ML20207Q124
| ML20207Q124 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/16/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20207Q121 | List: |
| References | |
| NUDOCS 8701230069 | |
| Download: ML20207Q124 (8) | |
Text
.
o UNITED STATES f
T,,p, NUCLEAR REGULATORY COMMISSION g
5j WASHINGTON, D. C. 20555
\\...../
l SAFETY EVA1UATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 95 TO FACILITY OPERATING LICENSE NO. DPP.-30 COMMONWEALTH EDISON CO*PANY AND IOWA-TLLIN0IS GAS AND ELECTRIC COMPANY OUAD CITIES NUCLEAR POWER STATION, UNIT 2 DOCKET NO. 50-265 1.0 TNTRODUCTION By letter dated September 18,1986 (Ref.1), Comonwealtn Edison Company ICECo) proposed to amend Appendix A of Facility Operating Licensee DPR-30..This would accommodate the Cycle 9 reload and incorporate single loop operation (SLO) provisions in the body of the Technical Specifications (TS) for Quad Cities 2.
2.0 CYCLE 9 RELOAD EVALUATION One hundred fifty-two fresh fuel assemblies are scheduled to be loaded for Cycle 9 noeration.
The staff review is discussed below.
2.1 Fuel Desion The fresh fuel (88 BP8DRB299L and 64 BP80RB299) is the General Electric j
Company (GE) 8x8 barrier type.
It has been previously approved (Amendment 13 to Reference 2) and we conclude that the fuel assemblies are acceptable for inclusion in the Quad Cities 2 Cycle 9 core. The 152 new assemolies will reside with 572 irradiated 8x8 assemblies of prior GE designs presently in the l
core.
l 2.2 Nuclear Design i
.The nuclear design and analysis of the proposed reload has been perfomed by the methods described in GESTAR II. That methodology has been approved for use in the design and analysis of reloads in BWR reactors and its use is acceptable for this reload.
2.3 Thermal-Hydraulic Design The objective of the review of the thermal-hycraulic design of the core for Cycle 9 operation is to confim that acceptable methods are used, and to assure that there is an acceptable margin of safety from conditions which could lead to fuel damage during nomal operation and anticipated transients, and to f
$12:30069 870216 p
ADOCK 05000265 PDR
2 assure that the core is not susceptible to thermal-hydraulic instability. A discussion of the review follows.
An operating limit Minimum Critical Power Ratio (MCPR) and a safety limit MCPR is imposed in the TS to assure that 99.9 percent of the fuel rods in the core will not experience boiling transition during normal operation and anticipated operational transients. As stated in Reference 1,the approved safety limit
. MCPR for the Quad Cities 2 reload core is 1.07. The safety limit of 1.07 was used for the Cycle 9 analyses.
To assure that the fuel cladding integrity safety limit MCPR will not be violated during any anticipated trn.sient, the most limiting events have been reanalyzed for this reload (Reference 3) by the licensee, in order to determine which event results in the largest reduction in MCPP faCPR).. The operating limit MCPR for each fuel type was then established from the ACPR and ODYl:
option B and the safety limit MCPR. The operating limit MCPR,1.38, for Cycle 9 ir. creased by 0.04 (0.03 + 0.01 margini over the value for the previous Cycle 8.
The added margin is to accommodate potential future cycle increases b the reovired aCPR.
V( find that, since approved methods (GESTAR IIT were used and the results show on Eceptable margin of safety from conditions which could lead to fuel damage during any anticipated operational transient, the thermal-hydraulic design of the Cycle 9 core is acceptable.
Generic Letter 86-02 informed BWR licensees of the technical resolution of Generic Issue B-19 (Thermal Hydraulic Stability) and cautioned licensees to examine each core reload to assure that an acceptable stability margin exists.
The licensee provided the results of a stability analysis for Quad Cities 2 Cycle 9.
The calculated core stability decay ratio was 0.56 for the least stable operating point. The staff accepts this core stability decay ratio as representative of a stable thermal hydraulic system.
2.4 Transient and Accident Analyses Transient and accident analysis methods are the approved GE methods described in GESTAR II.
Core wide transient analysis included the events of load re.iection without bypass (LRWOBP), loss of 145 F feedwater heating and feedwater controller failure. The limiting transient, based on ODYN with option B is the LRW0bP resulting in a MCPR of 1.37. The licensee will use an operating limit MCDP for the Cycle 9 core of 1.38.
