05000483/LER-2010-009-01, Regarding High Energy Line Break (HELB) Program Deficiencies

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Regarding High Energy Line Break (HELB) Program Deficiencies
ML112590397
Person / Time
Site: Callaway Ameren icon.png
Issue date: 09/16/2011
From: Diya F
Ameren Missouri
To:
Office of Nuclear Reactor Regulation, Document Control Desk
References
ULNRC-05819 LER 10-009-01
Download: ML112590397 (10)
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LER-2010-009, Regarding High Energy Line Break (HELB) Program Deficiencies
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(i)
10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded
10 CFR 50.73(a)(2)(viii)(A)
10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
10 CFR 50.73(a)(2)(viii)(B)
10 CFR 50.73(a)(2)(iii)
10 CFR 50.73(a)(2)(ix)(A)
10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(x)
10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor
10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown
10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
4832010009R01 - NRC Website
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text

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WAmeren MISSOURI September 16, 2011 ULNRC-05819 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Ladies and Gentlemen:

10 CFR 50. 73(a)(2)(ii)(B)

DOCKET NUMBER 50-483 CALLA WAY PLANT UNIT 1 UNION ELECTRIC CO.

FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2010-009-01 IDGH ENERGY LINE BREAK (HELD) PROGRAM DEFICIENCIES Fadi M. Diya Vice President Nuclear Operations Ameren Missouri Callaway Plant T 573.676.641 1 F 573.676.4056 Reference: ULNRC-05764, "Licensee Event Report 2010-009-00 High Energy Line Break (HELB) Program Deficiencies," January 27, 2011.

The enclosed licensee event report is submitted in accordance with 10 CFR 50.73 to report the identification of programmatic deficiencies in the implementation of the Callaway Plant High Energy Line Break (HELB) Program. These deficiencies resulted in previous events in which operability of plant equipment cannot be demonstrated.

The enclosed report supplements Licensee Event Report 2010-009-00 submitted via ULNRC-05764.

This letter does not contain new commitments.

ACS/nls Enclosure: LER 2010-009-01 Fadi MDiya Vice President Nuclear Operations Junction CC & Hwy 0 PO Box 620, MC CA-460 Fulton, MD 65251 AmerenMissouri.com

ULNRC-05819 September 16, 2011 Page2 cc:

Mr. Elmo E. Collins, Jr.

Regional Administrator U.S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Mohan C. Thadani (2 copies)

Senior Project Manager, Callaway Plant Office ofNuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 0-8G 14 Washington, DC 20555-2738 Mr. James Polickoski Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 0-8B 1 A Washington, DC 20555-2738

ULNRC-05819 September 16, 2011 Page 3 Index and send hardcopy to QA Flle A160.0761 Hardcopy:

Certrec Corporation 4200 South Hulen, Suite 422 Fort Worth, TX 76109 (Certrec receives ALL attachments as long as they are non-safeguards and may be publicly disclosed.)

LEREvents@inpo.org (must send the WORD version of the LER to this address)

Electronic distribution for the following can be made via LER ULNRC Distribution:

A. C. Heflin F. M. Diya C. 0. Reasoner III L. H. Graessle D. W. Neterer S. A. Maglio S. L. Gallagher K. W. Kuechenmeister D. T. Wingbermuehle J. D. Schnack C. B. Serfas R. M. Nelson NSRB Secretary T. B. Elwood D. E. Dumbacher (NRC)

B. D. Brooks (WCNOC)

Ms. Diane M. Hooper (WCNOC)

Mr. Tim Hope (Luminant Power)

Mr. Ron Barnes (APS)

Mr. Tom Baldwin (PG&E)

Mr. Wayne Harrison (STPNOC)

Ms. Linda Conklin (SCE)

Mr. John O'Neill (Pillsbury Winthrop Shaw Pittman LLP)

Missouri Public Service Commission Records Center (INPO)

NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150*0104 EXPIRES: 10/31/2013 (10-2010)

, the NRC may digits/characters for each block) not conducl or sponsor, and a person is not required to respond to, the information collection.

13. PAGE Callaway Plant Unit 1 05000483 1 OF 7
4. TITLE High Energy Line Break (HELB) Program Deficiencies
5. EVENT DATE
6. LEA NUMBER
7. REPORT DATE
8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.

MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 12 1

2010 2010. 009. 01 9

16 2011

9. OPERATING MODE
11. THIS REPORT IS SUBMITIED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)

D 20.2201 (b)

D 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C)

D 50.73(a)(2)(vii)

MODE1 D 20.2201 (d)

D 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A)

D 20.2203(a)(1)

D 20.2203(a)(4) 1:8:1 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(2)(i) 0 50.36(c)(1 )(i)(A)

D 50.73(a)(2)(iii)

D 50.73(a)(2)(ix)(A)

10. POWER LEVEL D 20.2203(a)(2)(ii) 0 50.36(c)(1 )(ii)(A)

D 50.73(a)(2)(iv)(A)

D 50.73(a)(2)(x)

D 20.2203(a)(2)(iii)

D 50.36(c)(2)

D 50.73(a)(2)(v)(A)

D 73.71 (a)(4)

D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii)

D 50.73(a)(2)(v)(B)

D 73.71 (a)(5) 100%

D 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A)

D 50.73(a)(2)(v)(C) 0 OTHER D 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)

D 50.73(a)(2)(v)(D)

Specify in Abstract below or in In the cases below involving HELB barrier impairments performed under Fire Protection Impairment Permits (FPIPs), the necessary compensatory measures (e.g., hourly or continuous fire watches) to maintain fire and pressure boundary functions were met. However, due to programmatic deficiencies in the HELB program, it is assumed for this analysis that compensatory measures were not sufficient to maintain HELB barrier function.

(The causes and events that led to the overall programmatic deficiencies are discussed in Section 6 of this LER.)

Case 1: Main Steam Line Break in the Main Steam Tunnel Affecting the Auxiliary Building Door DSK11273 provides a barrier between the main steam tunnel and the Auxiliary Building stairwell A-2.

This door was blocked open under twelve FPIPs in the previous three years. With DSK11273 open, its HELB barrier function is defeated, exposing the stairwell to the effects of a postulated Main Steam Line Break (MSLB) in the main steam tunnel.

The piping in the main steam tunnel is especially robust and designed not to exceed stress limits that would cause a pipe failure. However, a failure of this piping was assumed for the purposes of this analysis.

With door DSK11273 impaired, the elevated pressure following a postulated MSLB could have caused stairwell doors to three floors of the Auxiliary Building to fail. The resulting environment on these floors could adversely impact the 'A' Train level transmitters for the Reactor Vessel Level Indication System (RVLIS).

Operability of these transmitters cannot be demonstrated for this postulated MSLB scenario with DSK11273 impaired.

RVLIS is included in the Post-Accident Monitoring (PAM) instrumentation required by Callaway Plant Technical Specification (TS) 3.3.3. Required Action A.1 of TS 3.3.3 directs restoration of the inoperable channel within 30 days.

Within the three years preceding discovery of the event, the longest single impairment of DSK11273 lasted for 61 hours7.060185e-4 days <br />0.0169 hours <br />1.008598e-4 weeks <br />2.32105e-5 months <br />, 9 minutes. DSK11273 was impaired for a cumulative total of 161 hours0.00186 days <br />0.0447 hours <br />2.662037e-4 weeks <br />6.12605e-5 months <br />, 49 minutes over this period.

Case 2: Main Steam Line Break in the Turbine Building Doors DSK13291, DSK14032, and DSK33044 are HELB boundary doors that separate the Turbine Building from the Auxiliary Building. At least one of these three doors was blocked open under a number FPIPs since December 1, 2007. Impairing one of these doors allows a postulated MSLB in the Turbine Building to affect areas in the Auxiliary Building containing equipment not qualified to withstand a MSLB environment.

Individual analysis for each door is as follows:

A) Impairment of door DSK13291 provided a flow path from a postulated MSLB in the Turbine Building to the AFW pump vestibule and associated pipe chase rooms. However, analysis has provided reasonable assurance that equipment in this area required to mitigate this postulated MSLB would have performed the required functions in this scenario.

B) Impairment of door DSK14032 provided a flow path from a postulated MSLB in the Turbine Building to the Motor-Generator (MG) Set room. However, this door was only impaired in Modes 5, 6, and No Mode. No MSLB is required to be postulated in these Modes.

C) Impairment of door DSK33044 provided a flow path from a postulated MSLB in the Turbine Building to the 2000' elevation of the Auxiliary Building. The resulting environment in this area could have adversely impacted the 'A' Train level transmitters for RVLIS, similar to the condition described in Case 1.

Additionally, relays in control panel RP330 could also be adversely affected in this scenario. The affected relays control the following equipment in the 'A' Train:

  • Component Cooling Water (CCW) heat exchanger bypass valve
  • Control Room Air Conditioning System (CRAGS) air conditioning unit
  • Class 1 E electrical equipment air conditioning unit With DSK33044 impaired, operability for these components cannot be demonstrated in this postulated MSLB scenario.

The Technical Specifications for RVLIS, CCW and CRAGS are TS 3.3.3, TS 3.7.7 and TS 3.7.11, respectively. The most limiting Technical Specification associated with inoperability of the equipment supported by the Class 1 E air conditioning unit is LCO 3.0.3 until compensatory actions are taken. The actions required by the Technical Specifications for these conditions are as follows:

  • TS 3. 7. 7 Required Action A.1 directs restoration of the inoperable CCW train within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
  • TS 3. 7.11 Required Action A.1 directs restoration of the inoperable CRAGS train within 30 days.
  • LCO 3.0.3 directs Mode 3 entry within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />.

