ML20040H328
| ML20040H328 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 02/12/1982 |
| From: | Withers B PORTLAND GENERAL ELECTRIC CO. |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| TAC-42594, NUDOCS 8202180095 | |
| Download: ML20040H328 (5) | |
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February 12, 1982 Trojan Nuclear Plant Docket 50-344 License NPF-1 Director of Nuclear Reactor Regulation ATTN:
Mr. Robert A. Clark, Chief Operating Reactors Branch No. 3 Divisfon of Licensing U. S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Clark:
Containment Purging and Venting By letter dated December 4, 1981 the NRC requested information and proposed Technical Specification changes concerning the operation and testing of Containment purge and hydrogen vent valves at the Trojan Nuclear Plant. PGE's response to this NRC letter is contained in.
Sincerely, o
M Bart D. Withers Vice President Nuclear Attachment c:
Mr. Lynn Frank, Director State of Oregon Department of Energy pk 0202180095 820212 9% \\
PDR ADOCK 05000344 P
PDR 121 S.W Salmon Street Portanct Cugon 97204
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Mr. Robert A. Clark, Chicf Trojan Nuclear Plant Operating Reactors Branch No. 3 Docket 50-344 License NPF-1 Page 1 of 4 NRC REQUEST:
1.
NRC 7-28-81 Letter. Item 1: Conformance to SRP Section 6.2.4 Rev. I and BTP CSB 6-4 Rev. 1
'"... that you propose a Technical Specification to require that the containment purge valves be locked closed in Operational Modes 1 through 4, and... t at you propose a Technical Specification to h
require that the hydrogen vent valves be normally closed and opened only when and for the duration of time actually necessary." The surveillance requirement for verifying every 31 days that the purge valves are locked closed should be added to Specification 4.6.3.1.1.
PGE RESPONSE:
A Technical Specification change to require that electric power be removed from Containment purge supply and exhaust valves with motor operators and that the air supply be isolated from Containment purge supply and exhaust valves with air operators during Modes 1 - through 4 will be proposed by April 30, 1982. The proposed Technical Specification change will indicate that the Containment purge supply and exhaust valves are not testable during plant operation. Electric power and air supplies will be removed since it is not possible to physically lock the purge supply and exhaust valves closed. An additional surveillance requirement, 4.6.3.1.4, will be added to require verification every 31 days that electric power and air supplies to the purge supply and exhaust valves is removed during Operating Modes 1 through 4.
A Technical Specification change to require that the hydrogen vent supply and exhaust valves be normally closed, and opened only when and for the duration of time actually necessary will also bu proposed.
NRC REQUEST:
2.
NRC 7-28-81 Letter, Item 2: Valve Operability "You are requested to provide your expected schedule for submittal l
of hydrogen vent valve qualification data in your response to this letter."
i PCE RESPONSE:
i Our letter of October 2,1981, stated that new hydrogen vent supply and exhaust valves will be purchased and qualified in accordance with the NRC guidelines dated September 27, 1979. Qualification data for these valves is scheduled to be submitted by December 30, 1982.
NRC REQUEST:
3.
NRC 7-28-81 Letter Item 3: Safety Actuation System Signal Override "This item is still under NRC review, but completion is scheduled in the near future. Completion of this item is planned to include i
]
O Mr. Robert A. Clark, Chief Trojan Nuclear Plant Operating Reactors Branch No. 3 Docket 50-344 License NPF-1 Page 2 of 4 completion of item II.E.4.2, item 7 Radiation Signal on Purge Valves.
Although not indicated in the title, this will include a review of your design for closure of the hydrogen vent valves on a containment high radiation signal. A conforming revision to Technical Specification 4.6.3.1.2(b) (page 3/4 6-16) will be needed, which could most efficiently be included with your upcoming LCA."
PGE RESPONSE:
Plant modifications have been completed which cause the hydrogen vent supply and exhaust valves to close upon receipt of a Containment high radiation signal. A Technical Specification change to Surveillance Requirement 4.6.3.1.2(b) to require verification that Containment purge and hydrogen vent supply and exhaust valves will actuate to their isola-tion position on a high radiation signal will be proposed by April 30, 1982.
NRC REQUEST:
4.
NRC 7-28-81 Letter, Item 4 Containment Leakage Due to Seal Deterioration "We request that you submit proposed Technical Specifications as con-tained in enclosure (3) to our July 28 letter, modified as follows:
Leakage testing for the containment purge valves should be conducted prior to entering Mode 4 (if not performed in the previous 6 months) and at 6-month intervals thereafter.
There are two sound reasons for this. First, proof-testing before cntering Mode 4 will ensure that the valves are leak-tight before entering an extended operating pe riod.
