ML20151H780
| ML20151H780 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 07/18/1988 |
| From: | Musolf D NORTHERN STATES POWER CO. |
| To: | |
| Shared Package | |
| ML20151H778 | List: |
| References | |
| NUDOCS 8808020048 | |
| Download: ML20151H780 (5) | |
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UNITED STATES hTCLEAR REGULATORY COMMISSION NORTHERN STATES PO'JER COMPANY PPAIRIE IS1AND NUCLEAR GENERATING PLANT DOCKET NOS, 50 282 50 305 REQUEST FOR AMENDMENT TO OPERATING LICENSES DPR 42 6 DPR 60 LICENSE AMENDMENT REQUEST DATED JULY 18, 1988 i
Northern States Power Company, a Minnesota corporation, requests auth-orization for changes to Appendix A of the Prairie Island Operating Licenses as shown on the attachments hbeled Exhibits A and B.
Ex.
hibit A describes the proposed changes, reasons for the changes, and a significant hazards evaluation.
Exhibit B is a copy of the Prairie 1
Island Technical Specifications incorporating the proposed changes, i'
This letter contains no restricted or other defense information.
NORTHERN STATES PO'JER COMPAST By D. ? D k -,
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David Musolf
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Manager Nuclear Support Services On this M day of.
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, /9.t'I before me a notary public in and for said C(unty', personally appeared David Musolf, Man-ager Nuclear Support Services, and being first duly sworn acknowledged that t.e is authorized to execute this document on behalf of Northern States Pover Company, that he knows the contents thereof, and that to the best of his knowledge, information, and belief the statements made i
in it are true and that 1,s is not interposed for delay.
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f Exhibit A j
i Prairie Island Nuclear Generating Plant
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i License Amendment Request Dated July 18, 1988 i
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Description and Evaluation of Proposed f
l Change to Appendix A of Operating Licenses DPR 42 and DPR.60 I
i Pursuant to 10 CTR Part 50, Section 50.90, the holders of Operating l
I Licenses DPR.42 and DPR.60 hereby propose the following changes to i
Appendix A. Technical Specifications:
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Elimination of Lov Teedwater Trip l
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j Proposed Chane.es
- 1. Delete Specification 2.3.A.3(c).
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~I 2, Revise the Bases on page TS.2.3 6 to delete discussion of the lo<
j feedwater trip.
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- 3. Delete Table TS.3.5 2, Item 18, "Lo Feedvater Flow."
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- 4. Revise Table TS.4.1 1 by changing Item (12), "Steam Generator Flov l
Mismatch," to read "Steam Flov Steam Line Isolation."
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- 5. Add footnotes., where necessary, to indicate that the above proposed changes are applicable following installation of the new digital feed.
j vater system and the MSS.
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Refer to Exhibit B, pages TS.2.3 3. TS.2.3 6 Table TS.3.5 2 (Page 2 of 2), and Table 75.4.1 1 (Page 2 of 5).
j Reasons for Chanees j
l The Prairie Island Unit No. 1 and Unit No. 2 feedwater control systems are being upgraded with microprocessor based instrumentation. A steam generator narrow range level Median Signal Selector funetton j
i vill be added to improve the reliability of the steam generator level input. Addition of the MSS allows the elimination of the lov feed.
vater trip function (1. e steam flow > feedvater flow coincident with I
lov steam generator level).
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Proposed Technical Specification changes (1) through (3) above delete operability and surveillance requirements for the steam generator lov j
feedvater flow trip.
Change (4) replaces the surveillance requirement for steam flow mismatch with a test of only stean generator flow i
I (feedwatet flow will no longer be used in the protection logic).
I The new feedvater control systens vill result in significant improve.
l ments in plant reliability. The potential for feedvater control sys.
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EX111 BIT A
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tem failures to cause unplanned reactor trips and cha11engen to safe.
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J guards equipment will be reduced.
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Elimination of the low feedwater trip was discussed with the NRC Staff
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at a meeting held on September 15, 1987 in Bethesda, Maryland. At j
this meeting, the NRC Staf f stated the following minimurn requirements i
for low feedwater trip removal:
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- a. A safety evaluation showing that no credit is taken for the lov feedwater trip in any safety analysis.
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- b. An explanation of the design basis for the criginal installa.
I tion of the low feedwater trip.
- c. A review of NRC Bulletin responses to ensure that we did not take credit for the low feedwater trip in the past to resolve any safety concern.
