ML17329A388
| ML17329A388 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 02/13/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17329A387 | List: |
| References | |
| NUDOCS 9202250325 | |
| Download: ML17329A388 (4) | |
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n UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 RELATED TO AMENDMENT NO. 162 TO FACILITY OPERATING LICENSE NO. DPR-58 AND AMENDMENT NO. 146 TO FACILITY OPERATING LICENSE NO. DPR-74 INDIANA MICHIGAN POWER COMPANY DONALD C.
COOK NUCLEAR PLANT UNIT NOS.
1 AND 2 DOCKET NOS. 50-315 AND 50-316 Ih II C 0
0 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION
1.0 INTRODUCTION
By letter dated October 17, 1989, the Indiana Michigan Power Company (the licensee) requested amendments to Facility Operating License Nos.
DPR-58 and DPR-74 for the Donald C.
Cook Nuclear Plant, Unit Nos. I and 2 (the facilities).
The amendments would (a) revise the Appendix A Technical Specifications (TS) relating to controlled leakage, (b) delete a cross reference to previously removed reporting requirements for reactor coolant boundry isolation valve
- leakage, and (c) change the related Bases.
2.0 DISCUSSION AND EVALUATION "Controlled leakage" is the term applied to the cooled and filtered seal water flow supplied to the reactor coolant pump (RCP) seals by the chemical and volume control system (CVCS).
The controlled leakage flow originates at a branch connection from the charging pump discharge header.
The fluid is then discharged into the RCPs where part of it travels downward past the lower radial bearing and thermal barrier, and then joins the reactor coolant system (RCS).
The remainder of the flow travels upward and enters the pump seal.
From the pump seal, this portion of the controlled leakage flow is returned to the CVCS.
Although all controlled leakage either enters the RCS directly or is returned to the RCS via the
- CVCS, a technical specification limit is placed on the maximum combined seal injection flow rate due to the fact that, in the event of a loss-of-coolant accident (LOCA), the charging pumps are realigned to provide safety injection and the controlled leakage flow is assumed to be
'navailable for core cooling.
Since the controlled leakage flow is assumed to be diverted from the safety injection flow, placing a limit on the maximum amount of controlled leakage is necessary to, ensure conformance with the 10 CFR 50.46, Appendix K'(LOCA) analysis.
The present TS impose a maximum flow rate limit of 52 gpm on controlled leakage.
However, the Technical Specifications do not specify the RCS conditions for which this figure applies.
The licensee has submitted calculations, based on the Darcy fluid flow equation, which indicate that, while for normal conditions the controlled leakage flow would be 40 gpm, at 9202250325 9202i3 PDR ADOCK 05000315 P
the runout condition the flow would-be 79 gpm.
This is due to the higher pressure difference between the charging pump discharge header and the RCS that would exist under runout condition.
Since the present TS permit a leakage rate of 52 gpm under all RCS conditions, with the surveillance measurement taken under normal conditions, the present TS are non-conservative for certain accident conditions.
Upon discovery of this feature, the licensee acted to administratively limit controlled leakage to 40 gpm under normal conditions.
This ensures that controlled leakage will not be excessive under accident conditions.
As a permanent corrective measure, the, licensee proposes to eliminate the "gpm" 'limit and replace it with a seal line resistance c~efficient.
The resistance coefficient proposed by the licensee is 2.27 E-1 ft/gpm.
This would provide the benefit of specifying a leakage flow surveillance test acceptance criterion figure which is based on actual line resistance and is not affected by charging pump and RCS pressure conditions.
The value of 2.27 E-I ft/gpm is consistent with the accident analysis and is acceptable on that basis.
In the proposed formula for calculating the seal line resistance, the seal line resistance is a function of two variables:
(a) the pressure difference between the charging pump discharge header and the seal injection point, and (b) the squared value of the seal injection flow.
The charging pump header pressure and the seal injection flow are measured parameters and the seal injection pressure is an analytically derived value.
The seal line resistance acceptance criterion specified in the proposed TS formula results in a value of approximately 40 gpm for seal injection flow at minimum charging pump discharge pressure and the analytically derived seal injection pressure.
The seal line flow resistance measurement will be performed after entry into Mode 3 or 4 with the facility at normal pressure following completion of seal flow needle valve position adjustments.
This requires an exception to the requirements of TS 4.0.4 and is necessary to ensure an acceptable "as left" condition fol'lowing completion of the surveillance.
The proposed change would also provide an operational benefit by reducing the possibility of disturbing charging flow and pressurizer level during testing.
The proposed amendments would also delete a footnote reference to TS 6.9.1.
The footnote to be deleted states that excessive pressure isolation valve leakage need not be reported as required by TS 6.9.1, unless the valve has been declared inoperable.
- However, TS 6.9.1 was previously amended, consistent with Generic Letter 83-43, to delete reporting requirements already covered by the LER Rule (10 CFR 50.73).
The deletion of the reference to the reporting requirement from the TS is acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Michigan State official was notified of the proposed issuance of the amendments.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
These amendments change the requirements with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or change to the surveillance requirements.
The NRC staff has
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3 determined that the amendments involve 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 previously issued a
proposed finding that these amendments involve no significant hazards consideration and there has been no public comment on such finding (55 FR 14509).
Accordingly, these amendments meet 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 or environmental assessment need be prepared in connection with the issuance of these amendments.
5 ~ 0 CONCLUSION The staff has concluded, based on the considerations discussed above that ())
there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
W. Long Date:
February i3
)992
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