Second, the probability of a successful test 6 months later would be enhanced if the valves remained locked closed and undisturbed since the previous test.
Similar logic does not apply to the hydrogen vent valves since they are not locked closed and are operated frequently.
These should be tested every three months, as explained in enclosure (1) to our July 28, 1981 letter.
Since you are planning to replace these valves, you may want to consider replacement valves that de not have resilient seal material. Such valves would be outside of the scope of this generic issue.
It is probable that current Appendix J testing schedules would be acceptable."
PGE RESPONSE:
With respect to the testing of Containment purge supply and exhaust valves, a Technical Specification to require leak testing of purge supply and exhaust valves prior to entering Operating Mode 4 from a cold shutdown condition (if not performed in the previous 6 months) and to require that these valves remain undisturbed between leak testing and Plant operation
Mr. Robert A. Clark, Chief Trojan Nuclear Plant Operating Reactors Branch
.3
-Docket 50-344 License NPF-1 Page 3 of 4 will be proposed. Degradation of the valve seats due to environmental extremes is not expected to be a problem at Trojan, as described in the PGE to NRC letter dated October 2, 1981. The only other failure mode identified is improper seating or seat degradation through use of the valves. Leak testing of Containment purge supply and exhaust valves after the last cycling prior to entering Mode 4 from a cold shutdown condition will ensure that excessive leakage does not exist to begin with.
Since they will not be opened in Modes 1 through 4 it will not be necessary to test them during Plant operation.
Although one Containment purge valve has demonstrated excessive leakage during the last two local leak rate tests (LLRT) (even though it was kept closed during normal operation), this valve was cycled during the refueling outage prior to leak rate determination.
Improper seating of the valve (after cycling) was identified as the cause of leakage. The proposed Technical Specifi-cations will require that the Containment purge supply and exhaust valves remain closed after leak rate testing and while in power operation in order to eliminate thia leakage potential.
The IST program is being revised to delete the requirement to test the Containment purge supply and exhaust valves during power operation, and a Technical Specification is being added as described in Item 1 above to require that the Containment purge supply and exhaust valves remain closed during Modes 1 through 4.
These measures will provide adequate assurance that these valves will not demonstrate excessive leakage during power operation.
The hydrogen vent supply and exhaust valves are tested annually every refueling outage per the requirements of Appendix J.
Because the present hydrogen vent supply and exhaust valves have not demonstrated a recurring history of excessive leakage, and since it is planned to replace the hydrogen vent supply and exhaust valves during the 1983 refueling outage with valve with nonresilient seats, a Technical Specification change which increases the frequency of leak testing is not necessary. At the present time, the hydrogen vent supply valves are not utilized during Plant operation. Only the hydrogen vent exhaust valves are utilized to i
facilitate Containment pressure equalization. Until the hydrogen vent supply and exhaust valves are replaced in 1983 with valves having nonresil-ient seats, we will remove electric power from the motor operators for the hydrogen vent supply valves (M010005, M010006, M010007 and M010008) and keep the hydrogen vent supply valves shut during Modes 1 through 4.
The testing frequency for the hydrogen vent exhaust valves will be increased such that they will be tested prior to entering Mode 4 from a cold shutdown condition (if not tested in the previous 6 months) and every 6 months thereafter until they are replaced with valves having nonresilient seats.
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Mr. Robert A. Clark, Chief Trojan Nuclear Plant Operating Reactors Branch No. 3 Docket 50-344 License NPF-1 Page 4 of 4 NRC REQUEST:
L 5.
NUREG-0737, II.E.4.2, Containment Isolation Dependability 1
Items 1 through {, Implement Diverse Isolation "These items are resolved, as documented in NRC letter of April 23, 1980."
Item 5, Containment Pressure Setpoint "We have received your LCA 80 of October 16, 1981. We expect to issue the amendment related to this issue on or about November 23, 1981. When issued, this item will be resolved."
l Item 6, Containment Purge Valves
" Resolution of this item will be achieved when the actions described in I
paragraph 1 above have been completed."
Item 7, Radiation Signal on Purge Valves
" Resolution of this item is as described in paragraph 3 above."
Item 8, Technical Specificationa "This item concerns only the Category "A" Lessons Learned Technical Specifications and was resolved with the issuance of Amendment No. 56 on 1-21-81."'
PGE RESPONSE:
PGE concurs with the above-listed resolutions regarding items of NUREG-0737, II.E.4.2, Containment Isolation Dependability, as described in the referenced letters and in our response to Items 1 and 3 of this letter. Amendment 68 was issued on November 23, 1981 to close out Item 5 above.
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