ML20086G276
| ML20086G276 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/27/1991 |
| From: | Creel G BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20086G279 | List: |
| References | |
| GL-91-04, GL-91-4, NUDOCS 9112050008 | |
| Download: ML20086G276 (8) | |
Text
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, 13 ALT IM ORl" GAS AND E L E C T Fil C 10!,0 CALVERT CUf FS PARKWAY e LUSBY, MARYLAND 20657 4702 Gronar C CHE" November 27,1991 vice nt eitot Nvet t ast twt a,ov (460)#60 44%&
U. S. Nuclear Regulatory Commission Washington, DC 20555 A'lTENTION: Document Control Desk SUlijECT: Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50 317 & 50-318 Request for License Amendment and Exemption from 10 Cllt Part 50, Arpendix J
REFERENCE:
(a) Generic letter 91-04 " Changes in Technical Speci0 cation Surveillance Intervals to Accommodate a 24-Month Fuel Cycle,"
dated April 2,1991 Gentlemen:
The Baltimore Gas and Electric Company hereby requests an Amendment to its Operating License No . DPR.53 and DPR-69 and an exemption from the requirements of 10 CFR Part 50, Appendix J, for Calvert Cliffs Unit Nos. I and 2, respectively, with the submittal of these proposed changes to the Technical Specifications.
- 1. REOUEST FOR AMENDMENT 1)ESCRIPTION The proposed amendment would revise the Technical Specifications for both Units 1 and 2 to decrease the allowable leakage rate limits for Type Il and C containment penetrations, and allow a proportionate increase in the surveillance mtervals for the leakage rate testing. The increase in surveillance intervals is needed to improve coordination of the leakage rate testing schedule with the 24-month refueling outage schedule currently being utilized at Calvert Cliffs. The am:ndment would also require approval of an exemption to 10 CFR Part 50, Appendix J, to allow the surveillance intervals to exceed 24 months. Such an exemption is requested in Section 11 of this submittal. Both the license amendment request an/ the exemption request is made in accordance with the guidance provided in Generic letter 91-04.
g kilMEGROUND
. h )b Calvert Cliffs Technical Specifications require kwal leak rate testing (LLRT) o containment penetrations m accordance with 10 CFR Part 50, Appendix J. These requirements r
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, Document Control Desk November 27,1991 Page 2 include totalleakage rate limits and a schedule for conducting the tests. The schedule requirements provide for testing on intervals of "no greater than 24 months." lhwever, Calvert Cliffs is utilizing a 24 month fuel cycle which routinely requires an additional mid-cycle outage to complete LLRTs within their required schedule.
Generic letter 9144 (Reference a) recognized that many standard technical specification surveillance intervals do not accommodate a 24. month fuel cycle and provided generic guidance for preparing license amendment and exemption requests to extend these surveillance intervals. One particular type of surveillance discussed in the generic letter was local leak rate testing of containment penetrations. Enclosure 3 to Generic Letter 91-04 provided specific guidance on information needed to support an exemption to Appendix J of to CFR Part 50 to accommodate a
- 24. month fuel cycle. This enclosure indicated that two issues should be addressed to justify such a request: (1) the margin to the allowable leakage rate limit, and (2) the basis for concluding that the containment leakage rate would be maintained within the acceptable limits.
Generic Letter 9104 also indiated that the NRC staff is developing changes to AppendixJ to 10 CFR Part 50 to accommdate a 24 month fuel cycle and to resolve other problems with the regulation. The requested T(thnical Specification change and exemption are, therefore, expected to be temporary, in that they would provide an acceptable basis for testing intervals beyond 24 months until the regulations are revbed and other acceptable bases arc established.
