HL-4861, Application for Amends to Licenses DPR-57 & NPF-5.Amends Would Revise Secondary Containment Draw Down & Maintain Vacuum Surveillance Requirement Acceptance Criteria

Application for Amends to Licenses DPR-57 & NPF-5.Amends Would Revise Secondary Containment Draw Down & Maintain Vacuum Surveillance Requirement Acceptance Criteria

ML20085A153
Person / Time
Site:	Hatch
Issue date:	06/06/1995
From:	Beckham J GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20085A157	List: HL-4861, Application for Amends to Licenses DPR-57 & NPF-5.Amends Would Revise Secondary Containment Draw Down & Maintain Vacuum Surveillance Requirement Acceptance Criteria ML20085A166
References
HL-4861, NUDOCS 9506140075
Download: ML20085A153 (6)

Text

l

.- . Georgia Power Company - i

• F 401nverness Center Parkway

. : Post Office Box 1295 Birmingharn, Alabama 35201 Telephone 205 877-7279 m .

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, n GeorgiaPower Hatch Project tesovran obctnc systarn r

June 6, 1995 Docket Nos. 50-321 HL-4861 50-366 U.S. Nuclear Regulatory Commission k ATTN: Document Control Desk -

Washington, D.C. 20555 s

Edwin I. Hatch Nuclear Plant f Request to Revise Technical Specifications:  !

Secondary Containment Draw Down Accentance Criteria l Gentlemen:  :

In accordance with the provisions of 10 CFR 50.90, as required by 10 CRF 50.59(c)(1),

Georgia Power Company (GPC) hereby proposes a change to the Plant Hatch Unit I and ,

Unit 2 Technical Specifications, Appendix A to Operating Licenses DPR-57 and NPF-5.  !

The proposed change revises the secondary containment draw down and maintain vacuum surveillance requirement acceptance criteria to 2 0.20 inch of vacuum from 2 0.25 inch of vacuum. i i

Enclosure 1 provides a description of the proposed change and an explanation of the basis ,

for the change. Enclosure 2 details the bases for GPC's determination that the proposed i change does not involve a significant hazards consideration. Enclosure 3 provides page change instructions for incorporating the proposed change. Following Enclosure 3 are the i

+

revised Technical Specifications pages (utilizing Amendment 195 and 135 as the basis) and the corresponding marked up pages. Enclosure 4 provides, for your information, the  !

Bases changes which reflect the proposed change. The revised Bases pages (utilizing Revision 0 as the basis), along with a marked up copy of the pages, are included and will '

be made effective concurrently with the Technical Specifications change.

This change will provide adequate margin for the secondary containment surveillance ,

requirements that are a part ofimproved Technical Specifications implementation. GPC  !

requests that the proposed amendments be approved prior to July 27,1995. In addition, GPC requests that the proposed amendments, once approved by the NRC, be issued with an immediate effective date and implementation no later than 60 days after issuance. j 9506140075 950606 i PDR ADOCK 05000321 /

P PDR I h{

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GebrgiaPower d U.S. Nuclear Regulatory Commission Page Two June 6, 1995 In accordance with the requirements of 10 CFR 50.91, the designated State official will be  :

sent a copy of this letter and all applicable enclosures.  ;

Mr. J. T. Beckham, Jr. states he is Vice President of Georgia Power Company and is authorized to execute this oath on behalf of Georgia Power Company, and to the best of his knowledge and belief, the facts set forth in this letter are true.

Sincerely,

. h J. T. Beckham, Jr.

Sworn to andsubscribed before me this bdayof  % ,1995.

5 L V$n n '

Notary Public p gpges w w s eER3.11lE SRM/eb

Enclosures:

1. Basis for Change Request ,

2. 10 CFR 50.92 Evaluation ,

3. Page Change Instructions -

4. Bases Changes ,

cc: Georgia Power Company Mr. H. L. Sumner, Nuclear Plant General Manager NORMS U.S. Nuclear Regulatorv Commission. Washington. D.C.

Mr. K. Jabbour, Licensing Project Manager - Hatch  ;

U.S. Nuclear Regulatorv Commission. Region H '

Mr. S. D. Ebneter, Regional Administrator Mr. B. L. Holbrook, Senior Resident Inspector - Hatch State ofGeorgia Mr. J. D. Tanner, Commissioner - Department of Natural Resources HL-4861

- . ~ . - ~ . _ _ .-. . -

Enclosure 1 Edwin I. Hatch Nuclear Plant Request to Revise Technical Specifications:

Secondary Containment Draw Down Acceptance Criteria Basis for Change Reauest l

Proposed Change This proposed change revises the surveillance requirements to draw down, and maintain the secondary containment at a vacuum. The vacuum acceptance criteria for SR 3.6.4.1.3 and SR 3.6.4.1.4 are revised from "2 0.25 inch of vacuum" to "2 0.20 inch of vacuum."

Basis for Proposed Change A Surveiljance Requirement acceptance criteria of2 0.20 inch ofvacuum ensures that the secondary containment is sufficiently leak tight such that the conclusions of the accident -

analysis remains valid. The Technical Specifications Bases state;"The secondary containment performs no active function in response to either of these limiting events [ loss of coolant accident (LOCA) or fuel handling accident (FHA)]; however, its leak tightness is required to ensure that the release of radioactive materials from the primary containment is restricted to those leakage paths and associated leakage rates assumed in the accident analysis and that fission products entrapped within the secondary containment structure will be treated by the Unit I and Unit 2 SGT Systems prior to discharge to the environment." Technical Specifications SR 3.6.4.1.3 and SR 3.6.4.1.4 are intended to ensure secondary containment integrity.

