ML20210E096
| ML20210E096 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 02/04/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20210E090 | List: |
| References | |
| NUDOCS 8609220106 | |
| Download: ML20210E096 (6) | |
Text
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ATMNT 3 NUCLEAR REGULATORY COMf.llSSION o
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EAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 33 TO FACILITY OPERATING LICENSE NO. NPF-11 COMMONWEALTH EDISON COMPANY LA SALLE C0bNTY STATION, UNIT 1 DOCKET NO. 50-373
1.0 INTRODUCTION
By letter dated November 13, 1985, Commonwealth Edison Company flicensee) proposed an amendment that would change the La Salle County Station, Unit 1 Technical Specifications to include a previously approved reactor trip setting on low control rod drive (CRD) pump discharge water header pressure and to delete an associated surveillance requirement. The staff's initial evaluation of the CRD charging water header low pressure scram function was provided in Section 4.6.? of Supplement No. 2 and Section 7.2.3.2 of Supplement No. 7 to the Safety Evaluation Report, and accordingly, License Condition 2.C.(15) was included in the license for its completion prior to startup after the first refueling outage.
2.0 EVALUATION In our evaluation of the low CRD pump discharge water header pressure in Section 7.2.3.2, the scram trip points approved were 1267 psig and the associated allowable value 1185 psig. This identical scram modification was installed initially in La Salle, Unit 2 with these scram trip points.
However, it was discovered that with these scram trip points spurious scrams were occurring. As a result, the licensee changed the scram trip setpoints on Unit 2 from those previously approved of 1267 psig to 1157 psig, and the associated allowable value from 1185 psig to 1134 psig, and the spurious scram problem was rectified. The licensee is now proposing these same setpoint changes on' Unit 1.
To arrive at the new setpoints, the calibrated range of the pressure sensors has been reduced from 0-2500 psig to 500-1500 psig, thus reducing the uncertainties involved in calculating the setpoint values (i.e., instrument accuracy is increased).
The licensee has performed an analysis which demonstrates that accumulator pressure will be sufficient to accomplish a scram for at least three minutes after CRD charging water pressure has decreased below the low pressure scram setpoint allowable value of 1134 psig. A reactor scram will occur ten seconds after charging water header pressure reaches the trip setpoint value of 1157 psig. The CRD low charging pressure scram logic includes a ten second time delay to avoid reactor scrams due to spurious pressure fluctuations.
The licensee has not deleted or changed any Technical Specification oper-ability requirements or limiting conditions for operation for the scram accumulators.
Based on the above, the staff concludes that the proposed setpoint changes are acceptable.
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. The licensee has proposed to delete surveillance requirement 4.1.3.5.b.2 to measure and record the time that each individual accumulator check valve maintains the associated accumulator pressure above the low pressure alarm setpoint with no control rod drive pump operating. This test (check
' valve leakage rate) was required to be performed once per 18 months. With implementation of the CRD charging water header low pressure scram function, a reactor scram will occur before CRD charging pressure, and hence accumu-lator pressure, decreases (for whatever reason, including check valve leakage) to the point where cnntrol rod insertion is no' longer possible.
Because sufficient pressure will be available to accomplish a scram, for all modes of operation, the staff concludes that deletion of the above surveil-lance requirement for the accumulator check valves is acceptable.
A: a result of this modification, new instrumentation has been incorporated into the design; and the licensee updated Tables 3.3.1-1 and Table 4.3.1.1-1 of the La Salle Unit 1 Technical Specifications to reflect this change.
The staff reviewed the proposed changes to the Tables.
Table 3.3.1-1 establishes the requirements for the minimum number of ' operable channels (including the applicable modes of operation) and the associated limiting conditions for operation when the minimum operability requirements are not met. All four charging water header pressure channels and the delay timer are required to be operable at startup and refueling with any control rod withdrawn.
Table 4.3.1.1-1 requires that a channel functional test be performed monthly for each pressure channel and the delay timer, and that these instruments be calibrated at each refueling outage. The proposed Technical Specification operability requirements limiting conditions for operations, and surveillance requirements for the CRD charging water header low pressure scram instrumentation are consistent with other pro-tection system instrumentation at La Salle Unit 1 and the BWR-5 Standard Technical Specifications, and therefore, are acceptable. The licensee I
has stated that the CRD charging water header low pressure alarm (which is independent of the trip function) will be tested at each refueling outage as.part of calibration procedures LISRD-204 and 404. Response time testing is not required for these instruments because credit is not taken for the CRD charging water header low pressure scram function in any of the Chapter 15 analyses of the Final Safety Analysis Report.
Based on the above, the NRC staff concludes that the proposed changes to the La Salle Unit 1 Technical Specifications concerning implementation of the CRD charging water header low pressure scram function are acceptable, and accordingly the licensee has satisfied the License Condition 2.C.(15).
3.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change in the installation and use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes in surveillance requirements.
The staff has determined that this 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 cumula-tive occupational radiation exposure. The Commission has previously issued i
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e a proposed finding that this amendment 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 pre-
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pared in connection with the issuance of this' amendment.
4.0 CONCLUSION
The Commission made a. proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Register (50 FR 49784) on December 4, 1985.
No public comments were received, and the state of Illinois did not have any comments.
We have concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the will not be endangered by operation in the proposed man.ner, and (2) public such activities will be conducted in compliarce 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.