Within the three years preceding discovery of the event, the longest single impairment of DSK33044 lasted for 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, 9 minutes. DSK33044 was impaired five times in Mode 1 for a cumulative total of 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br />, 48 minutes in this period.

Case 3: Auxiliary Steam HELB Affecting the Essential Service Water Pipe Room The initial disposition of this case was concerned with the exposure of equipment in the Essential Service Water (ESW) pipe chase room to a harsh environment following a postulated auxiliary steam line break in the Auxiliary Building 1974' elevation hallway via door DSK11 011. Based on the results of a seismic analysis performed on the auxiliary steam lines in this hallway, however, an auxiliary steam line break is not required to be postulated in this location.

Case 4: Auxiliary Steam HELB in the Boric Acid Batching Tank Room Boric acid batching tank auxiliary steam isolation valve FBV0147 serves as a HELB boundary for the associated auxiliary steam line. When FBV0147 is open, the auxiliary steam line downstream of the valve must be considered a high energy line. In this case, a harsh environment following an auxiliary steam line HELB affecting the Auxiliary Building 2026' level corridor must be postulated.

HELB analysis assumes FBV0147 is maintained closed. However, FBV0147 was maintained open for the majority of the previous three years. This configuration discrepancy had been previously identified at Callaway Plant, but the analysis performed at the time erroneously determined that the integrity of the barrier into the 2026' level corridor would be maintained in a HELB event. This barrier, boric acid batching tank room door DSK14071, is now expected to fail in this scenario. Thus, analysis of this scenario now considers a harsh environment to have existed in the adjoining corridor whenever FBV0147 was open, regardless of the status of DSK14071.

Analysis of this scenario provides reasonable assurance that equipment in the 2026' elevation corridor would have performed the functions required to mitigate this postulated HELB. However, one additional door configuration was identified during the period FBV0147 was maintained open in which the doors to the electrical penetration rooms (rooms 1409 and 141 0) were opened to the 2026' elevation corridor. When these doors and FBV0147 were open concurrently, the electrical penetration rooms could have been exposed to a harsh environment following a postulated HELB in the boric acid batching tank room.

In this scenario, operability of 'A' Train motor control center NG01 B cannot be demonstrated following the postulated line break. NG01 B is located in room 1410, the electrical penetration room nearest the boric acid batching tank room. The pathway configuration for this scenario existed in Mode 1, 100% power, under an impairment permit that was in effect from 3/12/08 0749 to 3/17/08 0713 to allow for room painting and drying.

The exact duration(s) of this door configuration is not known. However, based on the impairment description and the Job notes, it can be assumed that the doors into room 141 0 were open for no more than 1 0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> at a time.

The Technical Specification associated with NG01 B is TS 3.8.9, Distribution Systems-Operating. Required Action A.1 of TS 3.8.9 directs restoration of the inoperable distribution subsystem within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and also within 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of failure to meet the LCO. If the distribution subsystem is not restored within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, TS 3.8.9 Condition D is then entered. TS 3.8.9 Required Action D.1 requires Mode 3 entry within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Thus, an impairment period of 1 0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> would have ended two hours into TS 3.8.9 Required Action D.1.

Case 5: Auxiliary Building Equipment Hatches and Stairwell Doors In addition to the other cases described in this section, multiple configurations of Auxiliary Building equipment hatches and stairwell doors were known to have been impaired since December 2007. These hatches and doors are credited as HELB barriers in the analysis of record. Without adequate compensatory measures, the impairment of one or more of these hatches and doors could have allowed the harsh environment from a postulated Auxiliary Building HELB to spread to other levels in the Auxiliary Building containing equipment not qualified for the pressure, temperature and steam conditions associated with a HELB.

Analysis has shown, however, that the impairment of Auxiliary Building equipment hatches and stairwells would not have caused inoperability of equipment required to mitigate a postulated Auxiliary Building HELB beyond what is described in the other cases in this section.

4. ASSESSMENT OF SAFETY CONSEQUENCES

In order to have significant safety consequences following a postulated MSLB or HELB, structures, systems, or components required to mitigate the initiating accident or hazard would have to be rendered non-functional.

This LER documents numerous scenarios which had the potential to affect both trains of multiple systems which would be required to function following a MSLB or HELB event. However, for all situations in which the functionality of one train of a required system could have been adversely impacted, it was shown that the opposite train was available and capable of performing the credited safety function in the resultant environmental conditions. Detailed equipment qualification analysis at the individual component level, inherently robust mechanical and electrical equipment, and/or the physical separation of redundant trains provided assurance that at no time were there any substantial safety consequences.

