United States Nuclear Regulatory Commission - Protecting People and the Environment

EA-96-244 - Beaver Valley 1 & 2 (Duquesne Light Company, DLC)

September 11, 1996

EA 96-244

Mr. J. E. Cross
Senior Vice President
Nuclear Power Division
Duquesne Light Company
Post Office Box 4
Shippingport, Pennsylvania 15077


Dear Mr. Cross:

This letter refers to the NRC inspection conducted from May 14 through June 26, 1996, at your Beaver Valley Power Station facilities in Shippingport, Pennsylvania. The findings of the inspection were discussed with your staff during exit meetings and follow-up discussions on June 27, July 11, and July 12, 1996. During the inspection, the inspectors reviewed the circumstances surrounding a design deficiency associated with the Anticipated Transient Without Scram (ATWS) Mitigating System Actuation Circuitry (AMSAC). The deficiency, which was identified by your staff and reported to the NRC, constitutes a violation of NRC requirements and was described in the NRC inspection report sent to you with our letter, dated July 24, 1996. On August 28, 1996, a predecisional enforcement conference was conducted with you and members of your staff to discuss the violations, their causes, and your corrective actions.

The violation, which is set forth in the enclosed Notice of Violation, involved the failure to comply with 10 CFR 50.62 which requires that you provide an alternate means, independent of the Reactor Protection System, of tripping the turbine and actuating auxiliary feedwater under conditions indicative of an ATWS. This system must be designed to perform its functions in a reliable manner. The AMSAC system protects the reactor coolant system from overpressurization in cases where there is a concurrent failure of the Reactor Protection System. The specific AMSAC design deficiency that existed in this case involved the failure to consider, when the AMSAC system was designed and installed, the effect of static pressure on feedwater flow transmitters, as well as the effect of hydraulic fluctuations on feedwater flow, when establishing the "flow out-of-range" setpoint. As a result, under one particular scenario where the main feedwater valves close with the pumps continuing to operate, the AMSAC system may have failed. As such, the AMSAC system was not designed in a manner to perform its function in a reliable manner. This violation has existed since AMSAC was initially installed in Unit 1 in 1988 and Unit 2 in 1989.

The equipment required by 10 CFR 50.62 is intended to serve an important safety function in the event of the failure of the plant principal Reactor Protection System. This regulation was adopted following actual failures of the reactor trip system at another pressurized water reactor in 1983 and is intended to reduce the risk posed by such events. Your failure to ensure proper functioning and reliability of this system since the original installation is a significant regulatory concern. Therefore, this violation has been categorized at Severity Level III in accordance with the "General Statement of Policy and Procedure for NRC Enforcement Actions," (Enforcement Policy), NUREG-1600.

The NRC commends the technical inquisitiveness of the engineer who identified this issue during his follow-up review, after the turbine trip of May 31, 1996, during which AMSAC should have initiated, and after your initial post-trip review also failed to detect the deficiency. If not for his inquisitiveness, this deficiency likely would have remained undetected. Nonetheless, two other AMSAC related problems were identified in 1993 and 1994, namely, the failure to have a lock-in circuit for a variable time delay, as well as a deficiency with the AMSAC blocking logic. Although those deficiencies were not specifically related to this recently identified problem, a more thorough review of those issues at the time might have led to identification of this problem. In each case, however, a broader evaluation was not performed and this deficiency went undetected. Also, an Information Notice (Reference: Information Notice No. 91-75) was issued in 1991 which informed licensees of the need to consider the static pressure effect on transmitters. However, at that time, you failed to consider the static pressure effect on the transmitter used for AMSAC signals.

These findings demonstrate the need for management taking appropriate action to assure that your staff in general, and your engineers in particular, are sensitive to the importance of performing comprehensive, rather than narrowly-focused, evaluations in response to generic communications or site-specific identified problems. Such broader reviews are needed to assure that all potentially degraded features are promptly identified and corrected. This is particularly important for engineering issues identified on systems in which generic designs were altered prior to installation, as was the case with the AMSAC system.

In accordance with the Enforcement Policy, a base civil penalty in the amount of $50,000 is considered for a Severity Level III violation. Because your facility has not been the subject of escalated enforcement actions within the last 2 years, the NRC considered whether credit was warranted for Corrective Action in accordance with the civil penalty assessment process in Section VI.B.2 of the Enforcement Policy. Credit is warranted because your corrective actions were both prompt and comprehensive. Your corrective actions included prompt correction of the AMSAC system via both hardware and software design modifications implemented within one week of identification; revision of the feedwater flow transmitter calibration procedures to account for the static pressure effect, and subsequent recalibration of the flow transmitters; a review of the extent of static pressure effect on other transmitters installed in the facility; and a focused design review of AMSAC and three other systems, to ensure that similar deficiencies do not exist. The NRC also recognizes and commends, as indicated previously, the inquisitiveness of your staff in identifying this issue.

