HL-5694, Revised Application for Amends to Licenses DPR-57 & NPF-5, Revising TS for Increase in Allowable Values for Reactor Bldg & Refueling Floor Ventilation Exhaust Radiation Monitors

Revised Application for Amends to Licenses DPR-57 & NPF-5, Revising TS for Increase in Allowable Values for Reactor Bldg & Refueling Floor Ventilation Exhaust Radiation Monitors

ML20199J894
Person / Time
Site:	Hatch
Issue date:	01/21/1999
From:	Sumner H SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20199J899	List: HL-5694, Revised Application for Amends to Licenses DPR-57 & NPF-5, Revising TS for Increase in Allowable Values for Reactor Bldg & Refueling Floor Ventilation Exhaust Radiation Monitors ML20199J908
References
HL-5694, NUDOCS 9901260283
Download: ML20199J894 (6)

Text

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< tawis Summer Southern Nuclear

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• - jl* Vice President Operating Company,Inc.

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Hetch Project Support ' 40 Inverness Parkway  ;

. Post Office Box 1295 Birmingham. Alabama 35201 j Tel 205.9923279 l Fax 205.992.0341 somnuiu m COMPANY l Energ to Serve MrWorld" j January 21, 1999 i Docket Nos. 50-321 HL-5694 50-366 U.S. Nuclear Regulatory Commission A'ITN: Document Cor. trol Desk Washington, D.C. 20555 )

Edwin 1. Hatch Nuclear Plant  :

Revision to a Requert to Revise Technical Specifications  !

for an increase in Allowable Values for the Reactor Building and Refueling Floor Ventilation Exhaust Radiation Monitors Ladies and Gentlemen: ,

On July 22,1998, we submitted to you a request to revise the Hatch Unit I and 2 Tecimical Specifications for the Reactor Building and Refueling Floor exhaust radiation monitor setpoints.

This is a revision to that request and supersedes the original submittal.

He proposed changes in the original submittal increased the Allowable Value for the reactor building and refueling floor exhaust high radiation trips to 100 mR/hr from 20 mR/hr and .

60 mR/hr. The proposed changes apply to Tecimical Specifications Tables 3.3.6.2-1, " Primary Containment Isolation Instrumentation," Functions 2.d and 2.e, and 3.3.6.2-1, " Secondary Containment Isolation Instrumentation," Functions 3 and 4.

The original request used an analytical limit of 136 mR/hr for the determination of the allowable values His analytical limit was based on the doses for the fuel handling accident being a small fraction (10%) of the 10 CFR 100 limits. The allowable value proposed in the original submittal however, is too high for the 136 mR/hr analytical limit. Hor;yer, the actual licensing basis for the '

fuel handling accident for Plant Hatch Units I and .~.

., Gat dcses remain well within (25% of) the l(

l 10 CFR 100 limits. His revision is being made to clarify that the actual analytical limit is i

i 340 mR/hr. Additionally, the allowable values proposed will be redued to 80 mR/hr to avoid having the allowable value at the upper range of the instrument.

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Enclosure I provides a description of the proposed change and an explanation of the basis for the q0 0\

i change. Enclosure 2 details the basis for SNC's determination the proposed change does not involve a significant hazards consideration. Enclosure 3 r rovides page change instructions for X incorporating the revised Technical Specifications changes. The resised pages and the corresponding markups follow the page change instructions. 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.

nen043 0 9901260283 990121 PDR ADOCK 05000321[

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U.S. Nuclear Regulatory Commission Page 2 January 21, 1999 Mr. H. L. Sumner, Jr. states he is Vice President of Southern Nuclear Operating Company and is authorized to execute this oath on behalfof Southern Nuclear Operating Company, and to the best of his knowledge and belief, the facts set forth in this letter are true.

Respectfully submitted, H. L. Sumner, Jr.

Sworn to andsubscribedbefore me this 42 l day of am I999.

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baM Notary Public Commission Expiration Date:

OCV/eb

Enclosures:

1. Basis for Change Request

2. 10 CFR 50.92 Evaluation

3. Page Change Instructions and Resised Pages cc: Southern Nuclear Operatina Company Mr, P. H. Wells, Nuclear Plant General Manager SNC Document Management (R-Type A02.001)

U.S. Nuclear Regulatory Commission. Washington. D.C.

