~ P. O. Box 1551 o Raleigh, N. C. 27602 cc:

Mr. B.

C. Buckley (NRC)

Mr.

G. F. Maxwell (NRC-SHNPP)

Mr. J.

P. O'Reilly (NRC-RII)

Mr. Travis Payne (KUDZU)

Mr. Daniel F.

Read (CHANGE/ELP)

Mr. R.

P.

Gruber (NCUC)

Chapel Hill Public Library Wake County Public Library

('310260147 83i020 PDR ADOCK 05000400 E

PDR goI i/

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Shearon Harris Nuclear Power Plant Draft SER 0 en Item No.63 The NRC has requested that we perform a minimum containment pressure analysis assuming that offsite power is available to the containment spray system and to the containment fan coolers, and verify that the resulting pressure is above the pressure assumed in the peak clad temperature following a loss of coolant accident analysis.

Response

In 10CFR40.46 ECC.S performance

analyses, the limiting assumption regarding availability of offsite power in terms of the acceptance criteria, i.e., calculated peak clad temperature (PCT), must be made.

As indicated in MCAP-8471, the three loop plant limiting case break (CD ~ 0.4 DECLG) yields lower calculated PCT values with offsite power available (reactor coolant pumps run case) than if offsite power is lost (reactor coolant pumps trip case).

This results from core thermal-hydraulics during blowdown and is true even though calculated containment pressure may be lower in the offsite power available case due to faster actuation of the engineered safeguards.

The applicability of the generic conclusion regarding offsite power status to the Shearon Harris ECCS analysis is presented in detail below.

A review of the original three-loop plant generic sensitivity runs demonstrated the large. benefit in calculated clad temperature which exists at end of blowdown in the offsite power available case.

Calculated clad temperature at end,of blowdown at the limiting fuel rod elevation (7.25 ft) is 1528'F with offsite power lost; with offsite power available, the calculated clad temperature at the equivalent location is only 1453'F at end of blowdown.

Hence, the blowdown performance calculated with offsite power available produces a clad temperature result at end of blowdown which is 75'F better than with loss of offsite power assumed.

This benefit will remain in effect throughout the core reflood transient, during which time the PCT is calculated.

The impact of containment pressure on ECCS performance is important only during the core reflood transient.

If offsite power is presumed available, the start times of the containment fan coolers and sprays at Shearon Harris will be reduced by ten seconds.

The ten seconds of additional heat removal by these systems will reduce calculated containment pressure during reflood by less than 0.4 psi; the impact of this pressure reduction on calculated PCT is less than 25'F.

Overall, then, the total effect of assuming offsite power to be available during a large break LOCA event at Shearon Harris is to obtain a more favorable result.

The Westinghouse ECCS performance analysis generic assumption of loss of offsite power is limiting for Shearon Harris, and the results presented in the FSAR demonstrate compliance with 10CFR50.46 for this limiting case.

Shearon Harris Nuclear Power Plant Draft SER Open Item No.

67 (FSAR Section 6.2.4),

NRC Question 480.22 (FSAR Section 6.2.1.5)

Open Item 67 Justify the proposed continuous operation of the normal containment purge system during the reactor operational modes of power operation,

startup, hot standby, and hot shutdown.

NRC Question 480.22 Branch Technical Position (BTP)

CSB 6-1 states that the initial containment internal conditions used as input information for the minimum containment pressure model for ECCS performance evaluation should include the minimum containment gas temperature and the minimum containment pressure that may be encountered under limiting normal operating conditions.

Provide additional information in the following areas concerning the initial values presented in FSAR Section 6.2.1.5.2:

(1)

Justify the use of 80'F as the minimum containment atmosphere temperature that may be encountered under limiting normal operating conditions.

(2)

The use of -1.0 in. wg for the initial containment pressure is not conservative, since the Shearon Harris site is at an elevation of approximately 260 feet, and since the Technical Specifications allow internal containment pressure to vary between +3.0 psig and -2.0 psig.

Justify the use of -1.0 in. wg, or revise the analysis using the minimum containment pressure that may be encountered under limiting normal operation.

NOTE:

Table 15.6.5-3 shows that the peak clad temperature for the

DECLG, CD ~

0.4, is 2181'F.

This is within 19'F of the 2200'F limit and, therefore, we are concerned with the sensitivity of the analysis to the assumed initial containment internal conditions.

Response

In previous discussions with the NRC, the staff has agreed that the design of the purge system is acceptable (refer to CP&L letter dated 5/9/83).

In addition, the maximum time for which the purge system may be used will be addressed in the development of Technical specifica-tions.

In view of the prospect of not having the capability for unlimited use of the purge system, CP&L's previous response to SRQ 480.22 (submitted on 8/2/82) has been modified as shown below.

The initial temperature condition that may be encountered under limiting normal operating conditions used in the ECCS performance analysis was assumed to be 90'F.

An evaluation determined that the containment cannot fall below 80'F, and the normal expected average containment temperature estimated at 100'F.

The 90'F value was chosen because it was shown to be a conservatively low value consistent with representative normal full power operation of other nuclear plants.

I

Shearon Harris Nuclear Power Plant Draft SER Open Item No.

67 (FSAR Section 6.2.4),

NRC Question 480.22 (FSAR Section 6.2.1.5)

(Cont'd)

The normal operating range for containment pressure is expected to be between negative 1 inch wg to positive 4 inch wg with the nominal pressure expected to be slightly positive.

The value of 14.7 psia was assumed for the ECCS performance analysis.

The containment is the atmospheric type per Item d of SRP 3.8.

The normal containment purge and makeup systems along with the containment cooling system will maintain the containment within the normal operating range.

The Normal Containment Purge Exhaust is first adjusted to allow the system to draw down the containment atmosphere to a slight negative pressure (to prevent outleakage).

When the containment pressure is reduced to -0.25 in.

wg one of the two 100% capacity makeup fans will automatically start.

The static pressure controller will regulate the respective supply fan inlet damper to modulate and maintain the containment pressure setpoint.

The pressure transmitter for controlling this lower value has a range of 0 to negative 1.0 inch wg.

Safety grade pressure transmitters with a range of -5 to 0 to +5 inch wg provide coverage of the normal expected containment pressure range to include the negative pressure transient requiring initiation of the containment vacum relief system.

Without continuous purging the containment pressure will buildup due to equipment air (instrument air) leakage.

Purging will be intermittent and will be limited to a duration consistent with NRC requests, plant operational requirements, and A~ considerations.

FSAR Section 6.2.1.1.2 will be revised to incorporate this information.

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