ML20042F931

Safety Evaluation Supporting Amend 169 to License DPR-57

ML20042F931
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Site:	Hatch
Issue date:	04/27/1990
From:	NRC
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Download: ML20042F931 (5)

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!r SAFETY EVA(UATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 169 TO FACILITY OPERATING LICENSE DPR-57

' GEORGIA POWER COMPANY OGLETHORPE POWER CORPORATION MUNICIPAL ELECTRIC AUTHORITY OF GEORGIA CITY OF DALTON. GEORGIA.

EDWIN !.

HATCH NUCLEAR PLANT. UNIT 1 DOCKET NO. 50-321

1.0 INTRODUCTION

f By- letter dated January 15, 1990, Georgia Power Company, the licensee for the Edwin I.

Hatch I.uclear Plant, Unit

.1, requested changes to Tables 3.2-9 and 4.2-9 of the Technical' Specifications l

(TSs).

Specifically, proposed Change 1 would revise Table 3.2-9 to.specify two operable channels per-trip system, thus providing

for a "two-out-of-two" logic scheme for each of the anticipated transients without scram recirculation pump trip (ATWS-RPT)

. systems, and would_ add a provision _ allowing continued plan t operation with one inoperable channel in either trip system, after J

placing the inoperable channel in its tripped position.

Proposed Change 2 would revise. the ATWS-RPT trip settings in Table 3.2-9 f or 3-the -Reac tor Vessel-Low Water Level and the Reactor Pressure, would identify thel Reactor Vessel Low Water Level trip ac _a '" Level 2"

trip, and would revise - Table 4.2-9 to require that the reactor vessel water level and reactor pressure instruments receive - an J

instrument check at a minimum frequency of "once per shift" and an

-instrument functional teut at a minimum frequency of "once per 4

month".-

2.0 EVALUATION 2.1 Proposed Change 1 The present initiation logic scheme for the reactor vessel low-water level and the reactor vessel high pressure trip signals use

~ j a "one-out-of-two" logic to trip the recirculation pumps.

Either one of two low water level signals or one of two high pressure signals will trip the recirculation pumps.

In its letter of l

December 14, 1988, to the licensee, the NRC staff noted that the "one-out-of-two" logic schems is not in conformance with the ATWS Rule guideline in that inadvertent actuations of the trip systems j -

are not minimized.

However, by letter dated October 19, 1988, the I

licensee had committed to upgrade the recirculation pump trip actuation logic to a "two-out-of two" design by the end of the 9005100179 900427

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1990 refueling outage for Unit 1.

The NRC staff found this

,3 commitment and this logic design acceptable.

Proposed Change 1 merely'follows through on the licensee's previous commitment.

i Proposed Change i also would insert a note in Table 3.2-9 stating that if the required number of operable channels cannot be met f or one of the trip systems, operation may be continued for a period of up to 14 days with the inoperable channel placed in its tripped i

condition.

If the required number of operable channels cannot be h

met for'both trip systems, action to shut down the reactor must be i

taken within one hour.

This is consistent with=the current BWR Standard Technical Specifications and with the proposed Improved

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Technical Specifications for BWRs.

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In summary, proposed Change 1 would revise logic schemes for the l

ATWS recirculation pump trips to meet requirements requested by j

the NRC s ta f f,

and would incorporate provisions for continued 1

operation with less than both channels of both' trip systems functional.

This is consistent with current BWR Technical Specifications and with the proposed Improved Technical l

Specifications f or BWRs.

The NRC staf f has reviewed these proposed changes and finds that they are consistent with previous staff guidance 'and with the BWR Standard Technical Specifications.

j Accordingly, we find them acceptable.

I 2.2 Proposed Change 2

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The values now shown as " Trip Settings" for ATWS-RPT in Table l

~ 3.2-9 actually are analytical limits rather than allowable values

,l for the trip setpoints.

Setpoint methodology prior to 1979 often did not differentiate between analytical limits and allowable l

values for trip setpoints, and in some cases the values specified in the TSs are analytical limits.

However, the current practice-in: the BWR Standard Technical Specifications and in the proposed Improved Technical Speci fications f or BWRs is to specify allowable

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values rather than analy tical limits, which is consistent with more 1

modern setpoint methodology.

The licensee proposes to change the.

f ATWS-RPT vessel pressure and vessel water level trip settings in i

Table-3.2-9' to reflect the allowable values rather than the analytical limits.

i-The setpoint methodology used to -make this conversion from ana l y tical limits to allowable values was approved by the NRC staff In Amendment'103 to the Unit 1 license, which supported the analog transmitter trip system (ATTS) installation.

The methodology, l

which is based on Regulatory Guide 1.105, uses analytical limits to calculate allowable values.

