ML20248B992
| ML20248B992 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 05/30/1989 |
| From: | Hunsader S COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20248B999 | List: |
| References | |
| 0145T, 145T, NUDOCS 8906090228 | |
| Download: ML20248B992 (2) | |
Text
FM Commonwrith Edison?
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A" e 72 West Adams Street, Chicago, Illinois Address heply to: Post Office BH'767 =
? Chicago, Illinois 60690 - 0767 Rw
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1989 Dr. Thomas-E. Murley, Director-
> Office of Nuclent Reactor Regulation-LU.S. Nuclear Regulatory Commission l
Washington, DC 20555 1
- Attn Document. Control Desk j.
Subjects. Braidwood Station Units 1 and 2 Control Room Integrity Demonstration NRC Docket Nos.
50-456/50-457 References (a) June 3, 1986 A.D. Miosi letter to H.R. Denton (b) December 23, 1986 S.C. Hunsader letter to H.R. Denton (c) March 4, 1987 S.A. Varga letter to D.L. Farrar (d) April 2, 1987 S.C. Hunsader letter'to it. R. Denton (e) April 22, 1987 S.C. Hunsader letter to T.E. Murley-(f) May.6, 1987 S.C. Hunsader letter to T.E. Murley (g) NUREG-1002, Safety Evaluation Report, Supplement #3 dated May, 1987
Dear Dr. Murley:
Reference (a) provided Commonwealth Edison's (Edison) initial evaluation using the guidance of Regulatory Guide 1.78 to justify the removal -
of the chlorine detectors from the Braidwood Control Room HVAC System.
Reference (b) provided Edison's notification that emergency planning measuresL had been' established with Will County, Illinois, in the event of a chlorine accident in the vicinity of Braidwood Station.
References (c) and (g).
Provided the NRC staff review and evaluation of the Ed3 son submittals and authorized the removal of the chlorine detectors based on (1) the small probability of a chlorine event, (2) Edison's commitment to maintain prompt notification communications with Will County, (3) a requirement to isolate the
. control' room upon receipt of notice of a toxic gas incident, and (4) a requirement to demonstrate control room integrity on a 18-month basis.
Reference (d) provided Commonwealth Edison's commitment to provide manual isolation capability of the control room envelope and to subsequently demonstrate this isolation capability on an 18-month basis, thereafter, via a Technical Specification surveillance. Reference (f) clarified Edison's position as presented in reference (e) with respect to implementing the requirements in reference (c) and (g) and stated that Edison would develop a procedure to address the control room integrity demonstration. The first demonstration of control room integrity was performed in January, 1988 on both control room ventilation (VC) system trains via an "in leakage" test while both Units 1 and 2 at Braidwood Station were in Mode 5 and 6, respectively.
j, aThe next "in leakage" test is scheduled to be performed in July, 1989.
P 3
r 8906090228 890530 PDR ADOCK 05000456
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-Dr. T.E. Murloy -
May 30, 1989 Edison has performed'an evaluation which shows that alternative measures exist to demonstrate control room integrity other than performing an "in leakage" test.
The results of this evaluation were discussed with the NRC staff in a meeting held at the NRC White Flint offices on May 12, 1989 and are provided here in Attachment "A".
Significant points made in Attachment "A" are as follows:
1)
In order to perform the in-leakage test, the running train of VC will be required to be in the isolated mede of operation for approximately 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br />.
The VC train ~1n the isonted condition will be inoperable.
The redundant train will be operable and capable of being manually l
alligned from the control room for emergency operation.
Edison believes it is not prudent to operate in this manner for the performance of the in-leakage test since it may place the VC system in a nonconservative configuration during modes of operation above-Mode 5.
(Reference Technical Specification 3/4 7.6).
2)
The control room envelope will continue to experience some small infiltration flow while the VC system is operated in the 100%
recirculation mode.
The maximum postulated infiltration represents 87% of the 2633 cfm allowable infiltration for trains A & B.
This indicates that margin exists such that the toxic gas analysis will not be exceeded.
3)
Compliance with SRP 6.4 has been met.
The allowable infiltration of 2633 cIm and the postulated inflitration of 2293 cfm are both greater than 50% of the gross control room envelope leakage at 1/8 pressure differential.
4)
Alternative means are in place to control leakage sources during maintenance and plant operations.
Edison's original analysis showed that the chlorine concentration 2-minutes after detection in the Braidwood control room will be lower than the expected toxicity level. Additionally, the accident rates selected for the probabilityanalysiswerefoundtobereasonableandtheexposureprobabilitgto the control room operator is much lower that the acceptance value of 1 x 10-per year.
Also, the analyses conducted by the NRC staff were highly conservative as provided in reference (g).
In view of the above, Edison believes the requirement to demonstrate the
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integrity of the control room envelope by "in leakage" testing is no longer necessary.
This information is being provided for NRC review and acceptance.
Please address any questions concerning this matter to this office.
Yours very truly, b
S. C. Hunsader Nuclear Licensing Administrator 1
cc: S. Sands (NRR)
J. Hinds (R III)
Resident Inspector - BWD
/lb:0145T 9-10
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