ML20050C308
| ML20050C308 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 04/02/1982 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20050C295 | List: |
| References | |
| NUDOCS 8204080392 | |
| Download: ML20050C308 (4) | |
Text
7590-01 3:
u o.
UNITED STATES NUCLEAR REGULATORY COMMISSION In the Matter of Consumers Power Company Docket No. 50-155 Big Rock Point Plant EXEMPTION I.
,t The Consumers Power Company is the holder of Facility Operating License No. DPR-6 which authorizes operation of the Big Rock Point Plant, located in Charlevoix County, Michigan. This license provides, among other things, that it is subject to all rules, regulations and Orders of the Codrnission now or hereafter in effect.
II.
Section IV.A.2.c of Appendix G to 10 CFR Part 50 requires that when the core is critical (other than for the purpose of low power physics.
- -tests) the temperature of the-reactor vessel shall be equal to or
~
greater than the minimum permissible temperature for the inservice system hydrostatic pressure test.
By letter dated March 10, 1982, ConsumersPowerC5mpanyrequested
' an exemption from Section IV.A.2.c of Appendix G to 10 CFR'Part 50 to allow criticality at a reactor vessel temperature of 120*F or greater.
The revised Appendix G to 10 CFR Part 50 now in the process of final Commission approval, permits a criticality temperature limit of-i This RTNDT is the reference. temperature of RTNDT + 60*F, where RTNDT.
8204000M 920402 l
7590-01
,( 4-
- 1. -
,c.g the closure flange regions that are highly stressed by the bolt This RT DT is for the flange region where the embrittle-preload.
H ment effect from neutron exposure is negligble; there is also a RTNDT for the beltline region of the vessel where neutron exposure does significantly shift RTNDT cver a long period of exposure.
' Consumers Power' Company agreed to a conservative estimate for RTNDT.
based on Standard Review Plan 5 3.2, of +60*F.
The jus,tification
,7 for the pending change,in Appendix G was contained in the Safety Evaluation Report written on Topical Report NED0-21778-A* and summarized in the Value Impact statement for the amendment 150 Appendix G.
That justification is also summarized below and provides the basis fbr the, conclusion that this exemption can be granted.
The amendment lowers the minimum permissible temperature for core criticality at low pressure for boiling water reactors (BW'Rs).
This change is important for Big Rock Point because it reduces delays in startup and helps prevent recirculation pump cavitation.
Big Rock, l
like other BWRs, cannot use pump heat during startup effectively because the elevation head of water is the reactor alone is insufficient to meet the NPSH (net pump; suction head) requirements of the pumps at all
- but the lowest speeds.
Hence, pump heat is low until there. is steam pressure in the reactor.
The decision to make this change was made following staff review of Tropical Report NED0-21778-A from the General Electric Conpany.
The review concluded that the probability of an overpressure transient
- NED0 21778-A " Transient Pressure Rises Affecting Fracture Toughness Requirements for Boiling Watec Reactors, General Electric Company, December 1978.
2 4
O.
7590-01 in a BWR at low temperatures that would violate the pressure-temperature limits was very low and would not be increased significantly by making thisIhange. The BWR primary system is not water salid; an air /
steam bubble is maintained at'the.4op of the syst'em. This bubble
~
makes control of the pressure easier and slows pressure transients.
Consequently, the proba,bility of overpressure is quite low. Therefore, the staff considered the relaxation of the requirements justified.
Based upon our evaluation as discussed above, we found that the proposed lower temperature limit for criticality of 120*F pro-posed by Consumers Power Company for the Big Rcok Point reactor vessel provides an. adequate margin of safety against vessel rupture. There-fore, we conclude that this is an acceptable alternative to Section IV'.A.2.c of Appendix G to 10 CFR Part 50 and that an exemption to Section IV.'A.2.c to allow criticality at 120*F should be granted.
III.
Accordingly, the. Comission has determined that, pursuant to 10 CFR 50.12, an exemption is authorized by law and will not endanger life or
' property or the comon defense and security 'and is otherwise in the
~public interest. Therefore, the Commission hereby approves the exemption request as specified;below:
Consumers Powe'r Company is hereby exempt from Section IV.A.2.c of Appendix G to 10 CFR Part 50 to allow criticality at a reactor vessel temperature of 120 F or greater.
e
.k t
~
~
7590-01
~
q"-
- i. - -
The NRC staff has determined that the granting of this e'.emption will not result in any significant environmental impact and that pursuant to 10 CFR 51.5(d)(4), an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with this action.'"
l OR THE NUCL REGULATORY COMMISSION I
Darre 1 G. Eisenhut, irector Division of Licensing 2nd day of dpr!!arylandil 1982.
Dated at Bethesda this e
9 9
9 e
e L
i I
e l
-