ML20073A015
| ML20073A015 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 09/06/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20072V590 | List: |
| References | |
| NUDOCS 9409200068 | |
| Download: ML20073A015 (3) | |
Text
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-, 3 0-E UNITED STATES NUCLEAR REGULATORY COMMISSION
- b WASHINGTON, D.C. 20555-0001 j
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION BELATED TO AMENDMENT NOS. 188 AND 169 TO FACILITY OPERATING LICENSE NOS. NPF-4 AND NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY OLD DOMINION ELECTRIC COOPERATIVE NORTH ANNA POWER SI_ TION. UNITS NO. 1 AND N0. 2 A
DOCKET NOS. 50-338 AND 50-339
1.0 INTRODUCTION
By letter dated March 30, 1994, the Virginia Electric and Power Company (the licensee) subnitted proposed changes to the Technical Specifications (TS) for the North Anna Power Station, Units No. I and No. 2 (NA-l&2). The changes revise the High Head Safety Injection (HHSI) flow balance surveillance requirements by removing explicit numerical values and replacing them with broader non-numerical requirements.
The new requirements would ensure that HHSI injection flow meets the loss of coolant accident (LOCA) analysis acceptance criteria of 10 CFR 50.46 and that total pump flow is less than the pump runout limit.
2.0 DISCUSSION The specific changes are as follows.
In TS 4.5.2.h.1.a, the current value (359 gpm) for the sum of the injection line flows (excluding the line with the highest flow) would be replaced by "the minimum flow rate required to demonstrate compliance with 10 CFR 50.46."
In TS 4.5.2.h.1.b, the current value (660 gpm) for total HHSI pump flow would be replaced by "the evaluated pump runcut limit."
Bases 3/4.5.2 and 3/4.5.3 would also be revised to reflect these changes.
1 The intent of the proposed TS changes is to establish a wider range for HHSI flow acceptance criteria, allowing for greater flexibility during testing.
The acceptance criteria of the current TS are too narrow to be consistently met during HHSI surveillance testing.
This led to the issuance of Emergency License Amendments 176 and 157 for Units 1 and 2 on November 23, 1993 as well as the documentation of test failures in LER 90-003-00 for Unit 2 and LER 91-001-00 for Unit 1.
In each case where the test results did not meet the acceptance criteria, system performance was evaluated and demonstrated to be within the limits of the applicable safety analysis. With the proposed removal of explicit numerical values from the subject TS, existing margins in the safety analysis will be used to broaden the band of acceptable performance.
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- 3.0 EVALUATION t
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Successful completion of HHSI flow balance testing is based on two requirements. The first requires that with one HHSI pump running, the sum of the flows through the two (of three) cold leg injection lines having the lowest flow rates is conservative with respect to the minimum HHSI injection flow required by the limiting safety analysis. The limiting analysis for this case is the small break LOCA. The injection line with the highest flow rate is excluded to reflect spillage in the faulted loop. The minimum HHSI flow a
must meet the acceptance criteria of 10 CFR 50.46 and is dependent on cycle-specific input parameters such as core peaking factors, fuel design parameters, and changes in system configuration like steam generator tube 4
plugging. These inputs are documented in the currently applicable reload analysis.
In proposed TS 4.5.2.h.l.a, the current value (359 gpm) for minimum HHSI flow is replaced by "the minimum flow rate required to demonstrate compliance with 10 CFR 50.46."
Any modification of the minimum HHSI flow requirement would be based on available margins existing in the current small break LOCA analysis-and would be determined in accordance with the Core Operating Limits Report, TS 6.9.1.7.
Since HHSI system performance will remain bounded by the limiting i
safety analysis, the staff finds the proposed TS 4.5.2.h.l.a to be acceptable.
The second condition for successful completion of HHSI flow balance testing j
requires thai; the total HHSI pump flow does not exceed the pump runout limit.
This.is necessary to prevent pump and motor damage.
Pump runout would be of concern during a large break LOCA which depressurizes thel reactor coolant
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system (RCS) to approximately containment pressure and results in maximum flow through the pump.
The pump runout limit is pump specific.
Furthermore, since the HHSI pumps function as charging pumps during normal operation, this limit i
varies with time in service.
In proposed TS 4.5.2.h.l.b, the current value (660 gpm) for total HHSI pump
- flow is replaced by the phrase "the evaluated pump runout limit." HHSI pump runout limit will be determined by the licensee in accordance with the pump manufacturer's recommendations and the determination will be appropriately documented. Therefore, the staff finds the proposed TS to be acceptable.
A detailed analytical model is employed by the licensee which computes-HHSI flow as a function of RCS pressure. This model is used in the LOCA anlyses and includes the various pump characteristics, cold leg injection line and RCP i
seal injection line flow resistances, pump runout limits, and allowances for measurement inaccuracies.
Flow rates determined by this model can then.be related to specific limits for the HHSI surveillance test.
l Finally, the proposed TS are also similar to the corresponding TS in NUREG-1431 (the Westinghouse Standard Technical Specifications) in that HHSI flow requirements are not specified as explicit numerical v21ues but, rather, as functional statements.
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Therefore, based on all of the above, the staff finds the proposed changes to be acceptable.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Virginia State official was notified of tha proposed issuance of the amendments. The State official had no comment.
5.0 ENVIRONMENTAL CONSIDERATION
These amendments involve changes to surveillance requirements. Ibe NRC staff has 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 findley (59 FR 22017). 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. assemannt need be.
prepared in connection with the issuance'of the amendments.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and' sandy 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.
1 Principal Contributor:
H. Abelson j
Date: September 6,1994 i
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