[en] For reactor containments, with un-bonded tendons, the tendon force is measured at regular in- service inspections to secure that the prestress level is sufficient. It is not possible to achieve a complete assurance concerning the prestress level due to the limited sample size and the measuring error. A reliability-based model can be used to show if the measured force exceeds the minimum required prestress with adequate margins. Statistical assumptions about the non tested tendons have to be made to be able to evaluate the prestress level. The risk of one or several tendons being defected should also be considered to achieve a comprehensive evaluation

[en] The main function of the reactor containment, i.e. to ensure tightness at a major internal accident, depends directly on the prestressing system. To secure that the prestress level is sufficient, the tendon force has been measured during the whole time of operation. The general results from these measurements show that the loss of prestress 30 years after tensioning is between 5 and 10%. This is much lower loss than predicted initially at the design stage. More advanced and today commonly used models for predicting prestress loss show better agreement with the results. The main reasons for the relatively low loss are assumed to be: (1) the confirmed slow drying process of the concrete and (2) the high concrete age at the initial tensioning. The results also indicate that the temperature has a major influence on the loss of prestress

[en] A containment scale-model test, performed at Sandia National Laboratories, was loaded by overpressurization and the first leak was concluded to be caused by tears in the steel liner found near the equipment hatch. These tears were located in the vicinity of the vertical fold in between the general curved part and the embossment (vertical bend line). A 3D finite element analysis of the region near the equipment hatch, shows that high localized strains will develop in the vicinity of the bend line. It is shown that the liner separates from the concrete wall near the bend line when the containment expands. The tensioned liner will be in contact with the surface of the concrete wall in general, but near the vertical bend line the liner tends to be straightened out. This flexural behaviour cause high strains in the weld located in the bend line. The actual peak strain level is depending on the detailed geometry in the bend line and the failure strain level of a welded biaxial stressed zone is difficult to define. However, the analysis presented in this paper shows that the flexural behaviour in the bend line most likely contributed to the liner tears found in the scale-model test. A general conclusion from the study presented in this paper is that, the non-linear plastic behaviour of the liner is very sensitive to the detailed design and the interaction between the liner and the concrete

[en] A substantial part of nuclear containments in US and Europe are designed with an outer bearing concrete structure and an inner sealing consisting of a tight-welded steel liner. The liner constitutes the ultimate leak-barrier, which prevents leakage at high internal pressure loads. The purpose of this paper is to show which influence a through-wall concrete crack may have on the strain level in the liner. A non-linear bar model is used to evaluate the liner behavior. It is shown that the effect from friction between the concrete and liner could be significant and cause high concentration of plastic strain. The influence of friction on the liner is verified by an experimental program presented in this paper. One of the conclusions is that concentrations of strain due to friction increase with decreasing liner thickness. This is important to consider when results from scale tests are interpreted. Scale models, which have thinner liners, could get significantly higher liner strain than the actual full-scale containment

[en] Objective: Improved local control with the addition of brachytherapy to pelvic exenteration for recurrent cervical cancer has been reported to improve survival. We examined the sites of recurrence after pelvic exenteration to determine if these patients might have been salvaged by the improved local control promised by interstitial brachytherapy. We sought to identify risk factors available intraoperatively or perioperatively which might predict decreased local control. Methods: A retrospective review of 26 patients with recurrent cervical cancer who underwent total pelvic exenteration since 1988 at our institution was performed. Results: Overall, the mean follow-up was 29.5 months (range 6.1-81.6). Of the 26 patients, 14 had no evidence of disease (NED), 1 was alive with disease (AWD), 9 were dead of disease (DOD), and 2 died of unrelated causes (DOC). Seven of 26 patients (27%) had margins ≤ 5 mm, of whom 2 were NED, 4 DOD, and 1 AWD. Seven of 26 (27%) patients had lymphovascular involvement (LVI) or perineural invasion (PNI) with clear margins. Three of the seven with LVI or PNI and clear margins were NED, and four DOD. Of the 10 failures, 9 (90%) had close margins, PNI, or LVI. Conclusion: Our data reveal that 9 of 14 (64%) patients with close margins, LVI, or PNI were DOD or AWD, and 6 of 9 of those patients suffered local regional failure alone. Brachytherapy has the potential to cure 6 of 14 (43%) patients with these risk factors. Further study of brachytherapy at the time of pelvic extenteration is warranted

