ML20214C657
| ML20214C657 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 05/08/1987 |
| From: | James O'Reilly GEORGIA POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20214C658 | List: |
| References | |
| SL-2267, TAC-65446, NUDOCS 8705210046 | |
| Download: ML20214C657 (8) | |
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~~ Georgia Fbwgr Company'
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- 333 Piedmont Avenue -~
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Atlanta, Georgu 30308 i
Telephone 404 526-7851 -
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- Maihng Address; l
Pbst Office Box 4545..
L Atlanta, Georgia 30302.
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James P. O'Reilly -
tre sourtern ekttre systeyn Senior Vice President Nuclear Operations i
SL-2267 1268C X7GJ17-H600 May 8, 1987 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Hashington, D.C.
20555 PLANT HATCH - UNIT 2 l
NRC DOCKET 50-366' I
OP'UtATING LICENSE NPF-5 REQUEST TO REVISE TECHNICAL SPECIFICATIONS:
SURVEILLANCE REQUIREMENTS RELATIVE.T0 EXTRACTION STEAM NON-RETURN VALVES l
Gentlemen:
In accordance with the provisions of 10 CFR 50.90, as required by.
10 CFR 50.59(c)(1), Georgia Power Company (GPC) hereby proposes changes to the Plant Hatch Unit 2 Technical Specifications, ' Appendix A to Operating License NPF-5.
The proposed change would delete the Technical Specifications I
requirement (concained in Section 4.3.7.2) to perform weekly surveillance testing on the Plant Hatch Unit 2 extraction steam non-return' valves.
These check valves are considered ~ by the turbine vendor '(General Electric) to be '"non-critical" with regard to turt,ine overspeed-protection and ' nuclear safety. issues. ' Surveillance. testing would-continue to be performed in a manner recommended by General Electric. provides a detailed description of the proposed change and the basis for the r.hange request. details the basis for our determination ~that the proposed change does not involve a:significant hazards consideration.
-l provides page cnange instructions for incorporating the proposed change into the Unit 2 Technical Specifications.
The proposed changed
-Technical-Specifications page follows.
Payment of the filing' fee in' the amount of one hundred and fifty go) dollars is enclosed.
8705210046 870508 D PDR ADOCK 05000366
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U. S.~ Nuclear Regulatory Commission May 8, 1987; Page Two In, order to allow time for ' procedure revision and '. orderly incorporation into copies ;of the Technical Specifications. we request that.the proposed amendment, once approved -'by the NRC, be issued with -an
. effective date -to be no later than 60 days ~ from the issuance of the' amendment.
Pursuant to the requirements of 10 CFR 50.91,Ja copy of. this letter and all applicable enclosures will be sent to Mr. J. L. Ledbetter of the En'1ronmental Protection Division of the Georgia Department of Natural Resources.
Mr.' James P. O'Reilly states that she -is denior Vice President of Georgia Power Company and is authorized to execute this oath on behalf of Georgia Power Company, and that to the best of his knowledge.and belief, the facts set forth in this-letter and enclosures are true.
GEORGIA POWER COMPANY By:
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l James P. O'Re11 Sworn to and subscribed before me this 8 ay of May 198.
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NotarfPublic Neby Peac, cwa enmu, cmpa GKM/lc My commen rip.w ce. u. m
Enclosures:
1.
Basis For Change Request 2.
10 CFR 50.92 Evaluation 3.
Instructions For Incorporation c:
Georaia Power Comoany Mr. J. T. Beckham, Jr.
GO-NORMS U.S. Nuclear Reaulatory Commission. Washinaton Mr. L. P. Crocker, Licensing Project Manager - Hatch U.S. Nuclear Reaulatory Commission. Reaion II Dr. J. N. Grace, Regional Administrator Mr. P. Holmes-Ray, Senior Resident Inspector - Hatch State'of Georaia Mr. J. L.'Ledbetter
-1268C
G'corgia Power A ENCLOSURE 1 PLANT HATCH - UNIT 2 NRC DOCKET 50-366 OPERAT*NG LICENSE NPF-5 REQUEST TO. REVISE TECHNICAL SPECIFICATIONS:
SURVEILLANCE. REQUIREMENTS RELATIVE TO EXTRACTION STEAM NON-RETURN VALVES BASIS FOR CHANGE RE0 VEST PROPOSED CHANGE:
The proposed change would delete the Unit 2 Technical Specifications requirement to perform weekly surveillance testing on the main turbine extraction steam, non-return (check) valves.
