ML20041G052
| ML20041G052 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 03/08/1982 |
| From: | Clark R Office of Nuclear Reactor Regulation |
| To: | Mayer L NORTHERN STATES POWER CO. |
| References | |
| TASK-2.E.4.2, TASK-TM NUDOCS 8203190128 | |
| Download: ML20041G052 (10) | |
Text
{{#Wiki_filter:. q K ', j;7 fl t. l kCYY MR 8 1993 yS (G&Q% i Docket Nos. 50-282 TT 50-306 M"Q / y[ \\tg i ui .s sd 41 GN " (C Mr. L. O. Mayer, Manager -i i n 7 {M Nuclear Support Services .9 Northern States Power Company M M,. ;. S l 414 Nicollet Ma11-8th Floor ,s M Minneapolis, Minnesota 55401 X'q"m \\ t i-2
Dear Mr. Mayer:
In our letter of November 29, 1978, we identified the generic concerns i of purging and venting of containments to all operating reactor licensees and requested your response to these concerns. Our review of your response i was interrupted by the TMI accident and its demands on staff resources. J Consequently, as you know, an Interim Position on containment purging and venting was transmitted to you on October 29, 1979. You were requested to i comit to our interim position and this comitment is to remain in effect 4 pending completion of our long term review of your response to our [ November 29, 1978 letter. l By letters dated November 14, 1979 November 7, 1980 and December 3, 1981 you committed to our interim position by specifically committing to keep i the isolation valves in the purge and vent systems closed whenever the l reactor is above cold shutdown. This commitment will remain in effect until: i Containment ventilation logic modifications have been completed and found acceptable by the NRC Staff j i The evaluation of containment purge and vent valve operability ( l hhas been completed and found acceptable by the NRC Staff. i As a result of our review of these submittals, we find your commitment to our interim position acceptable and this decision was confirmed by our letter dated November 2,1981. Over the past several months we and our contractors have been reviewing the responses to our November 1978 letter to close out long-term review of this rather complex issue. The components of this review are as i follows: l I. Confomance to Standard Review Plan Section 6.2.4 Revision 1 and l Branch Technical Position CSB 6-4 Revision 1 These documents were provided as enclosures to our November 1978 l 1etter. 4 cmce > su.w we> 8203190128 820308 ~ ~ - - - - ~ ~~ - -- - PDR ADOCK 05000282 t-p PDR OFFICIAL RECORD COPY usom--mee r r
? Ll. ~ l l II. Valve Operability Although the Interim Position allowed blocking of the valves at partial-open positions, this is indeed an interimposition. Earlier we requested a program demonstrating operability of the valves in accordance with our " Guidelines for Demonstrative Operability of Purge and Vent Valves." These Guidelines were sent to you in our letter of September 27, 1979. There is an acceptable alternative which you may wish to consider in lieu of completing the valve qualification program for the large butterfly-type valves. This would be the installation of a fully-qualified mini-purge system with valves 8-inches or smaller to bypass the larger valves. Such a system change might prove more timely and more cost-effective. The system would meet BTP CSB 6-4 item B.I.c. III. Safety Actuation Sicnal Override This involves the review of afety actuation signal circuits to ensure that overriding of one safety actuation signal does not also cause the bypass of any other safety actuation signal. IV. Containment Leakage Due to Seal Deterioration Position B.4 of the BTB CSB 6-4 requires that provisions be made to test the availability of the isolation function and the leak-age rate of the isolation valves in the vent and purge lines, individually, during reactor operations. But CSB 6-4 does not explain when or how these tests are to be performed. Enclosure 1 is an amplification of Position B.4 concerning these tests. The status of our long-term review of the above items for the Pralrie 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 A. In order that we nay 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 c schedule for the debris screens for Units 1 and 2. l (b) Commit to limit the use of the purge system to a specified l annual time that is commensurate with identified safety needs. By letter dated December 3,1931 you comitted [ that when purge and vent operation is resumed it would be on an "a s low as acht evable" basis pend 1ng comt letion or ...._.the long-term review. #-other-4ssues --T5-- ym 2re-r.aqueste d...................... omce > sumur > .....to..da.fint.."n..l.u,.u. whievable...1 0...t.erms.. 9.f...M p.t9.ds.t,9,,,hp,t ts,,p.e,t.,,,,,,,,,,, m afety needs, ....a..n..n..u......b.a. g:.e..d o..n past s om> l NRC FORM 318 (10-80) NACA* 0240 OFFiClAL RECORD COPY usam mi-w.ea
