ML20024H422
| ML20024H422 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 05/24/1991 |
| From: | Creel G BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20024H423 | List: |
| References | |
| NUDOCS 9106030341 | |
| Download: ML20024H422 (5) | |
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DALTIMORE GAS AND ELECTRIC CHARLES CENTER e P.O. BOX 1475
- BALTIMORE, MARYLAND 21203 1475 Gtonot C Cntet C,$",'lf,',l',
May 24,1991 l3CsiJfD de85 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50 318 pcense Amendment Request: containment Irakage Testing REFERENCES.
(a)
ANSI N45.41972," Leakage Rate Testing of Containment Structures for Nuclear Reactors," dated March 16,1972 l
l (b)
ANSI /ANS 56.8-1987, " Containment System lxakage Testing l
Requirements," dated January 20,1987 (c) 53FR45890,10 CFR Part 50, Alte native Method of lxakage Rate Testing, dated November 15,1988 Gentlemen:
(
The Baltimore Gas and Electric Company (13G&E) hereby requests an Amendment to its Operating 1.icense Nos. DPR 53 and DPR-69 for Calvert Cliffs Unit Nos.1 & 2, respectively, with the submittal of proposed changes to the Technical Specifications.
JH:SCRilTION:
The proposed amendment would revise the Technical Specification for both Un;ts 1 and 2 to allow the use of the Mass Point method for conducting containment integrated leak rate tests and revise the required schedule for conducting such tests in accordance with 10 CFR Part 50, Appendix J.
RI:OUESTEI) CII ANG E-Change pages 3/4 6-2 of the Unit I and Unit 2 Technical Specifications to delete the reference to ANSI N45.41972 and revise the Type A leak rate testing schedule as shown on the marked-up pages attached to this transmittal.
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Document ControlI esk
' hiay 24,1991 Page 2 IIACKGIM)UNil:
Calvert Clif fs Nuclear Power Plant (CCNPP) Technical Specification Surveillance llequirement 4Al.2 (Containment lxakage) currently requires the exclusive use of ANSI N45.51972 to determine containment leakage rates. This standard provides two acceptable methods of Containment Integrated lxakage Itate Tening (Cil.itT) calculations. The first method, Point.to.
Point, is suited for uninsulated containments where atmospheric stability is alfected by outside diurnal changes. The second method, To'.at Time, is appropriate for insulated containments (e.g.,
concrete) that are unaffected by diurnal enanges. This method, used by CCNPP, calculates a series of leakage rates based on most recera data and the data taken at the start of the test. Each successive calculated leakage rate is ihmefore bawd on a longer period of time. The hourly leakage rate is determined by applying a lim r,r least square fit to the calculated leakage rates at each time point.
Technical Specification 4 6.1.2 also requires that three Cll.itTs be conducted at 40110 month intervals during each to year senice period. Ilowever, Calvert Clif fs is on a 24 month fuel cycle which does not allow meeting both this surveillance intenal and the interval required by 10 Cirit Pari 50, Appendix J.
SAfl!!Y ANAllSISLlUNTIFICATIOS:
Advances in leakage rate testing subsequent to the issuance of both ANSI N45.4 and our Technical Specifications have provided a newer method of evaluating test data called the hlass Point method.
The hiass Point method is described in ANSI /ANS 56A19S711(cference (b)l, and is considered to be an acceptable method of determining containment integrated leakage rates. The hiass Point method involves calculating the containment air mass at dif ferent times by application of the ideal Gas 1.aw. The data is then analy/ed by the method of linear least squares. The slope of this line represents the rate of change of air mass with respect to time, which is the leakage rate.
The Nuclear llegulatory Commission has amended 10 CI11 Part 50, Appendix J, 'Trimary Containment lxakage Testing for Water-Cooled Power iteactors" to explicitly permit the use of the hiass Point statistical data analysis method liteference (c)] alter recogniting the biass Point method as an improved alternative method of calculating containment integrated leakage rates. 13G & E proposes to revise the Technical Specification to delete the reference to ANSI N45.4 which precludes the use of this approved testing method.
10 Cllt Part 50, Appendix J also requires that the Type A test of the containment be performed periodically. These tests are to be scheduled as a set of three tests, at approximately equal in'ervals, during each 10 year service period, with the third test to coincide with the 10 year inservice inspections. Currently, the Calvert Clif fs Surveillance llequirement schedule requires the Type A tests to be conducted at 40i10 month intervals during each ten year senice period. This '13 required schedule is readily adaptable for 12 and 18 month fuel cycles. Ilowever, a.'4 month fuel cycle does not provide for three tests within a 10 year service period with 40110 months between each test. In a 24 month fuel cycle, the tests must be conduc'ed every other refueling outage to be within the 30 to 50 month range allowed; however, this would require a minimum of 12 years to conduct the required set of three tests. IlG&li proposes to revise the Technical SpeciGeation to match the wording of to CI:lt Part 50, Appendix J. which requires only that the tests be conducted "at approximately equal intervals" during the 10 year senice period. Typically, this would result in test being conducted at intervals of four years, four years and two years over a ten year period.
