ML20205C165
| ML20205C165 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 03/19/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20205C150 | List: |
| References | |
| NUDOCS 9904010088 | |
| Download: ML20205C165 (3) | |
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UNITED STATES j
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NUCLEAR REGULATORY COMMISSION o
WASHINGTON, D.C. 2065H001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION i
l RELATED TO AMENDMENT NO.105 TO FACILITY OPERATING LICENSE NO. DPR-22 j
NORTHERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT i
DOCKET NO. 50-263
1.0 INTRODUCTION
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.By letter dated November 25,1997, as supplemented September 25 and November 11,1998, and January 28,1999, the Northem States Power Company (the licensee) requested an amendment to the Technical Specifications (TS) appended to Facility Operating License No.
l DPR-22 for the Monticello Nuclear Generating Plant. The proposed amendment would revise the TS for the condensate storage tank (CST) low level suction transfer setpoint for the high pressure coolant injection (HPCI) and reactor core isolation cooling (RCIC) systems to allow removing one CST from service for maintenance.
The November 25,1997, letter and September 25 and November 11,1998, cupplements were referenced in the original Federa/ Rogister notice. The January 28,1999, supplement provided an updated TS page following the incorporation of Amendment 103, issued De:: ember 23, 1998. This information was within the scope of the original FederalRegisternotice and did not change the staff's initial proposed no significant hazards considerations determination.
2.0 EVALUATION
2.1 Background
HPCI and RCIC system pump suctions are normally aligned to the two parallel-connected CSTs. In the event these systems are initiated for any reason, demineralized water will be injected into the reactor vessel. The CSTs are not safety related, and there are no TS requirements related to operability or use of the CSTs. The safety grade source of water for HPCI and RCIC is the suppression pool. Safety related automatic circuitry is provided to transfer HPCI arid RCIC pump suction from the CSTs to the suppression pool on sensing low level in the CSTs. Level switches LS 23-74 and LS 23-75 are used in a one-out-of-two logic scheme to open redundant HPCI and RCIC suction valves from the suppression pool. CST suction valves for HPCI and RCIC automatically close when their respective suppression pool suction valves are fully open.
The TS currently require both LS 23-74 and LS 23-75 to be operable to provide redundancy in the HPCl/RCIC suction transfer logic. In the event one or both switches are inoperable, continued plant operation is permitted for up to 30 days provided HPCI and RCIC pump 9904010088 990319 PDR ADOCK 05000263-P PDR _
~ suctions are aligned to the suppression pool if both switches are not restored to operability within 30 days, the plant must be shutdown.
The CSTs need periodic maintenance which often takes in excess of the 30 days allowed by the current TS. Under the current TS, a level switch is considered to be inoperable if the CST is empty for maintenance. Routine CST maintenance could require a plant shutdown because of an inoperable level instrument, when the reason the instrument is inoperable is that there is no water level in the CST for the instrument to sense. The proposed change would eliminate the problem by allowing both instruments to be aligned to the operable CST without requiring entry into the 30-day limiting condition for operation. The suction transfer settings would be revised to reflect the use of an allowable value concept and are consistent with either one or two CST operation.
2.2 Evaluation of Proposed Chanaes The licensee proposes to add a definition of " Allowable Value" to TS Section 1.0, " Definitions."
The definition is consistent with the General Electric instrument setpoint methodology used at Monticello and is acceptable to the staff.
The licensee proposes to revise the trip setting for Function C,"HPCl/RCIC Turbine Suction
- Transfer," in TS Table 3.2.8, "Other Instrumentation," to read:
a.
Condensate Storage 22'3" above Tank Low Level tank bottom Allowable Values (Two Tank Operation) 26'9" above tank bottom (One Tank Operation)
The revised suction transfer settings reflect the use of an allowable value concept and are consistent with either one or two CST operation. The licensee also proposes to revise TS Table 3.2.8, Required Condition C, to retain the requirement to, " Align HPCI and RCIC suction to the suppression pool," and delete the requirement to, " Restore channels to operable status within 30 days or place the plant in Required Condition A for HPCI, or B for RCIC." The requirement to enter a 30-day limiting condition for operation is not required, s!nce HPCI and RCIC suctions will be aligned to the suppression pool when one of the CST level instruments is
> inoperable. The action is equivalent to carrying out the safety related function of the level switches. The proposed changes are acceptable to the staff.
. The licensee proposes to Jelete the allowable low condensate storage level setpoint deviation from TS Bases 3.2, page 71a. The deviation is no longer required because the setpoint is based on an allowable value, which accounts for instrument uncertainty, in proposed TS Table 3.2.8. The proposed change is acceptable to the staff.
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Minnesota State official was notified of the proposed issuance of the amendment. The State official had no comments.
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4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. 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 previously issued a proposed finding that the amendment involves no -
significant hazards consideration and there has been no public comment on such finding (63 FR 69344). Accordingly, the 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 or environmental assessment r;eed be prepared in connection with the issuance of the amendment.
1 5.0 PONCLUSION The Commission has 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, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the heelth'and safety of the public.
Principal Contributor: A. Utses 1
Date:
March 19, 1999 i
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