ML20213F352
| ML20213F352 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 11/12/1986 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| CON-NRC-86-110 IEB-86-003, IEB-86-3, VPNPD-86-465, NUDOCS 8611140171 | |
| Download: ML20213F352 (3) | |
Text
i Wisconsin Electnc eom couen 231 W. MICHIGAN, P o. BOX 2046, MILWAUKEE, WI 53201 (414)277-2345 VPNPD-86-465 NRC-86-110 November 12, 1986 Mr. J. G. Keppler, Regional Administrator Office of Inspection and Enforcement, Region III U. S. NUCLEAR REGULATORY COMMISSION 799 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
DOCKETS 50-266 AND 50-301 RESPONSE TO IE BULLETIN 86-03 POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 This letter is in response to the request for information in IE Compliance Bulletin 86-03.
On July 24, 1986, Point Beach Nuclear Plant notified the NRC, pursuant to the provisions of 10 CFR 21, of the potential defect in the design of the control circuit for the safety injection (SI) pump recirculation flow path isolation valves, SI-897A&B.
It was discovered that a failure of the power supply breaker from the control circuitry of either 897 valve would result in closure of the valves as well as loss of annunciator and status light indication intended to alert the operator that an 897 valve was shut.
Shutting of either 897 valve without operator knowledge or action could result in failure of either or both SI pump (s) if pressure was above the pump shutoff head.
At Point Beach Nuclear Plant, the SI pumps have a common return header to the refueling water storage tank (RWST).
This path provides a route for water flow during testing as well as a recirculation path during pump operation while the reactor coolant system pressure is above the shutoff head of the pumps.
If the SI pumps are operated without any flow-through, l
overheating will damage the pump in a relatively short period of time.
Immediate operator action is warranted in these circumstances.
- pf' 8611140171 861112 PDR ADOCK 05000266 G
PDR 0
t Mr. J.
G. Keppler November 12, 1986 Page 2 The 897 valves are interlocked with the containment sump isolation valves, SI-851A&B.
This interlock prevents contaminated containment sump water from being pumped into the RWST during the safety injection recirculation phase of a design basis accident.
As discussed in the 10 CFR 21 report of July 24, 1986, the short-term corrective actions were outlined.
They included the following:
The manual handwheel operators on the 897 valves were positioned to override the automatic operators and maintain the valves in an open position.
This prevents closure of the 897 valves anytime either of them would lose control power.
It also prevents closure of the 897 valve whenever either of the 851 valves is open.
The control room control switches and the local manual valve operators for the 851 valves, which are normally closed, were locked shut.
The Emergency Operating Procedures which control the switchover from the injection phase to the recirculation phase require the 897 valves to be closed prior to the opening of either 851 valve.
An Operations Special Order was also issued explaining the reason for the locks on the valves and the conditions under which they could be removed and the valves opened.
The final corrective actions which have been installed are as follows:
The manual handwheel operators on the 897 valves will remain in the open position so that the automatic operators are overridden.
Locks on the local manual operators of the 851 valves will remain installed.
i Electrical interlocks which replace the locks on the control room control switches have been installed to prevent the opening of any 851 valve until at least one 897 valve is fully closed.
This assures that potentially highly contaminated sump water is not pumped to the RWST.
Additionally, the relay for the annunciator and status light has been changed from a normally deenergized relay with normally open contacts to a normally energized relay with normally closed contacts.
The relay change ensures that, upon a loss of control power, proper status light indication and annunciator action occur.
i
4 o
b Mr. J. G. Keppler November 12, 1986 Page 3 A review of the low head safety injection systems at Point Beach Nuclear Plant has been done.
We believe that no other potential for failure of multiple trains of pumps due to single failure of valves in minimum flow recirculation lines exists.
The low head safety injection system at Point Beach is the residual heat removal (RHR) system.
Each train has its own recirculation line.
If failure of a valve in one of the RHR train recirculation lines occurred, the other train would, therefore, not be affected.
If you have any questions concerning the information provided, please contact my office.
Very truly yours, CO
[
C. W. Fay Vice President Nuclear Power Copies to NRC Resident Inspector NRC Document Control Desk Washington, D.
C.
(with original)
Subscribed and sworn to before me this il N day of Novewbev 1986.
WNv4
'bt<
ettc)
Notary Public, State'of Wisconsin My Commission expires 5-l'7-9 0
_.. _ _. _,.