RI?OUESTED CIIANGE Change Specification 3/4.6.1.2 of the Unit 1 and Unit 2 Technical Specifications as shown on the marked.up pages attached to this transmittal. Rese changes include a reduction in the allowable ambined leakage rate for Type H and C tests, an increase in the surveillance intervah, and corresponding revisions to the Bases. Also included are a minor administrative revision to the Action statement to correspond more closely with the current Combustion Engineering Standard Technical Specifications (NUREG.0212), and an administrative revision to remove notes which are no longer applicable, fMFisIY ANAINSES! JUSTIFICATION 10 CFR Part 50, Appendix J, identifies a maximum allowable leakage rate, Lp at the calculated peak containment internal pressure related to the design basis accident. This maximum allowable lea tage rate is used as the input assumption in dose consequence calculations for design basis accidents. An overall, or integrated, containment leakage rate limit has been specified as 0.75La to provide a margin for increase of the leakage rate during the operating cycle, nis integrated leakage rate is
,eriodically verified through a Type A leak test. Similarly, a combined containment penetrations cakage rate limit has been specified as 0.60La to provide a margin for increase of the leakage rates of the individual penetrations during the operating cycle, His combined penetrations leakage limit is periodically verified through performance of Type B and Type C leak tests and a direct summation of their results, ne specified leakage rate limit of 0.60La provides a 0.40 La margin between the specified leakage limit and the maximum allowable leakage limit, La, which is used in accident dose calculations. Reducing the specified leakage limit to 0.50L aincreases this margin by 25 percent.
The proposed revision would also increase the maximum allowable surveillance interval from 24 months to 30 mor,ths by removing the "no greater than" restriction on the current 24-month surveillance interval. Removal of the restriction would allow application of Specification 4.0.2 which
. Document Control Desk November 27,1991 page 3 provides for a maximum allowable extension of 25 percent of the specified surveillance inten al. 'this merease in the maximum allowable surveillance mterval is the same as the proposed increase in maigin between the specified leakage limit and the maximum allowable leakage limit and would preserve the bases for this margin.
Many of the containment penetration leak rate tests must be conducted during shutdown since the test requires removing from senice the system which utilizes the penetration and also requires significant manpower within the containment. Ily allowing the standard extension of the surveillance interval, considerable flexibility is provided for scheduling refueling outages. Without the requested Dexibility, refueling outages could be scheduled at no more than 24 month intervals. A short, unplanned outage during an ex,ected 24-month fuel cycle would then result in an additional outage tc. perform the penetration lea c testing on the required schedule, or would result in an early entry into the refue!ing outage without complete fuel utilitation. Additional outages result in additional shutdown and startup transients and cycles for plant equipment. Therefore, removing the need for these additional outages would improve the overallsafety of the plant.
Approximately twenty localleak rate tests have been performed for both Unit 1 (11 tests) and Unit 2 (9 tests) at Calvert Cliffs. Of these, three have identilis d as found leakage rates in excess of the maximum allowable leak. ige rate,aL . 'lhe largest of these occurred in 1979 on Unit I and was approximately six times La. Another failure of approximately 1.6 times Lp occurred on Unit 1 in 1986, and the single Unit 2 failure of approximately 2.9 times La occursed m 1989. Except for one occasion (see Licensee Event Report 82-22), as.left leakage rate data for Type B and C tests for Calvert Cliffs Units 1 and 2 have been only a small fraction of ths 160La. For instance, a recent combined Type B and C test total for Unit I was approxirnately 38,(KM) seem and Unit 2 was approximately 31,(XX) secm. These ' totals represent less than 20 percent of the specified allowable leakage of 0.60La, or 207,600 scem. Further, trending of leakage rates for the Type B and C penetrations at Calvert Cliffs projects that, over a 30-month surveillance interval, the leakage rates would still be well within the maximum allowable leakage rate, La-Prior to trending the leakage rates, data from the past testing of penetrations was reviewed to determine if the causes of the leakage were recurring m nature (and trendabic) or if the causes were random and non recurring. Both types ofleakage were considered in the evaluation of this proposed change. The trendable leakage is addressed in the following paragraphs. The random, non. recurring leakage events were evaluated on a risk basis. For these events, high individual penetration leakage rates are reviewed to identify the cause, and corrective actions are taken, as appropriate, on the individual penetration and any similar penetrations. The corrective actions are chosen to both reduce the individual penetration leakage as well as to minimite the probability of recurrence of high leakage due to the same cause. Although leakage due to random, non. recurring causes win continue to occur with some probability, the leakage rate failures at Calvert Cliffs have been in the 'small" leakage event category as discussed in NUREG 1273, Technicalfindines and Rgrulatory @alysis for Generic Safety issue ILE 4.3. " Containment integrity Check" . Further, the risk associated with the possible increase in leakage rate due to these causes is considered not significant as discussed in NUREG/CR 3539, Jmnact of Containment Building 1.cahage on LWR Accident Risl i7, One projection of the trendable leakage rate at the end of a 30-month surveillance period was performed considering the leakage rate increase on a monthly basis for all past surveillance intervals.
