ML20217G502
| ML20217G502 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 09/30/1997 |
| From: | Miraglia F NRC (Affiliation Not Assigned) |
| To: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| Shared Package | |
| ML20217G493 | List: |
| References | |
| NUDOCS 9710100237 | |
| Download: ML20217G502 (8) | |
Text
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7590-01-P UNITED STATES OF AMERICA NQQLEAR REGULATORY COMMISSION in the Matter of
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Consumers Energy Company
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Docket No. 50-255
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(Palisades Plant)
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EXEMPTION 1.
Consumers Energy Company (the licensee) is the holder of Facility Operating License No. DPR-20 which authorizes operation of the Palisades Plant. The Palisades facility is a -
pressurized-water reactor located at the licensee's site in Van Buren County, Michigen. The license provides, among other things, that the facility is subject to all rules, regulations, and orders of the Commission now or hereafter in effect.
II.
Pursuant to 10 CFR 50.12(a), " Specific exemptions," the Commission may grant exemptions from the requirements of the regulations of this part (1) which are authorized by law, will not present an undue risk to the public health and safety, and are consistent with the common defense and security; and (2) where special circumstances are present.
Section ll.G. of 10 CFR Part 50, Appendix J, Option A, defines Type B tests as ' tests intended to detect local leaks and to measure leakage across each pressure-containing or leakage-limiting boundary...." which includes air lock door seals.
Section Ill.D.2.(b)(ii) of 10 CFR Part 50, Appendix J, Option A, requires air locks opened during periods where containment integrity is not required to undergo a ful air lock pressure test at the end of such periods.
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Section Ill.D.2.(b)(iii) of 10 CFR Part 50, Appendix J, Option A, requires air locks opened during periods where containment integrity is required to undergo a full air lock pressure test within 3 days after being opened.
Ill.
by letters dated January 10,1996, and February 20,1997, the licensee requested an exemption from 10 CFR Part 50, Appendix J, Option A, Sections Ill.D.2.(b)(ii) and Ill.D.2.(5)(iii), for Type B testing of the emergency escape air lock. Specifically, this exemption would permit the licensee to perform a door seal contact verification check in lieu l
of the final pressure test required by Appendix J following opening the air lock doors for post-test restoration or seal adjustment.
The exemption request is necessary due to the original design of the emercency escape air lock. During specist testing in 1992, the licensee showed that the annulus be, men the door seals could not be successfully tested without the door strongback installed even at pressures as low as 2 psig. This testing, along with information from the vendor.
confirms that between-the-seal pressure testing on the emerger y escape air lock doors cannot be properly neasured or evaluated if the door strongbacks are not installed.
Similarly, the inner door does not fully seal with the reverse-direction pressure of a full air lock pressure test unless the strongback is installed.
Since the removal of the inner door strongback after pressure testing requires the outer door to be opened, a between-the-seals test of the outer door would be required by the regulation. This test would require the installation of a strongback on the outer door.
Further, full pressure testing or the pressure induced by the strongback may cause the seals to take a set, it is therefore necessary to open both doors (one at a time) after any pressure m..____
a 3-
- testing to ensure full seal contact, and there is a potential need to readjust the seals to restore seal contact.
As an attemative to a final pressure test reqrired by Appendix J for verification of door seal functionality, the licensee has proposed a final door seal contact verification. This seal performance verification is completed following the full pressure air lock test, after the removal of the inner door strongback, and just prior to final closure of the air lock doors. The requested exemption would not affect compliance with the present requirement to perform a full pressure emergency escape air lock test at 6-month intervals. It would also not affect the requirement to perform a full pressure emergency escape air lock test within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of opening either door during periods when containment integrity is required. The seal contact check replaces the pressure test required by App 0ndix J for the door opening (s) and/or seal adjustments associated with restoration from the required full pressure tests.
The licensee has performed additional low pressure between-the-eeals testing on the escape lock door seals to measure seal leak rates at low initial pressures and without the
- door strongbacks installed, to see if such tests would yield useful results. The tests indicated that meaningful between-the-seals testing is not possible with the present design of the escape air lock, without strongbacks installed.
The licensee has also considered possible modifications to the existing emergency escape air lock doors in an attempt to identify other methods of complying with the Appendix J requirements. The modifications that were considered were:
1.
Modify the seal desian or chance the seat material.
A proposal was received from the air lock vendor to perform testing of diffe:ent seal shapes and materials. This was later withdrawn. The vendor believes, and the licensee concurs, that the seal material and shape currently in use are reliable and ma
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- adequate to maintain containment integrity. Simply changing the seal material or shape would be unlikely to allow meaningful between-the-seals tests with strongbacks removed.
2.
Perform door modifications by removino the doors and.alterina the sealina surfaces.
Minor modifications were considered for the door mechanisms in conjunction with reconfigured sealing surfaces. This modification has never been performed by the air lock vendor and would be experimental. There is no guarantee that these efforts would be successfulin allowing Palisades to perform between-the-seals testing The cost of this modification is estimated by the licensee to be roughly equal to performing an air lock retront, as described below.
3.
Perform an air lock retrofit which would include removino r.3d reolacha the doors. the ends of the bulkhead. and the door mechanisms.
The doors would be replaced with doors of a design whose samis can be tested per Appendix J without additional restraint or subsequent seal restoration. The mechanisms would be updated for smoother operation but their function would not be altered.
