ML20080F130
| ML20080F130 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/24/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20080F127 | List: |
| References | |
| NUDOCS 8402100339 | |
| Download: ML20080F130 (4) | |
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sg UNITED STATES
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- i NUCLEAR REGULATORY COMMISS!ON
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WASHINGTON, D. C. 20555 3 ~ !Ley g
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$AFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0. 80 TO FACILITY LICENSE NO. DPR-30 COMMONwmA.TH EDIS0N COMPANY i
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' IOWA-ILLINDIS GAS AND ELECTRIC COMPANY OUAD CITIES NUCLEAR POWER STATION, UNIT 2 l
00CKET NO. 50-265 1.0 Introduction By letters dated July 5 and July 15, 1983, Comonwealth Edison Company (CECO, the licensee) proposed changes to the Technical Specifications (TS) #or Guad Cities Unit 2 (see References 1 and 2). Although a previously approved anendment (Reference 3) sufficiently bounded the upcoming operating Cycle 7, additional changes are requested in order to (1) reduce the current minimum critical power ratio 01CPR) operating limit to nrovide editional operating margin, (2) explicitly apply a maximum average planar linear heat generation rate (MAPLGHR) curve to a fuel type to be.used in the upcoming operating cycle, and (3) change the pressure setpoints for three safety-relief valves as a result of Mark I containment modifications.
2.0 Evaluation 2.1 Operating Limit Minimum Critical Power Ratio The operating limit minimum critical power ratio (OL-MCPR) for Guad Cities Unit 2 uses the computer code ODYN Option B approach, taking credit for actual scram time performance compared to the scram time TS surveillance limitt B (Reference 6). Under Option B, when the actual scram. time exceeds the TS surveillance limitiB, a MCPR penalty is applied in the form of a linearly increasing value from the Option B value (currently 1.37) to the Option A limiting value of 1.42.
The licensee has reaursted a change in the Technical Specification OL-MCPR for the upcoming ooerating Cycle 7.
The transient analyses performed by General Electric (GE) for Cycle 7 show the most limiting transient to be the turbine trip without bypass event.
For this event, the analysis yields an operating limit MCPR of 1.32.
This is a less restrictive limit than the present limit of 1.37, and comes about from the reduced time-of-transfer of the recirculation pump motor / generator sets to offsite power during this transient. The shorter transfer time precludes circulation pump runup during tho limiting operatio.nel transient, resultir.g in a reduced operating limit MCPR.
8402100339 840124 PDR ADOCK 05000265 p
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2-The licensee's request is for an amendment to reduce the TS limit MCPR from the current value of 1.37 to 1.34.
This new value is more conservative than the value of 1.32 resulting from the analysis of the most limiting transient for Cycle 7, but still provides the desired improved operating margin.
We have reviewed the licensee's submittal (Reference 1) and the appropriate parts of the reference document (Reference 5).
The supporting analysis was performed by GE using previously approved methodology and models (Reference 4).
We find the proposed change in operating limit MCPR to be acceptable.
2.2 MAPLHGR' Limits The reference document containing the ECCS analysis for Quad Cities Units 1 I
and 2 has previously been approved by the NRC staff and continues to be the basis for MAPLHGR limits for fuel types'used in these units (Reference 5).
This document has been updated as appropriate for cther fuel types by issuance of Errata and Addenda to Reference 5.
Barrier fuel type BP80RB265H will be used in the core for the upcoming operating cycle. This fuel is of the same nuclear design as non-barrier fuel type P8DRB265L, which has previously been approved for use in Quad Cities Unit 2.
Since the two fuel types are of the same nuclear design, the MAPLHGR curve.for the previously approved fuel type P8DRB265L applies also to barrier fuel type BP8DRB265H, as documented by GE in Errata and Addenda No. 10 to Reference 5, and the licensee's request to incorporate this into their Technical Specifications is acceptable.
2.3 Safety / Relief Valve Setpoint.. Changes t
In analyses associated with the Mark I containment program, it was discovered that the torus cculd be subjected to excessive loads if a relief valve actuation occurs shortly after closure.
This loading is the result of a water leg entrapped in the relief valve discharge line from the vacuum caused by the condensed steam in this line. To prevent such loadings, a modification to the electromatic relief (EMR) valye logic is currently being installed which will delay automatic opening of two EMR valves up to ten seconds from the last closure of the valve.
In order to maintain very similar overall Target Rock and EMR valve performance with the logic change and prevent excessive loading, th~e two affected EMR valves TS pressure setpoints must be lowered so that they are the first to actuate and the setpoint of one valve (Target Rock) must be raised.
For the limiting transient (load rejection w/o bypass) the pressurization is estimated by GE to be milder because there is a net relief valve setpoint decrease, thus slightly lowering the peak pressure and power for the transient.
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. - The ASME overpressurization event (no credit for EMR valve actuation) is estimated by GE to have slightly increased peak pressure (no more than 5 psi) because the Target Rock SRV setpoint is slightly increased. This peak pressure increase is insignificant compared to the calculated margin to 1375 psig of 50 psi.
The delay in actuation between successive valve openings is required because of the possibility of an automatic depressurization immediately following opening of a valve for pressure relief. The calculated minimum acceptable delay time reported by the licensee is 6.2 seconds.
This compares con-servatively with the ten-second delay proposed for the TS, with ample margin.
We have reviewed the proposed changes in the SRV setpoints and the proposed delay for successive actuations and find the change to have minimal effect on safety limits, and therefore, we find the proposed changes to be acceptable.
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j 3.0 Environmental Consideration We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact.
Having made this determination, we have further concluded that the amendnent involves an action which is insianificant from the standpoint 'f environmental impact, and pursuant to l'0 CFR ss1.5(d)(4),
o that an environmental impact statement, or negative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of this amendment.
4.0 Conclusion We have concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
Roby Bevan Dated:
January 24, 1984 4
a-References 1.
Letter, Ryback (CECO) to Denton (NRC), dated July 5,1983.
2.
Letter, Ryback (CECO) to Denton (NRC), dated Jul.v 15, 1983.
3.
Letter, Ippolito (NRC) to De1 George (CECO), dated December 23, 1983.
4.
NED0-24011-A-1, " General Electric BWR Generic Reload Fuel Application",
luly 1979.
5.
NED0-24146A, "LOCA Report for Dresden'2 and 3 and Quad Cities 1 and 2 Nuclear Power Stations", Revision 1, April 1979. as modified Errata and Addenda Nos. 1 through 10.
6.
Letter, Bucholz (GE) to Check (NRC) "0DYN Adjustment Methods for Determination of Operating Linits", dated January 19, 1981.
7.
Letter, Bevan (NRC) to De1 George (CECO), dated December 15, 1982.
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