These valves-do not provide a
nuclear safety function in the Plant Hatch design.
Regular surveillance testing on the check valves will be performed per the turbine manufacturer's (General Electric's) recomm9ndations.
Background:
Bolling water reactors (BWRs) use the steam generated in the primary system to heat the feedwater prior to its entering the reactor vessel 'in order to optimize thermodynamic efficiency.
This steam is extracted at the main turbine and is piped to the feedwater heaters.
The extraction piping which carries the steam is fitted with non-return (check) valves located between the main turbine and the feedwater heaters.
These valves are intended to preclude the steam in the extraction piping from contributing to a turbine overspeed condition.
The valves also protect against a water leg in the lines which could lead to the accumulation of excess moisture in the turbine. These conditions could be harmful to the main turbine.
ASME Standard TOP-2-1985, " Recommended Practices for the Prevention of Hater Damage to Steam Turbines Used for Electric Power Generation,"
contains guidance relative to these valves.
Machine-specific inspection and operability requirements are outlined in General Electric's turbine operating manuals.
The General Electric turbines at Plant Hatch have two essentially separate and redundant systems to provide protection against shaft overspeed.
These two systems are the normal overspeed protection system and the emergency overspeed protection system.
The normal overspeed protection system implements normal speed control through proportional position signals to the control and intercept valves in the main and reheat steam lines, respectively.
The device is also equipped with a 1268C El-1 5/8/87 SL-2267
r GeorgiaPower d ENCLOSURE 1 (Continued)
B_4 SIS FOR CHANGE RE0 VEST B5ckground: (Con't) power-load unbalance sensing system which continually compares the generator electrical output with the turbine mechanical power.
If the turbine mechanical power exceeds the generator output, the power-load unbalance system will fast close the main control and intercept valves.
The power-load unbalance signal is a very early signal indicative of an imminent overspeed and permits a full Ioad rejection without the turbine shaft speed rising to the point of activating the emergency overspeed protection system.
The emergency overspeed protection system is a mechanical hydraulic system which has a mechanical ring mounted to the turbine shaft.
When an' overspeed occurs, the ring moves due to centrifugal force and activates a i
trip signal which causes fast closure of all main stop valves and reheat stop valves.
Both the normal and emergency overspeed protection systems send signals to air actuators which assist the extraction steam non-return (check) valves in closing.
The valves are forced closed by beginning reverse flow through the extraction lines.
General Electric classifies ' these valves as " critical" or "non-critical" depending on the energy content in the lines and the possible contribution to turbine overspeed.
Basis:
i Section 3/4.3.7 of the Unit 2 Technical Specifications provides limiting conditions for operation and surveillance requirements regarding the turbine overspeed protection systems of the main turbine.
Protection from turbine excessive overspeed is required for nuclear safety reasons, since overspeed could generate potentially damaging missiles which could impact and damage safety-related components, equipment, and/or structures.
The bases for the Unit 2 Technical Specifications are to ensure that:
(1) the turbine overspeed protection system instrumentation, the turbine speed control valves, and the extraction steam check valves are operable and (2) they will protect the turbine from excessive overspeed.
The reliability of the turbine overspeed protection systems and the probability of turbine-generated missiles have been evaluated by General Electric and found to be acceptable.
All the extraction steam check valves are classified as "non-critical;"
1.e.,
even with the valves inoperable, there is not enough energy in the extraction steam lines to challenge the' overspeed trip.
Therefore, I?68C El-2 5/8/87
-SL-2267
.. Georgia Power d ENCLOSURE 1 (Continued)
BASIS FOR CHANGE RE00EST 4
Basis: (Con't) operability of these valves is not required to avoid or mitigate an overspeed trip, and are not even considered in the probabilistic evaluations performed to show that the risk of turbine-generated missiles is acceptably low.
The Standard Technical Specifications (STS) for General Electric BHR/4 plants and the STS for all subsequent product lines consider the selection of the Technical Specifications dealing with the turbine overspeed protection systems to have optional content.
Also, the STS and all other individual plant Technical Specifications omit reference to the extraction steam check valves as components requiring regular surveillance for nuclear safety purposes.
General Electric recommends regular surveillance on the check valves in order to protect the turbine against water induction. Other BHR/4 plants similar to Plant Hatch perform surveillance consistent with GE recommendations, and GPC would do the same.