[en] Purpose: Oral hydroxyurea (HU) is a potent radiation sensitizer, but in vitro studies have suggested that prolonged exposure to HU by way of continuous parenteral infusion would enhance clinical efficacy. The objective of this study was to determine the maximal tolerated dose and identify the toxicities of continuous infusion HU in combination with pelvic and para-aortic external beam radiotherapy (RT) and intrauterine brachytherapy in patients with locally advanced carcinoma of the uterine cervix. Methods: This Phase I study of concomitant RT was designed with an escalating dose schedule of HU administered by continuous infusion. HU was administered parenterally as a continuous infusion, 5 d/wk, during the first 21 days of external radiation, during the final 5 days of external beam RT, followed by another 5-day infusion schedule bracketing the single fraction of brachytherapy. The maximal tolerated dose was defined as the highest dose level at which 3 of 3 or 5 of 6 patients could be treated without dose-limiting toxicity. Results: At dose level 1 (0.25 mg/m²/min), 0 of 4 patients experienced Grade 4 toxicities and 2 patients experienced Grade 3 hematologic toxicities that were not considered dose-limiting. One of the first 4 patients at level 2 (0.375 mg/m²/min) had Grade 3 diarrhea, but the 3 subsequent patients tolerated the dose. At level 3 (0.5 mg/m²/min), 4 of 5 patients failed to complete therapy without a >7-day interruption in HU. Conclusions: The maximal tolerated dose of parenteral HU was 0.375 mg/m²/min when administered with concomitant RT. The most common toxicities were hematologic. A new trial, incorporating concurrent cisplatin, HU, and RT is planned

[en] Purpose Uterine papillary serous carcinoma (UPSC) is an aggressive variant of endometrial carcinoma. The majority of patients with clinical Stage I UPSC are found to have extrauterine disease at the time of surgery. Most authors report survival rates of 35-50% for Stage I-II and 0-15% for Stage III and IV UPSC. Surgical treatment as the sole therapy for patients with Stage I-IV UPSC is unacceptable because of high recurrence rates. Chemotherapy, radiotherapy, or both have been added after surgery in an attempt to improve survival. However, the survival benefit to patients from such multimodality therapy remains uncertain. This study analyzes the patterns of failure in patients with FIGO Stages I-IV UPSC treated by multimodality therapy. Methods and materials Forty-two women with FIGO Stages I-IV UPSC who were treated by multimodality therapy were analyzed retrospectively between 1988 and 1998. Data were obtained from tumor registry, hospital, and radiotherapy chart reviews, operative notes, pathology, and chemotherapy flow sheets. All the patients underwent staging laparotomy, peritoneal cytology, total abdominal hysterectomy and salpingo oophorectomy, pelvic and para-aortic lymph node sampling, omentectomy, and cytoreductive surgery, when indicated followed by radiotherapy and/or chemotherapy. Therapy consisted of external beam radiation therapy in 11 patients (26%), systemic chemotherapy in 20 (48%), and both radiotherapy and chemotherapy in 11 (26%). The treatments were not assigned in a randomized fashion. The dose of external beam radiation therapy ranged from 45-50.40 Gy (median 45). Of the 31 patients (74%) who received chemotherapy, 18 received single-agent (58%), whereas 13 received multiagent chemotherapy (42%). Results Median follow-up for all patients was 19 months (range 4-72). Median follow-up for the surviving patients was 36 months (range 21-72). Their median age was 65 years. Six patients (14%) had Stage I, 8 patients (19%) had Stage II, 10 (24%) had Stage III, and 18 (43%) had Stage IV disease. Twenty-nine patients (69%) had suffered recurrence at the time of last follow-up. The actuarial failure rate at 2 and 5 years was 58% and 67%, respectively. The majority of the patients (19/29) recurred in the abdomen, vagina, or pelvis (66%). Metastases outside the abdomen were much less common as the first site of failure (17%). Twenty-five patients (60%) had died at the time of reporting; the observed survival rate at 2 years and 5 years was 52% and 43%, respectively. Conclusions Our data suggest that, after multimodality therapy of FIGO Stage I-IV UPSC, most patients developed abdominopelvic (locoregional) failure, and the great majority of the failures occurred in the abdomen, vagina, and pelvis (66%). Abdominopelvic failure as a component of distant failure occurred in an additional 5 patients (17%). Distant failure alone occurred in 17% of the patients. We propose that future studies should combine whole abdominal radiotherapy (WART) with pelvic and vaginal boosts, in addition to chemotherapy for FIGO Stage I-IV UPSC, especially in patients with minimal residual disease, to attempt to improve the dismal prognosis of patients with UPSC

