ML20141E072
| ML20141E072 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 05/09/1997 |
| From: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20141E077 | List: |
| References | |
| NUDOCS 9705200301 | |
| Download: ML20141E072 (9) | |
Text
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.w 10 CFR 50.90
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PECO NUCLEAR eeco toe <ov cemneev 965 Chesterbrook Boulevard i
A Unit of PECO Energy Wayne, PA 19087-5091 May 9,1997
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Docket Nos. 50-277 50-278 License Nos. DPR-44 i
i DPR-56 I
U.S. Nuclear Regulatory Commission Attn: Document Control Desk i
Washington, DC 20555 1
Subject Peach Bottom Atomic Power Station, Units 2 and 3 License Changa Application ECR 96-00982 i.
i
Dear Sir:
3 PECO Energy Company (PECO Energy) hereby submits License Change
- Application ECR 96-00982, in accordance with 10 CFR 50.90, requesting a i
change to the Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3 Facility Operating Licenses. This proposed change will revise Technical Specifications (TS) Surveillance Requirement 3.6.1. 3.16 concerning the l
replacement frequency of the Primary Containment purge and exhaust valve l
inflatable seals.
i information supporting this request is contained in Attachment 1 to this letter, and the marked up pages showing the proposed changes to the PBAPS, Units 2 j
and 3 TS and Bases are contained in Attachment 2. We request that this i
amendment to the PBAPS, Units 2 and 3 TS be approved by August 1,1997 in 4
order to avoid the costs associated with replacing the purge and exhaust valve l
inflatable seals during the upcoming Peach Bottom Atomic Power Station, Unit 3 refueling outage.
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If you have any questions, please do not hesitate to contact us.
I Very truly yours,
. N.
G. A. Hunger, Jr.
Director-Licensing g#
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Enclosures:
Affidavit, Attachment 1, Attachment 2 I
cc:
H. J. Miller, Administrator, Region I, USNRC 1
W. L. Schmidt, USNRC Senior Resident inspector, PBAPS o n fiOT7
. R. Janati, Commonwealth of Pennsylvania R
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- COMMONWEALTH OF PENNSYLVANIA:
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l COUNTY OF CHESTER J. B. Cotton, being first duly sworn, deposes and says:
That he is Vice President of PECO Energy Company; the Applicant herein; that he has read the attached License Change Application ECR 96-00982, for Peach Bottom Facility Operating Licenses DPR-44 and DPR-56, and knows the contents I
thereof; and that the statements and matters set forth therein are true and correct to the '
best of his knowledge, information and belief.
d*~-/$ /
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f Vice President
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Subscribed and sworn to nh before me this 7 day of
/Jr 1997.
6 k i A ekL Notary ublic m_
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t ATTACHMENT 1 PEACH BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 Docket Nos. 50-277 50-278 i
License Nos. DPR-44 DPR-56 I
LICENSE CHANGE APPLICATION ECR 96-00982 i
" Replacement Frequency of the Primary Containment Purge and Exhaust Valve inflatable Seals" Supporting information - 5 Pages i
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1 Docket Nos. 50-277 i*-
50-278 1
License Nos. DPR-44 i
DPR-56 i
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j introduction e
i PECO Energy Company, Licensee under Facility Operating Licenses DPR-44 and DPR-56 for the Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3, requests i
that the Technical Specifications (TS) contained in Appendix A to the Operating License be amended to revise Surveillance Requirement (SR) 3.6.1.3.16 and the associated Bases, to reflect changes in requirements for the replacement frequency of i
the Primary Containment purge and exhaust valve inflatable seals. The TS and Bases pages showing the proposed changes are contained in Attachment 2. This License i
Change Application provides a discussion and description of the proposed TS changes, a safety assessment of the proposed TS changes, information supporting a i
finding of No Significant Hazards Ccasideration and information supporting an l
Environraental Assessment.
Discussion and Description of the Proposed Chance I
i TS SR 3.6.1.3.16 currently requires the replacement of the inflatable seals of each 6-i inch and 18-inch Primary Containment purge valves (AO-2/3-07B-2/3505, AO-2/3-078-l 2/3519, AO-2/3-078-2/3520, & AO-2/3-07B-2/3521 A/B), and 18-inch Primary Containment exhaust valves (AO-2/3-07B-2/3506, AO-2/3-07B-2/3507, AO-2/3-078-2/3511, & AO-2/3-07B-2/3512) on a 48 month frequency. PECO Energy Company
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proposes that replacement frequency of SR 3.6.1.3.16 be revised to 96 months.
