ML20093D912
| ML20093D912 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 07/13/1984 |
| From: | Owen W DUKE POWER CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8407170295 | |
| Download: ML20093D912 (4) | |
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s DUKE POWER GOMPANY Powan BurLnixo, Box 00too, Ciuntorrz,N. G. 20242 July 13, 1984
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EstCutivt WE PetSe0Enf Em6enfEmesse & COassTmvCYeos 1704 373-esRO Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Re: Catawba Nuclear Station, Unit 1 Docket No. 50-413
Subject:
Applicants' Application for Partial Exemption from Appendix J
Dear Mr. Denton:
By letter dated July 11, 1984 Applicants requested an exemption from 10 CFR 50, Appendix J for the following items:
(a) Testing of bellows on mechanical penetrations (b) Venting and draining of certain penetrations during Type A tests (c) Testing of containment airlocks The purpose of this letter is to supplement the arguments concerning the exigent circumstances supporting issuance of these exemptions.
Concerning item (a), the Catawba mechanical penetrations are a second generation Duke Power Company design, based on the McGuire design which is performing satisfactorily. Enhancements over the McGuire design consist of a protective sleeve over the bellows and an improved weld design of the bellows. Duke has every expectation that the Catawba penetrations will perform their design func-tion equally as well as the original design used at McGuire. Based on satis-factory performance at McGuire, Duke would utilize the same basic design for a future station. In fact, penetrations for the Cherokee Nuclear Station, which represented a third generation design, retained the two-ply bellows feature, including the low between-the-plys test pressure. Stiffening of the inner ply to better resist increased test pressures would cause engineering ccmpromises contrary to the overall design requirements. Increased between-the-plys test prcssure would only increase sensitivity of the test to detect very small leaks and would not significantly increase the capability of the current test pres-sure to detect such leaks. Modified designs to increase this test pressure are not practical, are not necessary, and safety of the plant or the public would not be enhanced.
8407170295 840713 PDR ADOCK 05000413 Iff h
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Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission July 13, 1984 Page Two Estimated materials and labor costs to replace mechanical penetrations, designed and procured in the mid-1970's, would be in the tens of millions of dollars for one Catawba unit. Lost power and many other factors would also impose additional costs; all of which would result in costs and hardships without a compensating increase in the level of quality of safety.
As previously discussed, item (b) relates to venting and draining of certain penetrations equiped with a seal water system during Type A tests. The con-tainment isolation valve seal water system was developed for Catawba after prob-lems were identified at McGuire with obtaining acceptable Type C leakage rates from a number of valves. The seal water system relies on injection of a fluid i
into the bonnet of the isolation valve which prevents leakage from containment.
l The " reverse" check valves used to prevent overpressurization of the penetra-tion assembly are not amenable to a fluid seal b(cause there is no bonnet cavity.
Thus, these valves must be Type C tested. Additionally, leakage cannot be excluded in a Type A test since they may be open to containment atmosphere after a design basis accident.
In order for the penetrations to be drained for a Type A test, scaling water injection to the main isolation valves must be suspended (since the acceptable icvels of sealing water injection leakage could fill the
" reverse" check valve). This results in having the main isolation valves drained and exposed to the Type A leakrate test when, in fact, these valves will not be a potential leak path after an accident. A more accurate method of determining the Type A leak rate is to not drain and vent the penetrations listed in our April 5, 1984 letter, but to add the leakage of the " reverse" check valve determined by their Type C test to the results of the Type A test.
For this case Applicants have made a good faith effort to improve the design of Catawba based on problems identified at the McGuire Nuclear Station. Applicants would have to expend significant resources to bring Catawba into full compliance with Appendix J and these modifications would not enhance the level of safety presently attained by Catawba.
In regard to item (c), the current requirement contained in 10 CFR 50, Appendix J, III.D.2(b)(ii) poses a significant burden. The airlocks will usually be opened during outages to facilitate equipment transport into and out of containment. Then just prior to entry into Mode 4, the overall airlock leakage test must be performed.
Installing strongbacks, performing the test, and removing strongbacks will require at least six hours per airlock during which access through the airlock is pro-hibited. Any access and egress to lower containment during testing of the lower airlock will involve climbing through the emergency hatch between upper and lower containment. This will result in more contamination in upper containment which will usually be cleaner than lower containment. Similarly, access to upper con-tainment while testing the upper airlock will require passing through lower con-tainment where radiation levels will be higher, thus increasing radiation exposure to personnel and increasing contamination in upper containment. The proposed changes would allow better scheduling of the overall airlock leakage test during periods when the need for access to containment is minimal.
Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission July 13, 1984 Page Three
. Applicant's original request for exemption to Appendix J was for the duration of the license on Catawba Unit 1.
If NRC's review of this application warrants, Applicants would accept an exemption for the period of fuel loading and pre-critical testing. Exemption requests for operation subsequent to this period would be submitted at a later date.
Very truly yours, s
W. H. Owen NAR:scs cc:
Mr. J. P. O'Reilly, Regional Administrator Robert Guild, Esq.
U. S. Nuclear Regulatory Commission Attorney-At-Law Region II P. O. Box 12097 101 Marietta Street, NW, Suite 2900 Charleston, South Carolina 29412 Atlanta, Georgia 30323 Mr. Jesse L. Riley Palmetto Alliance Carolina Environmental Study Group 2135 1/2 Devine Street 854 Henley Place Columbia, South Carolina 29205 Charlotte, North Carolina 28207 NRC Resident Inspector Catawba Nuclear Station s
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r W. H. 0 WEN, being duly sworn, states that he is Executive Vice President of Duke Power Company; that he is authorized on the part of said Company to sign
.and file with the Nuclear Regulatory Commission this application; and that all statements and matters set forth therein are true and correct to the best of his knowledge.
1s/&
W. H. Owen, Executive Vice President Subscribed and sworn to before me this 13th day of July, 1984.
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My Cowniscion Expires:
S'eptember 20, 1984 O
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