ML20205M958
| ML20205M958 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 04/22/1986 |
| From: | Tam P Office of Nuclear Reactor Regulation |
| To: | Carey J DUQUESNE LIGHT CO. |
| References | |
| GL-85-12, TAC-62926, NUDOCS 8605010155 | |
| Download: ML20205M958 (13) | |
Text
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April 22,1986 Docket No. 50-412 DISTRIB TION
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P. Tam NRC PDR D. Miller Local PDR ACRS (10)
Mr. J. J. Carey, Vice President PAD #2 Rdg Tech Branch Duquesne Light Company T. Novak Gray File Nuclear Group OELD W. Lyon Post Office Box 4 E. Jordan Shippingport, PA 15077 B. Grimes J. Partlow
Dear Mr. Carey:
Subject:
Beaver Valley Unit 2, Interim Report on Reactor Coolant Pump Trip Criteria (Generic Letter 85-12)
By letters dated November 15, 1985 and March 10, 1986, you responded to Confirmatory Issue (41)(c) of the Beaver Valley Unit 2 SER. Our review of your submittals is ongoing.
Enclosed is an interim report documenting progress of our review, and information needs. Please review the enclosure. However, prior to providing a formal response and shortly after receipt of this letter, your staff should arrange for a conference call with the reviewer. We believe that most of the issues can be easily resolved over the phone. Results of this review will be documented in an upcoming SER supplement.
The information request affects fewer than 10 respondents, therefore, OMB clearance is not required under P.L.96-511.
Sincerely, Peter S. Tam, Project Manager i
PWR Project Directorate #2 Division of PWR Licensing-A Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: See next page
.t, L
PM: PAD D: PAD #2 er PTam:h LRubenstein 4/ /86 4g/8 4/R//86 i
8605010155 860422 i
hDR ADOCK 05000412 PDR
April 22,1986 Docket No. 50-412 DISTRIBUTION Docket File P. Tam NRC PDR D. Miller Local PDR ACRS (101 Mr. J. J. Carey, Vice President PAD #2 Rdg Tech Branch Duquesne Light Company T. Novak Gray File Nuclear Group OELD W. Lyon Post Office Box 4 E. Jordan Shippingport, PA 15077 B. Grimes J. Partlow
Dear Mr. Carey:
Subject:
Beaver Valley Unit 2, Interim Report on Reactor Coolant Pump Trip Criteria (Generic Letter 85-12)
By letters dated November 15, 1985 and March 10, 1986, you responded to Confinnatory Issue (41)(c) of the Beaver Valley Unit 2 SER. Our review of your submittals is ongoing.
Enclosed is an interim report documenting progress of our review, and information needs.
Please review the enclosure. However, prior to providing a formal response and shortly after receipt of this letter, your staff should arrange for a conference call with the reviewer. We believe that most of the issues can be easily resolved over the phone. Results of this review will be documented in an upcoming SER supplement.
The information request affects fewer than 10 respondents, therefore, OMB clearance is not required under P.L.96-511.
Sincerely,
't Peter S. Tam, Project Manager PWR Project Directorate #2 Division of PWR Licensing-A Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: See next page L h PM: PAD D: PAD #2' I
LRubenstein ler PTam:h 4
/86 4/2.{/8 4/8//86
Mr. J. J. Carey Duquesne Light Company Beaver Valley 2 Power Station CC*
Gerald Charnoff, Esq.
Mr. R. E. Martin, Manager Jay E. Silberg, Esq.
Regulatory Affairs Shaw, Pittman, Potts & Trowbridge Duquesne Light Company 1800 M Street, N.W.
Beaver Valley Two Pro.iect Washington, DC 20036 P. O. Box 328 Pittsburgh, Pennsylvania 15077 Mr. C. W. Ewing, Quality Assurance Zori Ferkin Manager Assistant Counsel Quality Assurance Department Governor Erergy Council Duquesne Light Company 1625 N. Front Street P. O. Box 186 Harrisburg, PA 15105 Shippingport, Pennsylvania 15077 Director, Pennsylvania Emergency Management Agency 1
Room B-151 Transportation & Safety Building Harrisburg, Pennsylvania 17120 Mr. T. J. Lex Mr. Thomas Gerusky Westinghouse Electric Corporation Bureau of Radiation Protection Power Systems PA Department of Environmental P. O. Box 355 Resources Pittsburgh, Pennsylvania 15230 P. O. Box 2063 Harrisburg, Peglvania 171?O Mr. P. RaySircar Stone & Webster Engineering Corporation BVPS-2 Records Management Supervisor P. O. Box 2325 Duquesne Light Company Boston, Massachusetts 02107 Post Office Box 4 Shippingport, Pennsylvania 15077 Mr. W. Troskoski U. S. NRC John A. Lee, Esq.
j P. O. 181 Duquesne Light Company 1
Shippingport, Pennsylvania 15077 1 0xford Centre 301 Grant Street Mr. Thomas E. Murley, Regional Admin.
