ML20082P287
| ML20082P287 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 11/22/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20082P280 | List: |
| References | |
| NUDOCS 8312080179 | |
| Download: ML20082P287 (3) | |
Text
.
< p ec,\\
o UNITED STATES
[ 9... g j NUCLEAR REGULATORY COMMISSION j
WASHINGTON, D. C. 20555 y
y SAFETY EVALUATION BY THE OFFICE OF NUCLIhR REACTOR REGULATION SUPPORTING AMENDMENT NO. 72 TO FACILITY OPERATING LICENSE N0. DPR-35 BOSTON EDISON COMPANY PILGRIM NUCLEAR POWER STATION DbCKETNO.50-293 1.0 Introduction By reference 1, Boston Edison Company (licensee) proposed the Technical Specification changes for Pilgrim Nuclear Power Station, during the Cycle 6 operation. The submittal proposes a revision to the Technical Specifications to allow rated power operation at any core flow rate between 87 percent and 100 percent of the rated flow as a result of extension of the load line limits. The purpose of the Technical Specification changes is to improve operating flexibility during power ascension.
2.0 Evaluation The objective Of the review is to confirm that the thermal-hydraulic design of the core has been accomplished using acceptable methods, and provides an acceptable margin of safety from conditions which co~uld lead to fuel damage during nonnal and anticipated operational transients, j
and is not susceptible to thermal-hydraulic instability.
The review includes the following areas:
(1) safet critical power ratio, (2) operating limit MCPR, (3)y limit minimum thermal hydraulic stability, and (4) changes to Table 3.2.C, Sections 2.1.B, and Figures 2.1.1 and 3.11-9 of the Technical Specifications.
The safety limit MCPR has been imposed to assure that 99.9 percent of the fuel rods in the core are not expected to experience boiling transition during normal operation and anticipated operational 4
transients'. As stated in reference 3, the safety limit MCPR is 1.07 for the reload fuel. A safety limit of 1.07 is used for the Pilgrim
- Cycle 6 operation.
The maximum value of operating limit MCPR, as indicated in the Technical l
Specifications, is 1.30.
This is calculated by using the ODYN methods for the most limiting transient, generator load rejection without bypass event, 'a-100 percent power and 100 percent flow condition (licensing basis for BWR/3's).
8312080179 831122 PDR ADOCK 05000 P
..The licensee has submitted revised power / flow map as shown in Eigure 1-1 of reference 2.
The proposed extension of the power / flow map is '
to allow ascension along the 108 percent APRM rod block line to 100 percent power at,87 percent flow and allow rated power operation at any core flow rate between 87 percent and 100 percent.
The ODYN results in reference 2 indicate that calculated ACPRs for the most limiting transient, generator load rejection without bypass event, are 0.33 and 0.30 for 8x8 fuel, and 0.36 and 0.33 Sr P8x8R fuel for the power / flow map at 100/100 and 1C./87 points respectively. Therefore, reference 2 concludes that (1) the 00YN results for power / flow at the 100/87 point are bounded by the licensing basis results which are based on the power / flow map at the 100/100 point, and (2) the OLMCPR's specified in the Technical Specifications are applicable to.the rated power operation at any core flow rate between 87 percent and 100 percent. We have reviewed the extended load line limit analysis (Ref. 2) discussed above and we find that the ODYN methods were used r.nd results have shown an acceptable margin of safety from conditions which could lead to fuel damage.during any anticipated operational transient.
The results of the hermal-hydraulic analysis (Ref. 2) show that the core.has the smallest stability margin for the power / flow map at the point where the extrapolated rod block line intercepts the natural circulation line and the corresponding maximum decay ratio is 0.65 as compared to 0.59 for the Cycle 5.
The'large difference of the maximum decay ratio is due to the higher 1
power / flow ratio for the extended load operation.
Since the calculated
- maximum core stability ratio is less than that of some of the operating plants (for example, Peach Bottom Units 2 and 3 have decay ratic of 0.98), we conclude that the thermal-hydraulic stability results are l
acceptable for extension of the load line limits of Cycle 6 operation.
l Table 3.2.C, Sections 2.1.A and 2.1.B and Figures 2.1.1 and 3.11-9 of the proposed Technical Specifications have been modified to include the extended operating power / flow map given in Figure 1.1 of reference 2.
The modifications include the changes of the APRM rod block and trip set points from 0.65 W + 42% to 0.58 W 4 50%, and 0.65 W + 55% to 0.58 W and 62% respectively, where W is the 1000 recirculation flow as a percentage of the loop recirculation flow which produced a rated core l-flow of 69 million lbs/hr.
We find that approved methods have been used, and that the results of thd extended load line limit analysis support the proposed MCPR limits, which avoid violation of the safety limit MCPR for design transients.
_~,--,_,.m....
-______...,,_,_m.
e o
We conclude that this core design will not adversely affect the capability to operate the Pilgrim Station safely during the remaining Cycle 6 operation and that proposed changes to Tables 3.2.C, Sections 2.1.A and 2.1.B Figures 2.1.1 and 3.11-9 of the Technical Specifications discussed above are acceptable.
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 amendment involves an-action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 951.5(d)(4), that an environmental impact statement, or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance af 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.
5.0 References 1.
Letter from W. Harrington (BE) to D. Vassallo (NRC4 dated May 31, 1983.
2.
NED0-22198, General Electric Boiling Water Reactor Extended Load Line Limit Analysis for Pilgrim Nuclear Power Station Unit 1, Cycle 6 May 1982.
3.
NED0-24011-A-4, General Electric Boiling Water Reactor Generic Reload Fuel Applications dated January 1982.
Principal Contributor:
S. Sun Dated: November 22, 1983 t
,