ML19317G788
| ML19317G788 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/13/1977 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19317G751 | List: |
| References | |
| NUDOCS 8004010616 | |
| Download: ML19317G788 (3) | |
Text
'
f"I umTno stares p
,l=
~*
NUCLEAR REGULATORY COMMISSION 1
()
3 ( M I, j WASHINGTON, D. C. 20555
/
g SAFETY EVALUATION SY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.11 TO FACILITY OPERATING LICENSE NO. DPR-54 AND EXEMPTION FROM APPENDIX J TO 10CFR50 SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO NUCLEAR GENERATING STATION i
DOCKET NO. 50-312 Introduction By our letter dated August 4,1975, the Sacramento Municipal Utility District (SMUD) was requested to review the Rancho Seco Nuclear Generating Station (the facility) containment leak testing program, and the associated Technical Specifications, Nr compliance with the requirements of Appendix J to 10 CFR Part 50.
Appendix J to 10 CFR 50 was published on February 14, 1973.
Since many operating nuclear plants had either received an operating license or were in advanced stages of design or construction at that time, some plants may not now be in full compliance with the requirements of this regulation. There-fore, beginning in August 1975, requests to establish the-degree of compliance with the requirements of Appendix J were made of each licensee.
Following the initial responses to these requests, we developed positions which would provide assurance that the objectives of the testing program were satisfied. These NRC staff positions have since been applied in our review of reports filed by the Rancho Seco licensee and the results are refl,ected in the following evaluation.
The licensee's response dated September 5,1975, stated that they did not comply with Appendix J in two areas: the penetrations subject to Type C testing and the testing of containment airlocks.
Based on discussions with the staff, the licensee has revised his proposed Technical Specifications by letter dated October 5,1976.
8004010 h [
s
- Evaluation i
Section II.H of Appendix J identifies those containment isolation valves which require Type C local leak rate testing. SMUD has reviewed its local leak testing program and has identified six penetrations which are not locally leak tested and which require Type C testing in accordance i
with Appendix J.
SMUD's proposed change to the Technical Specifications adds these. penetrations to the list of components subject to local leak rate testing. This change satisfies the requirements of Appendix J and is, therefore, acceptable.
Paragraph III.D.2 of Appendix J requires leak testing of airlocks at six-month intervals and after each opening. SMUD proposes to leak test the airlock door seals within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after each opening.
This exemption from the "after each opening" test requirements of Appendix J recognizes that a significant amount of time is required to conduct these intermediate tests in relation to the frequency of use of the airlock.
Based on operating experience at Rancho Seco, and other plants with a similar airlock door dual-seal design, the leakage rates past t ' ceals during leak testing have been negligible.
In addition, accumulated test data indicate that containment airlocks with two doors and dual-seals on each door are reliable components with resped to leak tightness. Consider-ing that a full pressure airlock test is to be performed every six months, we find that testing airlock door seals within three days after each opening will adequately demonstrate the leak tight integrity of the airlock.
Paragraph III.B.2 of Appendix J requires that Type B tests be performed at the peak calculated containment pressure, Pa, which is 52 psig for Rancho Seco. The airlock design for Rancho Seco is such that the test pressure, which is applied in a direction opposite that of the accident pressure, tends to lift the seals off their seats.
The condition necessitates the use of strong-backs or clamps to conduct the test at Pa, which results in the need for opening of the airlock doors to remove the clamp.s. This procedure defeats the purpose of the test. However, reduced pressure tests can be conducted without the use of clamping devices. SMUD has proposed to conduct the leak tests at 10 psig, which is the manufacturer's recommended pressure for reverse flow through the seals. The test results will be extrapolated to P using a
the following formula:
h,wherePisinpsig La"Lt This formula can be derived from the Hagan-Poiseuille equation assuming laminar, incompressible flow. We believe that this extrapolation formula will result in a conservative assessment of leak rates at Pa and is, therefore, acceptable.
p.
p
,e-3
. Conclusion We have reviewed SMUD's proposed change to the Technical Specifications and request for exemption from the requirements of Appendix J to 10 CFR
- 50. We find, based on the above discussions that the proposed Technical Specifications will satisfy the provisions of Appendix J. as modified by the exemptions. We find that the exemptions are acceptable on the bases that they satisfy the safety objectives of the regulation.
We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of '
environmental impact and pursuant to 10 CFp 151.5(d)(c) that an environmental impact statement, or negative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of this amendment.
We have concluded, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the amendment does not involve a sienificant hazards consideratien, (2) there is re:sonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the k
Commission's regulations 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.
~
Dated: July 13,1977 e
5 i
1