8 As discussed in Section 2,
- Containment isolation Operational llistory," pages 2 and 3.
2 As discussed in Section 5,
- Conclusions,* page 10.
Dhument Control Desk November 27,1991 ;
Page 4 All surveillance intervals were used in this analysis to maximize the available data base. 'the suncillarwe interval leakage rate increases were then averaged to get an historical leakage rate !
increase per month. 'this increase per rnonth was used to determine a projected total leakage increase occurring over a 30 month suncillance interval. Consenatively beginning with an as left leakage at the proposed limit, 0.50L , the projected leakage rate at the end of a 30-month ,
surveillance interval would still be well t"clow the maxirnum allowable leakage limit, La- !
Another analysis comisted of plotting the trendable leakage rates over tirne. An interpolation of the five rnost recent time dependent as found leakage rates provided a rate of increase of the leakage rate on a per month basis. An extrapolation of that rate was then used to project an expected leakage rate 30 months from the last testing. 'Ihc total time-dependent as found leakage rates for both Unit I and Unit 2 were projected to be signincantly less than the maximum allowable leakage rates, La, after a maximum 30 month surveillance interval.
ASME Section XI, Article IWV-3(XX) indicates that three data points are required to trend leakage, llowever, the five most recent leakage rates for each unit were used in the latter analysis. 'Ihc methods used for maintenance and leakage testing on penetrations and isolation valves during the periods covered by thesc Ove tests are considered to be representative of the current methods, and would therefore be expected to provide appropriate data for projecting trends. Projections using this same rate increase from either the last as-left total leakage rate, or more conservatively, from the proposed specified allowable leakat;c rate,0.5La, would also result in leakage rates significantly below the maximum allowable leakage rate, La , after a maximum 30 month surveillance inten al.
IRTERMINATION OF SIGNIFICANT llAZAlti)S The proposed change has been evaluated against the standards in 10 CFR 50.92 and has been determined to not involve a significant huards consideration, in that operation of the facility in accordance with the proposed amendment:
(1) IVouki not imvhe a significant increase in the pmbability or consequences of an accident previously evaluated.
Neither containment penetrations, nor their leak rate testing processes, are considered as initiators for any accidents previously evaluated. Therefore, the probability of previously evaluated accidents would not be lacreased by this change to the operating license. ,
Since the containment leakage rate is a direct assumption of dose calculations for all design basis accidents, the requested change could potentially affect the consequences of previously evaluated accidents, llowever, the assumed maximum allowable leakage rate is not changed and must continue to be met. While the surveillance interval between leak rate testing of containment penetrations is increased, the margin between the specified allowable leakage and the maximum allowable leakage is proportionately increased to provide an equivalent margin for increase of leakage during the surveillance inerval. Therefore, the consequences of previously evaluated accidents are not significantly affected by this change.
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. Document Control Desk November 27,1991 Page 5 (2) It'ould not create the pcusibility of a new or different type of accident frvin any accident previously evaluated.
This change in suncillance intenals does not affect the design or function of any equipment, nor the operation of such equipment. Therefore, the pioposed change does not create the possibility of a new or different type of accident from any accident previously evaluated.
(3) It'ould not involve a significant reduction in a margin of safety.
A significant margin, 0.40 L a, is provided between the specified allowable containment penetration leakage rate limits and the maximum allowable leakage rate limit which is used as the assumed containment leakage rate in accident dose calculations. His change would increase this margin by 25 percent to match the 25 percent increase in the surveillance interval. Therefore, the proposed change does not involve a significant reduction in a margin of safety.
II, JEQUERT FOR ILXEMPTION DISCUSSION AND JUSTIFIG'llON 10 CFR Part 50, Appendix J, paragraphs Ill.D.2 and Ill.D.3 require that 'Iype 11 and C containment penetration leak rate testing be performed at intervals no greater than two years. Each of these tests are also intended to be performed during reactor shutdowns for refueling. Ilowever, Calvert Cliffs is utilizing core designs which allow the intervals between reactor shutdowns for refueling to exceed the maximum allowable two year intcival. This use of new extes;ded-cycle core designs has been recognized as a growing trend to the industry by the Nuclear Regulatory Commission as discussed in Generic Letter 91-04, and guidance was provided therein for requesting an exemption to this regulation.