This represents an increase of 0.04 from the previous MCPR limitino condition of operation. We find this acceptable.
Limiting Pressurization Event - Analyses with main steam isolation valve closure with indirect (flux) scram and no relief valve credit show that the resulting pressures are within the TS safety limit for the steam dome pressure and the ASME vessel overpressurization limit. We find this acceptable.
3 Rod Withdrawal Error - This event was analyzed on a generic basis. The staff has approved the generic methodology and results. This has also been incorporated into GESTAR II and approved by the staff. The licensee stated that the analysis provided assurance that the 1.07 MCPR safety limit would not be violated at the 95/95 probability / confidence level. A Rod Block Monitor set point of 107 and a corresponding oCPR of 0.22 was chosen. The resulting 4CPR is bounded by the LRWOBP event. We find this acceptable.
Fuel Loading Error - A worst case bundle misorientation was analyzed and included an NRC imposed variable water gap penalty. This event was bounded by the LPWOBP event. We find this acceptable.
Rod Drop Accident (RDA) was not specifically analyzed. Quad Cities 2 uses a Bankeri Position Withdrawal Sequence for control rod withdrawal.
For plants using this system the RDA event has been statistically analyzed generically and it was found that with a high degree of confidence the peak fuel enthalpy would not approach the NRC required limit of 280 cal /gm for this event. This approach and analysis has been approved by the NRC (Reference 2). This approach is acceptable for Quad Cities 2.
Loss of Coolant Accident (LOCA) - LOCA analyses, were performed to provide Maximum Average Planar Linear Heat Generation Rate (MAPLHGR) values for the new reload fuel assemblies (PP8DRB299L and BP80RB299). The analyses were performed with approved methodologies as described in GESTAR II. The curve for fuel type P80RB282 was also extended to 40,000 MWD /STU. Since peak pellet burnup valuer yielding MAPLHGR values which correspond to the burrup limits of this fuel have been previously approved (Reference 2), the staff finds the extension to 40,000 MWD /STU as acceptable.
Fuel Handling Accident - This accident was not addressed by the licensee. The MAPLHGR curves for the fresh GE fuel types in the proposed TS have exposure limits to 45,000 MWD /STU. The NRC staff specifically reviewed on a generic basis a GE Topical Report on extended burnup methodology, NEDE-22148-P. Our Safety Evaluation (SE) on the GE report identified a concern with regard to the radiological consequence evaluation of the Fuel Handling Accident involving GE fuel assemblies with batch average exposure values greater than 38,000 MWD /MTU (34,500 MWD /STU). The MAPLHGR figures provide limits on the maximum burnup for a fuel segment. From this, the staff has estimated batch average exposure to be less than the 34,500 MWD /STU. We conclude that this type of accident will have insignificant effects on radiological consequences of the event.
3.0 SINGLE LOOP OPERATION (SLO) EVALUATION In 1981, the NRC approved restricted SLO at Quad Cities ? for power levels limited to 50% of rated. The licensee has proposed to delete those restric-tions from the license and incorporate more appropriate conditions for SLO in the body of the TS. The staff review is discussed below.
/
a.
4 3.1 Thermal Hydraulic Stability in Single Loop Operation We have evaluated the licensee's proposed TS changes relating to core stability in SLO. The calculated core stability decay ratio at the point of minimum stability (the intersection of the natural circulation line and the extended APRM block line) for this unit is 0.56.
This is indicative of a stable core since it is substantially less than the accepted value of 0.8 (for approved GE methods). Further, previous cores for Quad Cities 2 have a history of stable operation and low calculated stability decay ratios.
The licensee has concluded that stability monitoring surveillance provisions are not required for Quad Cities 2 SLO TS since it is demonstrably stable.
USNRC Generic Letter 86-09 is cited to justify this position for BWR/3s. While the staff agrees that this position is justifiable for operating Cycle 9, we do not agree that Generic Letter 86-09 supports the approval of permanent SLO without the inclusion of stability surveillance requirements in low flow operating regions. Recent operating experience at a foreign BWR-3 plant has shown that instabilities do occur in BWR-3 reactor types under some circum-stances of core design and operating conditions. While the staff accepts the proposed SLO TS without surveillance provisions for Cycle 9, the licensee is cautioned to reevaluate the need for stability surveillance specifications in future operating cycles based on the stability characteristics of t N proposed operation. This determination can be made by tha licensee based on calcula-tions or other evidence which demonstrates that the low stability decay ratio is being maintained in future reload core designs.
