ML20008G275
| ML20008G275 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 06/30/1981 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Varga S Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20008G276 | List: |
| References | |
| RTR-NUREG-0578, RTR-NUREG-578 TAC-47919, NUDOCS 8107070255 | |
| Download: ML20008G275 (3) | |
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June 30, 1981 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Attn:
Mr. Steven A. Varga, Chief Operating Reactors Branch No. 1 Division of Licensing Washington, DC 20555
Reference:
Bea._r Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Shielding Design Review Gentlemen:
In accordance with your request of June 3,1981, forwarded herewith is the information in answer concerning the Beaver Valley Power Station, Unit No. I review of plant shielding design. A final shielding deaign revi2w and description of the results are contained in Attachment 1 (QUAD-1-80-040 Design Review of Plant Shielding of Spaces for Post-Accident Operation) prepar-d for Duquesne Light Company by QUADREX Corporation.
A description of the modifications mode, or proposed, to implement the results of the shielding design review are contained in Attachment 2.
We believe that the steps taken as a result of the Shielding Design Review will assure the access and performance of the personnel in post-accident operations.
If you have any questions regarding this response, please contact my office.
Very truly yours, J. J. Carey Vice President, Nuclear g
cc:
Mr. D. A. Beckman, Resident Inspector g
U.S. Nuclear Regulatory Commission Beaver Valley Power Station Shippingport, PA 15077 U.S. Nuclear Regulatory Commission c/o Document Management Branch Washington, DC 20555 8107070255 810630 PDR ADOCK 05000334 P
ATTACHMENT 2 Response to Recommendations of the Design Review of Plant Shielding of Spaces For Post-Accident Operation There are four recommendations from the Design Review that required design changes, herein is a description of the modifications made as a
-result of those recommendations.
Shielding of the Hydrogen Recombiner Control Panels In the evaluation of options by the Design Review, it was recommended that shielding be applied as near the Low Head Safety Injection lines as possible to prevent excessive radiation levels at the hydrogen recombiner control panels during a post-accident period of operation. Preliminary reports indicate that the equivalent of 9 inches of steel or 5 1/2 inches of lead would be required to reduce the radiation level at the control panels to 450 mR/hr at 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> after an accident.
According to preliminary studies, only about 10 feet of the Low H<ad Safety Injection lines would require the full thickness of shielding, i.e.,, the section of the lines directly below the fir >r grating of the hydrogen recombiner control panels. The shielding will then be tapered off beyond the 10 foot section.
Upon completion of the shielding material selection and arrangement, the design of the shielding supports will be made including seismic calculations to demonstrate that the shielding installation will not
'3 endanger the Low Head Safety Injection lines during a Category 1 seismic event.
The design and' installation of the shield supports will be classified as seismic Category 1.
Changing the Hydrogen Recombiner Manual Isolation Valves to Motor Operated Valves The hydrogen recombiner manual isolation valves (lHY101, 1HY102, lHY103, lHY104) will be changed to motor operated valves because these valves would be subjected to high levels of radiation (primarily from the Low Head Safety Injection lines) following an accident. Power for the replacement valves will be from the same emergency bus as for the associated hydrogen recombiner to provide redundancy required in the post design base accident hydrogen control system. Each motor operated valve has a control switch and two sets of valve position indicating lights.
One set of indicating lights and a control switch are to be mounted on a local control panel located near the existing post design base accident hydrogen control panel.
The other set of indicating lights is located in the control room.
'All control switches for motor operated valves are key locked in the closed l position and the two inch va'ves, interconnecting piping and valve controls are safety related and c1 ssified as seismic Category 1.
q Changing the Containment Air bbnual Cross-Connect Valve (lIA-90) To A Mechanical Remote Operator Changing the containment air manual cross-connect valve (llA-90) to a remote operator was another recommendation of the Design Review.
In this case, a Reach Rod was fitted to the existing valve so that an operator would be in a better shielded location and have adequate protection from radiation hazards during an accident situation.
The valve lIA-90 is located outside containment near pipe penetration No. 47 in the safeguards area. A hole was drilled in the ceiling above the "B" penetration area between the 722' and 735' level of the auxiliary building to allow a shaft to be brought through the hole and extending into the west cable vault area.
The shaft was attached to the valve handwheel via a right angle gearbox on one end and a handwheel on the other for remote operation of the valve. The two inch valve, interconnecting piping and valve controls are safety related and classified as seismic Category 1.
Shielding to be Added Near the Fbnual Charging Pump Suction and Discharge Isolation Valve The NRC criteria, GDC-19, is that an operator not receive a dose in excess of 5 rem to the whole body for the duration of the accident. A trial run was made by a shift supervisor and established that it would take one minute to enter the area, shut one valve and exit the area.
The total stay time is estimated at four minutes.
The estimated dose rate at the Charging Pump Reach Rod area is 20-30 rem / hour (.5 rem / minute).
Thus, the total exposure to complete the operation would be 2 rem, which is not in excess of the NRC 5 rem requirement.
Based upon this information, strict administrative controls which limit the entry times of operators subsequent to an accident will be imposed.
These controls will eliminate the necessity of installing shielding in these areas.