[Federal Register Volume 60, Number 227 (Monday, November 27, 1995)]
[Pages 58387-58390]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-28835]



Report to Congress on Abnormal Occurrences April-June, 1995; 
Dissemination of Information

    Section 208 of the Energy Reorganization Act of 1974, as amended, 
requires NRC to disseminate information on abnormal occurrences (AOs) 
(i.e., unscheduled incidents or events that the Commission determines 
are significant from the standpoint of public health and safety). 
During the second quarter of CY 1995, the following incidents at NRC 
licensed facilities were determined to be AOs and are described below, 
together with the remedial actions taken. Each event is also being 
included in NUREG-0090, Vol. 18, No. 2, (``Report to Congress on 
Abnormal Occurrences: April-June 1995''). This report will be available 
at NRC's Public Document Room, 2120 L Street NW. (Lower Level), 
Washington, DC, about three weeks after the publication date of this 
Federal Register Notice.

Nuclear Power Plants

95-2  Reactor Coolant System Blowdown at Wolf Creek Nuclear Generating 

    One of the AO reporting guidelines notes that major deficiencies in 
design, construction, use of, or management controls for licensed 
facilities or material can be considered an AO.
    Date and Place--September 17, 1994; Wolf Creek Nuclear Generating 
Station, a Westinghouse-designed pressurized water reactor nuclear 
power plant, operated by Wolf Creek Nuclear Operating Corporation and 
located about 5.63 kilometers (3.5 miles) northeast of Burlington, 
    Nature and Probable Consequences--An inadvertent blowdown of 
approximately 34,868 liters (9200 gallons) of reactor coolant through 
the residual heat removal (RHR) system to the refueling water storage 
tank (RWST) occurred because of incompatible, concurrent RHR valve 
manipulations. At the time of the event, the reactor had been shutdown 
for 28 hours and was on RHR cooling (2413 kPa gauge and 149 C [350 psi 
gauge and 300 F]). The event was successfully terminated in 1 minute by 
operator intervention. There was only minimal interruption to heat 
removal processes, and no core damage or fission product release 
occurred. However, if the blowdown continued, the licensee estimated 
that RHR cooling could have failed in about 3.5 minutes, the RWST 
header could have filled with steam in about 6 minutes, and uncovering 
of the core could have begun in about 30 minutes.
    All of the emergency core cooling system (ECCS) pumps take their 
suction from the RWST header line. If the ECCS pumps were started to 
mitigate the blowdown after the RWST header filled with steam, a 
common-mode failure of all ECCS pumps could have occurred as a result 
of steam binding. The ECCS pumps could also have failed as a result of 
pressure pulses caused by cold RWST 

[[Page 58388]]
water collapsing the steam in the RWST and RWST header. If they failed, 
successful mitigation of such an event would depend on the control room 
operators' cognitive abilities to establish core heat removal via the 
steam generators.
    If core damage did occur, then a possibility for a significant 
offsite release existed because the blowdown path in place at the time 
bypassed the reactor containment.
    Cause or Causes--This event was attributed to the following three 
    (1) Unrecognized design vulnerability--An RHR-RWST connecting line 
was designed to provide operational convenience for refilling the RWST 
after a refueling outage, but not for safety purposes. The 
inappropriate use of this line while on RHR cooling could result in a 
rapid blowdown event and a subsequent common-mode failure of all ECCS 
    (2) Inappropriate use of the RHR-RWST connecting line--The licensee 
inappropriately used the RHR-RWST connecting line to increase the boron 
concentration of the RHR train. (Other boration paths existed that 
would not have resulted in an inadvertent blowdown.)
    (3) Inadequate work control--The licensee was deficient in the 
control of maintenance and operational evolutions by allowing 
incompatible activities to occur simultaneously. The control room crew 
had ample warning of the potential adverse effects of these activities 
just prior to the event, but failed to limit the concurrent 
manipulation of selected RHR valves.
    The licensee also had previous warnings of blowdown events from its 
experience at Wolf Creek and from the following NRC Information 
Notices: 90-55, ``Recent Operating Experience on Loss of Reactor 
Coolant Inventory While in a Shutdown Condition''; and 91-42, ``Plant 
Outage Events Involving Poor Coordination Between Operations and 
Maintenance Personnel During Valve Testing and Manipulations.'' The 
licensee's response to these warnings was that its administrative 
controls adequately addressed the concerns.

