ML19095A219
| ML19095A219 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 05/26/1978 |
| From: | Stallings C Virginia Electric & Power Co (VEPCO) |
| To: | Case E, Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| Serial No. 269A/050578 | |
| Download: ML19095A219 (3) | |
Text
__,
l...
,~
REGULATORY o*KET FllE COPY VIRGINIA ELECTRIC AND PowE:a CoMPANY Ri:cHMOND,VI:RGI:N.IA 23261 May 26, 1978, Hr. Edson G. Case, Acting Director Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Attn: Mr. Albert Schwencer, Chief Operating Reactors Branch 1
Dear Mr. Case:
Serial No. 269A/050578 PO&M/ALH:das Docket Nos. 50-280 50-281 License Nos. DPR-32 DPR-37 We have completed the inspection of the Surry Unit No. 1 outside recircula-tion spray (ORS) pumps and one low head safety injection (LHSI) pump as we agreed to do during our meeting of May 10, 1978'-.
We have reviewed the inspection results with Mr. Zudans of your staff and have allowed Hr. Zudans to personally inspect these pumps.
There is a remarkable difference between the condition of the ORS pumps and the LHSI pump.
The radial bearing clearances on the LHSI pump varied from 5 to 7 mils, and the shaft wear in the journal areas varied from 2 to 3 mils.
The LHSI bearings were smoothly worn and showed no signs of debris damage.
One LHSI bearing had a chip out of the upper edge, but this area does not bear on the shaft.
A phone conversation with the LHSI manufacturer indicated that this chip is not detrimental.
As a result of the condition of the LHSI pump that we inspected, we do not plan to pursue modifications to the pump or to design a cross connect sys-tem.
The condition of the ORS pumps from Surry Unit No. 1 was not nearly as good as the condition of the LHSI pump.
There were signs of debris damage t-0 the bear-ings and shafts in one pump were bowed.
Radial bearing clearances on ORS pump 11A 11 varied from 12 mils to 63 mils.
Shaft wear varied from 1 mil to 7 mils.
Bearing wear was smooth and exhibited a cylindrical wear pattern.
The three lower bearings on the pump shaft were in very poor condition.
Indications were that large pieces of debris had been lodged between the shaft and the bearing.
Very deep gouges were evident.as were signs of localized overheating.
Accurate dimensions on these bearings could not be taken due to their condition.
The "B 11 ORS pump experienced no severe go_uging of any bearings, but obvious signs of severely bowed shafts were present.
The radial bearing clearances varied from 10 mils to 206 mils.
The shaft wear varied from l mil to 8 mils.
Most bear-
__ iJ].gs showed a cylindrical wear pattern, but some showed cone shaped cross sections.
This is due to shafts that are bowed in or very near to the bearing.
Shafts for "B" ORS pump will be straightened at the pump manufacturer's facilities in Shreveport, La.
The Unit l ORS pump shafts are being chrome plated, optical align-ment of the ORS pump columns is in progress and all necessary bearings have been priority ordered.
The work on the Unit 1 ORS pumps should be completed by mid-June, 1978-.
11001 / s ~
I
e e
VIROINIA ELECTRIC AND POWER COMPANY TO Mr. Edson G. Case Page No. 2 The critical item on our schedule is the availability of bearings.
We have personally contacted the pump manufacturer and the bearing manufacturer to ensure that attention is given to our order.
The long delivery is due to the fact that the bearings must be made to fit the Surry pumps and that another utility has also ordered bearings on a priority basis.
We expect one shipment of bearings in about one week, but the manufacturer would not guarantee this.
The remaining shipments are expected by June 30, 1978:, but again no guarantees could be obtained.
We are still working with the manufacturer to improve this schedule.
We have also tried to obtain bearings from another utility, but they have none available beyond there.
own needs.
We have considered other steps to permit a rapid resolution of the Unit 2 ORS pump problem.
We examined the possibility of using North Anna 2 ORS pumps at Surry.
The pumps are sufficiently different that proper orientation in the sump could not be achieved.
We considered putting Surry Unit 1 ORS pump internals in Surry Unit.2.
This is not advisable since the pump parts are essentially ma-chined uniquely for each pump and match marked.
Interchanging pump parts could result in additional alignment and balance problems.
We examined the possibility*
of mounting the complete Surry Unit No. 1 ORS pumps in Unit 2.
This would require careful alignment of the pump in the sump can which. also would likely require machining of the pump foundation to assure proper seismic clearance.
We believe that these measurements are too risky and.we do not think that they should be at-tempted.
Irreversible damage could occur to the pumps or sump cans which would result in an extremely long outage.
We are planning to complete all maintenance work on Surry Unit No. l by about June 27,, 1978:.
We then plan to shutdown Unit 2 to perform modifications on the Unit 2 ORS pumps.
This will require operation of Unit 2 until that time~
The following facts have been considered regarding. the continued operation of Unit 2:
1).
2).
- 3)
- 4)
- 5)
- 6)
The current approved LOCA-ECCS analysis shows that the peak clad temperature does not exceed 2200°F during LOCA.
The dose equivalent I-131" level in Unit 2 is about 2 x 10-3 micro-curie/gm which is a fraction of a percent of the allowable Technical Specification level.
This indicates virtually no fuel defects* in Unit
- 2.
The LHSI pumps are in excellent condition as indicated by the inspec-tion of the Unit 1 LHSI pump.
We have checked the operability of the Unit 2 inside and outside re-circulation spray pumps.
All four pumps can be rotated easily by hand and have passed the required periodic test within the last 30 days.
All other ECCS equipment is operable and should function properly during LOCA.
The probability of a LOCA during the next month is approximately* 1 x 10~4 (ref. WASH-1400).
e VIRGINIA ELECTRIC AND POWER COMPANY TO Mr. Edson G. Case Page No. 3 7}
Twenty-four hours after a LOCA, only one of the four recirculation spray pumps is required to operate to provide contaimnent heat re-moval.
We believe that a LOCA is very unlikely during the next month.
If a LOCA were to occur, the LHSI pumps will operate as required to provide safety injec-tion flow to the reactor core.
Since the ORS and IRS pumps now operate satis-factorily, we* believe that they will all operate* properly for at least the first twenty-four hours after LOCA.
At that point only one recirculation spray pump is required to provide containment cooling, and we believe that the failure probabili-ty of three out of the four installed recirculation spray pumps is extremely small.
We believe that the LHSI and recirculation spray pumps will operate to mi-tigate the consequences of a LOCA in the unlikely event that such an incident should occur.
Therefore, continued operation of Surry Unit No. 2 until the end of June 1978'. poses no threat to the health and safety of the general public.
cc: Mr. J *. P. O'Reilly Very truly yours,
'Zf;.)7;.~;,,y C. M. Stallings Vice President-Power Supply and Production Operations
---~ -