ML20052E829
| ML20052E829 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 04/30/1982 |
| From: | Mayer L NORTHERN STATES POWER CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8205110466 | |
| Download: ML20052E829 (11) | |
Text
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Northern States Power Company 414 Nicollet Mall Minneapohs, Minnesota 55401 g elephone (612) 330-5500 V
April 30, 1982
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PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Response to Request for Additional Information Related to Containment Purge and Vent System Isolation Valves In a letter dated March 8, 1982 f rom Mr Robert A Clark, Chief, Operating Reactors Branch #3, Division of Licensing, USNRC, we were requested to provide information required by the NRC Staff's long-term review of the Prairie Island containment purge and vent isolation valves. The purpose of this letter is to provide the information needed to resolve this issue.
The requested information is provided in the attachment to this letter.
Please contact us if you have any questions related to the information we have provided or the commitments we have made.
. d.
L 0 Mayer, PE Manager of Nuclear Support Services LOM/DMM/bd cc: Regional Administrator-III NRR Project Manager, NRC Resident Inspector, NRC G Charnoff Attachments 8205110466 820430 i
[Sl1 PDR ADOCK 05000282 P
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Dir ctor of NRR April 30, 1982 Attachm:nt PRAIRIE ISLAND NUCLEAR GENERATING PLANT IfEORMATION REQUIRED FOR CONTAINMENT PURGE AND VENT VALVE LONG-TERM NRC STAFF REVIEW The status of our long-term review of the above items for the Prairie Island Nuclear Generating Plant Units 1 and 2 is as follows:
1.
Conformance to Standard Review Plan Section 6.2.4 Revision 1 and Branch Technical Position CSB 6-4 Revision 1 In order that we may complete our safety evaluation on this issue, the following items need to be resolved.
(a) Commit to the installation of debris screens in the purge supply and exhaust lines that meet the requirements described in Enclosure 2.
You are also requested to provide an installation schedule for the debris screens for Units 1 and 2.
(b) Commit to limit the use of the purge system to a specified annual time that is commensurate with identified safety needs. By letter dated December 3,1981 you committed that when purge and vent opera-tion is resumed it would be on an "as low as achievable" basis pending completion of the. long-term review of other issues. Thus you are requested to define,"as low as achievable" in terms of approximate hours per annum based on past safety needs.
(c)
Propose a Technical Specification to require that you perform leakage integrity tests of the isolation valves in the containment purge lines at least once every three months. The proposed technical specification applies to the isolation valves in the low volume purge system since you have committed by letter dated December 3, 1981 not to use the high volume purge system when the reactor is above cold shutdown condition.
The proposed technical specifications are also to include a provision that the resilient seals of the isolation valves in the high volume purge and vent system will be protected against the exposure of the containment atmosphere when the reactor is above cold shutdown.
If this provision cannot be net then high volume purge and vent system will be leak tested at least once every six months.
If however the resilient seals of the high volume purge are protected, then by a proposed technical specification, we will require leak testing of the high volume purge system as a prerequisite to bring the reactor above cold shutdown provided that the high volume purge was used during the shutdown period.
Leak testing is to include the isolation valves as well as the protective devices for the resilient seals.
2.
Valve Operability Your letter of December 3, 1981 transmitted the Henry Pratt Company analysis of the purge valves at the Prairie Island Nuclear Generating Plant Units 1 and 2.
This analysis is currently being reviewed by the staff and additional input is not required at this time.
1-1
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Director of NRR April 30, 1982 Attachment 3.
Safety Actuation Override Your letters of January 5,1979, April 12,1979, March 17,1980,' June 3, 1980, November 7, 1980 and May 6, 1981 addressed the issue of the safety actuation override at the Prairie Island Nuclear Generating Plant Units 1 and 2.
This is under review by the staff and additional information is not required at this time.
It is noted that a somewhat parallel review of engineered safety features resent is being carried out in conjunction with I&E Bulletin 80-06..That review will be handled separately outside the framework of the purge and vent review.
4.
Containment Leakage Due to Seal Deterioration A recently developed sample technical specification is provided for your consideration as Enclosure 3.
We request that you review existing TSs against the sample provided herein. In addition we request that you sub-mit the details of your proposed leak rate test program together with the -
TS change incorporating the test requirement (1(c) above).
RESPONSE
1(a) Debris screens will be installed in each 18-inch containment purge and vent line whenever the system is in use.
The debris screens will be designed in accordance with the guidelines provided in Enclosure (2) to Mr Clark's March 8, 1982 letter. Refer to Figure (1).
The 36-inch purge and vent system penetrations for each unit will be sealed off with double-gasketed covers when the associated unit is above cold shut-down. The system will only be used during outages. Debris screens will not be required.
1(b) The 18-inch purge system will be used on an "as low as achievable" basis.
We do not expect to use the system when above cold shutdown for periods of more than 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> total per calendar year per unit..The system is not normally required to maintain acceptable temperature, pressure, or humidity in containment. The 36-inch purge system will not be used above cold shutdown.
1(c) Double-gasketed covers will be installed on the containment side of all 18-inch and 36-inch containment purge and vent system penetrations. These covers will be removed on the 36-inch only when the associated unit is in cold or re-fueling shutdown. Covers on the 18-inch system will be removed immediately prior to using the system.
This modification will provide a barrier to leakage via these penetrations.
The flanges will be subject to Type B local leakage tests following removal and replacement and at other intervals specified in 10 CFR Part 50, Appendix J.
Valve leakage tests will be conducted prior to or immediately following removing penetration covers when using the 18-inch system above cold shutdown.
Appropriate Technical Specification changes will be submitted within 90 days of receipt of the NRC Staff's Safety Evaluation Report related to this issue.
The modification to the 36-inch system is scheduled for the next refueling outage of each unit.
Modification of the 18-inch system is scheduled for the 1982 Unit 1 outage and the 1983 Unit 2 outage.
1-2
Director of NRR April 30, 1982 Attachment 2.
Following NRC Staff review of the Henry Pratt Company stress analysis of the Prairie Island 18-inch inservice purge system butterfly valves, a question arose concerning the stress analysis for the actuator bolts.
Corrected pages for Attachment (2) of our December 3,1981 report are attached.
3.
No additional information is required for this item.
4.
A Technical Specification change request will be submitted as noted in the response to 1.A(c) above.
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101 SOLTil ll! Gilt.tND.uESYE AUROILS. IllJ.NOIS tXAir7 April 26, 1982 Mr. Gary Miller Prairie Island 1;uclear Generating Station Route #2 Welsh, Minnesota 55089
SUBJECT:
Purge Valve Analysis for 18"r.Pratt Valves with Bettis Actuators Cus tomer P. O.
MC-05174 Pratt Order No:
D-029253-2
Dear Mr. Miller:
Per our telephone conversa tion, attached you will -find corrected pages 2,
16, 17, 18, and 19 of attachment #2 of the subject, report.
Very truly yours,
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- Manager, Contract & Proposal Engineering l
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SilMMAltY OF RTStil.TS VALvii CO..!PON!!NTS COMPONENT LOAD
. ANALYSIS -
STRESS ALL0tfA!fE CONI)iTION ItEF. PAGli 1.EYlit STitESSI:S
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ANALYSIS OF BOLTS
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CRITERIA:
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Bolts are critical co'mponents from the stand-point of scismic analysis.
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Considering the combined offect of seismic and the max. load.(P ) carried by a bolt will be:
direct loading, 2
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Length of thread engagement (h) =
87 I inche:
(d ") =
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Max. Shear Stress ( h ) = P_s.
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, Allowabic Stres s.ntensity -
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Comment:
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