i \\ .o-1 i t ~ l (c) Propose a Technical Specification to require that you perform leakage integrity tests of the isolation valves in the con-l tainment purge lines at least once every three months. The i l proposed technical specification applies to the isolation l valves in the low volume purge system since you have comitted j by letter dated December 3,1981 not to use the high volume l purge system when the reactor is above cold shutdown condition. [ The proposed technical specifications are also to include a pro-l vision that the resilient seals of the isolation valves in the t l 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 met then high volume purge and vent system will be leak tested at least once every six months. If hcwever the resilient seals of the high volume purge j 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 f that the high volume purge was used during the shutdown period. Leak testing is to include the isolation valves as well as the l protective devices for the resilient seals. You are requested to respond to items (a) and (b) within 45 days of the date of this letter. For item (a) provide a comitment to the debris screen require-l ments (i.e., enclosure 2) and provide your installation schedule. The technical specifications requested in item (c) should be proposed within 90 days of the l receipt of our safety evaluation report covering this purge and vent issue. However you are requested to provide a comitment related to your position on r the protection of the resilient seals of the isolation valves in the high volume purge and vent system within 45 days of the date of your receipt of this letter. { i Your commitment for the protection of resilient seals is to include a brief i decription of the mechanical changes to be made in the system in order to achieve the desired results. These technical specifications are also discussed below j in paragraph 4 of this letter and a model for this technical specification is l l included as part of Enclosure 3. ( 2. Valve Operability Your letter of December 3,1981 transmitted the Henry Pratt Company analysis of the purge valves at the Prairie Island Nuclear Gener-ating Plant Units 1 and 2. This analysis is currently being re-viewed by the staff and additional input is not required at this time. 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 .., m a.a a.n . a.. a. ...< a, an, + w - u <, ,_w ..b..a't a...s.o.m.e 5.g.t. P.a'ra5. 5e1 3evieiof eheareds'a5ty features reset a l omcc> gg d'6' 'j s'd'i'i's"'d'S"'M'B'mM" M'a'.' "N" ' ' ' ' 6 j sonname) ..,9,.g $ g.ggg..s mu4 Mdh h LcrcA d W-mp .and..went.. review.............. omy Nac ronu sia oo.apacu oua OFFICIAL RECORD COPY usam mi mm
f y< ',u'.. m m l . 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 submit the details of your proposed i leak rate test program together with the TS (.hange incorporating the test requirement (1.A.(c) above). In closing, you may have noted the similarity of this long-term generic issue \\ with Item II.E.4.2 of NUREG-0737. TMI Action Plan. Except for Position 5 of Item II.E.4.2, the review of the remaining outstanding positions of Item II. E.4.2 will be completed by this purge and vent review. Our acceptance of Prairie Island Units 1 and 2 with respect to Item II.E.4.2.(5) has been docu-mentedin our letter dated December 2,1981. Thus, your assistance in complet- 'ing the outstanding purge and vent items, noted above, is necessary to complete Item II.E.4.2. Please contact your NRC Project Manager should you have any questions. Sincerely. Original signed by Robert A. Clark Robert A. Clark, Chief Operating Reactors Branch #3 i Division of Licensing
Enclosures:
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~ Northern States Power Company CC: Gerald Charnoff, Esquire Bernard M. Cranum Shaw,.Pi ttman, Potts and.Trowbridge - Bureau of Indian Affairs, DOI ' 1800 M Street, N.W. 15 South 5th Street Washington, D. C. 20036 Minneapolis, Minnesota 55402 Mr. Louis' J. Breimburst Mr. R. L. T.annner Executive Dir ctor County Auditor Minnesota Pollution Control Agency Red Wing, Minnesota 55066 1935 W. County Road B2 Roseville, Minnesota 55113 U. S. Enyironmental Protection Agency Federak Activities Branch The Environmental Conservation Library Region Y Office Minneapolis Public Library ATTN: Regional Radiation 300 Nicollet Mall Representative Minneapolis, Minnesota 55401 230 South Dearborn Street Chicago,_ Illinois 60604 Mr. F. P. Tierney, Plant Manager Prairie Island Nuclear Generating Plant v Northern States Power Company . Route 2 Welch, Minnesota 55089 Jocelyn F. Olson, Esquire Special Assistant Attorney General Minnesota Pollution Control Agency 1935 W. County Road B2 Roseville, Minneosta 55113 U.S. Nuclear Regulatory Commission Resident Inspectors Office Route #2, Box 500A Welch, Minnesota 55089 Regic.nal Administrator Nuclear Regulatory Commission, Region III Office of Inspection and Enforcement 799' Roosevelt Road Glen Ellyn,'Ill.inois 60137 W