Pittsburgh, Pennsylvania 15279 U. S. NRC, Region I 631 Park Avenue King of Prussia, Pennsylvania 152?9
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ENCLOSURE PRELIMINARY REVIEW 0F REACTOR COOLANT PUMP (RCP) TRIP CRITERIA BEAVER VALLEY UNIT 2 I
INTRODUCTION Listed below are the evaluation criteria the staff is applying to RCP trip review and our preliminary appraisal of whether sufficient information was provided for the staff to complete its review. The organization of this Enclosure is a staff provided guidance or evaluation criterion statement based upon Generic Letter 85-12 (Ref.1), generally followed by a staff critique of theapplicantsubmittals(Refs.2,3,and4).
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The staff plan to complete the review is to use this Enclosure as the basis for a telephone conference call prior to initiation of a significant response effort on the part of the applicant. The staff then plans to document the results of the preliminary review and the telephone conference call, and to i
provide that documentation to the applicant. Then the applicant can provide a written response regarding the accuracy of the staff perception of the j
telephone conference call, together with any desired corrections and supplemental information. This should allow the staff to complete the review and prepare a Safety Evaluation Report (SER). An alternate, if the applicant desires (and which is not presently contemplated), is for the staff to prepare formal cuestions for applicant consideration.
OVERALL GUIDANCE PERTINENT TO RCP TRIP 1
During a small break accident in certain break size ranges, there exists a j
window in time during which tripping RCPs will make the accident wor:se.
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i Therefore, in a small break situation, one must trip RCPs prior to entering the window.
If one wishes to depend upon manual trip, two criteria are applicable:
1.
One must show that at least 2 minutes exist within which to trip RCPs following " receipt of a trip signal" using licensing calculations as a basis.
2.
One must show that at least 10 minutes exist within which to trip RCPs following " receipt of a trip signal" using best estimate calculations as i
a basis.
If, for some reason, the RCPs have not been tripped within 10 minutes of the time at which plant conditions indicate trip should be perfonned, they are to be left running until after the window is closed. Closure can be indicated by parameters such as regaining both adequate subcooling margin and adequate pressurizer level after they have been lost.
4 Analyses are required to establish timing relative to items 1 and 2, as well as to establish the dimensions of the window.
It is desirable to leave pumps running for control purposes during other transients and accidents, including steam generator tube rupture accidents of sizes up to one tube broken. Therefore, insofar as is practical, procedures and criteria should be developed to attain this goal. Note that leaving pumps running during "non-break" transients and accidents is not a 100% requirement, as contrasted to the small break, where trip must be accomplished to remain in compliance with the regulations.
(Failure to trip as required could lead to exceeding Appendix K specified temperatures.) For "non-break" transients and accidents, RCPs may be tripped when desirable.
If in doubt, the small break criteria are to be applied.
New plants coming on line should have dealt with RCP trip prior to power operation.
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Note much of the work pertinent to the above criteria has been done on a generic basis, and is applicable to individual plants. Where this is the case, it is sufficient to establish applicability, and the generic work need not be repeated on a plant specific basis.
SPECIFIC EVALUATION CRITERIA AND COMMENTS The evaluation criteria are generally those provided in Reference 1, including the Safety Evaluation and its appendices, which were an enclosure to Reference 1.
A.
Determination of RCP Trip Criteria Demonstrate and justify that proposed RCP-trip setpoints are adequate for small-break LOCAs but will not cause RCP trip for other non-LOCA transients and accidents such as SGTRs. This is to include performance of safety analyses to prove the adequacy of the setpoints.
Consider using partial or staggered RCP-trip schemes.
Staff Evaluation. The applicant has selected the Reactor Coolant System (RCS) / secondary pressure criterion as the basis for RCP trip, with the additional qualification that at least one charging /high head safety i
injection pump be running in order to trip the RCPs. The pressure differential selected is to trip if less than 145 psid. The pressure differential criterion is one of the three criteria which the staff previously found acceptable on a generic basis, and is the one which the-staff recommended as the first choice, again, on a generic basis.
However, the additional requirement that a charging or high head safety injection pump be running was not a part of the staff generic acceptance criterion.
The staff requests that the licensee provide a summary of the selection process which illustrates the rational leading to the selected trip 3
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criterion. Particular attention should be paid to the charging or high head safety injection pump requirement since the staff has not reviewed this topic.
A1.