Document Control Desk hiay 24,1991 Page 3 I)lst'EltMINATION OI.'filGNil'ICANT II AZ All1)F.:
This proposed change has been evaluated against the standards in 10 CFR Part 50.92 ar," 'as been determined to involve no signiGeant hazards considerations, in that operation of the
. "y in t.ecordance with the proposed amendment:
(1)
IVould not involve a significant increase in the probability or consequences of n accidentpreviously evaluated.
The proposed chrac to Surveillance Requirement 4.6.1.2 will only delete reference to ANSI N45.4-
. A Confermance with Appendix J to 10 CFR Part 50 will still be required. Appendix J presently allows Containment Integrated Leakage Rate Test (CILRT) aralysis methods in accordance with ANSI N45.41972, as well as the hiass Point method described in ANSI /ANS 56.8-1987 (when used with at least a 24-hour duration).
The proposed change allows the use of an improved alternative method of evaluating CILRT data. The hiass Point method is recognized to be a more reliable method a verifying that the leakage from the containment is maintained within acceptab!c limits. Therefore, the assessment of containment integrity through integrated leak rate testing is enhanced. As such, the consequences of previcusly evaluated accidents are not impacted. Since the change would only affect the allowed techniques for surveillance testing, there will be no increase in the probability of accidents previously evaluated.
The proposed change to the schedule provides only flexibility in meeting the same requirement for three tests in ten years. The additional flexibility is needed due to the M month fuel cycle currently being used. Since the testing type and bases are not changed, the probability and consequences of previously evaluated accidents are not significantly increased.
(2)
IVo dd not create the possibility of a new or different ',,pe of accident from any accident previously evaluated.
The technique uwd to calculMe leakage rates in itself is not considered to be an initiator of any accidents, tranu:nts, incidents or events. The proposed change to the schedule only provides Dexibility in meeting the same requirement for three tests in ten years. The testmg type and bases are not changed. Therefore, these proposed changes will not create the possibility of a new or different type of accident from any previously evaluated.
(3)
IVould not invowe a significant reduction in a margn of safe *y, Should use cf the hiass Point method be allowed, an enhanced determination of containment leakage through CILRT is available. As such, the confidence level of containment i stegrity would also be enhanced. The Technical Specification Bases indicated ont, that "the surveillance testing for measuring leakage lates are consistent with the.quirements of Appendix J to 10 CFR Part 50." The proposed change to the schedule only provides flexibility in meeting the same requirement for three tests in ten years. The testing type and bases are not changed. Both changes would cominue to provide for testing that is consistent with the requirement of Appendix J.
Therefore, this change does not adversely impact the margin of safety.
~
t Document Control Desk May 24,1991 Page 4 SCIIEI)UI.li:
We reouest approval of this change by September 30,1991, to allow time for appropriate planning of the next refueling outage. Ilowever, issuance of this amendment has not been identified as having an impact on plant operation or outage completion.
SAFisIY COMMl'ITEE HlWilM:
These proposed changes to the Technical Specifications and our determination of significant hazards have been reviewed by our Plant Operations and Safety Review Committee and 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 yot 7
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STATE OF MARYLAND t t
TO WIT COUNTY OF CALVERT t
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I hereby certify that on the 8 day of
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,19 9/, before me, the subscriber, a Notary Public of the State of Maryland in and' for (L.7Ter/ dowth/
personally appeared George C. Cicel, being duly sworn, and states that he is Vice Picsident of the Baltimore Gas and Electric Company, a corporation of the State of Maryland; that he provides the foregoing information for the purposes therein set forth; that the statements made are true and correct to the best of his knowledge, information, and be!ief; and that he was authoriecd to provide the information on behalf of said Corporation.
WITNESS my lland and Notarial Scal:
Nic 6
Notary Public My C(.mmission Expires:
a44/ h,[fk Dfe GCC/ERGidim Attachment
- Document Control Desk
.May 24,1991 Page 5 cc:
D. A.13 rune, Esquire J. E. Silberg, Esquire R. A. Capra, NRC D. G. Mcdonald, Jr., NRC T. T. Martin, NRC L F. Nicholson, NRC R. I.- McLean, DNR J.11.. Walter, PSC i
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