ML20198D159
| ML20198D159 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 05/06/1992 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| ULNRC-2634, NUDOCS 9205180204 | |
| Download: ML20198D159 (4) | |
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[M' ION May 6.1992 w m umy h,LECTIUC E
Mr. A. Bert Davis Regional Administrator ULNRC-2634 U. S. Nuclear Regulatory Commission Region 111 799 Roosevelt Road Ulen Ellyn, IL 60137
Dear Mr. Davis:
INITIAL SALP 10 llO4Rll REPultT NO. 50-4S3/92001 CALLAWAY PLANT This responds to your letter dated March 30.1992. which transmitted the initial SAL P 10 Board Report for Callaway Plant covering the period February 1, 1990 through January 31,1992.
We have reviewed the report and have the following cununents and clarifica; ions:
A.
Page 3, paragraph 2:
We experienced six at-power reactor trips during this assessment period.
'lhe error in this paragraph may be due 10 couming tne b/12/90 manual trip in this group. It actually occurred when saberitical.
B.
Page 3. paragraph 3:
The core alteration described in this paragraph was an attempt to remove a reactor vessel specimen. These specimens are located outside the reactor core barrel. The potential reae:!vity chang during this operation is too small to measure. Literally spca!.ing. n: ming a vessel specimen can be interpreted as a core alteratior I.a the report shoulJ characterize the operation as having no impa;t on safety.
1140 IO 9205180204 920506 PDR ADOCK 05000483 P
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Mr. A. Bert Davis Page 2 May 6,1992 C.
Page 4, paragraph 5:
We acknowledge that total person-rem dose during Refuel IV was higher than expected. However, it is inaccurate to say that outage scheduling pressure was a primary contributor to increased dose. As pointed out in our April 22 meeting, we terminated RTD bypass piping decontamination efforts simply because the hydrolazer didn't work as expected. The greater-than-expected dose accumulated during ISI might have been reduced through better work planning as job problems were encountered.
We have since instituted a programmatic requirement to conduct in-progress dose assessments during the performance ofjobs witl high dose potential. Again, we do not believe schedule pressure was a primary contributor.
Our experience during Refuel IV prompted a number of initiatives to improve ALARA performance. As we discussed with you, we have:
1.
initiated design changes to reduce dose fields; 2.
reduced source through an improved methodology for RCS chemical shock:
3.
improved planning for work in containment through the use of a revised containment grid locator system; 4.
increased accountability for ALARA through the establishment of an outage review board; and 5.
increased work productivity through the use of special tool and specialized vendors.
Experience in the current outage indicates significant savings in dose have occurred, and such benefits will continue to accrue in the future.
D.
Page 10, paragraph 1:
The only weakness identified in the MOV program, as documented in inspection report 50-483/91020, was our use of a nonconservative power factor in degraded voltage analyses. Based on discussions in our April 22 meeting, we understand the SALP report will be revised to correct this paragraph.
Mr. a. Bert Davis Page 3 May 6,1992 E.
Page 11, paragraph 1:
We are troubled by the examples used to demonstrate that management effectiveness in insuring quality was mixed. As pointed out in our meeting, estimated critical position errors were Hrst recognized in cycle 4.
A task team evaluated these errors, initiated improvements and verificel that they did not represent a nuclear safety concern. Estimated critical positions calculated during startup for cycle 5 and after the December 30, 1990 trip showed good agreement between actual and predicted ECPs.
The next indication of a problem in ECP prediction did not occur until recovery from the November 1991 trip. Prior to this event, we had no indication that cycle 4 improvements had not resolved the ECP prediction error. Some months earlier, we had formed a cycle 5 task team to evaluate the cause of axial flux responses which did not match those predicted. The ECP error was linked with the axial Dux response and addressed by that team. Our cycle 5 team systematically investigated both problems, providing input to revised operating limits and assuring these problems were not a nuclear safety concern.
Regarding our reactor trip reduction efforts, we agree that results over the two-year SALP period are less satisfactory than expected. As you point out on page 3, however, no pattern or common root cause for the trips was discerned and none were caused by licensed operator error. Our program has initiated many improvements that have reduced the probability of reactor trips, and we acknowledge the need to continue efforts in this area.
We have already discussed the assertion that schedule pressure resulted in increased dose during the 1990 refueling outage.
F.
Page 11, paragraph 2:
Your belief that suf6cient evidence of a mispositioned throttle valve existed to make an earlier declaration of safety injectic' pump inoperability is a matter of opinion. We disagree with your characterization of this situation as a "less than conservative approach to safety" due to the timing of a declaration ofinoperability. We believe this overlooks the depth, scope and aggressiveness of the review effort performed to identify the actual facts in this situation. The concern involving safety injection Dows was identified by our engineering personnel during a related procedure development effort. Resolution of the concern was aggressively pursued
~
Mr. A. Bert Davis Page 4 May 5,1992 over a 72-hour period. The investigation involved reviews of records over several refueling outages and development and implementation of a comprehensive action plan which ultimately identified a mispositioned valve, A parallel effort evaluated the nuclear safety impact of the safety injection flow unbalance and concleded that the difference in flow would have no irrpact on the ability of the system to carry out its safety function.
An earlier declaration ofinoperability would have shortened our period of noncompliance with Technical Specifications, but it would not have hastened resolution on the issue from a nuclear safety perspective.
We appreciate the opportunity to d:scuss the items noted here with members of the Region III staff and representatives of NRR during our SALP meeting on l'
April 22,1992. We appreciate your recognition of our performance and acknowledge those sections of the report which identify areas for increased l
attention and improvement. Your critique of our operation and support of Callaway and our discussion of your observation; will help us continue to improve the safety and performance of the plant.
Very truly yours, f
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m Donald F. Schnell DFS/JCG/lkr cc:
R. L. Hague - Chief, Reactor Projects Section 3C, USNRC Region til L. R. Wharton - USNRC Licensing Project Manager (2 copies)
USNRC Document Control Dcd Manager - Electric Department, Missouri Public Service Conunission B. L. Bartlett - USNRC Senior Resident inspector Shaw, Pittman, Potts & Trou bridge