~ -~ ~ ._2_ L Enciosure 1 PURGE / VENT VALVE LEAKAGE TESTS 'he long tenn resolution of Generic Issue B-24, " Containment Purging tion of .During Normal Plant Operation," includes, in part, the implementaItem B.4 specifies Item B.4 of Branch Technical Position (BTP) CSB 6-4. that provisions should be made for leakage' rate testing of the (purge / vent Although system) isolation valves, individually, during reactor operation. Item B.4 does not address the testing frequency, Appendix J to 10 CFR Part 50 specifies a maximum test interval of 2 years. As a result of the numerous reports on unsatisfactory performance of the resili_ent seats for the isolation valves in containment purge and vent lines (addressed in OIE Circular 77-11, dated September 6,1977), Generic Issue B-20, " Containment Leakage Due to Seal Deterioration," was established to evaluate the matter and establish an appropriate testing frequency for the Excessive leakage past the resilient seats of isolation isolation valves. valves in purge / vent lines is typically caused by severe environmental con-Consequently, the leakage test ditions and/or wear due to frequent use. frequency for these valves should be keyed to the. occurrence of severe environ-mental conditions and the use of the valves, rather than the current require-ments of 10 CFR 50, Appendix J. It is re' commended that the f'ollowing provision be added to the Technical Specifications for the leak testing of purge / vent line isolation valves: " Leakage integrity tests shall be perfonned on the containment with resilient material seals in (a) active isolation valves purge / vent systems (i.e., those which may be operated'during plant operating Modes 1 through 4) at least once every three months and (b) passive purge systems (i.e., those which must be administrative 1y contro11.ed closed during reactor operating Modes 1 through 4) at least once every six months." By way of clarification, the above proposed surveillance specification is predicated on our expectation that a plant would have a need to go to cold To cover the possibility that this may shutdown several times a year. However, it not occur, a maximum test interval of 6 months is specified. l is not our intent to require a plant to shutdown just to conduct the valve l If licensees anticipate long. duration power oper-leakage integrity tests. ations with infrequent shutdown, then installation of a leak test connection This. that is accessible from outside containment may be appropriate.It will not be-will pennit simultaneous testing of-the redundant valves. possible to satisfy, explicitly the guidance of Item B.4 of BTP CSB 6-4 (which states that valves should be tested individually), but at least some testing of the valves during reactor operation will be possible. D 9
4 . i It is intended that the above proposed surveillance specification be applied 1.e., the to the active purge / vent lines, as well as passive purge lines: purge lines that are administrative 1y controlled closed during reactor oper-The reason for including the passive p. urge lines is that I ating modes 1-4. B-20 is concerned wtih the potential adverse effect of seasonal weather con-Consequently, passive ditions on the integrity of the isolation valves. purge lines must also be included in the surveillance program. The purpose of the leakage integrity tests of the isolation valves in the containment purge and vent lines is to identify exces;ive degradation o the resilient seats for these valves. with the precision required for the Type C isolation valve tests in 10 CFR These tests would be performed in addition to the quantitative Type C tests required by Appendix J and would not relieve th Part 50, Appendix J. licensee of the responsibility to conform to the-requirements of Appendix J In view of the wide variety of valve types and seating basis. e e e 8 9 e t
