ML20055H153
| ML20055H153 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 07/19/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20055H151 | List: |
| References | |
| NUDOCS 9007250253 | |
| Download: ML20055H153 (5) | |
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SAFETY EVALUATION, BY THE OFFICE OF NUC'. EAR REACTOR REGULATION RELATED TO AMENDMENT N05.18' AND 8 TO FACILITY OPERATING LICENSE A05. NPF-76 AND NPF l HOUSTON LIGHTING & POWER COMPAN_Y.
1 CITYPUBLICSERVICEBOARDOFSANANTON10 CENTRAL-POWER'AND LIGHT COMPANY CITY OF AUSTIN. TEXAS-DOCKET NOS. 50-498 AND 50-_99 4
SOUTH TEXAS PROJECT UNITS _1 AND 2 INTRODUCTION By-application dated June 28, 1989,.as supplemented on November 29, 1989 (Ref.
1, 2), Houston Lighting & Power Company,(Appendix A to facility Operating et. al., (the licensee) requested changes to the Technical Specifications LicenseNos.NPF-76andNPF-80)fortheSouthTexasProject, Units 1and2.
-The proposed changes would revise the surveillance-requirements for the reactor containment' building.
DISCUSSION.
TheSouthTexasProject(STP)consictsoftwoconcretereactor. containments.
The cylindrical wall-and hemispherical dome of each containment are post-tensioned with high strength tendons, while the containment mat is conventionally L
reinforced. There are 96 inverted U-tendons-and 133 hoop tendons in each i
containment. Each tendon consists of 186-1/4 in. -diameter wires inserted into a sheet metal duct and the associated anchorage components-(bearing plates, shims, anchor heads, etc.). The tendons are protected'from corrosion by filling the tendon ducts with corrosion inhibiting grease.- The. tendons are initially tensioned to approximately:70 percent of their minimum Guaranteed Ultimate Tensile Strength (GUTS).
Regulatory Guide 1.35 delineates the provisions for In-Service Inspection of Ungrouted Tendons in Prestressed Concrete Containments. The present Technical Specification for tendon surveillance requirements for the two units of-the-STP are based on Rev. 2 of the Regulatory Guide. A "For Comment" version of-
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Revision 3 of the guide was published in April 19 9.
The final version of Revision 3 of the guide is expected to be published in July of 1990. Subsection IWL of ASME B&PV,Section XI was published in January 1989. This Subsection includes the requirements for inservice inspection of ungrouted prestressing tendon in prestressed concrete containments. With a few exceptions, the requirements in Subsection IWL are similar to the provisions of Revision 3 of Regulatory Guide 1.35. The staff has also prepared a sample technical specification (STS) related to the tendon surveillance. The STS incorporates the provision of Regulatory Guide 1.35 (Rev. 3) and incorporates the LCOs commensurate with the type of degradations observed during an inspection.
EVALUATION ThefollowingisadiscussionofthemajorTechnicalSpecification(TS) changes.
Section 3.6.1.6 - Limiting Condition of Operation (LCO)
The existing LCO requirements are based on the Standard Technical Specification existing at the time of the licensing of the STP. Since then, the staff has initiated a number of' studies (Ref. 3, 4) related to the technical content of Regulatory Guide 1.35. As a result of those studies, the staff had decided that the current LCO is-too demanding for plant shutdown. The staff had l
developed an LCO which would reflect a reasonable condition for shutdown of tne plant in the STS.
In the proposed TS, the licensee adopts the staff l
recommended position and provides a strong justification for making the change, This change is thus acceptable to the staff.
Section 4.6.1.6 - Surveillance Requirements Two Containments at a Site - The existing TS requires the licensee to perform a full inspection for both the STP containments. The staff position allows the licensee to perform full inspection on one containment, with only visual inspection on the other. However, the full inspection must be performed on an alternating basis. The licensee opts to take advantage of the relaxation.
This proposed change is acceptable to the staff.
The inspection on alternate basis is conditioned upon a premise that the tendons in both containments are f*om a single population. Therefore, if a significant degradation is found in one containment during its full inspection, a similar degradation is automatically assumed in the second containment.
Both the containments would require evaluation.