The credited safety functions necessary to achieve and maintain a safe shutdown, remove residual decay heat, control the release of radioactive material, and mitigate the consequences of the initiating accident or hazard were maintained at all times.

5. REPORTING REQUIREMENTS

Cases 1, 2, and 4 describe situations in which components may not have been able to perform their HELB mitigation function if the associated HELB event occurred. As such, this LER is submitted pursuant to 10 CFR

6. LER NUMBER I

SEQUENTIAL I NUMBER 009 REV NO.

01

3. PAGE 6

OF 50.73(a)(2)(ii)(B) as an unanalyzed condition that significantly degraded plant safety because plant equipment that would have required to respond to a postulated HELB event may not have been able to respond to the event as assumed. Cases 3 and 5 do not describe situations in which components may not be able to perform required HELB mitigation functions.

As indicated in the individual cases, each impairment was restored within the allowances of the associated Technical Specification(s). Operation prohibited by Technical Specifications did not occur as a result of the HELB program deficiencies described herein.

Additionally, the impairments described in Section 3 would not have prevented fulfillment of the associated safety function. One train of equipment remained available to perform the required HELB mitigation functions in each of the cases specified in Section 3.

6. CAUSEOFTHEEVENT Section 3 of this LER documents a series of cases in which Operability criteria for plant equipment required to mitigate a HELB were not met. These cases are symptomatic of a greater programmatic deficiency in which HELB calculations and guidance were not sufficient to prevent challenges to equipment operability.

Two root causes were determined for this deficiency. The first root cause is that the technical guidance in Hazard Barrier Program procedure APA-ZZ-00750 was insufficient to successfully implement the guidance of RIS 2001-09. Without sufficient guidance, HELB evaluations permitted barrier impairments that did not consistently maintain equipment operability. The second root cause is that management oversight of Engineering programs-specifically, the HELB Program -was not sufficient to prevent challenges to protected equipment. This root cause enabled insufficient technical guidance to persist and also allowed for the inappropriate evaluation of HELB boundaries and barriers. Taken together, these root causes allowed deficiencies to exist within the Callaway Plant HELB defenses.

7. CORRECTIVE ACTIONS

A number of corrective actions have been determined to address the root causes (listed above) and contributing causes of these programmatic deficiencies. These corrective actions include, but are not limited to, the following:

  • The pressure capacities of the Auxiliary Building HELB doors and the pressure produced by each type of high energy hazard will be calculated and documented. This will identify the door capabilities and available margin so that proper impairment evaluations can be made in the future. This evaluation has been completed and is pending formal acceptance by Callaway Plant.
  • Appropriate compensatory actions for HELB barriers continue to be developed. This will allow equipment Operability requirements to be met when HELB barriers are impaired.
  • A list of hazard barriers that are not permitted to be opened in conjunction with other barriers is being developed. This will identify which HELB barriers would be required to provide hazard protection when another HELB barrier is impaired.
  • The HELB Program has been designated as an official Engineering Program. This designation requires additional program ownership and oversight.
6. LER NUMBER l

SEQUENTIAL I NUMBER 009 REV NO.

01

3. PAGE 7

OF

  • A review and verification of the assumptions made in the calculation of record has been performed. This ensures that the analysis reflects current plant configuration.

As stated in Section 3 of this LER, a standing order was es_tablished to obtain an engineering evaluation prior to impairing HELB barriers. This order will be lifted once the appropriate corrective actions are implemented.

8. PREVIOUS SIMILAR EVENTS

In December 2009, Callaway Plant personnel identified that auxiliary steam isolation valve FBV0146 was maintained open, contrary to HELB analysis calculations. This event was initially reported to the NRC under Event Notification 45571 as an unanalyzed condition that significantly degrades plant safety. This notification was subsequently retracted when subsequent analysis concluded that the condition did not render safety-related components inoperable.

9. OTHER INFORMATION The Energy Industry Identification System (EllS) identifiers for the components and systems mentioned in this report are as follows:

System: SB, Main Steam System System: CC, Component Cooling Water System Component:

HCV, Hand Control Valve System: BA, Auxiliary Feedwater System System: 81, Essential Service Water System System: SA, Auxiliary Steam System Component: ISV, Isolation Valve System: ED, Low Voltage Power System, Class 1 E Component: MCC, Motor Control Center System: AB, Reactor Coolant System Component: L T, Level Transmitter System: IP, Post Accident Monitoring System System: CB, Chemical Volume and Control System Component: TK, Tank System: VI, Control Building Environmental Control System Component: ACU, Air Conditioning Unit System: JL, Panels Components: PL, Panel; RL Y, Relay 7

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