3.2 Accidents (Other Than Loss of Coolant Accident) and Transients Affected by One Recirculation Loop Out of Service 3.2.1 One Pump Seizure Accident The licensee states that the one-pump seizure accident is a relatively mild event during two recirculation pump operation. Similar analyses were performM j
to determine the impact this accident would have on one recirculation pump operation. These analyses were performed using NRC approved models for a large core BWR/4 plant (Ref. 4). The analyses assumed steady-state operation, with the added condition of one inactive recirculation loop, at the following initial conditions:
l a.
Thermal Power = 75% and core flow = 58% of rated, b.
Thermal Power = 82% and core flow = 58% of rated.
These conditions were chosen because they represent reasonable upper limits af SLO within existing MAPLHGR and PCFR limits at the same maximum pump speed.
l Pump seizure was simulated with the single operating pump going to zero speed instantaneously.
l The anticipated sequence of events following a recirculation pump seizure whict l
occurs during plant operation with the alternate recirculation loop out of service is as follows:
l
~
5 a.
The recirculation loop flow in the loop in which the pump seizure occurs drops instantaneously to zero.
b.
Core voids increase which results in a negative reactivity insertion-and sharp decrease in neutron flux.
c.
Heat flux drops more slowly because of the fuel time constant.
d.
Neutron flux, heat flux, reactor water level, steam flow, and feed-water flow all exhibic transient behavior. However, it is not anticipated that the increase in water level will cause a turbine trip and result in scram.
It is expected that the transient will terminate at a condition of natural circulation and an orderly reactor shutdown will be accomplished. There will also be a snell decrease in system pressure.
The licensee concludes that the MCPR for the pump seizure accident for the large core PWR/4 plant was determined to be greater than the fuel cladding integrity safety limit; therefore, no fuel failures were postulated to occur as a result of this analyzed event. The licensee further states that the results are applicable to Quad Cities 2.
NRC staff agrees with the licensee's conclusion.
3.2.2 Abnormal Transients The highest power attainable during SLO is expected to be between 18 and 28%
less than rated two loop thermal power. To assure that abnormal transients initiated from SLO are conservatively bounded by two loop analyses the licensee has proposed that the TS include the following:
a.
Increasing the safety limit MCPR (Minimum Critical Power Ratici and the operating limit MCPR by 0.01. This is to account for increased uncertainties in core flow and tip readings during SLO. This is acceptable.
b.
An adjustment of the APRM scram and Rod Block and RBM flow biased setpoints. This is to account for reverse flow in the idle loop jet pumps during SLO which alters the normal two loop drive flow to core flow relationship. The licensee states that if the correction is not made, the result of a transient during SLO would be a flow biased trip occurring at a higher neutron flux to core flow ratio than planned. The staff concurs.
c.
Isolating the idle recirculation loop and closing the crosstie (equalizer) lines. This will result in forward or reverse flow in the idle jet pumps being dependent on the speed of the operating recirculating pump. The staff concurs.
~
~_
e 6
3.3 Loss of Coolant Accident (LOCA)
General Electric (GE) performed a single loop operation analysis for LOCA. The licensee states that evaluation of these calculations (that are performed utilizing staff approved raethodology outlined in NEDO-20566-2 Rev.1) indicates that a multiplier of 0.84 for 8x8R and P8x8R fuel types should be applied to the MAPLHGR limits for single loop operation of Quad Cities 2.
Since an approved methodology has been used we find the use of these MAPLHGR multipliers to be acceptable.
4.0 PROPOSED TS CHANGES The proposed TS changes are as follows:
1.
Deletion of the existino license condition for SLO as described in Amendment No. 66, Section 3.J.
This is acceptable, since, as discussed below, SLO is to be incorporated into the body of the TS.
2.
Editorial change on pg 11 of the Table of Contents. This is acceptable.
3.
Addition of definitions of SLO and Dual Loop Operation (DLO) to page 1.0-5 of DEFINITIONS. This is acceptable.
4.
Revision of Figure 2.1-1.
This incorporates SLO and DLO scram and rod block settings and is acceptable.
