ML20045E010
| ML20045E010 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 06/21/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20045E009 | List: |
| References | |
| GL-90-06, GL-90-6, NUDOCS 9306300316 | |
| Download: ML20045E010 (5) | |
Text
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UNITED STATES
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.j NUCLEAR REGULATORY COMMISSION f
WASHINGTON, D.C,205560001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS.106 AND 99 TO FACILITY OPERATING LICENSE NOS. DPR-42 AND DPR-60 NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT. UNIT NOS. 1 AND 2 DOCKET NOS. 50-282 AND 50-306 i
1.0 INTRODUCTION
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t By letter dated June 25, 1991, the Northern States Power Company (NSP or the j
licensee) requested amendments to.the Technical Specifications (TS) appended to Facility Operating License Nos. DPR-42 and DPR-60 for the Prairie Island Nuclear Generating Plant, Unit Nos. I and 2.
The proposed amendments would l
revise TS Section 3.1.A.2.C and Table TS 4.1-2A'and the associated Bases in j
response to Generic Letter 90-06, " Resolution of Generic Issue 70, ' Power-l l
Operated Relief Valve and Block Valve Reliability,' and Generic Issue 94, l
' Additional Low-Temperature Overpressure Protection for Light-Water Reactors,'
l Pursuant to 10 CFR 50.54(f)." Generic Letter 90-06 provided NRC staff l
guidance on TS changes that should be implemented to improve the reliability I
of the Pressurizer Power Operated Relief Valves (PORV) and the availability of the low temperature overpressure protection system.
1 Generic Issue 70, " Power-0perated Relief Valve and Block Valve Reliability,"
involves the evaluation of the reliability of power-operated relief valves (PORVs) and block valves and their ' safety significance in PWR plants.
The generic letter discussed how PORVs are increasingly being relied on to perform safety-related functions and the corresponding need to improve the reliability of both PORVs and their associhted block valves.
Proposed. staff positions and improvements to the plants' technical specifications were recommended to be l
implemented at all affected facilities. This issue is applicable to all Westinghouse, Babcox & Wilcox,.and Combustion Engineering designed facilities with PORVs.
Generic Issue 94, " Additional Low-Temperature Overpressure Protection for Light-Water Reactors," addresses concerns with the implementation of the requirements set forth in the resolution of Unresolved Safety Issue (USI)
A-26, " Reactor Vessel Pressure Transient Protection (Overpressure Protection)." The generic letter discussed the continuing occurrence of overpressure events and the need to further restrict the allowed outage time for a low-temperature overpressure protection channel in operating MODES 4, 5, and 6.
This issue is only applicable to Westinghouse and Combustion Engineering facilities.
l 9306300316 930621 l
PDR ADOCK 050002B2 P-PDR l
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e 2.0 EVALUATION The changes to the Prairie Island TS being proposed in reference to Generic Letter (GL) 90-06 are described below.
A.
TS Section 3.1.A.2.c (1) 1.
The PORV Specification for reactor coolant average temperature. greater than or equal to 310' is being revised to delete the' limitations on criticality and startup operation. These limitations on~ criticality and startup operation are mode. change limitations. The modified Standard Technical Specifications (STS) provided in Attachment A-1 to GL 90-06 specified that the provisions of' Specification 3.0.4 are not applicable to the PORV Specification.
The pressurizer PORV Specification mode change restrictions were incorporated into the Prairie Island TS by License' Amendments 91 and 84, approved October 27, 1989 which incorporated a large upgrade into the Prairie Island TS. They were added to the PORV Specification as part of an effort to standardize the LCOs throughout the Prairie Island TS. However, at that time NSP was not aware of the.STS exception to the requirements of Specification 3.0.4 for pressurizer PORVs. These moda change restrictions were mistakenly incorporated into the Prairie Island PORV Specification as part of standardized LCO
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wording.
The pressurizer PORV mode change restrictions will be eliminated from the Prairie Island TS because the STS state that the provisions of 3.0.4 are not applicable and because the restrictions were mistakenly incorporated by a previous license amendment.
2.
The requirement for the PORVs to be operable whenever the reactor is critical is being deleted because it is redundant to.the ' requirement that the PORVs be operable'whenever reactor coolant average-temperature is greater than 310*F.
The requirement to be operable above 310*F is more restrictive and encompasses the reactor critical-condition.
3.
The required action with one or both PORVs inoperable is being clarified to differentiate between the actions to be taken if the PORV is inoperable due to excessive seat leakage or is inoperable for other reasons. These changes include new requirements on maintaining power to the block valves and new time limitations / shutdown requirements for the inoperability of PORVs for reasons other than excessive seat leakage. The current action statement does not address.the cause of the inoperability or the status of the power supply to the block valves.
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The required action with one or more' PORV block valves inoperable is-t being-revised to eliminate the option of closing thelinoperable' block" valve:and to-include. new ' actions, including-new. time limitations, shutdown requirements:and restrictions.on automatic:PORV operation'.:
This action would eliminate the option-of continued operation withian) r inoperable PORV' block' valve.
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Technical Specification Section 3.1. A.2.c. (2)-
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1.