Generic Letter 91-04 also indicated that the NRC staff is developing changes to Appendix J to 10CFR Part 50 to accommodate a 24. month fuel cycle and to resolve other problems with the regulation. The requested Technical Specification change and exemption arc, therefore, expected to be temporary, in that they would provide an acceptable basis for testing intervals beyond 24 months until the regulations are revised and other acceptable bases are established.
- 10 CFR 50.12 allon the Commission to grant exemptions from the rec uirements of regulation contained in 10 CFR Part 50 provided that: (1) the exemption is aut aorized by law; (2) the exemption will not present an undue risk to the public health and safety; (3) the exemption is consistent with the common defense and security; and (4) special circumstances, as defined in 10 CFR 50.12(a)(2), are present. Each of these criteria are discussed below.
- 1. The Requested Exemntion is Authorized by Law Similar schedule exemptions have been granted on an individual penetration basis for other facilitics and for Calvert Cliffs. Therefore, the Commission is authorized by law to grant this exemption.
. Document Control Desk November 27,1991 Page 6
- 2. The Requested themption Does Not Present an Undue Risk to the Public Ilealttuind Safety The schedule exemption is compensated for by a proportionate increase in the margin between the specified allowable leakage and the rnaximum allowable leakage. Therefore, the requested exemption does not present an undue risk to the public heahh and safety.
- 3. The Requested Ihemntion Will Notfndanger the Common Defense add Sectgily Containment penetration leak rate ter. ting is not considered in the common defense and security of the nation. Therefore, this exemption will not impact the common defense and security.
- 4. Special Circumstances >re_ Present 10 CFR 50.12(a)(2) indicates that special chcumstances include conditions under which compliance would result in hardship or other costs that are significantly in excess of those i contemplated when the regulation was adopted. When the regulation was adopted, a 1
presucption was made that a two year test interval would casily accommodate performance of these tests durin ; a refueling outage. Ilowever, the development of new core designs have resulted in fuel cyc es of 24 months (or longer when there are unplanned outages during the cycle), and Calvert Cliffs is utille.ing this improved core design and lengthened fuel cycle.
Calvert Cliffs has been meeting the schedular requirements through the use of additional mid-cycle outages which requires additional outage time and significant cost beyond that intended by the regulation.1herefore, special circumstances are present.
ENVIRONMENTAI, IMPACI' This schedular exemption would not result in the modification of any plant structures, systems or components. Neither would it result in a change in the way plant systems are operated. The requested exemption involves an administratively controlled surveillance test program and does not represent any increase in the maximum allowable routine or postulated post accident releases of radioactive material to the environment or occup41onal exposures. Therefore, the environment would not be adversely impacted.
Ill. SCIIEDUI.E This change is requested to be ap 3 roved and issued by February 6,1992. Issuance of this amendment on this schedule would remove tl1e need for a forced outage beginning February 28,1992, prior to the next refueling outage scheduled to begin March 6,1992.
. Document Control Desk November 27,1WI
! Page 7 SAflTlY COhlhilllLlLilllllM These proposed changes to the Technical Specifications, our determination of significant hazards and the exem ation request have been reviewed by our Plant Operations and Safety Review Committee ant Off-Site Safety Review Committee, and they have concluded that implementation of these changes will not result in an undue risk to the health and safety of the public.
Very truly yours, r; e jj p /
STATE OF MARYLAND 1 TO WIT COUNTY OF CALVERT I hereby certify that on the 37* day of [)om /W ,191, before me, the subscriber, m ho r hn/
a Notary Public of the State of Mai) land in and for personally appeared George C. Creel, being duly sworn, and states that he is Vice President of the llattimore Oas and Electric Company, a corporation of the State of Maryland; that he provides the foregoing infortnation for the purposes therein set forth; that the statements made are true and correct to the best of his knowledge, information, and belief; and that he was authorized to provide the information on behalf of said Corporation.
WITNESS my lland and Notarial Seah ['A' C L U b-Nn 4 - k Notary Public My Ccr mission Expires: / <2 ! a .1 w '
W*
, Date GCC/ERO/crgdlm Attachment i
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. Document Control Desk November 27,1991 i
. Page 8 cc: D. A.11 rune,lhquire J.11. Silberg. Ihquire #
R. A. Capra, NRC i D. O. Mcdonald, Jr., NRC T. T. Martin, NRC L II. Nicholson, NRC i
R.1. Mclean, DNR J.11. Walter, PSC i
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