U-602654, Responds to GL 96-06, Assurance of Equipment Operability & Containment Integrity During Design-Basis Accident Conditions
| ML20129J187 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 10/28/1996 |
| From: | Connell W ILLINOIS POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-96-06, GL-96-6, L30-96(10-28)LP, U-602654, WC-326-96, NUDOCS 9611050039 | |
| Download: ML20129J187 (5) | |
Text
1 Ilhnois Power Company
)
Clinton Power Station P.O. Box 678 Clinton. IL 61727 Tel 217 935-5623 Fax 217 935-4632 Wilfred Connell Vice President i
ILLIN9BS u 6o2654 P4pWER uo-96ao-2s xi
)
8G.12o j
WC-326-96 October 28, 1996 i
i Docket No. 50-461 Document Control Desk Nuclear. Regulatory Commission Washington, D.C. 20555 i
Subject:
Illinois Power's (IP's) Response to Generic Letter (GL) %-06, i
" Assurance of Equipment Operability and Containment l
Jntegrity During Design-Basis Accident Conditions"
Dear Madam or Sir:
This letter is responding to GL.96-06 which requires that addressees determine:
(1) if containment air cooler cooling water systems are susceptible to either waterhammer or two-phase flow conditions during postulated accident conditions; (2) if piping systems that penetrate containment are susceptible to thermal expansion of fluid so that overpressurization of piping could occur.
This response is fulfilling the 120-day written summary repont regarding Item (1) for Clinton Power Station (CPS). Item (2) will be further addressed in the 120-day rcsponse. The information regarding Item (2) will be supplied as requested within the 120-day time frame specified in the generic letter. Below is.a brief synopsis ofIP's response. Attachment 2 contains a more detailed report of the GL 96-06 conclusions.
Illinois Power reviewed systems which could be impacted by waterhammer and determined that four lines penetrating containment would meet the criteria necessary to experience a waterhammer phenomenon. These Shutdown Service Water (SX) lines had already been evaluated for waterhammer concerns. CPS has also evaluated the SX flow through these lines and determined no flow is required through these lines.
CPS does not rely on safety-related coolers in containment or the drywell for post Loss ~of Coolant Accident (LOCA) containment cooling. The drywell non-safety related cooling system and supplemental cooling system can be used for supplemental cooling per I
4D~79 1
9611050039 961028 ADOCK0500g1 PDR P
i U-602654 I
Page 2 the emergency operating procedures (EOPs) but are not required. These two systems are closed loops with compression tanks maintaining p' "tive pressure in the systems.
j Therefore, two phase conditions and subsequent %erhammer would not exist in these j
systems.
CPS has reviewed applicability to which penetrations could be most affected by thermal expansion and overpressurization. CPS has determined that additional analysis is j
required for twenty-one penetrations. The results of this analysis will be forwarded in the l
CPS 120-day response.
b
- provides an affidavit supponing the facts set fonh in this letter.
s Sincerely yours, WWh 0~d i
Wilfred Connell Vice President 4
JSP/csm 3
Attachments cc:
NRC Clinton Licensing Project Manager NRC Resident Office, V-690 Regional Administrator, Region III, USNRC Illinois Department ofNuclear Safety
l Attachment I to U-602654 Wilfred Connell, being first duly sworn, deposes and says: That heis Vice President of the Nuclear Program at Illinois Power; that this letter supplying information for Generic Letter 96-06 has been prepared under his supervision and direction; that he knows the contents thereof; and that to the best of his knowledge and belief said letter and the facts contained therein are tme and correct.
Date: This Jd' day of October 1996.
i l
Signed:
M d%d Wbfred Connell
_ _ _ _ _ _ _ _ _; :: : - :_ :. ^ ^ ^ ^
"~
'0ITC18LE8L b
g gaselSulB 3e4[e COUNTY J
',;,,[ComadeslangqirestW_
,::::::===~ ----
Subscribed and sworn to before me this 2& day of October 1996.
u,w d iv d A d a d
$tary Public)
/
i i
j
+
2 to U-602654 Page1 of2 Listed below are the requested actions from GL %-06 and IP's response:
(1) if containment air cooler cooling water systems are susceptible to either j
waterhammer or two-phase flow conditions during postulated accident conditions; 4
f The containment peak temperature at Clinton Power Station (CPS) is 185'F.
Therefore, steam could not be produced in lines that are in the containment unless a substantial vacuum were present (-6.2 psig). Only those lines that could drain down a
" sealed high point loop" sufficiently to create a significant vacuum would be susceptible.
If the containment penetration is isolated under a contaimnent isolation signal (Iow reactor pressure vessel level or high drywell pressure) and would not be re-opened, f
repressurization of the lines and subsequent waterhammer would not be introduced.
CPS does not rely on safety-related coolers for containment cooling. Coolers are used in the Combustible Gas Control Compressor rooms for equipment qualification considerations.
A review oflines penetrating containment was performed. Based on the review, lines associated with the four containment penetrations were identified as potential j
concerns. The lines are three-inch nominal pipe size and are part of the safety-related shutdown service water (SX) system that provides cooling water to the Combustible Gas Control Compressor room coolers. The SX system, including the piping in question, has been evaluated for waterhammer. In addition, CPS has evaluated the SX supply to the Combustible Gas Control Compressor rooms and determined that no flow is required to maintain equipment qualification.
Drywell temperatures at CPS are higher than in containment. The drywell can j
reach 330 F which could cause a waterhammer within piping in the drywell if piping went to a two-phased state. The SX lines discussed above do not go into the drywell. It should, however be noted that CPS Emergency Operating Procedure 4402.01 (EOP-6) allows for the defeating of containment isolation interlocks of the non-safety Drywell Cooling (VP) system and supplemental drywell cooling (WO) if drywell temperature cannot be held below 135'F. The design of the WO and VP systems are closed loops with compression tanks that maintain a positive pressure in the system. As such, the lines would not drain down causing vapor cavities in the piping in containment or drywell.
Therefore, waterhammer would not be postulated to occur in these two systems.
(2) if piping systems that penetrate containment are susceptible to thermal expansion of fluid so that overpressurization of piping could occur.
A review was performed to identify potentially susceptible penetrations.
Penetrations that did not have isolation valves on both the inside and outside of containment were not considered susceptible. These included penetrations such as
to U-602654 i
Page 2 of 2 suppression pool suction lines which have valves on the outside only. Lines with a means to relieve the pressure such as check valves, relief valves or those which do not contain water were also excluded. After excluding these penetrations, twenty-one penetrations were identified as not meeting the above prerequisites for exclusion. CPS intends to funher evaluate these twenty-one penetrations. The results of the analysis will be forwarded to the NRC in the 120-day response.
4 h
n i
l 1
i i
.i a
i 4
J s
I k
t 1
4
_. ~
,e-