Northern States Power Company has verified that no credit la taken for I
the low feedwater trip in any accident analysis in the Updated Safety
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Analysis Report (USAR) or in any current analysis methodology.
Review j
of past responses to NRC Bulletins indicates that no credit has been j
taken for the low feedwater trip.
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The low feedvater trip was originally required to provide compliance j
with IEEE Standard 279 1971, paragraph 4.7.3, "Control and Protec.
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tion Interaction Criteria." With the addition of the MSS function, a j
failed instrument channel can no longer cause a dinturbance in the
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l feedvater control system which can initiate a transient requiring i
j protective action. The low feedwater trip is therefore no longer i
required. This issue will be discussed in detail in a proprietary Westinghouse licensing topical report which is being submitted sepa.
rately.
Safety Evaluation and Determination of Significant
}{arards Considerations The proposed changes to Appendix A of the Operating License have been j
evaluated to deteruine whether they constitute a significant hazards i
l consideration as required by 10 CTR Part 50 Section 50.91 using the i
l standards provided in Section 50.92.
T51: evaluation is provided I
I below-l
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- 1. The proposed amendment will not involve a significant l
increase in the probability or consequences of an
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accident previously evaluated.
l The proposed amendeent would revise the Technical Specifications to delete the low feedvater trip function. This function will no 1
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EXHIBIT A I
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longer be required to meet IEEE 279 1971 control and protection L
j system requirements following the installation of the Median Sig-i j
nal Selector as part of the new digital feedwater contrni system.
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Removal of the low feedwater flow trip will reduce the probability i
of unplanned reactor trips and unnecessary challenges to safe.
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i guards systems. Overall plant safety and reliability will be t
j enhanced.
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l No credit is taken for the low feedwater trip in any safety
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analysis. Therefore, removal of the trip cannot affect the probability or consequences calculated for any evaluated accident.
j 2.
The proposed amendment will not create the possibility I
j of a new or different kind of accident froa any accident j
previously evaluated.
The proposed Technical Specification changes deal exclusively with j
i the removal of the low feedwater trip function and installation of I
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the MSS function. No safety analysis takes credit for the low feedvater trip function, f
l Abnormal operational transients which could result from feedwater i
control system failures are analyzed in the USAR These analyses bound all postulated feedwater control system failures. Thers is l
therefore no possibility of a, new or different kind of accident not previously evaluated.
3.
The proposed amendment will not involve a significant reduction in the marein of safety.
m The proposed Techaical Specification changes will allow improve-ments to be made to the feedwater control system. The low feed.
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water trip function, which is no longer required, will be re-j moved. A new digital feedwater control system and MSS functier.
i will significantly reduce the potential for feedwater control t
system related reactor trips and unnecessary challenges to safe-l guards equipment.
Plant reliability will be enhanced with no
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j reduction in the existing margins of safety.
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j The Commission has provided guidance concerning the application of the j
Standards for determinin6 whether a significant hazards consideration 1
exists by providing certain examples of amendments that are considered q
not likely to involve significant hazards considerations.
These exam-1 ples were published in the Federal Register on March 6,1986, i
Changes proposed in this License Amendm+nt Request are representative of example (ix). They are related to a repair or replacement of a I
major component or system important to safety meeting the following i
conditions:
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EXHIBIT A
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(1) The repair or replacement process involves prac.
l tices which have been successfully implemented at least once on similar components or systems elsewhere in the nuclear industry or in other industries, and does not involve a significant increase in the probabi.
lity or consequences of an accident previously eval.
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usted or create the possibility of a new or different I
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kind or accidant frem any accident previously eval.
usted; and i
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(2) The repaired or replacement component or system does not result in a significant change in its safety i
function or a significant reduction in any safety limit
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(or limiting condition of operation) associated with j
the component or system, 1
j As previously discussed, the proposed Technical Specification changes l
reflect the installation of a feedwater control system which i
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incorporates a Median Signal Selector function.
The low feedwater l
flow trip is no longer required and is being removed. No safety 4
1 analyses are affected by these changes.
Equipment to be installed l
reflects current state of the. art digital control system design and t
j standard industry practice.
The overall effect of the change is to I
improve plant safety.
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Environmental Assessment I
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This License Amendment Request does not change the types or total 1
amounts of effluents, nor does it involve an increase in power level.
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Therefore, this change will not result in any significant environmen-l tal impact.
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