The current surveillance requirement acceptance criteria to draw down and maintain the j secondary containment at 2 0.25 inch of vacuum is besed on convention. It is estimated ,

that at wind speeds less than 35 mph (PSAR V-26) there would be little or no exfiltration from the secondary containment ifit were maintained at 0.25 inch of vacuum. Assuming .

dynamic pressure is proportional to the square of the velocity, the acceptance criteria revision to 2 0.20 inch of vacuum would lead to no exfiltration at wind speeds less than 31 mph. Plant Hatch meteorological conditions are such that wind speeds greater than 24 mph are not frequent (<0.5% of the time based on 1992-1994 meteorological data).

The dose effects from this wind speed would not be limiting in dose calculations performed with x/Qs prepared in accordance with Regulatory Guide 1.145, Revision 1.

Furthermore, at 24 mph wind speed, it is estimated that a 0.12 inch vacuum would result ,

in a condition ofno exfiltiction.

The HNP secondary containment is designed to be a low leakage building. The LOCA and FHA dose analyses do not assume that the secondary containment is at a specific -

vacuum. The analyses conservatively assume that releases are unfiltered and occur at ground level prior to secondary containment draw down (120 seconds after Standby Gas HL-4861 El-1 l - - -- . _ _ _ . . _ . _ _

Enclosure 1 i

Request to Revise Technical Specifications: 1 Secondary Containment Draw Down Acceptance Criteria Basis for Change Request Treatment (SGT) system initiation). The analyses further assume, that the releases (excluding bypass leakage) are filtered by the SGT system and occur at an elevated point after the 123 seconds. The dose analysis dispersion factors are conservatively based on neutral to stable siabilibj class conditions which maximize doses.

From a realistic standpoint the following would be expected:

1. It is not likely that the meteorological conditions would be such that stability class would be " neutral or stable" concurrent with high wind speeds at the time of the event.

2. The secondary containment atmosphere would not include the accident source term activity (particularly for the Design Basis Accident LOCA) upon SGT system initiation. This is because SGT would be started from the accident signal (low water level /or high drywell pressure) which would occur prior to any postulated fuel melt.

Additionally transit time for the source term activity to migrate from primary to secondary containment is ignored and no credit is taken for plateout. Therefore, the secondary containment would be at a negative pressure long before a source term activity was present. Similarly, as discussed in the Unit 2 UFSAR, section 15.1.41, '

for the FHA, the SGT initiation signal (from the refueling floor ventilation radiation monitors) and SGT initiation occurs prior to release of the refueling floor environment to the exhaust plenum.

Based on the infrequent occurrence of winds that would produce exfiltration from the secondary containment and the conseivatisms in the dose calculations, the resision in acceptance criteria is acceptable.

I t

HL-4861 El-2 1

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Enclosure 2 Edwin 1. Hatch Nuclear Plant Request to Revise Technical Specifications:

Secondary Containment Draw Down Acceptance Criteria 10 CFR 50.92 Evaluation Proposed Channe This proposed change revises the acceptance criteria for SR 3.6.4.1.3 and SR 3.6.4.1.4 from "2 0.25 inch of vacuum" to "2 0.20 iach of vacuum." 7 10 CFR 50.92 Evaluation Georgia Power Company (GPC) has reviewed the proposed Technical Specifications -

change described above and determined it does not involve a significant hazards consideration based on the following: -

1. The change does not involve a significant increase in the probability or consequences of an accident previously evaluated. The secondary containment serves a mitigation function and therefore this change does not increase the probability of an accident previously evaluated. The consequences of the previously evaluated accidents are not affected because at the wind conditions assumed in the accident analysis the building will be at a negative pressure and no exfiltration is postulated . Furthermore, the estimated wind speed at which exfiltration might take place (31 mph) is not a frequent occurrence (wind speeds of greater than 24 mph occur <0.5% of the time based on  !

Plant Hatch specific meteorological data).

2. The proposed change does not create the possibility of a new or different kind of accident from any accident previously analyzed. Revising the surveillance  :

requirement acceptance criteria does not physically modify the plant nor does it modify the operation of any existing equipment.

3. The proposed change does not involve a significant reduction in the margin of safety.

The change in vacuum acceptance criteria results in a slightly lower wind speed that may result in exfiltration from the building. However, this wind speed (31 mph) is in the realm of wind speeds which are infrequent at Plant Hatch. Furthermore, there are i numerous conservatisms in the existing dose calculations including: neutral to stable meteorological conditions, ground level release until establishment of the required vacuum, accident source term activities at event initiation, and no credit for plateout.

The secondary containment would be maintained at a slight negative pressure shortly after the Standby Gas Treatment fans are running and the releases would be from the main stack (well before the accident source term activity would be present in the secondary containment). Some plateout would also occur and this is conservatively ignored. Therefore the margin of safety is not significantly reduced.

i HL-4861 E2-1

Enclosure 3  :

l Edwin I. Hatch Nuclear Plant  ;

Request to Revise Technical Specifications:

Secondary Containment Draw Down Acceptance Criteria Page Change Instructions Instt Replace 3.6-38 3.6-38 t

.URill Insert Replace 3.6-40 3.6-40 j

i HL-4861 E3-1