Identify the instrumentation to be used to detennine the RCP trip set point, including the degree of redundance of each parameter signal needed for the criterion chosen. Establish the quality level for the instrumentation, identify the basis for the sensing-instruments' design features, and identify the basis for the degree of redundance.
Staff Evaluation. Charging /high head safety injection pump breaker position, RCP breaker position, RCS pressure, and rain steam line
' pressure instrumentation is identified by number. The applicant considers the identified instrumentation to represent the minimum designated by Emergency Operating Procedure backup documents.
Additionally, the operators are stated to be trained to use all available, redundant instrumentation to determine the existence of an RCP trip condition.
Redundancy is not directly addressed. However, two RCS pressure indicators are identified, and three steam line pressures are identified for each steam generator. Breaker position redundancy is not as clear.
Nor is it clear that an indication of a closed breaker assures that a pump is running. Quality level and bases are not mentioned.
A2.
Identify the instrumentation uncertainties for both normal and adverse containment conditions. Describe the basis for the selection of the adverse containment parameters. Address, as appropriate, 1ccal conditions, such as fluid jets or pipe whip, which might influence instrumentation reliability.
Staff Evaluation. The applicant reports that wide range pressure instrument channel uncertainty is 76 psi under both nonnal and abnormal containment conditions, and states that the uncertainty considers all error components from the sensor through to the display of the PSMS.
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Pressure transmitters are not affected by an adverse containment condition since they are located outside containment.
Steamline pressure channel uncertainty is stated to be 33 psi, and its determination and independence of containment conditions is similar to.
that of the wide range pressure.
Overall uncertainty, via the square root of the sum of the squares method, is 83 psi.
Stone and Webster Engineering is cited as having verified that all RCS wide range pressure and steamline pressure indications will be protected for all LOCA and secondary side line breaks, and therefore, there is no impact upon instrument reliability. This includes fluid jets and pipe whip.
The staff requests information pertinent to the following:
1.
Can accidents outside containment reasonably create an adverse environment which affects the referenced instrumentation?
2.
What is the influence of an adverse containment on the line i
connecting between the RCS and the wide range pressure transmitter?
3.
Did the Stone and Webster verification exclude all interactions, or did it conclude that only one channel of infonnation would be affected, with the remainder of the information available?
A3.
In addressing criterion selection, provide consideration of uncertainties associated with the WOG supplied analyses values. These uncertainties are to include uncertainties in computer program results and uncertainties resulting from plant specific features not representative of the generic data group.
If a licensee (or applicant) determines that the WOG alternative criteria are marginal for preventing unneeded RCP trip, it is recomended that a more discriminating plant-specific procedure be developed. Licensees (or 5
applicants) should take credit for all equipment (instrumentation) available to the operators for which the licensee (or applicant) has sufficient confidence that it will be operable during the expected conditions.
Staff Evaluation. The computer program result uncertainties evaluation is based on the assumption of no changes in initial plant conditions (such as full power, pressurizer level, all SI pumps running, all AFW pumps running). The major contributors to uncertainty are stated to be break flow rate SI flow rate, decay heat generation rate, and auxiliary feedwater flow rate. The break flow model is stated to be about 30%
high, SI flow rate has roughly a +/- 10% uncertainty, and decay heat is about 5% high when contrasted to best estimate models.
(AFW is best estimate as used in the code.) Parameter study results are mentioned which show little sensitivity to decay heat and AFW flow. The applicant concluded that the calculational uncertainty is -30 to +300 psi for the RCS/ Secondary Differential Pressure RCP setpoint based upon uncertainty in the break flow model and SI flow rate.
(Other parameters were not included since they were felt to be negligible.)
The WOG analyses were performed with the licensed Westinghouse LOFTRAN computer code for plants under non-LOCA conditions.
f The applicant has not directly addressed such topics as the accuracy of the numerical solution scheme or of nodalization.
Further, there is no determination of the influence of equipment or operational failures.
Information pertinent to the former result from comparisons of the LOFTRAN code to operational and experimental data, and as a result will have been included in the uncertainty number. Determination of equipment or operational failures is not a necessity as long as the expected
- configuration of the plant is addressed since the object. e of RCP trip is to provide reasonable assurance of not tripping for ients for which a trip is undesirable.
It is not necessary to es'
'1 that one will never trip since the plant is capable of being saf 1 trolled if 6
an unnecessary trip does occur. Thus, no additional information is needed for the staff to complete review of this item.
s B.
Potential Reactor Coolant Pump Problems Bl. Assure that containment isolation, including inadvertent isolation, will not cause problems if it occurs for non-LOCA transients and accidents.