Actions Taken to Prevent Recurrence

    Licensee--The licensee implemented the following actions: (1) Chain 
locked the isolation valve in the RHR-RWST connecting line, and made 
the plant manager and operations manager solely responsible for access 
to this valve; (2) removed the use of the RHR-RWST connecting line from 
the RHR boration procedures; and (3) approached the Westinghouse Owners 
Group to address the issue generically.
    NRC--NRC issued Information Notice No. 95-03, ``Loss of Reactor 
Coolant Inventory and Potential Loss of Emergency Mitigation Functions 
While in a Shutdown Condition,'' to inform all reactor licensees of the 
circumstances and potential consequences associated with the Wolf Creek 

95-3 Previously Unidentified Path for the Potential Release of 
Radioactivity at Millstone Nuclear Power Station Unit 2

    One of the AO reporting guidelines notes that a loss of plant 
capability to perform essential safety functions, such that a potential 
release of radioactivity in excess of 10 CFR Part 100 guidelines could 
result from a postulated transient or accident (e.g., loss of emergency 
core cooling system, loss of control rod system), can be considered an 
    Date and Place--December 6, 1994; Millstone Nuclear Power Station 
Unit 2, a Combustion Engineering-designed pressurized water reactor 
nuclear power plant, operated by Northeast Nuclear Energy Company and 
located about 5.15 kilometers (3.2 miles) west-southwest of New London 
County, Connecticut.
    Nature and Probable Consequences--While the plant was in a 
refueling outage, a systems engineer employed by the licensee 
identified a condition that established a potential unfiltered release 
path to the atmosphere that could have resulted in offsite doses in 
excess of 10 CFR Part 100 guidelines in the event of a postulated loss-
of-coolant accident (LOCA). The licensee immediately declared the 
enclosure building inoperable and promptly reported the condition to 
    The Millstone Unit 2 design includes an Enclosure Building around 
the reactor Containment Building to collect all leakage out of the 
containment during a postulated LOCA. The Enclosure Building 
Ventilation System contains a charcoal bed filtration unit to remove 
radioactive iodine prior to discharging the Enclosure Building air out 
of the 114.4-meter (375-foot) high Unit-1 stack. The condition 
identified on December 6, 1994, was that the ventilation system 
associated with the Hydrogen Analyzer cabinet and waste gas sample hood 
fan, located within the East Electrical Penetration Room of the 
Enclosure Building, would not isolate in the event of a LOCA. During a 
postulated accident, this ventilation system, which does not contain a 
charcoal filter unit, would draw Enclosure Building air (contaminated 
with any containment leakage) from the East Penetration Room and 
discharge it through the 45.8-meter (150-foot) high Unit 2 vent. The 
lack of a charcoal filter and the lower release point would 
significantly increase the potential of a thyroid dose in excess of the 
10 CFR Part 100 guideline at the exclusion area boundary.
    The Technical Specifications for Millstone Unit 2 require that the 
Enclosure Building integrity be maintained to ensure that the Enclosure 
Building Ventilation System limits the site boundary doses to within 10 
CFR Part 100 guidelines following a postulated design basis accident. 
NRC performed a design basis dose calculation which took into account 
the lack of charcoal filtration and the lower elevation release path 
which would result from the noted design deficiency. This calculation 
indicated that an exclusion area boundary dose to the thyroid greater 
than the 10 CFR Part 100 guideline of 3000 millisievert (mSv) (300 rem) 
would occur. It also indicated that the whole body dose would not 
exceed the 250 mSv (25 rem) 10 CFR Part 100 guideline. The NRC 
calculation was very conservative in that it assumed that all of the 
designed allowable containment leakage, following the design basis 
accident, would be through the penetrations in the East Electrical 
Penetration Room and released from the Enclosure Building through the 
Hydrogen Analyzer Ventilation system.
    Cause or Causes--The cause of this condition was an original design 
deficiency of the hydrogen analyzer cabinet exhaust system.

Actions Taken to Prevent Recurrence

    Licensee--The licensee modified the design to route the exhaust 
path from the hydrogen analyzer cabinet into the enclosure building 
ventilation system, thereby going through the appropriate filtration, 
in order to reduce any post-LOCA radioactive release to below 10 CFR 
Part 100 guidelines. The waste gas sample sink was relocated from the 
enclosure building to the auxiliary building. This design modification 
was implemented prior to the start up of Millstone Unit 2.
    NRC--On February 16, 1995, NRC exercised enforcement discretion and 
did not issue a violation. In accordance with the ``General Statement 
of Policy and Procedure for NRC Enforcement Actions,'' (Enforcement 
Policy) then set out at 10 CFR Part 2, Appendix C, this design 
deficiency would normally be categorized as a Severity Level III 
violation and enforcement action would normally be considered because 
it involved a violation of the Technical Specifications and could have 
resulted in 10 CFR Part 100 guidelines being exceeded in the event of a 
LOCA. However, the exercise of discretion for the apparent Severity 
Level III violation 

