ML20064B175
| ML20064B175 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 09/27/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20064B173 | List: |
| References | |
| NUDOCS 9010150088 | |
| Download: ML20064B175 (5) | |
Text
[p as t.g'c, UNIT ED STATES
['Y, e f i NUCLE AR REGULATORY COMMISSION "V
b W AsHINGT oN, D. C. 20sss qS 4[f g~
SAFETY EVALUATION SY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 49 TO FACIL TY OPERATING LICENSE NO. NPF-47 GULF STATES UTILITIES COMPANY RIVER BEND STATION, UNIT 1 DOCKET NO. 50-458 INTRODUCTION By letter dated March 21, 1989, and supplemented by letter dated August 3, 1990, Gulf States Utilities Company (GSU) (the licensee) requested an amendment to Facility Operating License No. NPF-47 for the River Bend Station (RBS), Unit 1, pursuant to 10 CFR 50.90 and 10 CFR 50.55a(g)(5)(ii).
The proposed amendment would relocate part of the snubber Technical Specifications (TSs) to the Inservice Inspection (ISI) Plan while retaining the Limiting Condition for Operation (LCO) applicability and ACTION requirements in the 155.
The proposed amendment would reference the ISI Plan in the TSs.
The detailed surveillance requirements regarding snubbers are contained in the RBS ISI Plan.
Any changes to the section of the ISI Plan pertaining to snubbers will be submitted to the staff for prior review and approval.
EVALUATION The requirements of 10CFR50.55a(g)(5)(ii) state that, "if a revised inservice inspection program for a facility conflicts with the technical specifications for the facility, the licensee shall apply to the Commission for amendment of the technical specifications to conform the techni;al specification to the revised program." The current RBS Snubber TS (3/4.7.4) dif fers from the RBS ISI Plan which was approved by NRC on October 20, 1987.
These differences and other amendments to the TSs are discussed below.
(1) Limiting Condition for Operation The licensee has proposed to add the word ' required' in the LIMITINC CONDITION FOR OPERATION and ACTION statement to limit this specification to only those snubbers that must be OPERABLE in the applicable operational mode (s) of the plant.
There may be conditions where the system is required to be operable, but the snubber may not be required to be
- operable, Current TSs require three evaluations to be performed within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The proposed ACTION statement would be subdivided to delineate the time periods for the engineering evaluations previously required by item g to be completed.
The proposed amendment would require the system operability evaluation to be performed within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> while the cause of f ailure and conimon cause evaluations would not be required to be l
performed within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
These evaluations are addressed in further 9010150088 900927 PDR ADOCK 05000450 P
PNV 1
.g.
detail by Section 12.2.9 of the current ISI Plan:
An evaluation to decide if the system or component meets design requirements.
This evaluation is required before returning the system or component to service.
An evaluation that returns a required snubber to operation without removing it also must be completed within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of determining it inoperable or the system ACTION must be followed.
An evaluation of the snubber to determine the cause of failure.
This evaluation is not required before returning the system or component to service unless the snubber is to be repaired and returned to service.
A failure mode evaluation to determine if snubbers of the same design are subject to the same failura.
No evaluation is required before returning the system or snubber to service.
(2) Detailed Surveillance Requirements The following differences exist between the TS requirements and the RBS 151 Plan with regard to the classification, visual inspection and functional testing of snubbers.
The licensee is proposing amendments to the TS so that the TS requirements would be identical to the ISI Plan.
Inspection Type Technical Specification Surveillance Requirement 4.7.4.a states that,
"(a)s used in this specification, type of snubber shall mean snubbers of the same design and manufacturer, irrespective of (load) capacity." With regard to this definition, RBS has only one type of snubber installed.
Therefore, in the RBS ISI Plan, load capacity is also considered as a criterion for snubber type classification for the purpose of establishing test sample scopes for functional testing.
The load capacity of a snubber is a design parameter.
As such, test samples should correspondingly reflect this.
The NRC approved ISI Plan incorporates this additional criterion for inspection type determination based on the following factors:
Based on data obtained from-test agencies and industry surveys, snubbers of dif ferent load capacities have been found to fail functional testing at considerably different rates.
The differences in failure rates are substantial enough to warrant considering load capacity as a separate aspect of test sample selection.