GUIDELINES FOR USE IN EVALUATION OF PURGE AND VENT SYSTEM DEBRIj SCREEN DESIGri The debris screen should satisfy the following criteria: I design and installed about .The debris screen should be seismic Category 1. one pipe diameter away from the inner side of the inboard isolation v The piping between the debris screen and the isolation valve should a 2. be seismic Category I design. The debris screen should be designed to withstand--the LOCA differenti 3. pressure. The debris screen should be designed similar to that shown in the att 4. Figures 1 and 2. ENCLOSURE 2
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i ENCLOSURE. 3 ~ i CONTAINMENT SYSTEMS LIMITING CONDITION FOR OPERATION P The containment purge supply and exhaust iso'lation valves may 3.6.1.7 The ' be open for safety-related reasons [or shall be locked' closed]. containment vent line isolation valves may be open for safety-related reasons [or shall be locked closed]. t ' APPLICABILITY: MODES 1, 2, 3, and 4. ACTION: (For plants with valves closed by technical spe,cification) With one containment purge supply and/or one exhaust isolation valve open, close the open valve (s) within one hour or-be in at least HOT l STANDBY within the next 6 hours and in COLD SHUTDOWN within the following -v 30 hours. L (For plants with valves that may be opened by technical specifications) With one containment purge supply and/or o.ne exhaust isolation or vent. 1. valve inoperabic, close the associated OPERASLE valve and either restore the inoperable valve to OPERABLE status within 72 hours or lock the OPERABLE valve closad. Operation may then continue until perfomance of t,he next required 2. valve test provided that the OPERABLE valve is verified to be locked t closed at least once per 31 days. i Otherwise, be in at'least HOT STANDBY within the next six hours and 3. in COLD SHUTDOWN within the following 30 hours. The provisions of Specification 3.0.4 are not applicable. '4. SURVEILLANCE RE0VIREMENTS -inch containment purge supply and exhaust isolation valves The 4.6.1.7.1 -incli~ vent line isolation valves shall be determined locked closed and the at least7nce per 31 days. The valve seals of the purge supply and exhaus_t isolation valves 4. 6.1. 7. 2 and the vent line isolation valves shall be replaced at least one per __ years. 1 3/4 6-10 r JCA--
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~* CONTAINMENT SYSTEMS 3/4 4.6.3 CONTAINMENT ISOLATION VALVES _ LIMITING CONDITION FOR OPERATION 3.6.3, The containment isolation valves specified in Table 3.6-1 shall be OPERABLE with isolation times as shown in Table 3.6-1. APPLICABILITY: MODES 1, 2, 3 and 4. ACTION: With one or more of the isolation valves (s) specified in Table 3.6-1 inoperable, maintain at least one isolation valve OPERABLE in each affected penetration that is open and either: Restore the inoperable valve (s) to OPERABLk status within 4 hours a. - -s - or Isolate each affected penetration within 4 hours by use of at least b. one deactivated automatic valve secured in the isolation position, or Isolate each affected penetration within 4 hours by use "of at least. c. one closed manual valve or blind flange; or Be in at least HOT STANDBY within the next 6 hours and in COLD d. SHUTDOWN within the following 30 hours. SURVEILLANCE REOUIREMENTS The isolation valves specified in Table 3.6-1 shall be demonstated l 4.6.3.1 OPERABLE prior to returning the valve to service after maintenance, repair or replacement work is performed on the valve or its associated actuator, control or power' circuit by performance of a cycling test, and verification of isola-tion time. I 3/4 6-14
a ~ E ' ~ CONTAINMENT SYSTEMS -~ SURVEILLANCE REQUIREMENTS (Continued) 4.6.3.2 Each isolation valve specified in Table 3.6-1 shall be demonstrated OPERABLE during the COLD SHUTOOWN or REFUELING MODE at least once per 18 months by: Ver ;fying that on a Phase A containment isolation test signal, each a. Phase A isolation valve actuates to its i, solation position. b. Verifying that on a Phase B containment isolation test signal, each Phase B isolation valve actuates to its isolation position. 4.6.3.3 The isolation time of each power operated or automatic valve of Table 3.6-1 shal1 be determined to be within its li_mit when tested pursuant to Specification 4.0.5. 4.6.3.4 The containment purge and vent iso 1'ation v'Ilve's shall be demonstated ~ OPERABLE at intervals not to exceed months. Yalve OPERABILITY shall be determined by verifying that when th'e measuued leakage rate is added to the leakage rates determined pursu. ant to Specification 4.6.1.2.d for all other Type B and C penetration, the combined leakage rate is less than or equal to 0.60La. However, the leakage rate for the containment purge and vent isolation valves, shall be compared to the previously measured leakage rate to detect excessive valve degradation. e 3/4,6-15 e W g t .}}