Therequirements;fortheloperabilityof1thePraisiellslandilowi l~
temperature overpressure protection system ~are, currently.Sprovided by. '
4 the PORY Specification'for reactor coolantisystem average temperature, below 310*FJ(Specification 3.1. A.2.c.(2)).. Thi.s lspecificationfis.1 being revised to provide separate low temperature: overpressure?
protection system specifications for:two reactor coolant system; low?
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temperature ranges, below 200*F and between 200*and 310*F.
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2.
Expanded action statementsTare'beingiincorporated for;the-inoperability of. PORVsiduringleither lowLtemperaturetrange. These?
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expanded ' action statements include 'new' time? limitations for ;the '
inoperability of:one or both PORVs andispecificirequirementsLfor;the!
size of the reactorJcoolant ventito be utilized 11f the' PORVsiarei
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inoperable longer than the allowedJoutiof servic'ei time.L : The proposed 3 square' inch reactor coolant? system vent. opening is: based on the j
l 2.956 square inch crossJsectional flow area of-a pressurizer PORV.
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C.
Technical Snecification Table TS2401-2A" 1.
A note is being.addedito the= PORV. block valve quarterly'surveillanc'
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e requirement (Item 6) which states that 'a block. valve: quarterly; surveillance need not-be' perfcrmed,1fithe' valve has been closed in '
j response to, proposed action statements?3.I'A!2.c(1).(b).2 or!
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3.1.A.2.c.(1).(b).3.
2.
A typographical error'is being corrected in thelfrequency discussion.
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of Item'5. The word "floodes" is being corrected to " flooded"/
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A typographical error.is being corrected inLthe frequencydiscu'ssion of Item 6. LThe. word "Quaterly" is being corrected to " Quarterly."
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Item 12, which is just a reference to;a previously deleted item,fis^
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being deleted to" provide room tofincorporatetthe new textrin: Item 6.-
L D.
Technical Specificatiion Bases '
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- 1. lPer-the guidance provided in. Attachment A-3 to Generic Letter 90-06,.
'f information is;being' incorporated'into the PORV.TS Bases;to' aid.in the p
. determination ^of the operability of the:PORVs.
2.
Information-on the b' asis of.the.3isquare inch; reactor coolant system:
. vent opening is being~ incorporated into the Bases for the1PORY:TS.
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j Guidance on the.d' action statements 3.1.A.2.c.(1) (b).4'and 5.. manual opera 3.
support propose l
~ 4.. Editorial changes are being made-to the. PORV. TSlBases-such thatL consistent terminology is utilized:when discussing the' low temperature overpressure protection' system.-
5.
Information on the basis;for-the low temperature; overpressure 1
protection system;PORV setpoint, and:when-itois required:to be:
updated,-is being incorporated into the; Bases 2for:the? low temperaturel overpressure-protection TS.
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6.
Pertheg'uidanceprovided11nAttachmentB-2toGenericLetter[90f06, 1
I information is being incorporated into the low temperature ;
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r overpressure protection 1TS Bases to aid in the determination ofJthej 3
operability of the: low temperature. overpressure protection system.;
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Several pages of the Bases' for TS LSection. 3.1lare being renumbered,
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~ because of.the. additional text being incorporated by. the changes?
r described above.
Since the! proposed modifications'are consistent:with theLstaff's: position..
previously stated inithe. generic. letter'and:any deviations arel ustified in the 'above-analysis,' the staff finds the. proposed modifications: to be; 1,
acceptab1e..
. 3.0 SJATE CONSULTATION
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In accordance with the Comission's regulations, the Minnesota = State 0fficial ~
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was notified _of the proposed' issuance of.the-amendments'. The State' Official-
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had no comments.
4.0- ENVIRONMENTAL CONSIDERATION
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--The amendments change a requirement with. respect 1toLinsta11ation or use of a l
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facility component ~ located within the restricted area'as defined'in 10 CFR-1 Part 20. 1he' NRC.: staff has 'determinedithat1 the ' amendments' involve: no
'significant increase in the' amounts,-:and4no'.significant change in the types, l
4 of any effluents that mayfbe released;offsited and' that.there:is no.
1 lsignificant increase in individual or cumulative" occupational: radiation exposure..2The Commission.has,previouslysissuediaiproposed; finding that'the L;'
- amendments involve no significant hazards consideration 1and there.has beenino-
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. public'commant on'such finding (56 FR 43811). 'Accordingly, the-amendments; meet the 'eligibilityTeriteria for categorical. exclusion set' forth inE10 CFR, L
51'.22(c)(9)JPursuant to 110 CFR 51:22(b)Lno environmental-.impactfstatement;
. or" environmental. assessment need be. prepared in connection with the; issuance :
of.the; amendments.
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5.0 CONCLUSION
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j The Comission has concluded, based 'on the considerations" discussed above,
, i that: L(1) there is reasonable assurance that the' health and safety of-the :
public will not be endangered by operation 1:in the' proposedLmanner,, (2).suchi activities.will be conducted in compliance with the' Commission's regulations,z and. (3)' the issuance of the amendments.will not be' inimical.to the comon ' '
' defense and security or to the health and safety of the public :
t Principal Contributor: M ' Gamberoni Date: June 21,-1993 e
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