Snubbers of dif ferent load capacities have internal design dif ferences which affect the manner in which the snubber translates linear motion to rotational motion.
Although these design differences are minor, they have been shown to have an effect on snubber failure rates.
,, b The combination of these two aspects of snubber failure rates as a function of load capacity prompted the inclusion of this test sample selection criterion in the RBS ISI Plan.
Since only accessibility i
determines the scope of subsequent visual inspections, this additional criterion will have no impact on the scope of subsequent' visual surveillances.
This additional criterion for sample type selection has been approved by the NRC in Revision 2 to the RBS ISI Plan.
Therefore, i
the staff finds the proposed criterion for snubber type classification acceptable.
l Visual Inspections TS Surveillance Requirement 4.7.4.b currently requires that snubbers be classified as accessible or inaccessible during reactor operation.
A baseline examination of all snubbers is required to be performed after four (4) months but within ten (10) months following commencement of initial power operation.
If inoperable snubbers are found during visual inspections, subsequent visual inspections are required to be conducted in accordance with the following schedule:
No. of Inoperable Snubbers of Subsequent Visual each Type Per Inspection Period Inspection Period 0
18 months +/-25%
1 12 months +/-25%
2 6 months +/-25%-
3, 4 124 days +/-25%
5, 6, 7 62 days +/-25%
8 or more 31 days +/-25%
TS Surveillance Requirement 4.7.4.b allows accessible and inaccessible snubbers to be inspected independently according to the above schedule.
The RBS 151 Plan also requires that snubbers be' classified as either accessible or inaccessible during reactor operation, and that the inspection schedule above be used for subsequent examinations of accessible snubbers.
However, subsequent examination of inaccessible snubbers are allowed to be performed during the next reactor shutdown of i
sufficient duration as to provide accessibility.
This provision was also included in Revision 2 of the Standard Technical Specifications.
- Further,
-Article IWF of ASME Section XI allows subsequent examinations of inaccessible snubbers to be delayed until the next inspection period.
Therefore, the staff finds the proposed change to be acceptable.
Functional Test Requirements TS Surveillance Requirement 4.7.4.e currently allows the licensee to select one of the three sampling plans for snubber testing.
One sample plan presently allowed by the TS and also the ASME Standard OMa, Part 4, 1988 Edition, requires an initial sample size of at least 10 percent of each
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type of snubber to be tested each outage.
The ISI Plan also allows the 10 percent plan and is selected as the bases for the examination schedule.
The actual examinations during the last two outages were over 16 percent of each type of snubber required to meet the ASME Section XI requirement of 100 percent snubber testing in a 10 year period, again exceeding OMa-4 requirements.
The present OMa-4 only requires additional test lot sizes to be one-half the size of the original sample.
The present 151 Plan requires that additional sample lots are the same size as the initial samples thereby providing additional assurance of snubber operability.
Thus, the staff finds the 10 percent plan acceptable.
Since 3/4.7.4 will remain in the RBS TS, the BASES will remain with the proposed modifications.
The changes as discussed above will reference the ISI Plan instead of specific TS requirements.
In a telephone call on September 27, 1990, the licensee committed to submit any future changes to the ISI Plan pertaining to snubbers to the staff for review and approval.
SUMMARY
The amendments to TS 3/4.7.4 as proposed have been reviewed by the staff and found to be acceptable.
Any future changes to the snubber section of the ISI Plan will be submitted to the staff for prior review and approval.
Additionally, when the Improved Standard TSs are issued, CSU will, if necessary, make changes to conform to the staff's position regarding snubbers.
ENVIRONMENTAL CONSIDERATION The amendment involves a change in 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 and changes in surveillance requirements.
The staff has determined that the amendment involves no significant increase in the amounts, and no signi-ficant 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 exposures.
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.
Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Section
$1.22(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 the amendment.
CONCLUSION The staff 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, and (2) such
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activities will be conducted in compliance with the Commission's regulations,-
and the issuance of the amendment will not be inimical to the common defense i
and security or to the health and safety of the public.
The staff therefore' i
concludes that the proposed changes are acceptable.
Dated:- September 27. 1990 i
Principal Contributor:
J. Rajan. EMEB f
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