Mr. L. N. Olshan, Project Manager - Hatch U.S. Nuclear Regulatory Commission. Recion 11 Mr. L. A. Reyes, Regional Administrator Mr. J. T. Munday, Senior Resident inspector - Hatch Slate ofGeornia Mr. J. D. Tanner, Commissioner - Department of Natural Resources HI-5694

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Enclosure 1 Edwin I. Hatch Nuclear Plant Revision to a Request to Revise Technical Specification for an Increase in Allowable Values for the Reactor Building and Refueling Floor Ventilation Exhaust Radiation Monitors Basis for Chance Reauest Backernund The function of the reactor building and the refueling floor ventilation exhaust radiation monitors, in combination with other accident mitigation systems, is to limit fission product release during and following postulated design basis accidents. The monitors automatically initiate closure of the appropriate secondary containment isolation valves and start the standby gas treatment system.

The reactor building and the refueling floor ventilation exhaust radiation monitors also initiate I closure of the Group 2 primary containment isolation valves to isolate possible reactor coolant pressure boundary (RCPB) leaks; however, the monitors serve as a third redundant method of detecting and isolating breaks in the RCPB (Unit 1 FSAR paragraph 7.3.4). Secondary containment isolation and establishment of a vacuum with the standby gas treatment system within the assumed time limits ensure offsite doses following design basis accidents are naintained within applicable limits. The Allowable Values for the trip setpoints are chosen to ensure radioactive releases do not exceed offsite dose limits.

In determining the appropriate Allowable Values for the reactor building and refueling floor j ventilation exhaust high radiation trip setpoint, offsite doses that are well within (25% of) the 10 CFR 100 limits were chosen. This is the Hatch licensing basis for the fuel handling accident, as stated in the Unit I and Unit 2 Safety Evaluation Reports section 15.3 and 15.3.3.

Using the bounding source terms developed for the Regulatory Guide 1.25 analysis of a fuel l handling accident described in the Unit 2 FSAR, the architect / engineer calculated, in millirem per hour, the radiation field that would exist at each set of the ventilation monitors following the fuel handling accident and the corresponding monitor response to that field. Using Regulatory l Guide 1.25 guidance and extended power uprate conditions, (2763 CMWT) the expected offsite

! doses from a fuel handling accident were calculated. Finally, using the most conservative radiation monitor response, the analytical limit necessary to limit releases such that the resulting offsite i doses were well within 10 CFR 100.11 limits was determined. The analytical limit is 340 mR/hr.

i Because a conservative radiation monitor response and bounding source terms were used in determining the setpoint, it applies to the Unit I and Unit 2 reactor building and refueling floor ventilation exhaust radiation monitors.

Descrintion of Proposed Chan_ge l

The proposed changes increase the Allowable Values for the high radiation trip for the reactor building and the refueling floor ventilation exhaust monitors from either 5 20 mR/hr or 5 60 mR/hr to 5 80 mR/hr. He proposed changes apply to Technical Specifications Tables 3.3.6.1-1,

" Primary Containment Isolation Instrumentation," Functions 2.d and 2.e, and 3.3.6.2-1,

" Secondary Containment isolation Instrumentation," Functions 3 and 4. The changes, proposed in HI 5694 El-1

Enclosure 1 Revision to a Requerst to Revise Technical Specifications for an Incre&se in Allowable Value for Reactor Building and i Refueling Floor Ventilation Exhaust Radiation Monitors )

Basis for Change Request l

l Licensee Event Report 50-321/1998-003, provide consistency between the Unit I and Unit 2 Technical Specifications relative to the Allowable Values for the reactor building and the refueling ]

floor ventilatum exhaust radiation monitors.

l Basis for Pn,m J Chanac . i Providing consistency among the Allowable Values for the high radiation trip for the reactor building ami the refueling floor ventilation exhaust monitors improves the human factors associated with functionally testing and calibrating both sets of reactor building and refueling floor ventilation exhaus radiation monitors. The human factors are improved by eliminating the possibility the trip l setpoints could be confused. Raising the Allowable Values permits the actual trip setpoints to be  !

set with adequate margin below Technical Specifications limits, thus, reducing the possibility of '

human error and/or setpoint drift resulting in trip settings above Technical Specifications limits and allowing setpoints far enough above background radiation levels to prevent spurious actuations.

