ML20027C166
| ML20027C166 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 10/08/1982 |
| From: | Clayton F ALABAMA POWER CO. |
| To: | Varga S Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19301B787 | List: |
| References | |
| TAC-48973, TAC-52539, TAC-53434, NUDOCS 8210130527 | |
| Download: ML20027C166 (5) | |
Text
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m Mamng Address Alittm2 Pow:r Comp:ny
- a 600 North 18th Strnt Po t dmce Box 2641 e Birmingham. Alabama 35291 Telernone 205 7834081 F. L. Ciayton, Jr.
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AlabamaPower g
itc sourten tszinc sniem October 8, 1932 Docket No. 50-364 Director, Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Attention:
Mr. S. A. Varga Joseph M. Farley Nuclear Plant - Unit 2 Turbine Valve Technical Specification Deletion Request i
l Gentlemen:
In accordance with the Unit 2 Technical Specification 3/4.3.4, Alabama Power Company is required to perform periodic surveillance testing and inspection of turbine valves to demonstrate the operability of the turbine overspeed protection system.
These surveillance requirements are intended to provide protection from excessive turbine overspeed conditions and thereby minimize the potential for the generation of missiles.
Alabama Power Company, in conjunction with Westinghouse Electric Corporation, has undertaken a comprehensive review of the effectiveness of the required surveillance testing of the turbine valves as related to the potential for turbine missile generation.
This evaluation has determined that the operability of the turbine overspeed protection system is not dependent on periodic valve testing.
Additionally, the reliability of the turbine overspeed protection system is sufficient to ensure a low risk of Ah turbine missile generation without conforming to Technical Specification
- 1fD(
3/4.3.4 and thereby satisfies the bases of the current surveillance 5
requirements.
Consequently, due to unnecessarily subjecting the nuclear qq) steam supply system to cyclical power transients, the cost to perform the f k surveillance test without conco,nitant safety benefits, and the potential I
for turbine missile generation being below that for which technical s/3ja' specification surveillance is required, Alabama Power Company respectfully
!v requests that Technical Specification 3/4.3.4 be deleted.
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The current technical specification surveillance requirements can be summarized as follows:
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- 1) Test all the turbine stop, governor, reheat stop and reheat intercept valves and observe their movement through the cycle.
8210130527 821008 PDR ADOCK 05000364 P
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October 8, 1982 Mt. S. A. Varga
.Page 2
.U. S. Nuclear Regulatory Commission _
- 2) Perform a channel calibration of the turbine overspeed protection
, system.
- 3)' Disassemble 'and perform-a visual and -surface' inspection of at least,
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one;of each of-the turbine stop, governor, reheat stop and reheat _
intercept: valves.
Low Potential For Missile Generation The enclosed WCAP-10161 evaluates the demonstrated reliability of the turbine overspeed protection system and:the potential for turbine missile generation.
The evaluation considered three cases of turbine overspeed; each overspeed case was viewed with respect to the ability to generate a missile assuming the occurrence of the particular overspeed case.
The probability of an overspeed event is not dependent on the performance of channel calibration or the dissassembly and inspection of the turbine valves in accordance with the current technical specification.
The failure data used in this study, however, assumed nominal industry
'7 preventive maintenance was performed by the surveyed utilities.
The promulgation of this proposed technical specification change will in no way compromise the responsibility of Alabama Power Company to satisfy the Farley Nuclear Plant comprehensive preventive maintenance program recommended by the turbine-generator manufacturer.
The evaluation determined the low probability for missile generation to-be below that requiring technical specification surveillance based on an i
annual cycle test of the turbine valves and a five-year inspection interval of the low-pressure turbine discs.
Alabama Power Company satisfies the-bases for the low probability for missile generation by the following:
- 1) In letter dated September 21, 1981, Alabama Power Company committed to inspect turbine discs in accordance with the criteria delineated in NRC letter dated August 24, 1981.
The inspection interval is 5 years or less and satisfies the recommendations of the turbine-generator manufacturer.
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- 2) As discussed in the evaluation, WCAP-10161, the only significant I
dif ference between turbine trip and a ' typical turbine valve test-is
-the absence of an observer at the' turbine valves.
Full turbine valve operation is also evident when unobserved turbine trips occur and 'the valves are verified to 'be closed.
Verification that all turbine ' valves are closed'following a turbine trip is required by present Farley system operating procedures.
Historically for the industry, the average nuclear plant shuts down six (6) times a year.
Even if a : plant shuts down only to refuel, the average refueling period is one (1) year and the annual cycle test of the turbine vcives is satisfied independently of the technical specification requirements.
l Mr. S. A.'Varga
' October 8, 1982 U
U. S.JNuclear Regulatory Commission Page 3 o
L Therefore,; Alabama Power Company has determined that the assumptions used to determine'the probability to generate a turbine; missile contained in o
WCAP-10161'are specifically ' applicable to Farley Nuclear Plant - Unit. 2.
