IR 05000237/1991006
| ML17202V069 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/17/1991 |
| From: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Reed C COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML17174A682 | List: |
| References | |
| EA-90-014, EA-90-14, NUDOCS 9104240070 | |
| Download: ML17202V069 (5) | |
Text
1*
Docket Ho.
50~231 License No. DRP-19 EA 91-014 **
Commonwealth Edisoh C6mpany ATTN:*
Mr. Corde 11 Reed Senior Vice President Opus West II I 1400 Opus Place Downers Grove~ Illinois 60515
Dear Mr.* Reed:
April 17, *1991" SUBJECT:
DRESDEN STATION, UNIT 2
'7'\\I'.
v-NOTICE OF VIOLATION AND PROPOSED* IMPOSITION OF CIVIL PENALTY - $100, 000 (NRC INSPECTION REPORT NO.. 50:-237/91006)
.
.
.
This refers ~o the insp~ct~6n conducted on January 23-28, 1991, ~f the events surrounding the December 17, 1990, failure of the containment integrated leakage
- rate test (CILRT) due to ~icessive leakage through the i~board flange on the torus purg~ exhaust containment isolation valve 2-1601-20A at the Dresden, Unit 2, facility.
The report documenting this inspectio~ was sent to you by letter dated February 7, 1991.
During this inspection a violation of NRC requirements was identified.
The event was reported.t.o the NRC in Licensee Event *Report No.90-018 _dated January 14, 1991.. An Enforc.enient Conference was held on February 14, 1991, at the NRC Region III Office to discuss the violation, its cause, and your corrective aC:tions.
Your letter dated Februa*ry 21, 1991, provided additional information c6ncerning your leakage rate calculations and potential safety significance evaluation; The report su~marizing this conference and discussing our position regarding your February 21, 1991, submittal was sent to you by letter dated March 15, 1991.
Finally, in a letter dated March 28, 1991, you pro.vided some additional information regarding assumptions and calculational methods.
.
.
'
.
'.
.
During the conduct 6f the CILRT in December 1990, your technical staff discovered a leak through the inboard flange of* the first of two torus purge exhaust con-tainment isolation valves..
Further investigation by your staff revealed that.
thi~ flange had last been wo~ked on during the winter 1988 refu~ling outage when the valve was replaced. * The leak rate at accident pressure was estimated to be considerably in excess of the 1.2 weight percent per day Technical Specification limit. Therefore, your staff concluded that Dresden Unit 2 had operated without required containment*integrity for the entire operating cycle from February 19, 1989, until September 23, 1990, when.Unit 2 ~as shut ~own fo~ refueling.
CERT! FI ED MAIL RETURN RECEIPT REQUESTED 9104240070 910417
- PDR ADOCK 05000237 Q
- Common~ealth Edison Company
- 2 -
Apri 1 17, 1991 The root causes of the ev~nt involved both maintenance and testing deficie~cies.
The flange. bolts were not s~fficiently tightened after the valve was.replaced.
The maintenance procedure used did not specify any acceptance criteria for
- flange_ fit-up and left it to the craft personnel to. determine the required bolt tightness.
We note that you repla~ed. seven additional purge valves during the same outage and that none of these valves ex~ibited flange leakage.
Addition-ally, your technical staff failed to recognize that the inboard flange of th~s valv'e, and other similar valves, constituted a containment.boundary that should hav~ been leakage tested after ~eplacing the valve.
As a result, the post-maintenance test did not test this boundary, and the lack.of containment integrity.was not discovered or ~orrected prior to returning the valve to.
service.
- The potential safety consequences of this even.tare significant. Since both containment isolation valves for the penetration are located outside of con-tainment, leakage thr*ough the flange goes directly to the secondary containment atmosphere, thus eliminating a red~ndant containment isolation barrier (i.e. the second containment isolation valve).
The flange leakage, by itself, resulted in a loss of containment iniegrfty.* The ~ontainment boundary is the last fission product barrier present. to prevent rad{ological exposure to the general public.