Therefore, to encourage prompt and comprehensive identification and correction of violations, and in recognition of the absence of previous escalated enforcement action, I have been authorized, after consultation with the Director, Office of Enforcement, not to propose a civil penalty in this case. However, significant violations in the future could result in a civil penalty.

You are required to respond to this letter and should follow the instructions specified in the enclosed Notice when preparing your response. In your response, you should document the specific actions taken 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 enforcement action is 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, its enclosure, and your response will be placed in the NRC Public Document Room (PDR).


                                  Hubert J. Miller
                                  Regional Administrator 

Docket Nos. 50-334, 50-412
License Nos. DPR-66, NPF-73

Enclosure: Notice of Violation

c w/encl:
S. Jain, Vice President, Nuclear Services
T. Noonan, Vice President, Nuclear Operations
L. Freeland, Manager, Nuclear Engineering Department
B. Tuite, General Manager, Nuclear Operations Unit
K. Ostrowski, Manager, Quality Services Unit
R. Brosi, Manager, Nuclear Safety Department
M. Clancy, Mayor
NRC Resident Inspector - Beaver Valley
Commonwealth of Pennsylvania
State of Ohio


Duquesne Light Company
Beaver Valley Power Station
Docket Nos. 50-334, 50-41
License Nos. DPR-66, NPE 73
EA 96-244

During an NRC inspection conducted between May 14 and June 26, 1996, for which exit meetings and follow-up discussions were held on June 27, July 11, and July 12, 1996, a violation of NRC requirements was identified. In accordance with the "General Statement of Policy and Procedure for NRC Enforcement Actions," NUREG 1600, the violation is listed below:

10 CFR 50.62(c)(1) requires, in part, that each pressurized water reactor must have equipment from sensor output to final actuation device, that is diverse from the reactor trip (protection) system, to automatically initiate the auxiliary feedwater system and initiate a turbine trip under conditions indicative of an anticipated transient without scram (ATWS), and that this equipment must be designed to perform its function in a reliable manner.

Contrary to the above, since original installation in 1988 until June 1996 for Unit 1, and since original installation in 1989 until June 1996 for Unit 2, the ATWS Mitigation System Circuitry (AMSAC), (i.e., the equipment installed to automatically initiate the auxiliary feedwater system and initiate a turbine trip under conditions indicative of an ATWS) had not been designed to perform its function in a reliable manner. This equipment was not designed to perform its function in a reliable manner in that a design deficiency that had been present since the original installation of the system, namely, the failure to incorporate static pressure effect and hydraulic fluctuations in the design margin for "out-of-range" flow signals. The deficiency was evidenced by the fact that on May 31, 1996, a transient occurred in which, although the reactor trip system functioned as required, conditions also existed (namely, a loss of normal feedwater) which should have caused the AMSAC to initiate. However, AMSAC failed to initiate as expected during this operational occurrence. (IFS 01013)

This is a Severity Level III violation (Supplement I).

Pursuant to the provisions of 10 CFR 2.201, Duquesne Light Company is hereby required to submit a written statement or explanation to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, D.C. 20555 with a copy to the Regional Administrator, Region I, and a copy to the NRC Resident Inspector at the facility that is the subject of this Notice, within 30 days of the date of the letter transmitting this Notice of Violation (Notice). This reply should be clearly marked as a "Reply to a Notice of Violation" and should include for each violation: (1) the reason for the violation, or, if contested, the basis for disputing the violation, (2) the corrective steps that have been taken and the results achieved, (3) the corrective steps that will be taken to avoid further violations, and (4) the date when full compliance will be achieved. Your response may reference or include previous docketed correspondence, if the correspondence adequately addresses the required response. If an adequate reply is not received within the time specified in this Notice, an Order or a Demand for Information may be issued as to why the license should not be modified, suspended, or revoked, or why such other action as may be proper should not be taken. Where good cause is shown, consideration will be given to extending the response time.

Under the authority of Section 182 of the Act, 42 U.S.C. 2232, this response shall be submitted under oath or affirmation.

Because your response will be placed in the NRC Public Document Room (PDR), to the extent possible, it should not include any personal privacy, proprietary, or safeguards information so that it can be placed in the PDR without redaction. If personal privacy or proprietary information is necessary to provide an acceptable response, then please provide a bracketed copy of your response that identifies the information that should be protected and a redacted copy of your response that deletes such information. If you request withholding of such material, you must specifically identify the portions of your response that you seek to have withheld and provide in detail the bases for your claim of withholding (e.g., explain why the disclosure of information will create an unwarranted invasion of personal privacy or provide the information required by 10 CFR 2.790(b) to support a request for withholding confidential commercial or financial information). If safeguards information is necessary to provide an acceptable response, please provide the level of protection described in 10 CFR 73.21.

Dated at King of Prussia, Pennsylvania
this 11th day of September 1996

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