i The T-ring seal replacement requirement was incorporated into the PBAPS, Units 2 i
and 3 TS in Amendment Nos.144 and 146, dated May 8,1989. The USNRC, in the Safety Evaluation Report for Amendment Nos.144 and 146, found that the replacement I
of the seals of the purge valves every third outage in conjunction with the SGIG System was an acceptable method of ensuring leak tightness. Subsequently, the frequency j
was modified to be every second refueling outage in Amendment Nos.179 and 182, i
dated August 2,1993, due to the extension of a refueling outage from 18 months to 24 l
months. This requirement was subsequently transferred to the improved Technical j
Specifications (Amendment Nos. 210 and 214, dated August 30,1995) as a deviation from NUREG-1433, " Standard Technical Specifications, General Electric Plants, j
3 BWR/4," dated September 1992.
The propcsed change to extend the seal replacement interval would result in a reduction in radiological dose and a reduction in costs associated the maintenance and engineering necessary to perform the replacement and the associated Local Leak Rate Test (LLRT). This submittal does not propose any change to the existing requirements
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contained in the PBAPS Technical Specifications for leak testing of the Prinary l
Containment purge and exhaust valves per 10 CFR 50, Appendix J, " Primary Reactor i
Containment Leakage Testing For Water-Cooled Power Reactors." This continued
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testing will assure the leak tightness of the purge and exhaust valves, j
Safety Assessment i
As stated in the PBAPS, Units 2 and 3 Updated Final Safety Analysis Report (UFSAR) i 1
I Docktt Nos. 50-277 50-278 License Nos. DPR-44 DPR 56 (Section 5.2, " Primary Containment"), the safety objective of the Primary Containment is to contain the released steam in the event of the design basis LOCA, which will limit i
the release to the reactor building of fission products associated with this accident. In l
order to maintain this safety objective, the Primary Containment has the capability of l
being purged with nitrogen to reduce and maintain the containment atmosphere at less than 4 percent oxygen during normal operation and also to maintain control of combustible gas concentrations after a LOCA. Purging is normally performed during l
the operational modes of startup, power operation and hot shutdown for the purpose of inerting or deinerting the Primary Containment The 6-inch and 18-inch Primary Containment purge valves, and 18-inch exhaust valves are only permitted to be opened for inerting, deinerting, pressure control, ALARA or air quality considerations for I
personr'el entry, or Technical Specification Surveillances that require the valves to be open.
Purging of the Primary Containment (i.e., the Drywell and Torus) is accomplished i
through the use of exhaust fans (deinerting) which remove nitrogen from Primary i
Containment or from the Containment Atmospheric Control (CAC) liquid nitrogen tank (inerting) which supplies nitrogen to Primary Containment. Each 18-inch purge line has
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2 air operated valves which will close on a Group 3 isolation signal. Two (2) air-operated,6-inch outboard isolation valves (one per unit), are located on the discharge of the liquid nitrogen storage tank. The venting (i.e., exhausting) of Primary Containment is accomplished through two 18-inch diameter lines (one each for the.
Drywell and Torus) which exhaust to the Standby Gas Treatment System. Each vent
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line has 2 air-operated,18-inch isolation valves.
The large Primary Containment purge and exhaust isolation valves are Fisher model 9210,150# butterfly valves with an Ethylene Propylene inflatable T-ring seal. These valves are used to purge and vent the Primary Containment environment. The critical characteristics of the inflatable T-ring seal are to assure very low rates of leakage through the valve seat when the valve is closed. Following valve closure, the seal chamber is automatically pressurized, establishing a tight seal against the periphery of the closed butterfly disc enhancing the leak tightness of the valve. Failure of this seal may provide a potential atmospheric leak path to secondary containment.
l The T-ring material (Ethylene Propylene) has been found to withstand normal and accident thermal exposures for the design life of the plant based on thermal aging analysis. The elastomer seat material will provide acceptable seat tightness when exposed to a total integrated radiation dose of 10E7 rads based on information provided by EPRI in technical report NP-2129, entitled " Radiation Effects on Organic Material in Nuclear Plants." The radiation dose of 10E7 rads bounds the design basis accident dose to which these valves would be exposed. The radiation dose these valves are exposed to during normal operation is insignificant as compared to the accident dose. Based on this, radiation effects from the additional exposure resulting from the extended replacement frequency will not adversely impact the T-ring seat
- material, l
Historical investigation indicates no significant wear or degradation of the old seals t
l identified during replacement at 48 month intervals. Additionally, during previous seal replacements, seals that were visually examined by engineering and maintenance l
indicated no noticeable wear or loss of resiliency. T-ring seal performance reviews l
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Docket Nos. 50-277 50-278 l
License Nos. DPR-44 DPR-56 i
since 1986 indicate that documented failures were not due to material condition, but were mainly the result of improper installation. These valves are physically located in i
the Reactor Building in areas normally accessible during power generation. These valves typically experience non-harsh temperatures, humidities, and normal plant l
background radiation. Based on the valves application and use in a non-harsh l
environment, current requirements to replace the inflatable seals every 48 months are unduly conservative.
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Review of the PBAPS purge and exhaust valve performance history has determined i
that these valves are relatively free of valve leakage problems. Review of valve leakage test data supports this assessment. Extension of the seat replacement frequency of SR 3.6.1.3.16 is also supported by the leakage test results for valves AO-2502A and AO-3502A. These valves are the Torus to Reactor Building vacuum breaker i
i isolation valves. These are 20-inch air-operated butterfly valves of the samo series and i
design as the Primary Containment purge and exhaust valves. The Torus to Reactor i
j Building vacuum breaker isolation valves employ the same T-ring seal as the Primary Containment purge and exhaust valves. These T-rings are also replaced on a 48 month frequency and a historical review indicates that there have been no documented cases of valve leakage due to T-ring elastomer degradation.