[en] Purpose: In recent years, high-dose-rate brachytherapy has become popular in the management of carcinoma of the uterine cervix, because it eliminates many of the problems associated with low-dose-rate brachytherapy. However, the optimum time-dose-fractionation remains controversial. Two fractions of high-dose-rate brachytherapy are convenient for patients, but most radiation oncologists in the United States do not use them, because of fear that they could lead to excessive rectal or bladder toxicity. Here we present our experience, which suggests that a two-fraction regimen is indeed safe and effective. Methods: We treated 49 patients with Stages I-III biopsy-proven carcinoma of the uterine cervix by external beam radiation therapy (EBRT), plus two fractions of high-dose-rate brachytherapy. The histology was squamous cell carcinoma in 43 patients (88%) and nonsquamous in 6 (12%). The median size of the primary tumor was 6 cm (range: 3-10 cm). Each patient received EBRT to the pelvis to a median dose of 45 Gy (range: 41.4-50.4 Gy), followed by a parametrial boost when indicated. Thirty patients (61%) also received irradiation to the para-aortic lymph nodes to a dose of 45 Gy. After EBRT, each patient underwent two applications of high-dose-rate brachytherapy, 1 week apart. The dose delivered to point A was 9 Gy per application for 49 applications (50%) and 9.4 Gy for 43 applications (44%), and it varied from 7 to 11 Gy for the rest (6%). The total dose to the rectum from both high-dose-rate brachytherapy applications ranged from 4.7 to 11.7 Gy (median: 7.1 Gy), and the total dose to the bladder from 3.8 to 15.5 Gy (median: 10.5 Gy). Twenty-five of the 49 patients (51%) received concomitant chemotherapy (cisplatin 20 mg/m²/day for 5 days) during the first and fourth weeks of EBRT and once after the second high-dose-rate brachytherapy application. Chemotherapy was not assigned in a randomized fashion. The use of chemotherapy increased during the time period spanned by this study as increasing evidence supporting the use of chemotherapy began to appear. Results: The observed survival rates after 2, 3, and 5 years were 83%, 78%, and 78%, respectively. The surviving patients have been followed up for a median of 3 years (range: 2-6 years). Eight of the 49 patients suffered local failures. Among patients treated without chemotherapy, the 3-year local control rate was 77%; it was 88% among those receiving chemotherapy. There have been no regional failures. Four patients developed distant metastases. At 3 years, 91% of the patients in each group were free of distant metastases. Ten of the 49 patients (20%) suffered Grade 3 acute toxicity; 11 (22%) had Grade 4. Among the 24 patients treated without chemotherapy, only 1 (4%) suffered Grade 3 toxicity. Among the 25 patients receiving chemotherapy, in contrast, 8 (32%) suffered Grade 3 and 12 (48%) Grade 4 acute toxicity. Only 2 patients suffered late toxicity: One suffered Grade 2 and the other Grade 3 late toxicity. The actuarial risk of Grade 2 or worse late toxicity was 5%, with or without chemotherapy. Conclusions: Our experience suggests that two fractions of high-dose-rate brachytherapy are safe and effective in the management of cervix cancer, even in conjunction with concomitant cisplatin. The fears that the use of two fractions would lead to excessive rectal or bladder toxicity proved unfounded. Guidelines for ensuring a low complication rate are discussed

[en] The tightness and integrity of all Swedish reactor containments depend directly and indirectly on the function of the post-tensioned system. The tendon force in containments with unbonded tendons is followed up at regular in-service inspections (ISI) to ensure that the remaining force is sufficient. At the inspections, the tendon force is measured with so-called lift-off technique, where a jack is used to lift the end anchor. The interpretation of the measuring results is not obvious. One difficulty, which affects all tendons to different extents, is the influence of friction between the tendon and duct. This influence can cause a redistribution of force along the tendons after the original tensioning. The ordinary lift-off method only measures the force at the end of the tendon, which not always represents the change of force in the rest of the tendon. A method for measuring average force along a tendon is presented in this article. In this method, the elongation of the tendon is measured when the jack force is increased to a reference level with known force distribution. Measuring results from the latest ISI in Sweden show that the end force has decreased more than the average force, especially for long tendons with high influence of friction

[en] A direct numerical simulation method based on the Maxwell stress tensor and a fictitious domain method has been developed to solve flows with suspended paramagnetic particles. The numerical scheme enables us to take into account both hydrodynamic and magnetic interactions between particles in a fully coupled manner. Particles are assumed to be non-Brownian with negligible inertia. Rigid body motions of particles in 2D are described by a rigid-ring description implemented by Lagrange multipliers. The magnetic force, acting on the particles due to magnetic fields, is represented by the divergence of the Maxwell stress tensor, which acts as a body force added to the momentum balance equation. Focusing on two-dimensional problems, we solve a single-particle problem for verification. With the magnetic force working on the particle, the proper number of collocation points is found to be two points per element. The convergence with mesh refinement is verified by comparing results from regular mesh problems with those from a boundary-fitted mesh problem as references. We apply the developed method to two application problems: two-particle interaction in a uniform magnetic field and the motion of a magnetic chain in a rotating field, demonstrating the capability of the method to tackle general problems. In the motion of a magnetic chain, especially, the deformation pattern at break-up is similar to the experimentally observed one. The present formulation can be extended to three-dimensional and viscoelastic flow problems