ML20246L719
| ML20246L719 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 05/10/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20246L715 | List: |
| References | |
| NUDOCS 8905180387 | |
| Download: ML20246L719 (3) | |
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UNITED STATES iV i L.
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NUCLE AR REGULATORY COMMISSION y
WASHINGTON, D. C. 20555
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SAFETY EVALUATION BY-THE 0FFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 64 TO FACILITY OPERATING LICENSE NO. DPR-22 l'
NORTHERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT DOCKET NO. 50-263 l
1.0 INTRODUCTION
By letter dated November 3, 1986, the Northern States Power Company, the
. licensee for Monticello Nuclear Generating Station proposed changes to the Technical Specifications (TS) 3.7.A.5 for containment purge and vent valve operation, Additional information was provided in letters dated May 1 and November 22, 1985.
Specifically, the licensee proposed to:
(a) Limit.the use of purge and vent valve flow paths over 2-inches to inerting and de-inerting operations only, (b) Require replacement of valve seals at five year intervals, (c) Revise the maximum operating time specified for containment purge and vent valves to 15 seconds on Table 3.7.1, (d) Reduce the number of outboard valves listed on Table 3.7.1 for "Drywell Purge Inlet" to one and add a new table entry, " Suppression Chamber Purge Inlet" with one outboard valve.
(e) Change the normal position to closed position on Table 3.7.1 for all drywell and suppression chamber vent and purge valves, and (f) Revise the heading for Section 3/4.7.A.5 to read " Containment Atmosphere l
Control" and correct a typographical error from 3.7.C.1(a) to 3.7.C.2(a) on TS page 166.
The licensee indicated that changes (a) through (c) are to comply with the generic concern related to demonstration of containment purge and vent valve I
operability (Multi-Plant Action B-24) for Monticello Nuclear Generating Station.
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Changes (d) through (f) are administrative in nature for clarification and corrections.
2.0 DISCUSSION AND EVALUATION We have evaluated each of the above listed changes proposed to the plant TS, j
and our determinations and findings relative to each change are as follows:
q 8905180387 890510 PDR ADOCK 05000263 p
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(a) Limitation on purge and vent operations above cold shutdown - The licensee has proposed to revise TS Section 3.7.A.5 to restrict purge.
and vent valve operations above cold shutdown to the-2-inch bypass flow path except for.inerting and de-inerting containment.
The licensee has also proposed to add 40-degree limit stops on 18" purge and vent valves to ensure their closure against full accident differential pressure.
These changes are proposed to comply with the staff's evaluation in letters dated March 6, 1984 and February 15, 1985 on generic concerr. related to the demonstration of containment purge and vent valve operability (MPf. B-24) for the Monticello Generating plant and, therefore, acceptable.
(b) Valve Seal Replacement - The licensee has proposed to add to the surveillance requirements in Section 3.7.d for replacement of the seals of the drywell and suppression chamber 18-inch purge and vent
- i valves at least every five years.
This is in response to staff position requiring accelerated local leakage testing of containment purge and vent valves due to the poor performance in the industry of large butterfly valves.
The licensee, in a letter dated November 22, 1985, has indicated that the. T-ring seal. valve design used at Monticello is relatively free of valve leakage. problems experienced at other facilities and that the existing preventive maintenance program with periodic seal replacement provides assurance that the valve will seal tightly and provided data from 1971 to 1985 to support it.
Based on the above review, the staff concludes that the proposed seal replacement at every five year interval for the 18-inch purge and vent valve is acceptable.
(c) Containment Purge and Vent Valve Operating Time - The licensee has proposed to revise the maximum operating time for containment purge and vent valve operation from 60 seconds to 15 seconds following the next refueling outage on Table 3.7.1.
Prior to this time, an allowable 20 seconds will be maintained.
This is in response to the staff evaluation dated April 13, 1984 on the consequences of a LOCA at Monticello while purging at power.
In the above evaluation, the staff has concluded that 15 seconds valve closure would assure that the purge valves would be closed before the onset of fuel failure following a LOCA.
Therefore, the above change for 15 seconds closure time is acceptable.
(d) Correct Valve Designation - The licensee has proposed to reduce one drywell purge inlet valve and add one suppression chamber purge inlet valve on Table 3.7.1 per existing plant design (USAR Figure 5.2-9).
This is an administrative change and, therefore, acceptable.
(e) Clarify Valve Position - The licensee has proposed to revise the Table 3.7.1 to show the normal position of all purge and vent valves as closed.
The licensee indicated that as an interim measure in mid-1970's (Reference Amendment 18 dated April 14,1976), a drywell to suppression chamber differential was maintained to reduce vent line submergence requiring some of these valves to be open to permit the necessary nitrogen make-up to the drywell and suction from the suppression chamber.
This differential pressure is no longer required because of containment modifications (Mark I containment long term program).
The staff considers this an administrative change and, therefore, acceptable.
l (f) Revise the Heading for Section 3/4.7.A.5 - The licensee proposed to.
revise the heading for Section 3/4.7.A.5 from oxygen concentration to i
containment atmosphere control to more clearly identify the purpose of that section as it deals with several aspects of containment etmosphere control, not' simply control of oxygen.
The licensee also proposed to-correct a typographical error from 3.7.C.1(a) to 3.7.C.2(a) on TS page 166.
The staff considers these are administrative changes and therefore, acceptable.
Based on the above evaluation, we conclude that the proposed changes to
-the Monticello Technical Specification Section 3.7. A.5 for limitation on purge and vent valve operation above cold shutdown, valve seal replaceme7t, and valve operating time related to demonstration of containment purge. valve operability relate to Multi-Plant Action B-24; and the administrative changes proposed to clarify the valve designation,
.ition, and section heading are acceptable.
- 3. 0 ENVIRONMENTAL CONSIDERATION This amendment involves a change in the installation or use of a facility
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component located within the restricted area as defined in 10 CFR Part 20 or a change to the surveillance requirements.
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 occupa-
.tional radiation exposure.
The Commission has previously published a proposed finding that this amendme.nt involves no significant hazards consideration and there has been no public comment on such finding.
Accordingly, this 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 need be prepared in connection with the issuance of this amendment.
4.0 CONCLUSION
The staff nas 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 this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
R. Goel Dated: May 10, 1989
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