Had a design basis loss of coolant ~ccident occurred during the last operating cycle you may have exceeded the 10 tFR Part 100 whole body limit fo~ the two
hour site boundary do~er a~ well as, the 10 CFR Part 50 Appendix A limits for the _whole body, thyroid, and skin dose for control.room habitability. *Therefore, in accordance with the "General Statement of Policy and Procedure for NRC Enforce-ment Actions, 11 (E.nforcement Policy) 10 CFR*Part 2, Appendix C (1990), this
.violation has been categorized at Severity Level III.
The decision to classify this violation at Severity Level III, rathe~ than Severity Level JI was made only
.after considerable deliberation.
As part of that deliberation, additional cal~u lations were performed subsequent to our letter of March 15, 1991 by the Office
~f Nuclear Reactor Regulation.
Rather tha~ continue to debate the merits of variou~ assumptions and calculational methods in ar~iving at potential dose assessments and in order to remain focused on the underlying failures to properly
~ssemble the valve flange and leak test that flange, a Se~erity Level III cate-gorization, which can be.supported by design basis assessments as well as all reasonable realistic assessments, was.assigned.
..
.*..
.
We recognize that you took immediate corrective actions upon discovering the flange leak.age to_ establish containment integrity in that the leaking flange was repaired and you successfully completed the.CILRT.
In regard to y6ur long term correct~ve actions, we acknowledge that you had undertaken a ~eview, which was substantially complete at the time the flange leakage occurred, to identify all containment penetrations, their containment isolation capabilities and the 10 CFR Part 50 Appendix J testing requirements for penetrations at your Dresden station and your other older. units.
We understand that the results of this review will be used by the mairitenance department t6 prompt ~ppropriate leakage rate testing review by the technical staff. This.will be implemented priorto.
the upcoming Dresden Unit 3 ref~eling outage. *We considered your corrective.
actions adequate to address this violation, however, we did not consider that the extent of those action~ warranted mitigation of the civil penalt~. You did not consider perf.orming a detailed comparison of this review with applicable
.e Commqnwealth Edison Company
- 3 April 17, 1991 maintenance procedures to identify other similar containment isolation components with potential post-maintenance testing deficiencies.
Although inadequate post-maintenance testing was identified as a root cause concern, corrective actiori in this regard was narrowly focused at 10 CFR Part 50 Appendix J testing of _flanges.
Other l~akage rate testing corrective actions include the evalua- :
tion of testi~g methods to allow localized post-maintenance testing ~f the subject flanges by April 15, 1991~ a temporary change to the valve replacement procedure prior to its next use to specify appr:opriate post-maintenance testing
~henever the. integrity of the flanges is disturbed, revision of the leakage rate program procedure to caution against inappropriate application Cf standard periodic local leak rate test line-up~ for post-maintenance testing, and a review of Information Noti~e 86-16 to determine if additional actions are-required.. We understand that a temporary procedure change to the valve replace-ment procedure will be made prior to it~ next use to include requirements for*
adequate flange fit~up including ~ightening of flange bolt~.. In the interim, you will be relying on the station ~ork analyst's pre-job ~hecklist to ensure that adequate guidance is provided in future work packages concerning bolting requirements:
You also committed to issuing a directive on bolting practices during the second quarter 1991.
- To emphasize the importance the NRC places on ensuring that the tontainment will be capable of performing its safety function of preventing significant releases of radioactive material to the environmen~.* the need to specify acceptance criteria for flange fit-up including bolt tightening, and the need to perform approp~iate.post-maintenance testing, I *have been authorized, after consultation with the Director, Office of Enforcement, and the Deputy Executive Director for Regional Oper~tibns, to issue the enclosed Notice of Violation and Proposed Imposition of Civil Penalty (Notice).in the amount of $100,000 for the Severity _Level III violation.. The<base value of a civil penalty. for a Severity Level III violation is $50,000.
Th~ es~alation and mitigation factors in the *
Enforcemerit Policy were considered.
.
.
Mitigation of the base civil penalty ~as* not warranted for identifica~ion and.
reporting i~ that the event was self~disclosing and was identified as a result of the failure of a required CILRT.