5.
Revision of Figure 2.1-3 to reflect the extended load limit analysis previously implemented. This is acceptable.
6.
Revised TS 3.5.Y to incorporate Cycle 9 P'CPR limit. This is acceptable.
7.
Deleted reference to LHGR waiver for barrier ramo test in TS 3.5.J.
This is acceptable.
8.
Figure 3.5-1, sheets 1-6, "MAPLPG9 vs. Average Planar Exposure", were replotted and rearranged. Fuel types 8DRB265L, 8D?50 and 80262 were deleted.
Fuel types BP8DRB299L and PP8DRB?.99 were added. The average planar exposure for fuel type P8DRB287. was extended to 40,000 MWD /STU.
The deleted fuels are no longer used and the added fuel is part of the reload listed and approved in GESTAR II. This is acceptable.
9.
Change of title for TS 3.6.H and TS 4.6.H to " Recirculation Pump Flow limitations" from " Recirculation Pump Flow Mismatch". This is acceptable.
The change in TS 4.6.G.1.b is more definitive and is therefore acceptable.
- 10. Revised TS 3.6.H.3 for SLO: The licensee stated that the operational limits, as discussed below, would be implemented "During Single Loop Operation for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />...." The staff considers this statement to be ambiguous and for clarification, has revised it to state " Prior to Single Loop Operation for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />...." Discussions with the licensee confirmed that the clarification is consistent with the original intent. The restrictions follow:
u,,
s.
7 a.
The MCPR safety limit and operating limit will be increased by 0.01.
b.
The MAFLHGR operating. limit to be reduced by a factor of 0.84 c.
The APRM Scram and Rod Block and RBM flow biased setpoints are to be reduced.
d.
The suction valve in the idle loop shall be closed and electrically isolated except when the idle loop is being prepared for return to service.
In addition, the licensee agreed that the required adjustments for TS 3.6.H.3' could be completed in less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, which the staff considers to be excessive. The licensee, by lettes (Ref. 6) has committed to incorporate into the plant operating procedures the following additional conditions for SLO:
(1) the required adjustments are to be accomplished within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of the start of SLO, and (2) the recirculation system contrn1r, will be placed in the manual flow control mode.
In conjunction with implementation of the cannitted operating procedures, we find the proposed revisions to the TS for SLO to be acceptable.
4.1 Jet Pump Monitoring The existing license condition for SLO includes a surveillance of core plate 4 p
~
noise and was not included in the proposed TS. The purpose of this monitoring is to detect excessive jet pump vibration which is of concern to the staff. At the staff's request, the licensee agreed to retain this surveillance in the j
Quad C1. ties ? procedures as a means to monitor the jet pump (Ref. 5). This is acceptable since the licensee continues to retain a TS for jet pumps.
5.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change to a requirement with respect to the installa-tion or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements. The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previousif issued a proposed finding that this amendment involves no significant hazerds consideration and there has been no public comment on such finding.
Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement nor environmental assessment need be prepared in connection with the issuance of this amendment.
+
6.0 CONCL'JSIONS 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 i
I a
, L,_. ~, -. _ _.
4 8
of the cendment will not be inimical to the common defense and security or to the health and safety of the public.
7.0 REFFRENCES 1.
Letter, J. R. Wojnarowski (Commonwealth Edison) to H. R. Denton (NRC) dated September 18, 1986.
E.
NEDE-24011-A-7, August 1985, " General Electric Standard Application for Peactor Fuel," (GESTAR II).
3.
" Supplemental Reload 1.icensing Submittal for Quad Cities Nuclear Power Station Unit 2, Reload 8 (Cycle 9)," General Electric Company Report 23A4758 Class 1, July 1986.
4 Dresden Nuclear Power Station Units 2 and 3 and Quad Cities Nuclear Power Station Units 1 and 2 Single Loop Operation, General Electric Company Report NED0-N807, November 1980.
5.
Letter I. M. Johnson (Concenwealth Edison) to P. R. Centon (NRC) dated December 10, 1986.
6.
Letter M. S. Turbak (Commonwealth Edison) to H. R. Denton (NRC) dated December 23, 1986.
Principal Contributor:
D. Katze, T. Rotella Dated: January 16, 1987
_ _ _ _ _ _ _ _ _ _ - _ - _ _ _ - _ _ _ _ - _ _ _