ML20245A381
| ML20245A381 | |
| Person / Time | |
|---|---|
| Issue date: | 12/30/1986 |
| From: | Houston R Office of Nuclear Reactor Regulation |
| To: | Rossi C Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20244D710 | List:
|
| References | |
| NUDOCS 8703200450 | |
| Download: ML20245A381 (4) | |
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NUCLEAR R'EGULATORY COMMISSION j
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%..I....ol December 30, 1986 N
MEMORANDUM FOR:
C. E. Rossi, Assistant Director Division of PWR Licensing-A FROM:
R.'
W.' Houston, Deputy Director Division of BWR Licensing
SUBJECT:
PROPOSED GENERIC LETTER ON CONTAINMENT INTEGRATED LEAK RATE TEST (CILRT)
As you are aware the Division of BWR Licensing would prefer that this matter be resolved by rulemaking, either by the addition of ANSI /ANS-56.8-1981 as an alternative acceptable reference standard in Appendix J, or by accelerating the schedule for final issuance of the general revision to Appendix J that was issued for public comment on October 29, 1986.
If, however, a management decision is made to issue a generic letter, I suggest a few modifications shown as a markup of the draft transmitted by Ron Ballard on December 18, 1986, enclosed.
N R. W. Houston, Deputy Director Division of BWR Licensing
Enclosure:
As stated cc:
R. Bernero 4
F. Miraglia If; \\
1.
. Lainas L. G. Hulman l
l 57'os20045% Hw X V
l Enclosure DRAFT TO: All Light Water Reactor Applicants and Licensees
SUBJECT:
CONTAINMENT INTEGRATED LEAKAGE RATE TESTS Gentlemen:
f Q J d w, A recent NRC review of the different types of test computations used to 4
ILg) j determine leakage rate for containment integrated lea e
t performed throughouj_the 2 @sfry has g cated that,,
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'cbiputafion method that is not,in c ence with e
t" es f:it..,-.. 0r/ ret"f &ert+ of 10 CFR 50, Appendix J.
method bah: "W 'cr :::,.t:th is the mass point caitul: tion described in ANSI /ANS-56.8-1981, " Containment System Leakaoe Testing F. requirements."
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-,e I cider t$ N}; tU fehElet0 y equ'r:=nt; of App;ndh J, :pp1Wts are lic :::: nat m: : tha w e y> w hetere :t:.;;a; en; cf a Gi.RT t;c-ited '. A!!SI !:'5.V1972, " Leakage-Rate Testing of Containment men ed:
Structures for Nuclear Reactors.3 Sertion III.A.3.(a) of Appendix J M N T h.
that i5 CILRTs shall be conducted in accordance with the provisions of ANSI l
,Section III.A.3.(c) of Appendix J also requires that test leakage rates be calculated using absolute values corrected for instrument error. Section 5.1 of ANSI N45.4 pemits two methods of performing CILRTs, the absolute method and the reference-vessel method.
In addition, Section 7.9 of the standard describes the types of leakage rate computations permitted for the 24-hour period absolute method CILRTs. The only types of leakage rate computations specified in this standard are the point-to-point and the total time calculations. Hence, compliance with the regulatory requirements of Appendix J for absolute method CILRTs can only be achieved through the use of the point-to-point or total time leakage rate computational methods, corrected for instrument error.
It should be noted that the total tine test methodology presented in the Bechtel Topical Report BN-TOP-1, Revision 1. " Testing Criteria for Integrated Leakage Rate Testing of Primary Containment Structures for Nuclear Power Plants" has been determined to be in accordance with ANSI N45.4, with a test duration as defined in BN-TOP-1.
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-2 ANS] N45.4 also requires that a " statistically averaged leakage rate be determined (Paragraph 7.9).
However, ANSI N45.4 does not provide a specific method for accounting for random and instrument error during a CILRT, as o quired by Appendix J.
The NRC staff believes that the calculated leakage rate as determined by using the mass point method described by ANSl/ANS-56.8-1981 has technical merit. Although the NRC staff has in some instances accepted test results calculated by this method, recent review has determined that compliance with the regu'tatory requirements requires a CILRT 1eakage rate calculated by total time or point-to-point, with a test duration of at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or as provided for in BN-TOP-1. Random and instrument error is typically accounted for by calculation of a st6tistically-detennined 951 confidence level. For a test witL a duration of at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the 95%
confidence level calculation will be acceptable if it is derived from either:
(1) the total time or point-to-point method; or (2) the mass point method, as provided in AN51/ANS-56.8-1981. for a test with a duration of less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the leakage rate and the b51 confidence level must be calculated in accordance with BN-TOP-1. The calculated leakage rate, with the 95% confidence level amount adced to it, must then meet the acceptance criterion of Appendix J (i.e., not exceed 0.75 La or 0.75 Lt. as appropriate).
The supplemental, or verification, test required by Section III.A.3.(b) of Appendix J must also have its leakage rate calculated by the same method (i.e.,
total time or point-to-point) as is the CILRT.
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[eacc s suggested that applicants and licensees review their f CILRT programs with respect to the above to assure future consistency with 1
1( regulatory requirements. 3 j
f In a related action, the NRC has released for public coment a general revision to Appendix J to 10 CFR 50 (51 FR 39538, dated October 29,1986). This revision would, among other changes, relax existing constraints on CILRT i
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L DRAFT calculational methodologies and would pemit the use of the mass point method for future CILPT determinations. A proposed Regulatory Guide (MS 021-5, October, 1986) has also been published for comment as a companion document to.
and referenced by, the Appendix J revision. The draft Regulatory Guide L
identifies the mass point method, with.certain constraints, as an acceptable l'
method for future C1LRT determinations, in accordance with the revised Appendix J.
However, until a revision is complete and in effect, the curroit Appendix J requirements apply.
No written response or specific action is required by this letter.
Therefore, no clearance from the Office of Management and Budget is required.
If you have any questions on this matter, please contact your project marager.
Sincerely.
Harold R. Denton, Director Office of Nuclear Reactor Regulation
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