Additionally, you had a~ple opportunities to identify the vi6lation prior to the December 1990 CILRT.. Your Dresden
. primary containment leakage testing program.assessment failed to identify that the flange was part of the containment boundary and was not being tested under the existing program.
Your local leakage rate testing improvement programi which included a review of 10 CFR Pa~t 50 Appendix J correspondence, failed to adequately address.Xnformation Notice 86-16 which discussed a similar problem; In Augu~t 1989, the Boiling Water Owners Group position from NED0-31722,
"Standardized Testing Recommendations for Containment Integrity Testing,
recommended that untestable leakage paths be either subjected to functional testing or made part of the type 11A 11 test* boundary. *The issue of ensuring that
. all valves and penetrations were addressed by the. containment testing program had also been identified.in.Dresden Inspection Report No. 50-237/90006 issued in Mar~h 1990, which included a violation for failure to incorporate the service air system into the CILRT valve line-up procedure.
A thorough review of Quad Cities Inspection Report No, 50-254/89024; 50-265/89024 issued in June 1990 and
- your reply to the report, should have enabled your staff to recogni~e that test i n*g of the inboard purg_e valve fl ariges was a.l so required at Dresden.
- Commonwealth Edison Company
-..4 April 17,. 1991
.Although the corrective actions you have taken and plan to take are acceptable*
as discussed above, we determined that they were not sufficiently comprehensive or tim~ly to ~~~rant mitigation.
Dresden Unit 2 did not.have contairiment inte-grity at any time wh~le the reactor was critical during the previous operating cycle which is a particularly significarit continuing violation. Therefdre, the*
base. civil penalty was. escalated by 100% for duration.
The other adjustment*
factors in the Policy were considered ~nd no further adjustment to the base civil penalty is considered appropriate.
Therefore,. based on the above,.the ba.se civil pen a 1 ty has ~een increased by 100%.
You are required to respond to this letter and should follow the instructions*
specified in the enclosed Notice when preparing your response.
ln ycur response,
~ou should.~ocument the specific actions take~ and any additional actions you plan to prevent recurrence. *After reviewing your response to this.Notice, including your proposed corrective actions and the results of future inspections, the NRC will determine whether further NRC en.forcement action i.s necessary *to ensure compliance with NRC regulatory requirements.
In accordance with 10 CFR 2.790 of the NRC's "Rules of Practice," a copy of this letter and its encloiure will be placed in the NRC Public Document Room.
The responses directed by this letter and the enclosed Notice are not subject to the clearance procedures of the Office of Management and Budget as required by the Pap_erwork Reduction Act of 1980, Pub. L. No.* 96-511.
Enclosure:
Notice of Violation and Proposed Imposition of Civil Penalty cc w/enclosure:
.
0. Galle, Vite President BWR Operations T. Kovach, Nuclear.
Licen~ing Manager E. D. Eenigeriburg, Station Manager*
.. DCD/DCB (RIDS)
OC/LFDCB Resident Inspectors LaSalle, Dresden, Quad Cities Richard Hubbard J. W. McCaffrey, Chief, Public Utilities Oi~ision Robert New~ann, Office of Public Counsel, State of Illinois Center*
James Lieberman, Director OffiG~_of Enforcement ().
Sincerel~,
Original signed by H. J. Miller for A. Bert Davis
.
Reg{onal Administrator t Rep... ~RI.. Rill
.
D:OE.
. DEDR
Peaerscin/db 0411~191.
w~-
11 er ~Greenman 4/,~/91 0411 p/91 (Rei: 1 d vi a FAX)
Lieberman Sniezek 04/08/91 04/12/91
Commonwealth Edison Company DISTRIBUTION:
PDR.
LPDR
. SECY CA J.Sniezek, DEDR J.Goldberg, OGC*
T.Murley, NRR J.Partlow, NRR Enforcement Coordinators RI, RII, RIV, RV F.Ingram, GPA/PA D.Williams, OIG B.Hayes, OI E.Jordan, AEOD J.Luehman, OE Day Fi le EA File State of Illinoi~
RAO: RI! I *
SLO: RI II PAO: RII I IMS:~III
- 5 -
April 17, 1991