[[Page 58389]]
was determined to be warranted in this instance because: (1) The 
condition was identified by the licensee's staff as a result of a 
questioning attitude by a system engineer and was promptly reported to 
the NRC; (2) the condition, which existed since initial startup, was 
difficult to discover and such identification was not likely by routine 
inspection, surveillance and quality assurance activities; (3) 
comprehensive corrective actions were taken within a reasonable time 
period that involved an adequate root cause determination and a review 
for failures caused by similar root causes; and (4) the condition was 
caused by an old performance failure that is not reasonably linked to 
present performance.
    This event was determined to be plant specific due to the unique 
design of the ventilation system.

Other NRC Licensees (Industrial Radiographers, Medical Institutions, 
Industrial Users, etc.)

95-4 Medical Brachytherapy Misadministration at the University of 
Virginia, in Charlottesville, Virginia

    One of the AO reporting guidelines notes that a therapeutic 
exposure to any part of the body not scheduled to receive radiation can 
be considered an AO.
    Date and Place--March 14, 1995; University of Virginia Medical 
Center; Charlottesville, Virginia.
    Nature and Probable Consequences--A patient was prescribed a manual 
brachytherapy procedure using cesium-137 (Cs-137) sources loaded in an 
applicator, for a total gynecological treatment dose of 3000 centigray 
(cGy) (3000 rad).
    During insertion of the applicator into the patient, one of the 
sources fell onto the patient's bed and was unnoticed by the licensee 
staff involved in performing the procedure. A nurse found the source in 
the bed on March 15 and removed it. The source was reloaded into the 
applicator and the physician revised the prescribed dose to 2500 cGy 
(2500 rad). The licensee estimated that the source remained at 
approximately 10 centimeters (4 inches) from the patient's foot for 18 
hours and delivered a dose of about 13 cGy (13 rad) to the foot.
    The licensee notified the referring physician and the patient of 
the misadministration. An NRC medical consultant was obtained who 
concluded that the patient was receiving appropriate follow-up care. In 
addition, the licensee and the medical consultant concluded that the 
patient will not experience any adverse health effects as a result of 
the misadministration.
    Cause or Causes--The licensee's staff involved in the brachytherapy 
procedure were not familiar with handling of the applicator that 
contained the Cs-137 sources. Also, because of anatomic characteristics 
of the patient, the physician had difficulty inserting the source 
carrier into the applicator. The design of the afterloading device 
allows the source to slide out of the carrier if any unusual 
manipulation of source carrier is required. The difficulty experienced 
by the physician in inserting the source in the applicator and the 
design of the source carrier resulted in the source falling out of the 
carrier during the insertion process.

Actions Taken to Prevent Recurrence

    Licensee--The licensee provided training for its staff, involved in 
brachytherapy procedures, concerning the precautions which must be 
taken when handling an applicator such as the one used in the subject 
procedure. Also, emphasis was placed on the need to be more attentive 
during the source insertion process in order to account for all 
prescribed sources.
    NRC--NRC conducted a special inspection on March 23-24, 1995, to 
review the circumstances surrounding the misadministration. The 
inspection report was issued on May 2, 1995. Enforcement action will be 
taken as appropriate.

95-5  Medical Therapeutic Radiopharmaceutical Misadministration of 
Iodine-131 at Massachusetts General Hospital in Boston, Massachusetts

    One of the AO reporting guidelines notes that administering a 
therapeutic dose of a radiopharmaceutical differing from the prescribed 
dose by more than 10 percent and the actual dose is greater than 1.5 
times the prescribed dose can be considered an AO.
    Date and Place--May 9, 1995; Massachusetts General Hospital; 
Boston, Massachusetts.
    Nature and Probable Consequences--A patient was prescribed a 296 
megabecquerel (MBq) (8 millicurie [mCi]) dosage of iodine-131 (I-131) 
for hyperthyroidism; however, a dosage of 1106.3 MBq (29.9 mCi) was 
    Representatives of the hospital informed the referring physician 
and the patient of the misadministration. An NRC medical consultant was 
obtained to evaluate the event and stated that the higher dosage given 
to the patient will result in a more likely achievement of the intended 
therapeutic goal to eliminate the patient's hyperthyroidism. 
Additionally, the consultant determined that it is unlikely that the 
patient is at significant risk of experiencing long-term consequences 
from receiving the higher dosage beyond the risk associated with the 
prescribed dosage. Therefore, the impact on the patient's health is 
expected to be negligible with no expected long-term disability. (The 
intent of the prescribed dose was to ablate the portion of the thyroid 
remaining after surgery and then support the patient with thyroid 
supplement the rest of her life. This did not change with the 
administered dose.)
    Cause or Causes--The licensee stated that this event occurred 
because of a human error. The technologist involved in this procedure 
inadvertently switched the labeled lids on the vial shields containing 
the I-131 dosages prescribed for different patients. Additionally, the 
technician failed to check for the correct dosage on the vial label, 
and the wrong dose was administered to the intended patient.