Section 4.6.1.6.1.a. b, and c - Adequacy o' Prestressing Forces Number of Tendons and Frequency of Inspection - Except as modified by the acknowledgement of two containments onsite, the frequency of inspection remains the same in the proposed TS. The number of tendons to be inspected in the existing TS are arbitrary numbers. The STS-specifies these numbers as a percentage of the tendon population in each group. The proposed TS adopts the STS. These changes are thus acceptable.
Tendon Prestress Force Acceptance Criteria - The existing TS is based on one sided approach of monitoring prestressing forces.
Based on the experience f
with the tendon testing, the STS provides multiple ways of establishing the adequacy of the prestressing forces (i.e., individual tendon evaluation, average tendon evaluation and trend of common tendons). With a few minor and acceptable changes, the licensee adopts the STS position.
This is l
acceptable to the staff.
Section 4.6.1.6.1.d - Operability of Sheathing Filler Grease The existing TS of STP can be considered as incomplete. Based on the experience with the use of the sheathing filler grease, the STS includes the provisions for monitoring chemical properties and water in the. grease. The licensee proposes to adopt these additional provisions...The licensee had originally proposed that the amount of grease replaced in excess of the grease removed be changed from the present value of 5 percent to 10 percent.
By letter dated February 14, 1990 (Ref. 5), the licensee withdrew that portion of the proposed changes. The value of excess grease remains at 5 percent.
Section 4.6.1.6.1 - End Anchorages and Adjacent Concrete Surfaces The existing TS and the proposed TS have similar requirements for examining the anchorages and adjacent concrete surfaces-except for the changes that reflect the examination requirements for two containments at a site as discussed t
earlier. The proposed TS requirement is thus acceptable to the staff.
Section 4.6.1.6.3 - Containment Surfaces The existing TS requires the examination of containment surfaces during Type A leak. rate testing when the containment is at its maximum pressure. The STS provides a specific guideline for determining significant degradation and leaves it up to the licensee to determine if the visual inspection be performed during Type A test or during tendon surveillance.
In the proposed TS, the licensee adopts to perform the visual examination of the exterior concrete surfaces during tendon surveillances. However, a general inspection of the interior surfaces shall be performed prior to Type A tests. This is-acceptable to the staff.
SUMMARY
Based on the review of the proposed changes in the Technical. Specifications for surveillance of prestressing tendons in prestressed concrete containments with respect to the staff developed Sample Technical Specification, the staff concludes that:
(1) the proposed TSs will be effective in ensuring the contain-ment structural integrity; and (2) the revised TSs are consistent with and support the conclusions of the original Safety Evaluation. The proposed changes to the TSs are, therefore, acceptable.
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ENVIRONMENTAL CONSIDERATION The amendents involve 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 detertrined that the amendments involve 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 Comission has previously issued a proposed finding thct the amendments involve no significant hazards consideration and there-has been no public consnent on such finding. Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR Section-51.22(c)(9).- Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessnent need be. prepared in connection with tie issuance of the amendrents.
CONCLUSION Based upon its evaluation of the proposed changes to the' South Texas Project, Units 1 and 2, Technical Specifications, the staff has concluded that:
(1) there is reasonable assurance that the health and safety of the-will not be endangered by operation in the pro 30 sed manner, and (2) public such activities will be conducted in compliance witrthe Comission's regulations and the issuance of the amendments will not be inimical to-the common defense and security or to the health and safety of-the public. The-staff, therefore, concludes that the preposed changes are acceptable.
Date:
July 19, 1990-Principal Contributor:
H. Ashar I
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REFERENCE 1.
Application for amendments to Licenses NPF-76 and NPF-80' modifying-Technical Specification Section 4.6.1.6.1, dated June 28, 1989.
-2.
Application for amendments to Licenses NPF-76 and NPF-80 revising Technical Specification requirements 3.6.1.6_and 4.6.1.6, dated i
November 29,'1989.
3.
NUREG/CR-2719."EvaluationoflInserviceIrspectionsofGreased Prestressing Tendons," September 1982.
4.
NOREG/CR-4712. " Regulatory Analysis of-Regulatory Guide 1.35
- (Revision 3, Draft 2) - Inservice Inspection of Ungrouted Tendons in Prestressed Concrete Containments," February 1987.
5.
Letter from licensee withdrawing request for change-in sheathing filler grease requirement surycillance, February 14, 1990.
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