ML17059A001
| ML17059A001 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 08/11/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17058B895 | List: |
| References | |
| NUDOCS 9309020128 | |
| Download: ML17059A001 (10) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055&4001 ENCLOSURE 2
SAFETY EVALUATIO BY THE OFFICE OF NUCLEAR REACTOR REGULATIO SCHEDUL R EXEMPTION FROH APPENDIX J INTERVAL FOR TYPE B
EAK RATE TESTING OF FOUR CONTAINMENT PENETRATIONS NIAGARA MOHAWK POWER CORPORA ION NINE MILE POINT NUCLEAR STATION UNIT 2 DOCKET NO. 50-410
- 1. 0 INTRODUCTION By letter dated Hay 28,
- 1993, Niagara Mohawk Power Corporation (NHPC) requested a schedular exemption pursuant to 10 CFR 50. 12(a) from the requirements of 10 CFR 50, Appendix J;Section III.B, for Nine Mile Point Nuclear Station, Unit 2 (NHP-2).
NMPC requested temporary relief from the requirement to perform Type B local leak tests (LLRTs) at intervals of no greater than 2 years for the expansion bellows in four Traversing Incore Probe (TIP) containment penetrations (2NMT*Z31A, C, D,
and E).
A one-time only delay, until the end of the 1993 refueling outage (currently scheduled to begin on October 1,
1993) was requested for the performance of these leak tests.
This request was necessitated to avoid a plant shutdown solely to perform the required leak tests.
- 2. 0 EVALUATION Appendix J of 10 CFR Part 50 requires Type B testing of the expansion bellows in the four subject TIP containment penetrations at intervals no greater than every 2 years to demonstrate the integrity of the NHP-2 containment.
The TIP penetrations are listed in the NMP-2 Updated Safety Analysis Report (USAR).
Table 6.2-56 with Note 34 applicable.
Note 34 states, "The metal bellows at the end of the TIP system drywell penetration flanges will be included in Type A testing.
The flanges themselves and the midspan flange in 2NHT*Z31B will be subject to Type B testing."
On April 23, 1993, the licensee determined that the bellows in the four subject penetrations were not in compliance with the requirements of 10 CFR Part 50, Appendix J, in that these bellows had been Type A tested rather than the required Type B tested.
Further investigation by the licensee determined that this noncompliance (Type A testing versus Type B testing) has existed since issuance of the facility operating license on October 31, 1986.
Note 34 was added to USAR Table 6.2-56 by the licensee via Licensing Document Change Notice (LDCN) 01458, dated November 29, 1984;
- however, no justification or backup data could be located to substantiate the addition of Note 34 or to indicate NRC approval of Type A testings.
When LDCN 01458 was issued in 1984, 9309020428 9308iI i
PDR ADQCK 05000410
the licensee had no method for performing Type 8 tests of these bellows.
Such methods are now available.
The Final Safety Analysis Report was subsequently interpreted by the licensee to imply that a Type A test only was acceptable for testing these bellows.
The maximum allowable overall containment leakage rate (L,) is limited by TS 3.6. 1.2 to l. 1 weight percent of containment air per day at the peak accident pressure of 39.75 psig during Type A tests.
The maximum allowable combined leakage from all penetrations subject to Type 8 and Type C tests is limited to 0.6 L.
The most recent Type A test performed in January 1991 measured the overall containment leakage to be 0.305 percent per day.
This value includes the TIP penetrations as well as the other Type 8 and Type C leakage paths.
The combined Type 8 and Type C leakage was 0.211 percent per day.
The unaccounted leakage of 0.094 percent per day is attributed to the containment liner, TIP penetrations, etc.
Therefore, even if all the unaccountable leakage was associated with the TIP penetrations, the combined leakage of TIP penetrations and that measured from the other Type 8 and Type C penetrations would still be less than the allowable leakage of 0.6 L, or 0.66 percent per day.
The metal expansion bellows are provided to absorb the relative movements between the primary and secondary containment that result from seismic, loss-of-coolant accidents, and suppression pool hydrodynamic events.
Under normal operating conditions, these differential movements are very small.
These bellows have not been exposed to the more frequent large movements and vibrations to which a process piping penetration may be exposed.
For this
- reason, these bellows have not been subjected to the level of degradation that a more active bellows might experience due to fatigue of the metallic convolutions.
