ML19208A674
| ML19208A674 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 09/11/1979 |
| From: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7909170217 | |
| Download: ML19208A674 (2) | |
Text
.
BALTIMORE GAS AN D ELECTRIC COM PANY GAS AN D ELECTRIC DUILOING 3 ALTl M O R E, M A RYLAN D 212 03 September 11, 1979 ARTHUR E. LUN OVALL,JR.
VtC E P AE SiO E 88 7 Sumv Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Attn:
Mr. Robert W. Reid, Chief Operating Reactors Branch #h Division of Operating Reactors
Subject:
Calvert C?iffs Nuclear Power Plant Units Nos. 1 & 2, Docket Nos. 50-317 & 50-318 CVCS Pinine Vibratory Loads
Reference:
BGLE letter dated 1/23/79 from R. F. Ash to R. W. Reid, same subject.
Gentlemen:
The referenced letter informed you of our intentions to purchase and install pulsation dampeners to limit vibration caused by the operation of the charging pumps. As discussed in a recent telephone conversation with our NRC project manager, this letter is being submitted to provide you vith the latest information on the details of our scheduled modifications and the timetable for their accomplishment.
Suetion Side Modifications The CVCS piping between the suction inlet of the charging pumps and the first suction isolation valve vill be changed from Schedule 10 stainless steel to Schedule h0 stainless steel. All socket velded fittings to the branch connections in this portion of piping vill be replaced with butt velded fittings.
In addition, suction stabilizers vill be installed in this piping.
These stabilizers are five gallon capacity, designed and manufactured by Greer Hydraulics, Inc. (Part No. 8hh633). They are sized to reduce pressure fluctuations in the suction lines caused by cavi#ation/
bubble collanse to within + 5% of the mean absolute line pressure.
It has been ascertained through measurements that suction line pressure fluctuations are affected by static suction head. which is supplied by the pressure in the Volume Control Tank (VCI), and that pressure fluctuations are minimal when VCT pressure is about 40 psig. The fluctuation a=plitude increases as VCT (suction) pressure decreases. The peak to peak pressure fluctuation noted at a suction pressure of 12 psig and a discharge pressure of 2h60 psig vas 60 psi.
It is expected that the suction stabilizer vill reduce this fluctuation to about 6 psi. Since ve intend to maintain VCT pressure closer to h0 psic, it is expected that the stabilizers will reduce pressure fluctu-ations to belov 5 psi.
352129 790917052. )2
Mr..R. W. Reid Page 2 September 11, 1979 i
Discharae Side Modifications The discharge side of the charging pumps presently contains 2 gallon capacity pulsation da=peners designed and manufactured by Greer Hydraulics, Inc. The bladder precharge pressure in these units is 1600 psi (nitrogen). However, the units are of insufficient size to prevert pressure pulsations when system pressure drops belov 1600 psi. Therefore, it has been necessary for the operator to bleed off the nitrogen pressure. To correct this situation, we intend to modify the presently installed 2 gallon Pulse-Tone unit by replacing the shell, bag and gas valve assembly with the corresponding 5 gallon parts designed and manufactured by Greer.
This modification vill make the da=peners effective for pump discharge pressure over the range of h60 psi to 3000 psi, limiting the pulsations to 1 % of discharge pressure.
Schedule All engineering work associated with the above modifications will be completed by December, 1979 Delivery for all equip =ent is expected by mid-January,1980. Modifications to Unit No.1 are scheduled for the Spring 1980 refueling outage, and Unit No. 2 for the Fall 1980 refueling outage.
The necessary piping fittings and dampeners vill not be delivered in time to accomplish any modifications to Unit No. 2 during the upcoming Fall 1979 refueling outage.
The pulsation dampening equipment is designed to ASME Boiler and Pressure Vessel Code Section III, Nuclear Class II, and the piping is Nuclear Class III.
In the interim until the above modifications are made, close monitoring of VCT pressure and charging system discharge pressure is expected to minimize the possibility of charging pump pressure fluctuations.
We hope that this infor=ation is sufficient to aid you in conducting your safety evaluation of this issue on the Calvert Cliffs dockets. If you have any additional questions, please do not hesitate to call.
Very truly yo rs,
)
"C%x :
[- QYduruA>
cc:
J. A. Biddison, Esquire G. F. Trowbridge, Esquire Mr. E. L. Conner, Jr. - NRC
% ' 130 d