Demonstrate that, if water services needed for RCP operations are terminated, they can be restored fast.enough once a non-LOCA situation is confirmed to prevent seal damage or failure. Confirm that containment isolation with continued pump operation will not lead to seal or pump I
damage or failure, j
Staff Evaluation. The staff was referred to the FSAR for information pertinent to this item.
It would be helpful to the review if information
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similar to that provided for Beaver Valley Unit I was provided to the staff reviewer.
If the information is identical for the two plants, a r
i statement to this effect would be sufficient.
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B2. Identify the components required to trip the RCPs, including relays, i
power supplies and breakers. Assure that RCP trip, when necessary, will l
occur. Exclude extended RCP operation in a voided system where pump head is more than 10% degraded unless analyses or tests can justify pump and l
pump-seal integrity when operating in voided systems.
If necessary, as a result of the location of any critical component, include the effects of adverse containment conditions on RCP trip reliability. Describe the I
basis for the adverse containment parameters selected.
t' Staff Evaluation. The various equipment items are identified by number and plant location. The licensee does not address whether they could be 4
influenced by conditions assuciated with the accidents in question.
Manual trip of the RCPs from an alternate location if they fail to trip in response to the initial operator action is not mentioned, nor is the time to accomplish this action is addressed.
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There is no discussion of 10% degraded operation.
C.
Operator Training and Procedures (RCP Trip)
C1. Describe the operator training program for RCP trip.
Include the general philosophy regarding the need to trip pumps versus the desire to keep pumps running. Also cover priorities for actions after engineered safety features actuation.
Assure that training and procedures provide direction for use of individual steam generators with and without operating RCPs.
Assume manual RCP trip does not occur earlier than two minutes after the RCP-trip set point is reached.
Determine the time available to the operator to trip the RCPs for the limiting cases if manual RCP trip is proposed. Best Estimate calculational procedures should be used. Most probable plant conditions should be identified and justified by the licensee, although NRC will accept conservative estimates in the absence of justifiable most probable conditions.
Justify that the time available to trip the RCPs is acceptable if it is less than the Draft ANSI Standard N660.
If this is the case, then address the consequences if RCP trip is delayed. Also develop contingency procedures and make them available for the operator to use in case the RCPs are not tripped in the preferred time frame.
Staff Evaluation. The licensee has provided a comprehensive discussion of background concerns and the need for RCP trip as contrasted to running RCPs.
The RCP trip criterion is stated to be to trip the RCPs if the RCS pressure is 145 psi greater than the highest steam generator pressure and high head safety injection flow is verified.
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Training is not directly addressed.
Is the background material presented in response to Item C1 provided to the operators during training?
C2.
Identify those procedures which include RCP trip related operation:
(a) RCP trip using WOG alternate criteria (b) RCP restart (c) Decay heat removal by natural circulation (d) Primary system void removal (e) Use of steam generators with and without RCPs operating (f) RCP trip for other reasons Ensure that emergency operating procedures exist for the timely restart of the-RCPs when conditions warrant.
d-Staff Evaluation. The licensee references the WOG Emergency Response Guidelines and states the Beaver Valley Unit 2 Emergency Operating Procedures comply. Selected procedures are listed.
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REFERENCES 1.
Thompson, Hugh L. Jr., " Implementation of TMI Action Item II.K.3.5,
' Automatic Trip of Reactor Coolant Pumps' (Generic Letter No. 85-12)",
)
NRC Letter Addressed to All Applicants and Licensees with Westinghouse 2)DesignedNuclearSteamSupplySystems(NSSSs),Jun. 28, 1985.
2.
Carey, J. J.,
" Beaver Valley Power Station - Unit No. 2, Docket No.
50-412, Generic Letter 85-12, ' Implementation of TMI Action Item K.3.5,
' Automatic Trip of Reactor Coolant Pumps,' Schedule'", letter from Duouesne Light to Hugh L. Thompson, Jr. of NRC, 2NRC-5-124, Aug. 27,
,1985.
3.
Carey, J.
J., " Beaver Valley Power Station - Unit No. 2, Docket No.
50-412, Generic Letter 85-12, ' Implementation of TMI Action Item K.35,
' Automatic Trip of Reactor Coolant Pumps,' Schedule'", letter from Duquesne Light to Hugh L. Thompson, Jr. of NRC, 2NRC-5-146, Nov. 15, 1985.
4.
Carey, J.
J., " Beaver Valley Power Station - Unit No. 2, Docket No.
50-412, Revised Response to Generic Letter 85-12, ' Implementation of TMI Action Item K.35, ' Automatic Trip of Reactor Coolant Pumps,' Schedule'",
letter from Duquesne Light to Hugh L. Thompson, Jr. of NRC, 2NRC-6-020, Mar. 10, 1986.
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