Additionally, visual examinations conducted during April 1993 did not show any visible degradation.
Therefore, since the January 1991 Type A test demonstrated that the subject TIP penetrations were not leaking excessively and since there is no evidence of any subsequent degradation, the NRC staff has concluded that Type 8 testing of these penetrations is not necessary at this time to demonstrate the integrity of the NMP-2 containment.
Type 8 testing of the TIP containment penetrations requires entry into the drywell.
The drywell is inaccessible during reactor operations since it is inerted and contains a nitrogen atmosphere.
Access into the drywell requires a reactor shutdown and deinerting of the drywell.
Therefore, the NRC staff has concluded that a reactor shutdown and deinerting of the drywell solely to perform Type 8 testing of the subject penetrations would result in an unnecessary and undue hardship on the licensee.
The exemption provides only temporary relief from the requirements to perform Type 8 tests at least every 2 years since the exemption will expire at the end of the 1993 refueling outage.
0 3.0 CONCLUS 0 Based on the above evaluation, the NRC staff finds the requested schedular exemption, to delay performance of Type B testing of four TIP containment penetrations until the 1993 refueling outage, to be acceptable.
The exemption will expire at the end of the 1993 refueling outage.
Principal Contributor:
Donald S.
Brinkman Date:
hueust 11, 1993
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increased confidence in containment integrity following successful testing is not significant enough to justify a plant outage solely to perform the tests prior to the 1993 refueling outage.
A plant shut down solely to perform the required test would be an undue hardship.
The licensee has presented information accepted by the Commission, which'ives a high degree of confidence that the components affected by this exemption will not degrade to an unacceptable extent.
The details of the NRC staff's review of the licensee's exemption request are discussed in a safety evaluation dated Aogggt. 'Q
] 993 Acceptabl e 1 eakage 1 imits are defined in Section III. B.3 (a) of Appendix J to 10 CFR Part 50.
Pursuant to 10 CFR 51.32, the Commission has determined that granting this Exemption will not have a significant impact on the environment (58 FR 37759).
This Exemption is effective upon issuance and shall expire at the end of the 1993 refueling outage which is currently scheduled to begin on October 1,
1993.
FOR THE NUCLEAR REGULATORY COMMISSION Original sipned, by:
Steven A. Varga, Director Division of Reactor Projects I/II Office of Nuclear Reactor Regulation Dated at Rockville, Maryland, this U.day of AUWIst 1993
- See revious concurrence DATE PDI-1:LA CVo an (4
'tI/ 5/93 PDI-1:PH DBrinkman:avl g /~/93 PDI-1 PH JHennin ) ~
(. /93 SCSB*
RBarrett 07/21/93 OGC*
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PE S ]0 93 DATE OFFICIAL RECORD COPY
/o 93 93 FILENAME:
. NHP2iNH286683. EXE
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Hr. B. Ralph Sylvia August 11, 1993 Copies of the Exemption and the NRC staff's supporting safety evaluation are enclosed.
The Exemption has been'forwarded to the Office of the, Federal Register for publication.
Sincerely, Original signed by:
Enclosure:
1.
Exemption 2.
Safety Evaluation cc w/enclosures:
See next page Robert A. Capra, Director Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation DISTRIBUTION:
Docket File NRC & Local PDRs PDI-1 Reading THurley/FMiragl ia, 12/G/18
- JPartlow, 12/G/18
- ERossi, 9/A/2 JLieberman, 7/H/5 SVarga JCalvo RACapra CVogan JMenning DBrinkman OGC
- EJordan, MNBB 3701 GHill (2)
ACRS (10)
OPA SECY (Orders only)
OC/LFDCB
- VMcCree, 17/G/21
- RBarrett, 8/H/7
- See revious concurrence OFFICE PDI-1:LA PDI-1 PH PDI-1:PH
- SCSB
- OGC NAHE DATE CVo an W DBrinkman:avl S'/~AS 8/s g3 JMennin '
RBarrett 07/21/93 CMarco 07/27/93 OFFICE NANE DATE PDI-1'D RACa ra
@93 ADRI JCalvo
/d 93 D:
E 93 OFFICIAL RECORD COPY FILENAME: G: iNMP2iNM286683. EXE
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