The only viable attemative found was the mplacement of the air lock doors, which the licensee has estimated would cost a minimum of $700,000. The licensee states that the cost of performing the modification is not warranted because no increase in riant or public safety would be realized. The other modifications to the present doors or seals would not ensure adequate performance improvement for unrectrained between-the-seals testing.
During its review, the staff questions d tyhether post-test seal adjustment or " fluffing" was necessary because the door seals were too old or wom out to rebound properly to their-original shape after leakage rate testing or whether past fluffing had damaged the seals, such
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. that replacement of the seals could result in acceptable between-the-seals testing. The licensee's response, dated F3bruary 20,1997, stated that the seals are replaced approximately every 3 years and that the seals have not exceeded their service lives. Also, the licensee stated that fluffing has not damaged the seals, as indicated by continued saccessful Type B tests on both the emergency escape air lock and on the personnel air lock, on whose seals fluffing is also performed.
The licensee's proposed test methods deviate from the requirements of Appendix J in two ways:
(1) The seals are not leakage rate tasted after opening the doors for post-test restoration, such as removing the strongbacks; and (2) The seals are not leakage rate tested after being adjusted (e.g., fluffe.f.
The following quotation from American National Standard ANSI /ANS-56.8-1994,
" Containment System Leakage Testing Requiremants," is pertinent. Section 3.3.4.2 states, in part:
An airlock test shall be performed whenever repairs or adjustments have been performed that affect the leakage rate characteristics of the airlock. Opening of the alriock for the purpose of removing airlock testing equipment following an airlock test does not require further testing of the airlock.
The quoted provisions have been endorsed by the staff through Regulatory Guide 1.163, " Performance-Based Containment Leak-Test Program," dated September 1995, for plants following Option B of Appendix J. Although Palisades follows Option A of Appendix J for Type B and C leakage tests, in this case the queted provisions represent a valid technical position that may be used to help establish a basis for granting an exemption from tie requirements of Option A of Appendix J.
Therefore, conceming deviation (1) described above, the staff's technical position is that leakage rate testing is not necessary after opening the doors for post-test restoration.
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-s-Option A of Appendix J requires a leakage rate test after opening a door, with the idea thrt the door opening is a relatively isolated event. Requiring another test immediately after s valid test simply because the door was opened again to remove test equipment is not necessary to meet the intent of the regulation, especially if it leads to an infinite series of tests, as in this case. Thus, deviation (1) is acceptable as part of an exemption from Option A of A pendix J.
t Concoming deviation (2) above, there is considerable evidence that post-test seal adjustment should not necessitate a follow-up leakage rate test in this case. The present-practice ensures proper door seal contact prior to final door closure. The performance of this door seal contact check Fas led to the successful completion of subsec'uent emergency i
escape air lock full pressure tests since the procedural practice began in 1987. ' Also, no L
ILRT in that period has failed because of emergency escape air lock door seal leakage.
Based on these hssults, the air lock doors have been proven to function as designed using currerrt methods of testing and maintenance, including seal contact checks. Altematives would only provide approxirr.ately the same level of protection for public health and safety as currently exists. Continuing with the current methods of testing will not result in undue risk to public health and safety and is consistent with the common defense and security. Further, the underlying purpose of between-the-seals testing is to verify the seal integrity after an air lock door is opened or its seals adjusted. The seal contact check performed.on the emergency escape air lock door seals selves this purpose and ensures the doors are sealing properly. Therefore, application of the regulation to perform between-the-seals Isakage rate 4
- tests after seal adjustment is not necessary in this case to achieve the underiying purpose of the rule.
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7 IV.
Accordingly, the Commission concludes that the licensee's proposal to perfon wal contact testing instead of Type D leakage rate between-the-seals testing on the emergency escape air lock door seals is acceptable. There is reasonable assurance that the containment leakage limiting function will be maintained.
The licensee's request cites the special circumstances of 10 CFR 50.12, Sections (a)(2)(ii) and (a)(2)(iii), as the basis for the exemption. Appendix J to 10 CFR Part 50 requires full pressure tests following air lock door openings. The licensee stated that the proposed altamate seal contact verification check will ensure that the air lock doors are sealing property. The licensee also stated that the only viable attemative to the proposed exemption would be to perform an air lock retrofit that would involve a significant cost to the licensee. The Commission concludes that the special circumstances of 10 CFR 50.12(a)(2)(li) are present in that application of the regulation in these particular circumstances is not necessary to achieve the undertying purpose of the rule.
V.
Accordingly, the Commission has determined, pursuant to 10 CFR 50.12(a), that this exemption is authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common defense and security. The Commission further determines that special circumstances as provided in 10 CFR 50.12(a)(2)(ii) are present justifying the exemption.
Theiefore, the Commission hereby grants the exemption from 10 CFR Part 50 Aprndix J, Option A, Sections Ill.D.2.(b)(ii) and lil.D.2 (b)(iii), to the extent that leakage rate testing is not necessary after opening the emergent;y escape air lock doors for post-test restoration or post-test adjustment of the airlock door heals.
. Pursuant to 10 CFR 51.32, the Commission has determined that the granting of this exemption will not have a significant effect on the quality of the human environraent (62 FR 34720).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 3kh day of Septaber 1997, FOR THE NUCLEAR REGULATORY COMMISSION ORIGINAL SIGNED BY-l l
Frank J. Miraglia, Acting Director.
- Oft:N of Nuclear Reactor Reguiation f
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