However, since these valves are classified as non-critical (i.e. do not significantly impact any nuclear safety issues), it is appropriate to delete them from the Unit 2 Technical Specifications, thereby allowing Plant Hatch Unit 2 to conform with standard industry practice.
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1268C El-3 5/8/87 SL-2267
p L Georgia Power A ENCLOSURE 2 PLANT HATCH - UNIT.2
'NRC DOCKET 50-366 OPERATING LICENSE NPF-5 REQUEST TO REVISE TECHNICAL SPECIFICATIONS:
SURVEILLANCE REQUIREMENTS-RELATIVE-TO
-EXTRACTION STEAM NON-RETURN VALVES 10 CFR 50.92'EVALUATILW Pursuant to' the requirements of 10 CFR.50.92, Georgia ' Power Company has' evaluated the proposed amendment to the operating license for Plant Hatch Unit 2 and has determined that its adoption would not involve - a significant hazards consideration.
The basis for this determination is as follows:
PROPOSED CHANGE:
The proposed change would delete the Unit 2 Technical Specifications requirement to perform weekly surveillance testing on the extraction steam, non-return valves.
The Unit 1 Technical Specifications do not include this requirement.
In addition, - the BNR/4 Standard Technical i
Specifications (STS) do not include surveillance requirements relative to the extraction steam check valves.
Basis for Proposed Chance:
The Plant Hatch Unit 2 Technical Specifications provide limiting conditions for operation and surveillance requirements regarding to the turbine overspeed protection systems of the ' main turbine.
Protection from turbine excessive overspeed is a nuclear _ safety concern, since overspeed could generate potentially damaging. missiles which could impact and damage safety-related components, equipment,' 'and/or structures.
The bases' for the Unit 2 Technical Specifications are,to ensure that:
(1) the turbine overspeed protection system instrumentatioW, the turbine speed control valves, and the extraction steam check valves are operable and (2) they will protect the turbine from excessive overspeed.
- However, the extraction steam check valves are classified as "non-critical;" i.e., there is.not enough energy in the extraction steam lines to challenge the overspeed trip with the valves inoperable.-
1 Therefore, operability of these valves _ is not. required to avoid or mitigate an overspeed trip.
However, it would be GPC's practice for_ the non-return valves to be periodically checked (per vendor recommendations) for operability to protect 'against water' induction into the turbine.
1268C E2-1 5/8/87-SL-2267 i
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Georgia Power d ENCLOSURE 2 (Continued) 10 CFR 50.92 EVALUATION Other BHR/4 plants similar to Plant Hatch adhere to this practice.
Since these valves are classified as non-critical (i.e., do not significantly impact any nuclear safety issues), it is appropriate to delete them from.
the Plant Hatch Unit 2 Technical Specifications, thereby allowing Unit 2 to conform with standard industry practice.
In conclusion, the Ter.hnical Specifications requirement. relative to the extraction steam non-return valves can be -deleted from the Unit 2 Technical Specifications.
The incorporation of this change will not involve a significant hazards consideration, because:
1.
The probability of the occurrence and the consequences of an accident or malfunction of equipment important to safety are not increased above those previously evaluated, because failure of the extraction steam check valves will not result in a turbine overspeed and will not significantly increase the severity of a turbine overspeed, should one occur.
The nuclear safety implications of a postulated turbine-generated missile have been analyzed by General Electric and have been found acceptable.
The operation of the extraction steam check valves is not important with regard to this nuclear safety issue; i.e., they are non-critical valves.
2.
The possibility of a different kind of accident from any ar.alyzed previously is not created by this change, because the extraction check valves do not affect the ability of the turbine overspeed protection systems to perform their functions with regard to the nuclear safety issue of turbine-generated missiles.
3.
Margins of safety are not significantly reduced by this change, since the function of the turbine overspeed protection systems relative to nuclear safety is still provided.
Surveillance requirements will be per the manufacturer's recommendations.
1268C E2-2 5/8/87 SL-2267
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Georgia Power d ENCLOSURE 3 PLANT HATCH - UNIT 2 NRC DOCKET 50-366 OPERATING LICENSE NPF-5 REQUEST TO REVISE-TECHNICAL SPECIFICATIONS:
SURVEILLANCE REQUIREMENTS RELATIVE TO EXTRACTION STEAN NON-RETURN VALVES _
PAGE CHANGE INSTRUCTIONS The proposed change to the Technical Specifications (Appendix A to Operating Licenses NPF-5) would be incorporated as follows:
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