The calculated allowable values are then inserted in the TSs.

The actual setpoints used at the Hatch

. plan t consider-instrumentation drifL and are developed from the allowable values, k

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The high reactor pressure " trip setting" (analytical limit) now shown as 1120 psig in Table 3.2-9 thus becomes 1095 psig when j

converted to the allowable value.

The ' analytical limit remains 1120 psig.

The actual setpoint in the plant would be equal-to or i

lower than the 1095 psig to assure that the allowable value will

- not be exceeded during the intervals between instrument testing or calibration.

- The ATWS-RPT on low water level is a Level 2 trip.

Prior to implementation of Amendment 103, both the Emergency-Core Cooling System (ECCS) " trip setting" and the ATWS-RPT " trip set ting" (both analytical limits) on reactor vessel water Level 2 were at -38 inches.

Amendment 103 provided for the installation of the new ATTS instrumentation, and the ECCS trip signal instrumentation was changed.

Amendment 103 also approved,a new analytical limit for the Level 2 ECCS setpoints of -58 inches, and based on the setpoint ca'l cu l a t ion methodology approved in that amendment, an allowable value of -47 inches water was calculated.

This allowable value of g

-47. inches was inserted in the TSs as the new " trip setting".

The ATWS-RPT Level 2 trip remained on the existing instrumentation -and was unaffected by Amendment 103.

The licensee now proposes to incorporate the ATWS-RPT Level 2 trip i

- into the ATTS instrumentation and to lower the analytical limit to

-S8 inches water.

This change provides for consistent " trip settings" for all Level 2 instrumentatica as specified in Tables 3.2-1, 3.2-2.'3.2-3 and 3.2-9 of the Unit 1 TSs.

While the change in trip setpoints from the

-38 inches to -47 inches > appears to be a non-conservative change, it has little impact on,the safety analyses.

For all ATWS events except the loss of feedwater flow, the Level 2 trip is a secondary signal to the trip on;high reactor vessel pressure.

For-the loss of feedwater flow, the change to -47 inches for the trip setpoint would result

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in a

delay of approximately 6 seconds in the trip of the recirculation pump.

However, the reactor will not be isolated since main steam isolation valve (MSIV) isolation does not occur

. until Level 1

(-113 inches), and the f uel remains adequately covered such that it would not experience boiling transition.

' Proposed Change 2 would also add the words " Level 2"

to the trip condition nomenclature of Table 3.2-9.

This change is purely editorial in nature and serves only to better describe the trip setting.

Finally, Table 4.2-9 would be changed to require instrument checks of.the ATWS-RPT trips at a minimum frequency of once per shift and instrument functional tests at a minimum frecuency of once per

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4 month.

These checks and functional tests are more frequent than

-those now specified and theref ore would provide equal or better assurance of system availability.

In summary, proposed Change 2 would revise the presently specified i

trip setpoints to allowable values rather than analytical limits.

At=the same time, the change to the reactor vessel low water level setpoint would be based upon the analytical limit of -58 inches f or Level 2,

as previously - approved by Amendment 103.

Table 3.2-9 would also be; amended to indicate that the low water level trip is a Level 2 trip.. Finally, Table 4.2-9 would be changed to require more frequent instrument checks and instrument functional tests.

The NRC staff has reviewed these proposed changes and finds that the change from the present " analytical limits" to " allowable values" for the trip settings is consistent with present practice in BWR Standard Technical Specifications, would help make the Unit i TSs more internally consistent, and was accomplished using the methods previously approved by the staff.

The change in the analytical limit f or the Level 2 trip also was previously approved by the staff. Insertion of the words " Level 2"

in Table 3.2-9 is t

editorial in nature and serves to clarify the table.

The changes in' frequency _for the instrument checks and instrument functional

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tests in Table:4.2-9 would result in equal or better assurance of system availabili ty.

Accordingly, we find proposed Change 2 acceptable.

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3.0 ENVIRONMENTAL CONSIDERATION

This. amendment involves changes in requirements with respect to

the installation or use of facility components located within the restricted area as defined in 10 CFR Part 20.

The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is -no significant increase in individual or cumulative occupational radia tion exposure.

The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such finding.

Accordingly, the amendment meets the eligibility criteria for s

categorical exclusion set forth in 10 CFR Di.22(c)(9).

Pursuant to 10 CFR Si.22(b),

no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

4.0 CONCLUSION

The Commission made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Reaister on March 7,

1990 (55 FR 8225),

and j

consulted with the State of Georgia.

No public comments were received, and the State of Georgia did not have any comments.

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5 We have concludet. based on the considerations discussed above, thatt (i) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor:

Lawrence P. Crocker. PDil-3, DRP I/II, NRR Dated: April 27, 1990

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