The proposed Allowable Value of 80 mR/hr is 76% below the analytical limit of 340 mR/hr. The i new Allowable Value need not be higher than the proposed limit of 80 mR/hr based upon the l following information:  !

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1. The upper limit on the range of the installed radiation instruments is 100 mR/hr.  !

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2. The new value provides adequate margin to the licensing basis offsite dose limit of 25% of 10 CFR 100.11 limits.

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3. The new Allowable Value is sufficiently high to permit actual trip setpoints to be set with adequate margin below Technical Specifications limits, while still being far enough above background radiation levels to prevent spurious actuations.

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Enclosure 2 l

Revision to a Request to Revise Technical Specifications for an Increase in Allowable Value for Reactor Building and Refueling Floor Ventilation Exhaust Radiation Monitors 10 CFR 50.92 Evaluation l l

J In 10 CFR 50.92(c), the Nuclear Regulatory Commission (NRC) provides the following standards to be used in determining the existence of a significant hazards consideration:

...a proposed amendment to an operating license for a facility licensed under l f 50.21(b) or {50.22 or for a testing facility involves no significant hazards consideration, if operation of the facility in accordance with the proposed amendment would not: (1) Involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3)

Involve a significant reduction in a margin of safety.

Basis for no significant hazards consideration determination:

Southem Nuclear Operating Company reviewed the proposed license amendment request and determined its adoption does not involve a significant hazards consideration based upon the following discussion:

1. Do the proposed changes involve a significant increase in the probability or consequences ofan accident previously evaluated?

The Unit 1 and Unit 2 reactor building and refueling floor ventilation exhaust radiation monitors perform no function in preventing, or decreasing the probability of, a previously  !

evaluated accident. The monitors are designed to monitor ventilation exhaust for indications j of a release of radioactive material resulting from a design basis accident and initiate i appropriate protective actions. Because the proposed changes affect only the ventilation exhaust radiation monitors, the probability of an accident previoesly evaluated remains the same.

The function of the reactor building and the refueling floor ventilation exhaust radiation monitors, in combination with other accident mitigation systems, is to limit fission product  !

release during and following postulated design basis accidents. The proposed new Allowable Values for the high radiation trip will continue to ensure the offsite doses resulting from a i design basis accident do not exceed the NRC-approved licensing basis. Therefore, the l

. proposed changes do not involve a significant increase in the consequences of an accident  !

previously evaluated.

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i HL-5694 E2-1 I

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l Enclosure 2. l Revision to a Request to Rcvise Technical Specifications for an Increase in Allowable Value for Reactor Building and

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Refueling Floor Ventilation Exhaust Radiation Monitors  !

10 CFR 50.92 Evaluation '

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2. Do the proposed changes create thepossibility ofa new or diferent kind ofaccidentfrom l any accidentpreviously evaluated?

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'Ihe proposed changes increase the radiation level at which the ventilation exhaust monitors actuate; however, the manner in which their actuation logic functions and the systems that l isolatc or actuate as a result are undrected by the proposed changes. Furthermore, the l ventilation exhaust monitors will continue to perform their design function oflimiting offsite  ;

doses to NRC-approved licensing limits at the higher Allowable Values. Therefore, the l l proposed changes cannot create the possibility of a new or different kind of accident from  :

any previously evaluated.

3. Do the proposed changes involve a significant reduction in a margin ofsafety?

'Ihe Bases for Unit I and Unit 2 Technical Specifications Tables 3.3.6.1-1 and 3.3.6.2-1 state that the Allowable Values for the reactor building and refueling floor ventilation exhaust radiation monitors "are chosen to ensure radioactive releases do not exceed offsite dose limits." The proposed Allowable Values ensure the radiation monitors actuate at a radiation level sufficient to ensure offsite doses are within the NRC-approved licensing basis.

The proposed Allowable Values comply with the margin of safety defined in the Technical Specifications Bases for the ventilation exhaust radiation monitors; therefore, the proposed changes do not reduce a margin of safety.

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