In addition, review of Regulatory Guide 1.163, " Performance-Based Containment Leak-i Test Program" (September 1995) states the following:....."the interval for Type C tests l
for.... containment purge and vent valves in PWRs and BWRs should be limited to 30
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months....with consideration given to operating experience and safety significance."
l This revision does not propose any change to the existing requirements contained in j
the PBAPS Technical Specifications for leak testing of the Primary Containment purge
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and exhaust valves. This testing will provide confidence in the ability of these valves to perform their safety function with respect to valve leak tightness.
Information Suooortina a Findina of No Sionificant Hazards Consideration i
We have concluded that the proposed changes to the PBAPS, Units 2 and 3 TS, which i
will revise TS SR 3.6.1.3.16, do not involve a Significant Hazards Consideration. In l
support of this determination, an evaluation of each of the three (3) standards set forth in 10 CFR 50.92 is provided below.
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The orooosed TS clanoes do not involve a sianificant increase in the orobability l
or consecuences 6 an accident oreviously evaluated.
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Revising SR 3.6.1.3.16 to replace the inflatable seals for the Primary j
Containment purge and exhaust valves from every 48 months to every 96 months will not involve a significant increase in the probability or consequences i
of an accident previously evaluated. The valves will continue to be leak tight j
throughout the lifetime of the plant. This change will not result in increased
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onsite or offsite radiological dose. This change will result in reduced q-occupational dose exposure, i
f This submittal does not propose any change to the existing requirements i
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4 Docket Nos. 50-277 l_
50-278 License Nos. DPR-44 DPR-56
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contained in the PBAPS Technical Specificatior's for leak testing of the Primary Containment purge and exhaust valves por 10 Cim 50, Appendix J, " Primary Reactor Containment Leakage Testing For Watcr-Cooled Sexer Reactors."
j This continued testing will assure the leak tightness of ti.a purge and exhaust l
valves.
L The T-ring material (Ethylene Propylene) has been found to withstand nonnal and accident thermal exposures for the design life of the plant based on fnermal l
aging analysis. The elastomer seat material will provide acceptable sesi j
tightness when exposed to a total integrated radiation dose of 10E7 rads based on information provided by EPRI in technical report NP-2129, entitled j
" Radiation Effects on Organic Materie! in Nuclear Plants." The radiation dose of L
10E7 rods bounds the design bis accid 6nt dose to which these valves would j
be exposed. The radiation dose these valves are exposed to during normal i
operation is insignificant as compared to the accident dose. Based on this, radiation effects from the additional exposure resulting from the extended replacement frequency will not adversely impact the T-ring seat material.
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The orooosed TS chanoes do not create the oossibility of a new or different kind of accident from any accident previously evaluated, Revising SR 3.6.1.3.16 to replace the inflatable seals for the Primary j
Containment purge and exhaust valves from every 48 months to every 96 i
months does not create the possibility of a new or different kind of accident frorn i
any accident previously evaluated. This change does not involve any physic <
changes to a plant structure, system, or component (SSC) which could act is an j
accident initiator. The design, function, and reliability of the Primary f
Containment purge and exhaust valves are also not impacted by this change.
j This activity does not adversely influence any equipment, which is required to be j
maintained operable for the prevention or mitigation of accidents or transients.
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Furthermore, implementation of the proposed change will not adversely affect l
the manner in which plant SSC are operated.
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The orooosed TS chanoes do not involve a sianificant reduction in a marain of i
- safety, j
No margins of safety are reduced as a result of the proposed TS changes. The proposed changes do not alter the intended operation of plant structures, i
systems, or components utilized in the mitigation of accidents or transients. The l
operating experience of these valves and the testing performed in accordance with 10 CFR 50, Appendix J provides a high level of confidence in the ability of
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these valves to perform their intended safety function with respect to valve leak j
tightness.
Information Suooortina an Environmental Assessment i
An environmental assessment is not required for the proposed changes since the proposed changes conform to the criteria for " actions eligible for categorical exclusion" i
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Docket Nos. 50-277 l-50-278 l
License Nos. DPR-44 DPR-56 as specified in 10 CFR 51.22(c)(9). The proposed changes will have no impact on the environment. The proposed changes do not irivolve a significant hazards consideration as discussed in the preceding section. The proposed changes do not involve a significant change in the types or significant increase in the amounts of any effluents that may be released offsite. In addition, the proposed changes do not involve a significant increase in individual or cumulative occupational radiation exposure.
Conclusion The Plant Operations Review Committee and the Nuclear Review Board have reviewed i
this proposed change to the PBAPS, Units 2 and 3 TS and have concluded that it does not involve an unreviewed safety question, and will not endanger the health and safety of the public.
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i-ATTACHMENT 2 l
PEACH ' BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 t
Docket Nos. 50-277 50-278
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i License Nos. DPR-44 DPR-56 TECHNICAL SPECIFICATIONS CHANGES List of Attached Pages Units 2 and 3
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TS Page 3.6-16 BASES Page 3.6-30 i
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