ML20247Q953
| ML20247Q953 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 05/24/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20247Q952 | List: |
| References | |
| NUDOCS 8906070092 | |
| Download: ML20247Q953 (4) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 31 TO FACILITY OPERATING LICENSE NO. NPF-42 WOLF CREEK NUCLEAR OPERATING CORPORATION
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WOLF CREEK GENERATING STATION DOCKET NO. 50-482
1.0 INTRODUCTION
By letter dated December 6,1985, as supplemented on March 29 and May 10, 1989, the licensee submitted proposed revisions to Section 3/4.6.1.6, Contain-ment Vessel Structural Integrity, of the Wolf Creek Technical Specifications (TS). This section includes a number of surveillance requirements that ensure that the structural integrity of the containment will be maintained in accordance with the safety analysis requirements for the life of the facility. A representative san;ple of containment tendons is examined at predetermined intervals to ensure that the containment will withstand the mu.imum pressure of 50 psig under design basis accident conditions. Surveil-lance requirements include verification of containment tendon lift-off forces and stresses, tensile strength tests of the tendon wires, examination for voids in the sheathing filler grease, and visual examination of tendons, anchorages and exposed interior and exterior containment surfaces.
TheexistingTShastwoLimitingConditionsforOperation(LCOs). The existing LCO (a) requires the plant to be in hot standby if the deficiencies related to the behavior of sample lift-off force measurements cannot be restored to the required level of integrity within 15 days.
If the lift-off force of any one tendon falls outside of the acceptance criteria, additional testing must be performed.
For all other conditions, LCO (b) requires that all parameters (lift-offstresses,tensilestrength,voidsinthegrease,etc..)
be restored to the required level of integrity within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The licensee's submittal of December 6, 1985 requested a number of changes to the TS. The most significant of these changes and the bases are as follows.
The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO would be eliminated. The LCO of 35 days weuld remain for LCO (a) while varying requirements would be substituted for LCO (b). Sub-sequent discussions with the licensee indicated their belief that 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> would be insufficient time to select accessible tendons and erect scaffolding if additional testing is desirable or required by the TS, obtain test or chemical analysis results back from off-site contractors, or adequately analyze and respond to new issues or unidentified problems.
Upon observing abnormaldegradationforconditionsotherthanthoseunderLC0(a),the licensee proposed additional reporting requirements and an engineering eval-uation to demonstrate continued containment structural integrity. This 8906070092 890524 DR p
ADOCK 05000482 PDC
. j relaxation would permit tendon parameters to be outside of their acceptance criteria provided that the overall containment structural integrity could be demonstrated. The licensee also proposed that the maximum void content of 5% in the sheathing filler grease would be removed.
It would be replaced 1
by a statement referring to an examination for wide-spread grease leakage on the containment exterior surface. This relaxation was sought because the initial filling operation did not require verification of voids less than 5%.
1 On March 16, 1988, the licensee met with the NRC staff to discuss the licensee's submittal. While some minor changes to the original submittal were agreed upon, the staff requested that the licensee submit a statistical analysis to justify continued plant operation for up to 15 days as proposed by the licensee once abnormal degradation has been observed.
The licensee submitted the requested statistical analysis along with' additional.
modifications to the TS in their submittal of March 29, 1989. Changes to the original TS submittal include the addition of a 30-day special reporting requirement when selected conditions are not satisfied, clarification to the original submittal by linking together the surveillance requirements and LCO that addressed lift-off forces and lift-off stresses, and reinsertion of the maximum limit of 5% voids in the grease-filled tendon sheaths provided it is linked with visual observation of widespread grease leakage.
2.0 EVALUATION The Wolf Creek and Callaway facilities have the identical TS regarding Contain-ment Vessel Structural Integrity. At the time of licensing, these TS represented the staff's latest thinking and represented the staff's stendard TS. The changes described above are being sought simultaneously by Wolf Creek and Callaway. While the staff was interested in providing flexibility to the licensees, the staff also sought plant-specific as well as a generic solution to the limiting conditions for operation when certain tendon degradation is indicated during containment inspections.
Under the premise that the staff was embarking on a future model of TS that other licensees may wish to consider, the staff proceeded both cautiously and deliberately in this area.
On May 3,1989 a meeting was held among the Wolf Creek and Callaway licensees, their contractors, and the tiRC project and technical staff. The purpose of the meeting was to review and discuss previous submittals and to find a tech-nical resolution of the issue. The licensee and their contractors initially presented their statistical analysis that provided justification for the 15-day LC0 once abnormal degradation has been identified. The staff rejected their analysis primarily because the data base was limited to plant-specific information from Wolf Creek and Callaway and did not expand to other available, historical data.
Further discussions on the previous submittals were not productive.
Following a caucus by the staff, an extended session was conducted with the licensees that dealt with clarifying the staff's position and modifying the licensees' submittals accordingly. A revised set of TS were agreed upon and were distributed to the licensees at the conclusion of the meeting.
The revised TS, which include aspects of the licensees' original submittals and provisions that the staff found essential for meeting the staff's require-ments, include providing the licensees with an option of demonstrating that containment integrity is maintained as opposed to restoring the nonconforming tendons to the required level of integrity when a measured or observed parameter falls outside its acceptance criteria for both the LCO's set out below, and retaining the 72-hour LCO if the average of all measured prestressing forces from the sample group fell outside the acceptance criteria. All other measured or observed parameters identified in the surveillance requirements would fall within a 15-day LCO. Other changes made to surveillance requirements falling under the 15-day LCO include reinserting the requirement to limit the void content in the grease-filled tendon sheaths to 5%, and adding an additional requirement to perform trending analysis of prestressing forces.
If the trending analysis predicts unacceptable values it will be considered as an indication of abnormal degradation and additional testing will be required to determine the cause and extent of such degradation.
The licensee's submittal of May 10, 1989 formalized this agreement.
Based upon this discussion and evaluation, the staff has concluded: (1)the TS met the staff's requirements for containment vessel structural integrity; (2) the TS provided both clarification and relaxation of some of the existing LCO's and Surveillance Requirements, as well as adding provisions which the staff found vital for monitoring the integrity of prestressed concrete contain-ments; and (3) the TS are consistent with and support the conclusions of the licensee's originally-submitted Safety Evaluation and no significant hazards consideration determination. The proposed changes to the TS are, therefore, acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change to a requirement with respect to the instal-lation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or a change to a surveillance requirement. 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 comment on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forthin10CFR51.22(c)(9).
Pursuantto10CFR51.22(b),noenvironmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
4.0 CONCLUSION
The staff has 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 manner; and (2) public such activities will-be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the comon defense and security or to the health and safety of the public.
Principal Contributors:
H. Ashar, ESGB C. Tan, ESGB D. Pickett, PDIY T. Alexion, PDIII-3 Dated: May 24, 1989
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