ML20137U262
| ML20137U262 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 02/10/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20137U260 | List: |
| References | |
| NUDOCS 8602190100 | |
| Download: ML20137U262 (4) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 34 TO FACILITY OPERATING LICENSE NO. NPF-11 COMMONWEALTH EDISON COMPANY LA SALLE COUNTY STATION UNIT 1 DOCKET N0. 50-373
1.0 INTRODUCTION
Under certain post accident conditions, the primary containment must be flooded above the top of th6 active fuel to provide for long term recovery.
The flooding level is obtained from the containment flood-up measurement system.
It is detennined indirectly from the difference of two values, namely:
a) the total pressure resulting from the flooded height (containment pressure and water level), and b) the containment gage pressure.
The containment flood-up measurement system is not a part of the protection system. The measurement systems are installed in Units 1 and 2.
Unit 2, however, has an excess flow check valve installed outside of its containment, in the containment gage pressure sensing line. Unit 1 does not have this valve installed. Neither Unit has an automatic valve to allow isolation from within the containment. The minimum design requirements for lines that penetrate the primary reactor containment and connect directly to the containment atmosphere are Criterion 56 of Appendix A to 10 CFR 50 and Reg-ulatory Guide 1.11. " Instrument Lines Penetrating Primary Reactor Containment."
By letter dated November 13, 1985, Comonwealth Edison Company (licensee),
requested staff review of their proposed modification of the Unit 1 con-tainment gage pressure sensing line of the containment flood-up measurement system. The modification is the addition of an excess flow check valve similar to Unit 2 to the existing 3/4 inch instrument line which senses containment gage pressure. This instrument line is a branch-off from a 2 inch bypass on a 26 inch vent line which penetrates containment. The 26 inch line which " sees" a containment atmosphere does not have an automatic valve within the containment.
2.0 EVALUATION This evaluation considers only the sensing line in which containment gage pressure is sensed.
In the event of a loss-of-coolant accident (LOCA),
the existing instrument line has a single barrier to prevent a pressurized containment from communicating with the environment. The addition of an excess flow check valve provides an additional barrier which would isolate the containment upon rupture of the instrument line.
8602190100 860210 PDR ADOCK 05000373 P
' We have evaluated the licensee's submittal to see if it meets Criterion 56 and Regulatory Guide 1.11. The guide describes a basis for implementing Criterion 56 in the event there is no automatic valve inside and outside the containment.
t Acceptance of sensing lines for instruments that are not part of the pro-tection system is given in the Regulatory Safety Guide Positions 1.b, 1.c, 1.d and 1.e.
- Regulatory Position 1.b relates to leakage resulting from a postulated failure of any piping or component in the line outside of the containment.
This position is met since the line size (3/4") is small and will minimize leakage. Also, by the addition of the excess flow check valve, leakage is prevented upon rupture of the sensing instrument.
Regulatory Position 1.c requires the line outside of containment to be provided with an isolation valve capable of automatic operation and located close to the containment.
This position is met since the valve will automatically close in the event of a downstream rupture when the containment is pressurized.
Otherwise spring action keeps the valve disc from seating.
In addition, the valve is approximately 10 ft. from the containment.
Regulatory Position 1.d requires the line up to and including the isolation valve to be conservative in design and be of quality at least equivalent to the containment.
This position is satisfied since the instrument line is Seismic Category I, ASME III, Class 2, according to the updated Final Safety Analysis Report.
- Regulatory Position 1.e requires the instrumentation response time not to be significantly affected by components in the line.
The availability of the added instrument line, as stated by the l
licensee, is required hours to days after certain post LOCA accidents.
In this period the transient, as related to containment pressure, should be varying relatively slowly. This eliminates the need to consider time lag in this line.
In view of the above, we consider Regulatory Guide 1.11 and, therefore, Criterion 56 to be met. We find that addition of the excess flow check valve to the existing line is acceptable and agree that the valve be listed as a containment isolation valve in Table 3.6.3-1 of the plant Technical Specifications.
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3.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change in the installation 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 this amendment involves no significant hazards consideration and there has been no public concent 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 Commission made a propesed determination that the amendment involves no significant hazards consideration which was published in the Federal Register (50 FR 40783) on December 4, 1985. No public comments were received, and the state of Illinois did not have any connents.
We have 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, and (2) such activities will be conducted in compliance with the Commission's regula-tions and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public, i
t Prinicipal Contributors:
D. Katze, Dated: FEB 10 1986 I
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AMEN 0 MENT NO. 34 TO FACILTTY OPERATING LICENSE NO. NPF LA SALLE, UNTT 1
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