Actions Taken to Prevent Recurrence

    Licensee--The licensee instituted a procedure for checking the vial 
label before giving a dose. In addition, the licensee is obtaining a 
second dose calibrator which will be used in the out-patient dosing 
room of the Thyroid Clinic. Each dose will be re-assayed immediately 
before the I-131 is administered to the patient, rather than relying on 
the assay which was performed in the Thyroid Lab before the dose was 
transported to the out-patient dosing room.
    NRC--NRC performed an inspection on May 12, 1995, to learn about 
the event and determined that it constituted a misadministration as 
defined in 10 CFR 35.2. NRC determined that this was an isolated 
violation of the licensee's Quality Management Program and issued a 
Notice of Violation at the Severity Level IV on June 26, 1995.

95-6  Multiple Medical Brachytherapy Misadministrations at Madigan Army 
Medical Center in Fort Lewis, Washington

    One of the AO reporting guidelines notes that administering a 
therapeutic dose from a sealed source such that the treatment dose 
differs from the prescribed dose by more than 10 percent and the event 
(regardless of health effects) affects two or more patients at the same 
facility can be considered an AO.
    Date and Place--February 1994 through May 1995; Madigan Army 
Medical Center (MAMC); Fort Lewis, Washington. 

[[Page 58390]]

    Nature and Probable Consequences--Four patients were prescribed 
brachytherapy procedures, using iridium-192 seeds of different source 
strengths, and received doses other than those prescribed because of 
the same computer input error. (The same computer input error could 
cause either underdoses or overdoses because the algorithm used was 
dose dependent.) Details of the misadministrations are as follows:
    Patient A: The patient was prescribed a dose of 2800 centigray 
(cGy) (2800 rad) for a gynecological brachytherapy treatment, but 
received a dose of about 1680 cGy (1680 rad) instead.
    Patient B: Event 1--The patient was prescribed a dose of 1600 cGy 
(1600 rad) for lung treatment, but received a dose of about 2128 cGy 
(2128 rad) instead.
    Event 2--On another day, the same patient was prescribed a dose of 
1500 cGy (1500 rad) for lung treatment, but received a dose of about 
2350 cGy (2350 rad) instead.
    Patient C: The patient was prescribed a dose of 3000 cGy (3000 rad) 
for gynecological treatment, but received a dose of about 5142 cGy 
(5142 rad) instead.
    Patient D: The patient was prescribed a dose of 1500 cGy (1500 rad) 
for a biliary tract treatment, but received a dose of about 2050 cGy 
(2050 rad) instead.
    The licensee does not expect the patients to experience any adverse 
health effects as a result of the misadministrations.
    Cause or Causes--Based upon NRC's initial review of the 
misadministrations, it appears that the probable causes of the 
treatment errors were failures to: (1) independently review or check 
the data input to the computerized treatment planning system, and (2) 
perform an independent check of dose rate calculations generated by the 
treatment planning system.

Actions Taken to Prevent Recurrence

    Licensee--The physics staff at MAMC promptly corrected the data 
entered into the computer treatment planning computer, recalculated the 
doses received by the patients, and took steps to ensure that 
appropriate data will be used for future treatment plans.
    NRC--NRC initiated an inspection on June 6, 1995, to review the 
circumstances associated with the misadministrations and to review the 
licensee's corrective actions. (As of the date of this report, the 
inspection is ongoing.) An NRC medical consultant will review each case 
in order to provide an independent assessment of the potential 
consequences of the overdoses.

    Dated at Rockville, MD this 20th day of November, 1995.

    For the Nuclear Regulatory Commission.
John C. Hoyle,
Secretary of the Commission.
[FR Doc. 95-28835 Filed 11-24-95; 8:45 am]