Principal Contributor:
A. Bournia, BWR Project Directorate No. 3, DBL Dated:
FE8 04 m
ATTACPMENT 4 LSCS-UFSAR 4
TABLE 6.2-21 (SHEET 20 of 24 l
These valves are under continuous leakage test because they
'are always subjected to a differential pressure acting across the seat.
Leakage through these valves is continuously monitored by the pressure switches in-the pump discharge lines, which have a low alarm setpoint in the main control room.
Even though a special leakage test is not merited on these valves for the reasons discussed above, a system leakage' test to meet the requirements of Type C testing and as hereinafter described will be performed to ensure the leak-tightness of the ECCS and RCIC systems.
The systems will be pressurized with water to a minimum pressure of 1.1 times Pa (peak drywell accident pressure) with the system totally isolated from primary containment.
A leakage rate for the entire system will then be determined and compared to an acceptance limit based on site boundary dose considerations (10 CFR 100: ECCS subsystem ~ Leakage not to exceed 1 gpm times number of valves in the subsystem tes.ted.
30.
The leakages through the Main Steamline valves will not be included in establishing the acceptance limits for the com-bined leakage in accordance with the 10 CFR 50, Appeqpix J, Type B and C tests.
Because the Main Steamlines are provided with a leakage control system, the leakage through these valves will not be added into the combined leakage rate.
This exclusion is in accordance with Article III.C.3 of 10 CFR 50, Appendix J.
31.
Although only one isolation valve signal is indicated for.
these valves, the valves also receive automatic signals from various system operational parameters.
For example, the ECCS pump minimum flow valves close aut'omatically when j
adequate flow is achieved in the system; the ECCS test lines.
close automatically on receipt of'an accident signal.
Although these signals are not considered isolation signals; and are therefore, excluded from this table, there are other system operation signals that control these valves to ensure their proper position for safe shutdown.
Reference to the logic diagrams for these valves indicates which other signals close these valves.
32.
To satisfy the requirements of General Design Criterion-56 and to per form their function, these instrument lines have been designed to meet the requirements of Regulatory Guide 1.11 (Safety Guide 11).
These lines are Seismic Category I and terminate in instru-ments that are Seismic Category I.
They are provided with manual isolation valves and excess flow check valves.
REV. 1 APRIL 1905 TABLE 6.2-21 l
LSCS-UFSAR TABLE 6.2-21 l
(SHEET 21 of 24)
The integrity of these lines is to be tested during the These lines and their associated instruments Type "A" Test.
Surveillance inspections are are to be pressurized to Pa.
performed to ensure that the leaktight integrity of Additional these lines and their associated instruments.
inservice inspection is included in the Technical Specifications.
This inservice inspection verifies the function of the excess flow check valves.
In the Isolation is provided by the excess flow check valve.
event of a line rupture downstream of the check valve and a containment pressure above 2~psig this valve would close to limit the amount of leakage.
To perform their function and to satisy the requirements of General Design Criterion 55, these instrument lines have 33.
been designed to meet the requirements of Regulatory Guide 1.11 (Safety Guide 11).
These lines are seismic Category I and terminate in instru-They are provided with ments that are Seismic Category I.
flow-restricting orifices, manual isolation valves, and excess flow check valves.
The flow-restricting orifice is sized to assure that in the event of a postulated failure of the piping or component, the potential offsite exposure would be substantially below the guidelines of 10 CFR 100.
In Isolation is provided by the excess flow check valve.
f the event of a line rupture downstream of the check valves, this valve would close to limit the amount of leakage.
The integrity of these lines are tested during the Surveillance inspections are performed Type "A" Test.
integrity of these lines and to ensure the leaktight Additional inservice inspection eneir associated instruments.
This inservice is included in the Technical Specifications.
inspection verifies the function of the excess flow check valves.
l l
i l
l TABLE 6.2-21 REV. I APRIL 1985 I
l l
A LSCS-UFSAR TABLE 6.2-21 (SHEET 23 of 24) l 37.
These valves are required to open on signals B and F during the post-LOCA conditions.
They remain closed during all other plant operating states, except. cold shdtdown.
Therefore, there is.no reason to provide them s
with any isolation signal other than remote manual.
38.
The ADS supply lines are maintained at a minimum pressure of 160 psig at all times.
Leakage-in these lines is monitored by pressure instrumentation which alarms in the main control room on low pressure.
Therefore, these lines are always under a continuous leak test, and a specific local leak rate test (Type C) will not be performed.
The intent of the requirement is satisfied however, by the system design itself.
39.
The ECCS and RCIC suction lines are normally filled with water on both the inboard and outboard side of containment, thereby forming a water seal to the containment environment.
The valves are open during post-LOCA conditions to supply a water source for the ECCS pumps.
Since a break in an ECCS line need not be considered in conjunction with a DBA, the' only possible situation requiring one of these valves to be closed during a DBA is an unacceptable leakage in an ECCS.
However, because these ECCS systems are constantly monitored for excessive leakage, this is not a credible event for design.
However, at the insistence of the NRC, these valves will 4
receive a leakage test as part of the low pressure system leakage test described in Note 29.
40.
These valves are required to open and remain open following s
a LOCA to allow the containment air to be sampled.
They are part of a system which constitutes a closed loop outside of the containment and will be open during Type A testing.
Therefore there is no reason to perform a Type C test on these valves.
9 4
TABLE 6.2-21 REV. 1 APRIL 1985
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