The enclosed evaluation, WCAP-10161, shows.th'at the combined worst-case probability for turbine misgile generation for all three turbine overspeed cases is less than 1.4 x 10-D'per year which is well below the missile generation' probability guidelines of 10-4 incidents per year established by Spenser H. Bush anu Regulatory Guide 1.115.
Consequently, the demonstrated reliability of the turbine overspeed protection system has
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. accomplished the objective of the technical specification surveillance requirements to ensure a low risk of turbine missile generation and therefore justifies the deletion of Technical Specification 3/4.3.4.
Ineffectiveness of Turbine Valve-Testing The weekly requirement to test turbine valves, which is now a portion of technical specification surveillance requirements, originated in the mid-50's as a result of engineering judgement associated with fossil plant experience and recognition of the economic importance of the reliable turbine-generation operation.
There has never been any safety implication associated with this recommendation.
The effectiveness of turbine valve-testing and observation of the valve movement as currently required by Technical Specification 3/4.3.4 is j
considered by the evaluation.
Again, the evaluation addressed the three cases of turbine overspeed.
The evaluation concluded that valve failure (i.e., nonoperability) is not dependent on periodic valve testing.
t This conclusion is based on the undemonstrated ability of valve testing / observation to influence valve lifetime by identifying necessary repairs or to identify failure precursors (i.e., identification of equipment conditions that could eventually lead to' valve failure if not corrected).
In other words, valve testing / observation does not preclude degradation leading to a valve -failure mode and has little recognized value in detecting an incipient condition leading to failure.
Turbine valve i
testing does not influence valve reliability or failure rates.- The primary i
benefit of valve testing / observation is the potential for detection of failed valves.
Consequently, the deletion aof turbine valve testing / observation surveillance requirements from Technical Specification 3/4.3.4 would have no adverse impact on the reliability of the turbine overspeed protection system nor reduce overall plant safety.
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. 1, Mr. S. A. Varga October 8, 1982 U. S. Nuclear Regulatory Commission Page 4 No Cost / Safety Benefits Moreover, the performance of the ineffective valve testing / observation represents unjustified loss of electric generation and unnecessarily subjects the nuclear steam supply system to cyclical power transients.
The performance of the weekly technical specification valve test requires
' power reduction to approximately 85%.
The estimated cost of replacement power to perform this weekly turbine valve test is $54,000 per month or
$650,000 per jear.
This inability of the valve testing / observation to provide increased assurance of the operability of the turbine overspeed protection system coupled with the unnecessary cyclical power transients and the economic loss associated with its performance justify the deletion of valve testing / observation from Technical Specification 3/4.3.4.
Conclusion In conclusion, WCAP-10161 has determined that the potential to generate a turbine missile from a turbine overspeed condition is well below that established by Spenser H. Bush and Regulatory Guide 1.115 and that the current survelliance requirement for turbine valve testing / observation is ineffective and without cost benefits.
These conclusions are based on an analysis that is not specifically dependent on the disassembly and inspection of the turbine valves or channel calibraton of the turbine
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overspeed protection system.
Therefore, Technical Specification 3/4.3.4 can be deleted without an adverse impact on the reliability of the turbine overspeed protection system or without a reduction in overall plant safety.
Due to the cost of performing the current technical specification surveillance requirements, approval of this proposed technical specification change is respectfully requested by the return to power from the first ref ueling outage which is currently scheduled for December 1, 1982.
Alabama Power Company's Plant Operations Review Committee has reviewed this proposed Technical Specification change ( Attachment 2) and has determined that this change does not involve an unreviewed safety question as shown in the attached safety evaluation (Attachment 1).
The Nuclear Operations Review Board is scheduled to review this change at the next meeting.
This submittal contains proprietary information of Westinghouse Electric Corporation.
In conformance with the requirements of 10CFR Section 2.790, as amended, of the Commission's regulations, enclosed with this submittal is an application for withholding f rom public disclosure and an affidavit.
The af fidavit sets forth the basis on which the information may be withheld from public disclosure by the Commission.
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q October 8,1982 Mr. S. A. Varga U. S. Nuclear Regulatdty Commission Page 5 Correspondence with respect to-the af fidavit or application for withholding should reference AW-82-51 and should be addressed to R. A. Wiesenann, Manager, Regulatory and Legislative Affairs, Westinghouse Electric Corporation, P. O. Box 355, Pittsburgh, Pennsylvania 15230.
This proposed amendment is designated as Class III for Unit 2 in accordance with 10 CFR 170.22 requirements.
Enclosed is a check for
$4,000.00 to cover the total amount of fees required.
In accordance with 10 CFR 50.30(c)(1)(1) three signed originals and forty (40) additionsl copies of the proposed changes are enclosed.
Yours truly, I
Y
[ 'L. Cl aytog, J r FLCJ r/ MAL :l sh-09 Attachments cc: Mr. R. A. Thomas SWORN TO AND SUBSCRIBED BEFORE ME Mr. G. F. Trowbridge THIS TO DAY OF(Vtnl% 1982 Mr. J. P. O'Reilly 2:5:0:Pr'a'rd Ms, A Notary Public My Commission Expires:
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